ELECTRONIC STRING INSTRUMENTS

AUTOMATIC PLAYING ELECTRONIC STRING INSTRUMENTS

PRIORITY CLAIM TO RELATED APPLICATIONS

This patent claims priority to provisional application 62/342,921 filed with the USPTO on 28 May 2016, entitled "Automatic Playing String Instruments," and to provisional application

62/449,801 filed with the USPTO on 24 January 2017, entitled "Automatic Playing Electronic String Instruments."

FIELD OF THE INVENTION

This invention relates to string instruments and the generation of notes and cords in string instruments.

BACKGROUND OF THE INVENTION

String Instruments are those instruments that use a vibrating string or strings to create a musical note or set of simultaneous notes. Common string instruments include the electric and acoustic guitar, bass guitar, violin, sitar, viola, cello, double bass, banjo, mandolin, ukulele, and others, including various modifications of these listed instruments from various cultures around the world. String instruments have existed in some manner for thousands of years. The piano is another string instrument that is coupled with a keyboard and hammers that are used to strike and thus vibrate the strings. One difference with the piano is that each string is fixed in length and properties, so that each string produces only one frequency or note; opposed to the previously mentioned instruments that provide the musician with the ability to adjust each string to produce numerous notes. The harp is another string instrument that employs fixed note strings.

In many instruments, the body of the instrument resonates with the vibrating string(s), thus vibrating along with the string(s) and projecting sound through the vibrating body or by transferring the vibrations to air inside the instrument cavity, directly projecting the sound through the air. Many instruments have been adapted for electronic amplification, where an electronic pickup and/or microphone within the instrument converts the vibrations to an electronic signal that is then amplified and broadcasted by separate or integrated electric speakers. High quality amplification allows a musician to play music at virtually any sound level. Electric instruments have traditionally used analog circuitry, but modern advances in electronics have led to digital systems that sample vibrations at very high rates thus creating a very accurate representation of the played music. Electric instruments were a very important development of the twentieth century and were adopted quickly because of their ability to create new music.

Playing a string instrument is a learned skill that typically takes a player many years to master. This requirement may make it difficult for someone interested in creating and composing music, that is not necessarily interested in performing the music. They may want to play the music to hear the created sounds, but do not have the training nor practice hours to achieve this feat. In the gaming industry, simulated string instruments such as guitars have become very popular.

Some of these guitars are far from true musical instruments, as they are not intended to produce musical sounds. These simulated guitars have the general shape of a common electric guitar, but lack strings. In their place are a set of buttons located at different positions on the neck of the guitar. The buttons are typically different colors. During a game, music is played by the gaming system and notes/chords are displayed on the gaming screen intended to correlate in some manner to the music being played. The notes and/or chords on the screen are represented by a specific color, in the shape of a button or symbol of a note, for example. The player must depress the matching button or set of buttons on the guitar that corresponds to those targets that are posted on the gaming screen and continuously updated. Players that closely match the screen by depressing the correct buttons with the proper timing receive a higher point total.

Recent developments of string instruments have focused on the quality of sound in the instrument or electronic system. Digital sampling systems have become equal to or greater than analog systems, and may be able to achieve a greater sound quality, although debates still exist. Research into the component configurations, advanced materials for various components, new electronic systems, and speaker system quality are a few areas that have seen recent work.

Development of instruments that enable musicians increased capabilities is lacking.

Accordingly, there is a need for string instruments that allow a player to easily create a note or set of notes. Further, such systems can open the market to an entirely new set of musicians. BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is an automated string instrument comprising an elongated structure having opposed first and second end portions. One or more motors comprising moveable shafts are connected to the first end portion. A string is connected each of the moveable shafts extends to and is connected to the second end portion of the structure so that the string connected to each shaft is under tension. A processor is coupled to memory and is connected to the elongated body. The processor in electrical communication with each of the one or more motors. In one embodiment the processor is configured to send commands to operate the motors to change the tension of the strings. The motors are configured to move their respective shafts to change the tension of each of the string after receipt of the commands. In another embodiment, the processor is further configured to obtain frequency data for each of the strings and to determine a frequency deviation for each of the strings. The processor can be further configured (i) to store the frequency deviations as an average deviation value into memory, (ii) to receive chord input data and store the chord input data into the memory, (iii) to process stored chord information and chord input data to determine a tension for each of the strings to provide a play frequency for each of the strings, (iv) to process motor shaft position data and determine a command for the one or more of the motors to move their respective shafts, and (v) to select a string or strings used to generate a note or a chord. In yet another

embodiment, the string instrument comprises one or more chord buttons. The chord buttons are in electrical communication with the processor and are configured to generate an electrical signal when depressed. Also provided is a method for generating musical sound using an automated string instrument. The automated string instrument comprises an elongated structure having opposed first and second end portions and one or more motors connected to the first end portion. The one or more motors having a moveable shaft and a string are connected to each of the moveable shafts of the one or more motors and extends to and are connected to the second end portion of the structure so that the string connected to each shaft is under tension. A processor is coupled to memory and is connected to the elongated body. The processor is in electrical communication with each of the one or more motors. The method comprises moving one or more of the shafts of the motors to change the tension of one or more of the strings and selecting one or more of the strings to generate a series of notes and/or a series of chords.

DESCRIPTION OF THE DRAWINGS

Figure 1 is a prior art guitar showing some components of the guitar, as used in the terminology of string instruments.

Figure 2 is a table showing the typical note/frequency map for a common prior art guitar for strings played open (string not depressed) and strings played depressed at one of the ten frets closest to the headstock.

Figure 3 is one embodiment of present invention showing a simple single string instrument. Figure 4 is one embodiment of present invention showing a six string instrument with pulleys aligned so that one of pulleys is aligned with one of instrument strings.

Figure 5 is one embodiment of present invention showing a single string instrument with solenoids arranged so that each of the solenoids is capable of depressing the string at a predetermined position along the length of the instrument string. Figure 6 is one embodiment of present invention showing a single string instrument with a device capable of automatically strumming the instrument string.

Figure 7 A is an isometric view generally towards the front portion of one automatic playing electric guitar embodiment of the present invention;

Figure 7B is a plan view of the bottom side of the automatic playing electric guitar of the present invention shown in FIG. 7A;

Figure 7C is an isometric view generally towards the back portion of the automatic playing electric guitar embodiment of the present invention shown in FIG. 7A and 7B;

Figure 8 shows an enlarged front view of a portion of the body of the automatic playing electric guitar embodiment shown in Figure 7; Figure 9 shows an enlarged isometric view of a portion of the body of the automatic playing electric guitar embodiment shown in Figs. 7 and 8 generally from the top-front; Figure 10 shows an enlarged back view of a portion of the body of the automatic playing electric guitar embodiment shown in Figs. 7 through 9;

Figure 11 shows an enlarged isometric view of a portion of the body of the automatic playing electric guitar embodiment shown in Figs. 7 through 10 generally from the top; Figure 12A shows an enlarged front view of a portion of the body of the automatic playing electric guitar embodiment of the present invention shown in Figs. 7 through 11 with a reference line indicating the location of the cross section cut;

Figure 12B shows an enlarged cross sectional view of the section indicated in FIG. 12A of the automatic playing electric guitar embodiment of the present invention shown in Figs. 7 through 11;

Figure 13 shows a view of the section indicated in FIG. 12A of the automatic playing electric guitar embodiment of the present invention shown in Figs. 7 through 11, with certain elements removed so that a single motor and drive train can be highlighted;

Figure 14 is a schematic representation of the tensioning lever, string, and other elements of the embodiment of the present invention shown in FIG. 13, at the midway position of the tensioning lever;

Figure 15 is a schematic representation of the tensioning lever, string, and other elements of the embodiment of the present invention shown in FIG. 13, at the full-forward position of the tensioning lever; Figure 16 is a schematic representation of the tensioning lever, string, and other elements of the embodiment of the present invention shown in FIG. 13, at the full-rearward position of the tensioning lever;

Figure 17 is a flow diagram that provides a depiction of some of the features of one embodiment of control logic for the present invention. Figure 18A and 18B shows a flow diagram that provides a depiction of some of the features of an alternative embodiment of control logic for the present invention.

Figure 19 is a table showing the note/frequency map for an instrument of the present invention for strings played open (string not depressed) and strings played depressed at one of the ten frets closest to the headstock with each string having an applied tension of less than 80 newton and the note/frequency map for the instrument with each string having an applied tension of over 200 newton.

DETAILED DESCRIPTION OF THE INVENTION

Although claimed subject matter will be described in terms of certain embodiments, other embodiments, including embodiments that do not provide all of the benefits and features set forth herein, are also within the scope of this invention. Various structural, logical, and process step may be made without departing from the spirit or scope of the invention. Accordingly, the scope of the invention is defined only by reference to the appended claims. The present invention includes embodiments for generating a note or set of notes on a string instrument when strumming, or otherwise vibrating the string or strings, either manually by the musician or automatically with an appropriate mechanism and/or action. The notes may be preprogrammed and/or they may be entered by the musician by simply depressing a button that may be located on the instrument or located remotely. For example, a series of buttons or other note or chord selection mechanisms can be connected to a remote device that is controlled by the player's foot. In some embodiments notes are created by automated string tensioning systems and control systems that control the resonate vibrating frequency of each string of the string instrument.

The automated note and chord generating systems disclosed herein may be fully integrated into the instrument, or may comprise multiple components that are connected by wires or wirelessly to the instrument.

String Instruments Including Acoustic and Electric Guitars

The present invention may be applied to any string instrument. To demonstrate certain features of the invention, application to the guitar is primarily described herein. Referring to the figures, FIG. 1 A shows a prior art guitar and the following indicates the terminology typically used in the art for certain components thereof. An acoustic type guitar 100 includes a hollow body 101, a sound hole 102 that projects sound from the hollow body 101, a neck 103 and headstock 104. The prior art guitar 100 further includes a bridge 105 used to secure the instrument strings 106 at one end and a set of six machine heads 107 connected to an equal number of tuning pegs 108 used in combination to apply tension to each of the strings 106. A fretboard 109 is included on the neck 103 and extends into part of the body 101. The fretboard 109 includes a series of frets 110 and fret markers 111 and the fretboard 109 terminates at the final fret called the nut 112 at the point where the neck 103 transitions to the headstock 104. The guitar body also includes a pick guard 113 that is used to protect the instrument body 101 as a musician uses a pick, fingers, or other device to cause the strings 106 to vibrate. Depending on the tension applied to the strings 106 by means of the machine heads 107 and the location, if any, of the fret 110 where the musician depresses a string, a primary resonant frequency will be one characteristic of the string at which it will vibrate when played by the musician. Figure IB shows a close up image of the guitar 100 at the point where the neck

103 transitions to the headstock 104 to show the angle 114 at which some of the strings 106 may form to allow clearance for all of the strings to connect to a machine head 107 without interfering with other strings 106.

An electric guitar is similar to an acoustic guitar, except for the projection of sound. In an acoustic guitar, sound is created by the strings which cause the hollow body to resonate and the sound is then projected out of the sound hole; an electric guitar may use a solid body because sound is projected through an electronic amplifier, which amplifies an electronic signal originating from a pickup. The pickup is commonly an electromagnetic device mounted on the body under the strings that creates an electric signal corresponding to the vibrations of the strings, as is well known in the art. Other types of pickups can be used, including piezoelectric and optical pickups. Of course, it is possible to include an electronic pickup on an acoustic guitar to allow the musician to project sound in a manner similar to an electric guitar.

Referring now to FIG. 2, a table of typical notes/frequencies as a function of the depressed fret on a guitar is shown. This table is based on the customary system of notes used in the U.S. and many western countries, and uses a common guitar tuning (the notes played by the open strings).

Many guitars have more than 10 frets, with some having 20 or more. The played frequency continues to increase as the string is depressed at a fret closer to the bridge (frets denoted with a higher number as indicated in FIG. 2 because the vibrating portion of the string is modified when a string is depressed at a fret (higher frets create shorter vibrating portions). When played at the twelfth fret, is common for a guitar string to have a resonant frequency twice that of a string played open (not depressed at a fret), which is the same note, one octave higher.

It is common for a guitar to have between 18 and 24 frets, allowing each string to have a total playing range of approximately 3x to 4x. For a guitar with 18 frets, this results in the resonant frequency of the string played at the fret closest to the bridge being 3 times that of the resonant frequency of the string played open.

Some Embodiments of the Present Invention

It is possible to produce a useful instrument that has a range less than that of a common guitar. Preferably, a string included with the instrument of the present invention will have a resonate frequency range of at least 1.5x when actuated solely with the tensioning systems described herein. In some embodiments, the played frequency of the strings may also be adjusted by depressing the string at the various frets simultaneously and/or in sequence with frequency adjustments from the tensioning systems described herein. More preferably, the string will have a resonate frequency range of at least 2.5x when actuated solely with the tensioning systems described herein. And most preferably, the string will have a resonate frequency range of at least 3x when actuated solely with the tensioning systems described herein.

Referring now to FIG. 3, one embodiment of the present invention is shown. Figure 3(A) shows an acoustic type guitar 300 that includes a hollow body 301, a sound hole 302 that projects sound from the hollow body 301, a neck 303 and headstock 304. This embodiment further includes a bridge 305 used to secure the instrument string 306 at one end and a pulley 307 connected to a gear motor 308 to secure the opposite end of the string 306. A fretboard 309 is included on the neck 303 and extends into part of the body 301. The guitar body also includes a pick guard 307 that is used to protect the instrument body 301 as a musician uses a pick, fingers, or other device to cause the strings 306 to vibrate. The gear motor 308 has power leads (wires) 310 that supply the motor 308 with operating power and are connected at the reverse side of the headstock 311 and the motor is secured to the headstock my means of a motor strap 312. An illustration of the reverse side of the headstock 311 is shown in reverse side image 313 in FIG. 3(B). The reverse side of the headstock 311 includes a control board on which there are batteries and electronic components 315 that are programmed to provide motor control. The reverse side of the headstock 311 also includes a set of chord buttons 316 that are connected to the control board by means of chord button wires 317. The control board includes a

microcontroller that is programed to create a predefined tension on the wire by generating a predefined torque output in the motor 308, depending on which chord button 316 or combination of chord buttons 316 that are depressed. Depending on the tension applied to the strings 306 by means of the pulley 307 and motor 308 and the location, if any, of the frets on the neck 309 where the musician depresses a string, a resonant frequency will be one characteristic of the string at which it will vibrate when played by the musician.

An additional embodiment of a string instrument of the present invention is illustrated in FIG. 4. An electric type guitar 400 includes a solid body 401, an electronic pickup 402 that converts vibration into an electronic signal, a neck 403 and headstock 404. More than one pickup may be used, placed at locations under the string or strings on the body of the instrument. This embodiment further includes a bridge 405 used to secure the six instrument strings 406 at one end and a set of six pulleys 407 that are each connected to a gear motor 408 to secure the opposite end of the strings 406. This embodiment includes six gear motors 408 at the headstock, but only one is indicated for convenience. A fretboard 409 is included on the neck 403 and extends into part of the body 401. The guitar body also includes a pick guard 410 that is used to protect the instrument body 401 as a musician uses a pick, fingers, or other device to cause the strings 406 to vibrate. The gear motors 408 have power leads (wires) 411 that supply the motors 408 with operating power and are connected at the reverse side of the headstock 412 and the motors are secured to the headstock my means of a motor straps 413. For drawing clarity, only select components are indicated on the drawing. The pulleys are connected to the motors by means of the motor shafts 414. The reverse side of the headstock 412 includes a control board on which there are batteries and electronic components that are programmed to provide motor control. Alternatively to, or in combination with, the batteries, an external power supply may be used. This may include a connector that makes it convenient to connect to a standard wall outlet and/or it may allow connection to a low voltage DC or AC power supply, or it may use other external power equipment. The reverse side of the headstock 412 also includes a set of chord buttons that are connected to the control board by means of chord button wires. The control board includes a microcontroller that is programed to generate a predefined tension on the wire by generating a predefined torque output in the motors 408, depending on which chord button or combination of chord buttons that are depressed. Depending on the tension applied to the strings 406 by means of the pulleys 407 and motors 408 and the location, if any, of the frets on the neck 409 where the musician depresses a string, a resonant frequency will be one characteristic of the string at which it will vibrate when played by the musician. The resulting vibrations are sensed by the pickup 402 and electronically connected by an output jack 415 and amplifier wire 416 that is connected to an external amplifier. Control knobs 417 allow the musician to adjust tone and volume, as typically found in electric guitars; this embodiment includes 3 control knobs.

An additional embodiment of a string instrument of the present invention is illustrated in FIG. 5. An electric type guitar 500 includes a solid body 501, an electronic pickup 502, a neck 503 and headstock 504. This embodiment further includes a bridge 505 used to secure the instrument string 506 at one end and a pulley 507 connected to a gear motor 508 to secure the opposite end of the string 506. A fretboard 509 is included on the neck 503 and extends into part of the body 501. The guitar body also includes a pick guard 510 that is used to protect the instrument body 501 as a musician uses a pick, fingers, or other device to cause the strings 506 to vibrate. The gear motor 508 has power leads (wires) 511 that supply the motor 508 with operating power and are connected at the reverse side of the headstock 512 to a control board and the motor is secured to the headstock my means of a motor strap 513. The reverse side of the headstock 512 includes a control board on which there are batteries and electronic components that are programmed to provide motor control. The reverse side of the headstock 512 also includes a set of chord buttons that are connected to the control board by means of chord button wires. The control board includes a microcontroller that is programed to generate a predefined tension on the wire by generating a predefined torque output in the motors 508, depending on which chord button or combination of chord buttons that are depressed. Vibrations of the strings 506 are sensed by the pickup 502 and electronically connected by a output jack 514 and amplifier wire 515 that is connected to an external amplifier. Control knobs 516 allow the musician to adjust sound properties.

The embodiment of the present invention shown in FIG. 5 further comprises a set of electronic solenoid actuators 517 that are connected to the control board by means of solenoid wires 518. The end of the actuating portion of the solenoids 517 are connected to a wire eyelet 519 that allows the string 506 to vibrate when not in use, but fixes the wire in place when one or more of the solenoids 517 is actuated. This may be accomplished by pulling on the string 506, by pinching the string 506, or by other means.

Yet another embodiment of the present invention is illustrated in FIG. 6. An electric type guitar

600 includes a solid body 601, an electronic pickup 602, a neck 603 and headstock 604. This embodiment further includes a bridge 605 used to secure the instrument string 606 at one end and a pulley 607 connected to a gear motor 608 to secure the opposite end of the string 606. A fretboard 609 is included on the neck 603 and extends into part of the body 601. The guitar body also includes a pick guard 610 that is used to protect the instrument body 601. The gear motor 608 has power leads (wires) 611 that supply the motor 608 with operating power and are connected at the reverse side of the headstock 612 to a control board and the motor is secured to the headstock my means of a motor strap 613. The reverse side of the headstock 612 includes a control board on which there are batteries and electronic components that are programmed to provide motor control. The control board includes a microcontroller that is programed to generate a predefined tension on the wire by generating a predefined torque output in the motors 608, depending on the timing of play. Vibrations of the strings 606 are sensed by the pickup 602 and electronically connected by a output jack 614 and amplifier wire 615 that is connected to an external amplifier. Control knobs 616 allow the musician to adjust sound properties.

The embodiment of the present invention shown in FIG. 6 further comprises an electric wiper motor 617 that is connected to a wiper type gear box 618 which is in turn connected to a wiper or pick 619. When operating, the wiper or pick moves back in forth, in a geared motion of similar construction to an automobile wiper blade design. The motor 617 is secured to the body

601 by mans of a strap 620 and connected to the control board by the wiper motor wires 621. During use, this instrument can play music in a fully automated manner, similar to a playing piano. Vibration Frequencies of the Strings

It is well known that each note of the customary musical scale most commonly used in the U.S. corresponds to a specific vibration frequency. In string instruments, each string has a resonate frequency that is heard as a note of the musical scale, if the frequency matches, or is sufficiency near, that of one of the defined notes. Otherwise, an "un-tuned" sound will be played. The vibrations of the string are induced by plucking, strumming, hitting, or by other inducing actions. There are three primary ways to change the resonate frequency (i.e., the note played) of a string.

(1) physical characteristics of the string

The frequency of a vibrating string is related to its linear density by relationship [1]: Frequency is proportional to: l/(square root of linear density) [1]

The linear density is the mass per unit length of string, and is typically constant for most string instruments used today. However, strings with a non-uniform or variable linear density would work with the present invention. Instrument designers and players use this relationship today by supplying the instrument with different type of strings. For example, a common electric guitar may use six different size strings, starting with a 9 gauge string with the highest vibration frequency, then an 11 gauge, 16 gauge, 24, gauge, 32 gauge, and then a 42 gauge string that provides the lowest notes. These strings may be simple wires made of various materials, but many modern guitar strings include a core wire that is surrounded by a wire that is continuously wrapped around this core. The complexity of the wire may make it difficult to calculate an anticipated frequency to a very high precision, but this is not an important issue in practice, since the strings are tuned by ear or with an electronic aid before playing. A heavier gauge wire will result in a lower resonate frequency.

(2) Applied tension

The frequency of a vibrating string is related to the tension applied to the string by relationship [2].

Frequency is proportional to: square root of tension [2]

The tension applied to the strings on string instruments is typically adjusted through the use of a mechanical system that allows the player to simply turn a nut or shaft near the end of the string. The string is connected to a post or other component that is connected to the nut/shaft through a bolt or gear, as is well known in the art of instrument design. Once the desired frequency of the string is set, the applied tension remains because the wire is prevented from loosening. Higher tension results in a higher played frequency.

For design purposes, this means that a tension multiple of about 9 will result in a string with a frequency range of about 3x. For example, a string with an applied tension of 90 newton will vibrate at a frequency of about 3 times that when the same string has an applied tension of 10 newton.

(3) Vibrating length

The frequency of a vibrating string is related to the length of the vibrating portion of the string by relationship [3].

Frequency is proportional to: l/(length of vibrating portion of string) [3]

The third common method of adjusting the frequency of a vibrating string is controlling the vibrating portion of the string. On instruments with a fingerboard notes are played by changing the active vibrating length of the string by depressing the string at a point on the fingerboard, creating a new, temporary, endpoint of the string. Long strings will have a lower resonate frequency when compared to shorter lengths of the same string. In practice, a string that is half the length of an otherwise identically constructed and tensioned string will produce a note that is twice the frequency, or to a musician: the same note one octave higher.

In addition to these three methods of adjusting the frequency of a vibrating string, others may exist and be employed in embodiments of the present invention. For example, it may be possible to adjust the frequency of a vibrating string by applying an electric field to the string, and/or by applying a voltage across the string and/or inducing current to flow in the string. In some cases, this may be a result of a shape memory material that effectively modifies the applied tension when subjected to an electric voltage and/or current and/or field. As advancements are made in materials science, they can be practically employed herein using sound engineering approaches.

Applied Tension to the Strings

Many different devices may be used to apply tension to the strings of the instrument of the present invention. These include AC and DC motors such as traditional DC and AC motors, DC and AC servo motors, stepper motors, other electromagnetic devices such as solenoids, electronic magnets and coils, electrically responsive materials that expand or contract in response to applied electricity or other input, and any other device that is compact to provide a sufficiently convenient instrument and capable of applying the desired tension or effect. These devices may be used directly or in combination with a gear or gear set to increase the maximum applied tension or to increase the speed of the output drive mechanism. In general, a gear or gear set will provide for increased torque/shaft force with a reduction in the speed of the output drive mechanism or reduced torque/shaft force and an increase in the speed of the output drive mechanism. The design of the mechanical actuators, the strings, and the instrument will determine the required torque and speed of a device that can be used to apply the proper tension and gear or gear set, if required.

The tension adjustment devices may be mounted at any convenient location on and/or within the instrument, including at the end of the neck, the neck, and/or the body. They may be mounted on the surface or within any portion of the instrument, or may be a combination of surface mount, internal mount, and/or located off the instrument. Further, a portion of devices may be mounted at one part of the instrument while other devices and/or components may be mounted at other locations. Still further, the tension adjustment devices may be mounted remotely and coupled to the strings through a coupling such as a flexible tensioning wire that can be fed through a convenient pass-thru on the instrument.

Motors

In some embodiments, a motor or set of motors is used to apply tension to the instrument strings. In one embodiment, one gear motor is connected to each tuning peg of an electric guitar. In this design, the output shaft of each gear motor is directly coupled to one tuning peg (also known as tuners, tuning machines, machine heads, pegheads, and tuning keys in the art of string instruments), by means of a mechanical coupler, such that one turn of the output shaft results in a predetermined number of turns, or fraction thereof, of the tuning peg.

When selecting a motor or gear motor several performance characteristics should be evaluated. These include torque rating, speed of the output shaft, power requirements, and package size. In general, the highest available gear ratio of a mating gear set will provide the highest torque output for a given motor. For design, the motors with the highest torque output for a given package size are generally preferred, provided they have a sufficient shaft speed as discussed below. However, if the designer identifies a set of motors with sufficient output torque, they would select the motor with the highest shaft speed. The speed of the motor is an important characteristic of the motor or gear motor, since it determines how fast the resonant frequency of a given string can be changed. Once a firm tension (e.g. a few Newton force) is applied to the end of the string, the end does not need to move a large distance to generate a higher tension, for many of the materials that may be used as strings in various embodiments, because many such materials have a high elastic modulus. For example, the elastic modulus of metals such as steel, stainless steel, nickel and nickel alloys fall within a relatively small range, from about 20 to 200 Gpa. As a result, for every micron (equal to one micro-meter, or 1/1,000,000 of a meter) the end is pulled on a string that is fixed in place on the opposing end, a measurable force is developed in the string. The force can be calculated using the elastic modulus (modulus of elasticity or Young's Modulus) with the following equation:

F = (E * A_o * dL) / (L_o) [4]

Where E is the elastic modulus, F is the force on the string under tension, A_o is the cross- sectional area of the string, dL is the change in length of the string, and L_o is the original length of the string.

For example, a 70 cm long, 32 gauge (0.032 inch diameter = 0.81 millimeter diameter) steel string with an elastic modulus of 200 Gpa, pulled on the end of the wire, while fixed at the opposite end, and elongates/expands a distance of ½ mm (500 microns) and results in an induced force of over 70 Newton (over 0.14 newton per micron). For a gear motor connected to a 1cm diameter pulley, that requires under 2/100 of one rotation of the output shaft. A relative reduction in the elongation distance required to achieve a certain tension is one reason a designer would consider a string material with a high elastic modulus and possibly select it instead of a material with a low elastic modulus.

The time required for adjustment between two notes (using a note separation of 3 semi-tones) is preferably less than 1 second, more preferably less than 0.1 second, and most preferably less than 0.05 second.

For a string instrument of the present invention to be able to adjust a string from near the lowest frequency to near the highest frequency in a reasonable amount of time to play music, a rotational speed in the range of 0.1 to 1 rotations per minute (RPM) is preferred, a rotational speed in the range of 1 to 10 RPM is more preferred, and a rotational speed greater than 10 RPM is most preferred.

Simple DC motors or gear motors are one option for embodiments of the present invention because direction of the spinning pulley can be easily reversed by changing the polarity of the input power, thus allowing for easy increase or decrease of tension. And applied torque can be changed by adjusting the level of input voltage, allowing for easy adjustment of the amount of tension applied to a string.

In one embodiment, DC servo motors are used to apply tension to the strings. One example of a suitable DC servo motor is model DS1015, a Hi Torque/Hi Speed Digital Servo motor sold under the XP brand and manufactured by Associated Electrics, Inc. of Lake Forest, CA. This motor is capable of applying up to 14.5 kg-cm of torque at the output shaft and can move the output shaft over a 60 degree rotation in 0.108 seconds.

Stepper motors may be used to adjust string tension as well. In some embodiments, the stepper motor must be combined with a gear set such that it can provide sufficient torque and thus sufficient tension to the string.

Piezoelectric Devices

Piezoelectric materials and devices are those that have a measureable relationship between an electric field and strain. In some materials, a strain may be induced into the piezoelectric material by applying a voltage across the material. When connected to a string of a string instrument, the induced tension within the piezoelectric material may be applied to the string, thus modifying the resonant frequency of the string.

Magnetic and Electromagnetic Devices

Electromagnetic devices such as solenoids can develop significant tension and are known to provide a very fast reaction time with respect to applied energy. In a common solenoid arrangement, a pin is pulled into a cylinder when a current is applied to the wire wrapped cylinder. The amount of force applied to the pin can be controlled by the level of current and/or voltage applied to the device. A string coupled to the pin would see an equivalent level of applied tension. Other types of electromagnetic devices may also be employed in various embodiments. Devices that incorporate specialty magnets, such as rare earth magnets, that provide a large magnetic force per unit volume are preferred.

Shape Memory Alloys

Shape memory alloys (SMAs) are a class of materials that have interesting mechanical properties. Nitinol, an alloy of nickel and titanium, is an SMA that was first developed by the U.S. Navy in the 1960s and is an excellent example of this class of material. Nitinol contracts when heated at a very high rate, in microns per degree, when compared to thermal expansion values of typical metals (typical metals expand when heated). By applying an electric current through the string (preferably at a level safe for, and undetectable to, the instrument player), a resulting temperature rise will occur in the string (preferable a temperature that is safe for, and undetectable to, the instrument player). When fixed at both ends, this rise in temperature will cause an induced tension in the string, resulting in a change in the resonate frequency. Nitinol has been shown to generate a shape resuming force or pressure of over 135 MPa (over approximately 20ksi), which can result in broad adjustment to resonate frequency. Various grades, or types, of Nitinol exist and can be used in various embodiments.

The shape memory alloy may be used as the instrument string and/or it may be used at the end of a traditional, or other type of, string to simply generate the tension on the vibrating string. In various embodiments, the shape memory alloy may comprise a portion of the vibrating string or it may be after the nut (last fret bar) and be a non-vibrating component.

Other electrically active materials not presently classified as shape memory alloys may be employed as well, provided the material undergoes or effects a change in played frequency when an electric voltage and/or current is applied.

Strings of the String Instruments

The strings used in the present invention should be capable of providing a minimum of ½ octave and more preferably a minimum of one octave of notes (1.5x to 2x range of vibration

frequencies) as a function of string tension (a "tension sensitive" string). Modern strings made by todays manufacturers can be used, including single wire strings, wound strings, and other strings known in the art of string instruments. These include strings manufactured and sold as Aquila Guitar Strings, Aranjuez Guitar Strings, Dean Markley Guitar Strings, DR Strings Guitar Strings, Ernie Ball Guitar Strings, Fender Guitar Strings, GHS Guitar Strings, Gibson Guitar Strings, Hannabach Guitar Strings, Rotosound Guitar Strings and many others.

In some embodiments, it is desirable to supply a string that provides a broad range of

frequencies at the smallest possible variance of tension, for ease and speed of adjustment during play. For these tension sensitive embodiments, the string will preferably have a resonate frequency range of at least 1.5x (1.5 times the resonate frequency in hertz) over a range of applied tension of 1 to 200 newtons. More preferably, the string will have a resonate frequency range of at least 2.5x over a range of applied tension of 1 to 200 newtons. And most preferably, the string will have a resonate frequency range of at least 3x over a range of applied tension of 1 to 200 newtons.

String Selection

Several properties of a potential instrument string provide useful information to an instrument designer. The modulus of elasticity and the yield strength of the string are used to determine the maximum elastic elongation of a string through the relationship shown in eq. [5]; additional tension applied to a string elongated to the max elongation would result in plastic deformation.

Max Elongation = Total length of String * Yield Strength / Elastic Modulus [5]

The yield strength of the string along with the cross sectional area of the string core are used to determine the maximum tension through eq. [6].

Maximum Applied Tension = Yield Strength * Cross Section Area of String Core [6]

The maximum elongation is realized when the maximum tension is applied to the string. In addition, the maximum vibration frequency of a string of fixed length will occur when the maximum tension is applied to the string. An estimate of the vibrating frequency of a string can be determined with Eq. [7], with the maximum frequency being estimated by using the calculated maximum applied tension.

Frequency = (4.34/Vibrating length of String) * Square root of (Tension Unit Weight of String) [7]

Where the vibrating length of the string is in cm, the applied tension is in newton, the unit weight of the string is in kg/cm, and frequency is in hertz. This information allows a designer to determine the full frequency range of a string, from the lowest vibration frequency at zero or near-zero applied tension to the highest vibration frequency when the applied tension is just under the tension that would cause the string to yield.

Equation [7] can be rearranged to perform other calculations. For example, it can be used to determine the tension required to produce a desired vibration frequency, provided other required values are known sufficiently.

Preferably, the instrument is designed to prevent any string from plastic deformation, also known as yielding, as a plastically deformed string will have a different, and typically hard-to- predict, vibration frequency response compared to the string that has not been yielded. One reason for this is that the string will not have a uniform diameter nor unit weight after yielding, as it will deform around and near the point of failure. One method to prevent yielding is to first require the player to input string information into a microcontroller that is programmed to determine the full range of elongation and force requirements; once the control system knows the material, core diameter, and total diameter, it can be programmed to calculate maximum applied tension through the following relationship: The control system would be programmed to limit the applied tension to any string to a value under that of the calculated Maximum Applied

Tension. Preferably, the control system is programmed to limit the load applied to a string to 99% of the calculated Maximum Applied Tension. More preferably, the control system is programmed to limit the load applied to a string to 95% of the calculated Maximum Applied Tension. Most preferably, the control system is programmed to limit the load applied to a string to 90% of the calculated Maximum Applied Tension.

A sensor system that automatically detects the material and string diameter/type, and/or use of a bar code or other identifying information on a string package that can be input into the control system may be used in a similar way to prevent yielding while making it more convenient for the player. An estimate of the fundamental vibration frequency for each string can also be calculated, if desired. An auto tuning sequence can then be performed, if desired.

Referring to Table 1 below, a list of some possible string materials for use in the present invention are shown with some limited property information. The purpose of the Table is to demonstrate some of the considerations used during string material selection. Some strings available on the market today are comprised of high strength steels and alloy steels and other materials not specifically listed in the table but work very well with the present invention.

One item of note from the Table is that the elastic stretch (defined as the amount of elongation of a string when subject to an applied load) is independent of string diameter and merely a function of the material's tensile modulus of elasticity and the total length of the string. This further means that the full range of elastic stretch (defined as the elongation of a material between no applied load and an applied load just prior to causing yielding of the string) is too a function of only the material and total length of the string. The total length of the string is typically longer than the vibrating length because it includes the string from the vibration isolation components, such as the nut and saddle, to the termination points such as the tuning pegs. Total length is used because the entire length of string that is subject to the applied tension contributes to the elongation of the string. An instrument with a string that has a long total length relative to its vibrating length may be designed to increase the range of output frequencies for a given string type and size. If more than one string uses the same material, the control algorithm can calculate the elastic stretch for one string and apply the calculation to all strings made from the same material. Alternatively, it can store information in a database and simply look up the

information instead of performing a calculation. In some embodiments, the control parameter is stretching distance and maximum applied load does not need to be considered by the control algorithm. The maximum applied load is related to the cross sectional area of the string, and thus related to the diameter of the core of the string. For wound strings commonly found in the market today, the relevant diameter for determining maximum applied load is the diameter of the string core, because the wound material wrapped around the core is not capable of contributing to load carry, since it can simply unwind with little applied force. The string core is the part of the string that is capable of carrying a tensile load.

For a given material type (e.g. grade of steel), it is preferred to select a subtype (e.g., heat treatment) with high yield strength, since it will result in a string with a greater possible frequency range compared to those with lower yield strengths. In many metallic materials, strength can be increased though one or more various methods such as heat treating and forming. Typically, an increase in strength is accompanied by a decrease in ductility, with the highest strength being accompanied by the lowest ductility for a given material type. Here, we describe ductility as the reduction in cross sectional area of a string during failure from a tensile load; that is, the smallest cross sectional area on the string near the point of failure after yielding divided by the cross sectional area before yielding (found at the point of greatest reduction) expressed in percent area reduction.

In some embodiments, high modulus strings are preferred, such that a large applied tension causes only a slight elongation/stretch of the entire string. High modulus wires include many types of metal strings such as carbon steel strings. High modulus strings allow for a large gear ratio and/or a large leverage ratio to be used in the tension adjustment device and/or mechanism while maintaining sufficient speed of adjustment. For example, looking at Table 1 example conditions we find that 1080 steel elongates only 1.8 mm before the string encounters plastic failure. The entire range of frequencies can be played through applied tensions to elongate within this range. For designs with a limited elastic stretch objective, a string will preferably have a full range of stretch (the amount a string stretches from zero applied tension to the tension which causes the string to yield) of less than 5 mm. More preferably, the string will have a full range of stretch of less than 3mm. Most preferably, the string will have a full range of stretch of less than 2mm.

Table 1 : Some of the possible materials that may be considered for strings for some

embodiments of the present invention.

Total Yield Elastic Max Applied Max. Elastic

Diameter Length Strength Modulus Force Stretch

Material (mm) (cm) (MPa) (MPa) (N) (mm)

1040 Steel, annealed 0.254 64.8 414 206843 20.96 1.296

1040 Steel, annealed 0.508 64.8 414 206843 83.85 1.296

1080 Steel, rolled 0.254 64.8 585 206843 29.63 1.832

304 Stainless Steel 0.254 64.8 205 193000 10.39 0.688

Maraging Steel 0.254 64.8 2068 183000 104.81 7.324

Phosphor Bronze 510 0.254 64.8 485 110000 24.58 2.857

Aramid Fibers 0.254 64.8 3045 90000 154.29 21.924

Nylon 6/6 0.254 64.8 93 3550 4.71 16.976

E-Glass 0.254 64.8 3450 35000 174.81 63.874

Carbon Fiber 0.254 64.8 4127 150000 209.12 17.829

Nylon 6/6 GF-30 (30%

glass-fiber reinforced) 0.254 64.8 180 11000 9.12 10.604

Polycarbonate - 30%

Carbon Fiber Reinforced 0.254 64.8 170 18000 8.61 6.120

In some embodiments, a low modulus string such as a plastic string is preferred. Low modulus strings will stretch a greater distance for a given applied tension when compared to a higher modulus string. Instrument designs for low modules strings will require the ability for more elongation of the string, but typically will require less tension to elongate when considering a given string diameter and other factors. In yet other embodiments, a mid-range modulus may be desired.

String Materials

Various material classes may be used to produce a tension-sensitive string, including polymer matrix composites, metal matrix composites, metals, alloys, intermetallics, ceramics, and others, as well as mixtures thereof. Metals, alloys, and some plastic materials are commonly used today in the manufacture of instrument strings.

Polymer Matrix Composites

One or more polymers and one or more strengthening phases may be used in a tension sensitive string fabricated of a polymer matrix composite. There is no restriction on the type of material that can be used, except that the final composite must meet the design requirements for the desired relationship between resonant frequency of the string and applied tension, and durability that would be set by the instrument designer. Thermoplastics and thermosetting polymers can be used. These materials form a mixture that offers a set of properties not available in any one single material. Extruding, injection molding, and/or compression molding polymers for the instrument string composites include, but are not limited to, nylon, polyethylene, polypropylene, polystyrene, acrylonitrile butadiene styrene (ABS), polyetherimide (PEI), polyvinyl chloride

(PVC), Polytetrafluoroethylene, Polyethylene terephthalate (PET), polyester, ionomers, amides, and combinations thereof.

Ceramics that can be used as the strengthening phase in the polymer matrix composite include, but are not limited to, silicon nitride (S13N4), silicon carbide (SiC), titanium diboride (T1B2), titanium carbide (TiC), aluminum oxide (AI2O3), zirconium oxide (ZrCh), boron carbide (B ₄ C), and combinations thereof. Metals, metal alloys, and other metallic compounds may also be used as the strengthening phase in the polymer matrix composite. Other materials in the polymer matrix composite may be used alone as the strengthening phase or in combination with other strengthening phase materials. For example, carbon fiber, carbon nanotubes (CNTs), graphene, and other materials may provide significant stiffening of a polymer or elastomer when used in a composite as described above. Furthermore, elastomers may also be employed as the matrix or mixed with a polymer to provide the matrix.

In one embodiment, a polymer matrix instrument string comprises an amorphous thermoplastic polyetherimide (PEI) (such as the material sold under the trade name Ultem® made by GE Plastics), and between about 20% by weight of silicon carbide whisker (SiC-W) material is added to the polymer which forms the composite. The string may be produced by extruding the composite through an extrusion press, as is well known in the art of plastic materials. The SiC- W may be added in the form of nanocomposites, for example SiC-W contained in a polymer carrier such as polypropylene or other polymer. The polymer composite string may comprise one or more layers. The string can comprise at least one additional layer surrounding the first composite string.

In another embodiment, a high stiffness string is made of nylon polymer containing between about 25% by weight zirconium oxide ceramic particles, which is first extruded to produce a primary string. This string is surrounded by an amid polymer layer by co-extruding the amid over the primary string. Preferably, between about 1% and 80% or more preferably between about 10% and 60% by weight, including all values and ranges there between, of the final layered string is amid polymer.

Metal Matrix Composites

Metal matrix composites (MMC) is another class of composites that may be used to manufacture tension sensitive strings. The MMC is comprised of at least two constituent parts: a metal and a strengthening phase. Metals that can be used include, but are not limited to, iron and alloys such as carbon steels, alloy steels, and stainless steels, magnesium, titanium, aluminum, cobalt, molybdenum, tungsten, nickel, and their well-known alloys and/or mixtures of these and other metallic compounds. The strengthening phase can be another metallic material or a ceramic, organic, or other type of material. Ceramics that can be used as the strengthening phase in the metal matrix composite include, but are not limited to, silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), titanium diboride (T1B2), titanium carbide (TiC), aluminum oxide (AI2O3), zirconium oxide (ZrCh), and boron carbide (B ₄ C). Other materials also may be used as or in the strengthening phase in the metal matrix composite. For example, carbon fiber, carbon nanotubes (CNTs), graphene, and other materials may provide significant stiffening when used in a composite as described above.

In one embodiment, a metal matrix instrument string comprises an aluminum alloy with ceramic particle and fiber reinforcements. A preform is first formed from a composition of ceramic particles and ceramic fibers through extruding along with a polymer blend that includes both organic and inorganic binders, as is known in the art of Metal Matrix Composites. Typically, the ceramic fibers are selected from the group of alumina-silica-zirconia fibers, alumina-silica fibers, silicon-carbon fibers, carbon-graphite fibers, and combinations thereof. An as-extruded preform contains a mixture of the ceramics and polymer blend, and is typically sintered to form the final preform. During sintering, the non-ceramic components of the as-extruded preform typically bum off, and the ceramic solids and inorganic binder remain in the final preform. After sintering, ceramics are typically present in the preform in a range from 20 to 80 parts by volume based on 100 parts by volume of the preform. To complete the metal matrix composite, the final preform is placed in a mold. Aluminum alloy is heated to a molten state and the molten aluminum is injected into the cavity of the mold under pressure in the range of 5,000 psi to 10,000 psi. During pressure injection, the molten aluminum infiltrates the final preform. The mold is allowed to cool and thus form the metal matrix composite.

Ceramics

Although it may be expensive to physically form a ceramic string, ceramics may provide excellent vibrational properties when used as an instrument string. They typically have a high modulus of elasticity and can have a unique physical appearance. Ceramics that can be used include, but are not limited to, silicon nitride (Si3N4), silicon carbide (SiC), titanium diboride (TiB2), titanium carbide (TiC), aluminum oxide (A1203), zirconium oxide (Zr02), boron carbide (B4C), and combinations thereof. A fraction of binders residual from the manufacturing process may be present in the instrument string.

Nanostructured Materials

Nanostructured materials are another class of materials that can be used to form tension sensitive instrument strings or used in polymer matrix or metal matrix composites as described above, or with traditional materials such as metals, alloys, intermetallics, ceramics, and others, as well as mixtures thereof. Nanostructured materials exhibit characteristics based on controlling the composition of the material at a sub-micrometer level, to vary the strength, stiffness, ductility, hardness, formability, crack propagation resistance, or other physical and mechanical properties, or a combination thereof. Nanostructured materials are materials that exhibit at least a significant portion of constituent grain size of less than about 300 nanometers. Nanostructured materials including metals, such as carbon steel, stainless steel and, titanium with controlled grain sizes, may be used to make instrument strings with beneficial characteristics due to grain size. Composite nanostructured materials may also be used to modify the properties of the instrument strings. For example, by varying the amount of nanostructured materials used as all or a fraction of the strengthening phase dispersion within a metal matrix composite, the strength, stiffness, and vibration characteristics of the base material used for the string may be tailored.

Production of Strings

For polymer based instrument strings disclosed herein, they may be made using processes and techniques such as extrusion, injection molding, drawing, casting, and/or compression molding. If fine, ultrafine, or nanostructured materials are incorporated into to a polymer that is extruded or molded, increasing the screw and back pressure during the process may improve dispersion of the material into the polymer.

For metals, metal alloys, and other metallic compounds, techniques such as extrusion, drawing, casting, and other methods used today to form wire of various sizes, as is known in the art of metallurgy, may be used.

Metal matrix composites may also be formed through a variety of techniques, including solid state and liquid state methods. Solid state methods include powder blending and consolidation (powder metallurgy) where a mixture of materials is placed in a mold and consolidated; and Foil diffusion bonding where layers are built and consolidated/sintered. Liquid state methods include electroplating and electroforming, stir casting, pressure infiltration, squeeze casting, spray deposition, and reactive processing. Other methods being developed today may be used as well.

For ceramics, well known forming processes known in the art of ceramic sciences may be used.

The process used to produce the instrument string may be designed to produce a string that has consistent properties throughout its length, or alternatively, strings that have variable properties along the length of the wire. String with variable properties may be beneficial in certain instrument designs, providing an approach to produce a string with resonant frequency that is very sensitive to applied tension or other method used to vary the resonant frequency of the string.

Coupling Strings to the Tensioning Device

Some ductility may be required in a string material to allow for coupling of the string to fasteners. For example, common tuning pegs found on a guitar require bending and wrapping of the string that may cause some plastic deformation of metal strings at that location. For metallic strings for instruments of the present invention, it is preferred to have a ductility of between 0.5 and 20 % reduction in area, more preferably of between 1 and 12% and most preferably between 1 and 8 %.

Nonmetallic materials may also require some amount of material flexibility, but may be described in terms other than ductility. Yet, some materials may be very brittle (little to no ductility) but provide other properties excellent for use as a string in the present invention.

Some ceramic materials and carbon fiber provide an excellent example. For these materials, it is important to use fasteners that couple the required mechanisms at each end of the instrument to the string that require little to no ductility in the string. Such fasteners include bonding agents such as adhesives and epoxies that adhere to the brittle string as well as a more ductile coupling string, fastener, or other element that can be coupled to the tensioning device or mechanism or simply to a tuning peg.

In some embodiments, one or more strings are not directly coupled to the tension adjusting device or mechanism, because it may break due to repeated motion. In one embodiment, a coupling wire is used as a transition between the adjusting device or mechanism and the string. The coupling wire should have properties that provide for a long service life, such as high toughness and may be of a diameter that is not identical to that of the string. Preferably, the coupling wire will not contribute to the vibration of the string during play. One method used to prevent the coupling wire from contributing to the sound of the string is to use a saddle. A saddle is a component that typically includes a set of grooves, such that each string on an instrument rests in one grove. Similar to the nut near the end of a guitar neck, the saddle is typically located on the base of a prior art guitar near the bridge and provides a restring point that separates the plucked or strummed vibrating portion of the string and the portion on the body that does not vibrate - it defines an end node for the string. In a preferred embodiment, the design provides for the coupling wire to be located between the tension adjustment device or mechanism and the saddle. Generally, the transition point where the string and coupling wire meet will be located between the tension adjustment device or mechanism and the saddle. In a preferred embodiment, the length of string between the transition point and the restring point of the saddle will be at least 1 mm. More preferably, the length of string will be at least 2mm, and most preferably the length of string will be at least 5 mm.

Pulley Coupling

In one embodiment, six gear motors are oriented perpendicular to the neck of a guitar and fixed in place on the headstock, with three on each side. The output shaft of each gear motor is directly coupled to a pulley. The gear motors are arranged so that the set of six pulleys are aligned in a manner that allows each of the six instrument strings to mate with one of the pulleys, such that each of the six strings will have a corresponding pulley, as shown in FIG. 4. The end of each string is wrapped around its corresponding pulley, with preferably at least one wrap of wire and more preferably at least 5 wraps of wire. In some embodiments, the shafts of the different motors and pulleys may be at different elevations to allow clearance for each of the strings, and/or the motors may be positioned at an angle deviating from perpendicular to allow clearance for other strings, similar to the prior art approach of making clearance with traditional tuning machines by placing a bend in the some of the strings near the headstock, shown in the prior art of FIG. 1. The gear motors and shafts may be similar to each other, or they may be different, depending on the required torque and output that are needed to meet the tension requirements that will typically vary between strings.

In some embodiments of the present invention, a designer may consider the following equation: T = F * r [8]

Where T is the torque applied to the shaft of the pulley, F is the force applied to the string, which is also referred to as the tension, and r is the radius of the pulley, taken at the point where the string departs the pulley, which is the distance from the center of the shaft to the point where the string departs the pulley. Although factors such as friction may cause some errors in this calculation, it will provide an excellent estimate of the achievable tension and thus frequency range for a given string system.

For example, a designer may want to implement a system with a 1 cm diameter pulley and need to generate 100 newton tension to provide the desired range of notes for the string. Using equation [8], the designer would find T = 100 N * 0.5 cm [9] and thus T = 50 N-cm, which would be used in the selection of the motor or gear motor, in addition to considering the speed of the output shaft, as described above, and the desired motor or gear motor package size and configuration.

Preferably, the tension application mechanism, which may be a motor or gear motor - pulley combination, a solenoid actuator, a servo motor combined with a lever, and others is capable of generating at least 10 newton force on the string, more preferably is capable of generating at least 75 newton force on the string, and even more preferably is capable of generating at least 150 newton force on the string. Control System

In most embodiments of the present invention the instrument will include a control system that provides suitable power and/or position signals to the tensioning devices to increase tension, decrease tension, hold tension, and/or other possible commands. The control system may have one or more computing devices or systems, such as computer containing a processor, memory and other components typically present in general purpose computing devices.

The memory stores information accessible by processor, including instructions and data that may be executed or otherwise used by the processor. The memory is capable of storing information accessible by the processor, and may comprise a computer-readable medium, or other medium that stores data that may be read with the aid of an electronic device, such as a memory card, hard-drive, ROM, RAM, DVD or other type of memory used in the art. Systems and methods may also include combinations of the foregoing.

The instructions may be any set of instructions to be executed directly (such as machine code) or indirectly (such as scripts) by the processor. For example, the instructions may be stored as computer code on the computer-readable medium. In that regard, the terms "instructions" and

"programs" may be used interchangeably herein. The instructions may be stored in object code format for direct processing by the processor, or in any other computer language including scripts or collections of independent source code modules that are interpreted on demand or compiled in advance. The data may be retrieved, stored or modified by the processor in accordance with the instructions. Although the system and method is not limited by any particular data structure, the data may be stored in computer registers, in a relational database as a table having a plurality of different fields and records, XML documents or flat files. The data may comprise any information sufficient to identify the relevant information, such as numbers, descriptive text, proprietary codes, references to data stored in other areas of the same memory or different memories (including other network locations) or information that is used by a function to calculate the relevant data.

The processor may be any conventional processor, such as commercial CPUs for personal computers. Alternatively, the processor may be a dedicated device such as an ASIC or microprocessor unit. The processor and memory may actually comprise multiple processors and memories that may or may not be stored within the same physical housing. Accordingly, references to a processor, computer, or memory will be understood to include references to a collection of processors or computers or memories that may or may not operate in parallel.

Rather than using a single processor to perform the steps described herein some of the components such as servo motor output commands may have their own processor that only performs calculations related to the component's specific function.

In various of the aspects described herein, the processor may be located remote from the instrument and communicate with the instrument wirelessly. In other aspects, some of the processes described herein are executed on a processor disposed within the instrument and others by a remote processor.

The control system can include all of the components normally used in connection with a computer such as a CPU, memory (e.g., RAM and internal hard drives) storing data and instructions, an electronic display (e.g., a monitor having a screen, a small LCD touch-screen or any other electrical device that is operable to display information), user input (e.g., dial selectors, input buttons, keyboard, touch screen and/or microphone), as well as various sensors (e.g.

frequency sensors).

The control device can be programed in many different ways. For example, the control device may be programed such that a set of buttons on the instrument corresponds to a set of notes played on the instrument, depending on which buttons, or which combination of buttons, is depressed; the control device may be programed to play a sequence of notes and/or cords at a defined interval or timing sequence so that a song is played on the instrument. Songs such as "I love Liam" or "I Love Tavin" and many others can be played.

The control system can perform several different functions, including reading and/or

interpretation of input signals, determining suitable output commands in response to inputs and/or timing and/or other factors, and generating control and other outputs. Inputs can include, vibration frequency of the string(s) from a sensor, information that determines what notes will be played, temperature, tuning selection, volume selection, excluded strings, and others. Outputs can include the audio output signal, signal and/or power to control the tension adjustment device(s), LED or other light outputs located on the fretboard or other locations, information that correlates to equivalent finger positions on the fretboard, text or other information for the player regarding tuning, frequency information, power levels, and/or other data, and other outputs.

One primary output objective of the control system is to control the tension adjustment device(s) so that each string is tensioned and/or positioned in a manner such that it vibrates at a predetermined fundamental frequency (with higher frequencies accompanying the fundamental frequency as found in all string instruments). The control system may use frequencies other than the fundamental frequency as the primary control logic, but using the fundamental frequency is preferred. The control device may be programed to recognize the input of the full or partial depression of a foot pedal, where the location of the foot pedal indicates a certain control output, such as increasing or decreasing the tension on each string so that they play one octave higher than prior to the command; many other programs and/or algorithms may be used to control the notes played on each string. The control system can include a main processing center such as a microprocessor and support components such as power regulators, capacitors, diodes, resistor, memory, and other components. The combination of a microprocessor and support components can be found in a single board package known as a microcontroller or microcontroller board that are produced by various manufacturers. In one embodiment, an Arduino Mega 2560 microcontroller board is used. This microcontroller is a collection of components including processor, memory, analog to digital data acquisition, and output functionality all mounted onto a single circuit board. This controller allows for numerous inputs and outputs. Inputs are an important consideration as they may allow for increased precision of notes for each string. In one embodiment, each string may be connected to a tension sensor, such as strain gauge, that can indicate the amount of tension applied to the connected string. The microcontroller input can be used to read this tension and adjust the output of the corresponding motor such that the desired tension, within a predetermined tolerance range, is achieved quickly. This type of feedback control system is well known in the art of electronic control systems. Other types of sensors may be used. In one embodiment, an instalment comprising an electric guitar of the present invention includes a control system that is comprised of a microprocessor, such as the Stamp model 2BSX manufactured by Parallax, of Rocklin, CA. Similar to the Arduino Mega, this microcontroller is a collection of components that can provide most of the required computing features. The control system further includes 6 servo motors (model DS1015, a Hi Torque/Hi Speed Digital

Servo motor sold under the XP brand and manufactured by Associated Electrics, Inc. of Lake Forest, CA.), with one providing torque for each of the 6 strings, and a set of 5 individual chord buttons used by the player to input desired pre-programmed chords, a DC power supply, wires to connect each of the control system elements to the microprocessor, and optionally on board memory in addition to the memory including within the Stamp B2SX for storing multiple songs and/or additional code for the system. During use, a player depresses a combination of the chord buttons according to the preprogrammed selection for each chord. The microprocessor receives the chord button information and determines what note will be played on each of the strings and what strings, if any, will be eliminated from the output of that particular note, notes, or chord which is being played. Next, the microprocessor sends control information and/or power to each of the desired tension adjustment devices. In some embodiments with servo motors, this comprises a repeated 5 volt pulse of predetermined time length. The control system then switches off, through mechanical relay(s), solid state devices or other method, each of the string outputs that are not required for the given set of notes. In one embodiment, the control system determines the fundamental frequency of each active string and determines if an adjustment in the tension is required for subsequent played notes, if the played frequency is different from the desired frequency by some predetermined level (e.g., 2 Hz). Preferably, an adjustment is made if the difference between the note being played and the desired note is greater than 10 Hz, more preferably if it is greater than 5 Hz, and most preferably is greater than 2Hz. The control system can include a device that precisely measures the movement and position of the output drive mechanism and/or position of the end of the string and/or other or multiple components. Although the operation of servo motors is based on control of position of the output shaft, a device that tracks movement and position of the motor output shaft, the output drive mechanism, the position of the end of the string and/or position of other or multiple components can be used to provide data to a microprocessor for control feedback. In addition, many other types of motors and tension adjustment devices do not provide position control and position sensing devices can provide the information required for a microprocessor to achieve precise control of position and thus achieve precise control of tension. Such position sensing devices include optical encoders, rotating potentiometers, linear potentiometers, linear variable differential transformers (LVDT) (also called linear variable displacement transformer, or linear variable displacement transducer), and other devices that are compact and provide sufficiently precise position information.

Pickups and Exclusion of a String or Strings from Output Signals

For some embodiments, it may be desired to exclude an individual string or a group of strings from contributing to the overall output signal of the instrument. For example, in a learn-to-play application where a user is learning to play new chords, it may be desirous to allow the player to simply strum all of the strings so that they may focus on the difficult task of positioning fingers at the proper locations on the fretboard. However, for some chords, certain strings should not vibrate. An expert player would simply strum only those strings required for the given chord, but in this learn-to-play scenario the player is not advanced enough to accomplish the task.

In some embodiments of the present invention, the signal from one or more individual strings may be excluded from the output signal by preventing, dampening, or quickly stopping their vibration. In a particular embodiment, an electric guitar with a traditional single electromagnet pickup includes a mechanical actuating device, such as a solenoid actuator, for each string of the instrument that may be excluded. The actuator includes an engaging head that is normally at rest under the string and does not interfere with vibration of the string. The engaging head is mounted on the mechanical actuator that is incorporated into the body or the neck of the guitar. When actuated, a plunger or other mechanical linkage is pushed out of the actuator and the engaging head is extended upward to engage the string with some level of tension, thereby minimizing vibration or preventing the string from vibrating. Preferably, the engaging head engages the string with at least 4 newtons of force, more preferably 10 newtons force, and even more preferably at least 20 newtons of force.

In other embodiments of the present invention, each string is either selected for inclusion with the musical output signal or deselected and eliminated from the musical output signal. After determining the desired frequency and select/deselect status for each string, the microprocessor would determine the required output signals for those strings selected for output, perform function(s) to generate the required output signals, perform function(s) to generate the required output signals to allow signals from the selected strings to reach the musical output and prevent signals from the deselected strings from reaching the musical output signal. The microprocessor would thereby simply prevent the output signal from each desired deselected/excluded string(s) from reaching the integrating amplifier; the strings would vibrate on the instrument, but they would not contribute to the musical output signal and therefore would not contribute to the amplified sound heard by the player or audience.

In one such embodiment, individual magnetic pickups are used instead of the common single electromagnetic pickup. With individual magnetic pickups, each string has a small magnet, or magnets, and wire wound coil around the magnet, or magnets, that is located near the string such as under the string fully or partially mounted in the body. Each magnet/coil or magnets/coil is limited in size such that it does not extend under any adjacent string. In this design, the objective is to generate an electrical output signal of a given pickup by only the vibration of the metal string located for that pickup. Each output is fed to an integrating type (also known as additive type) operational amplifier circuitry, as is well known in the art of instrument electronics. The integrated output sounds nearly identical to the output created by a single electromagnetic pickup. The output from any one string may be excluded by simply opening a mechanical switch leading from the relevant coil such that the electrical output from that coil does not reach the integrating amplifier. Of course, other switching mechanisms may be employed such as transistors, magnetic relays, other solid state devices and more, as is well known in the art of electronic engineering.

In another such electronically excluded string or strings embodiment, individual piezo-electric pickups are used. Piezo-electric devices convert an applied force (which may be motion) to electrical energy and are widely used in many industries. They have been used as instrumental pickups for decades. One such example is US Patent No. US 5123325 "Film piezoelectric pickup for stringed musical instruments," issued on June 23 ^rd , 1992 to Robert A. Turner. This invention includes a pickup configuration providing a multi-channel pickup producing multiple electrical output signals, in which each electrical output signal represents the output of one or more of the strings of the guitar. Each output is fed to an integrating type (also known as additive type) operational amplifier circuitry, as is well known in the art of instrument electronics. The output from any one string may be excluded by simply switching off the electrical output from its respective piezoelectric transducer such that the output does not reach the integrating amplifier, as is well known in the art of electrical engineering. In another such electronically excluded string or strings embodiment, individual optoelectronic pickups are used. Optoelectronic pickups use light energy (commonly visible or infrared light but may use other wavelengths) to convert string vibrations into an electronic signal. In a typical design, a light source from a light emitting diode (LED) or laser diode (LD) is projected onto a string; in the generally opposing side of the string, a light sensitive device such as a photodiode or phototransistor generates an electronic signal that closely matches the vibrations of the string, because the interference of light projecting onto the sensor continually changes while the string is vibrating. The output from a well-designed optoelectronic pickup sounds similar to the common electromagnetic pickup but with a clarity not achievable with an EM pickup because the optoelectronic pickup is not susceptible to electronic noise that is ubiquitous in most environments today. Because most optoelectronic pickup deigns utilize a sensor for each string, it is well suited for use with embodiments of the present invention. The output from any one string may be excluded by simply switching off the electrical output from its respective optoelectronic device such that the output does not reach the integrating amplifier, as is well known in the art of electrical engineering. Many optoelectronic pickup designs are suitable for use with the present embodiments. For example, "Light responsive transducer for musical instruments," Canadian Patent No.

CA921738, issued Feb. 27, 1973 to R. Hoag et al. is possibly the earliest example of an optoelectronic pickup that incorporated individual electronic signals for each string. Other optoelectronic systems have been developed since then, including "Photonic pickup for musical instrument," US4815353 to D. Christian Donald, and "Electric stringed musical instrument equipped with detector optically detecting string vibrations," in US 5214232. Designs disclosed within these patents may be used with the present invention.

Determining Fundamental Frequency of Vibrating Strings

For some embodiments, it may be beneficial to determine the fundamental frequency of a vibrating string. Alternatively, a higher subharmonic frequency may be determined or the frequency profile of the string may be determined, but are generally more difficult to obtain and process so the fundamental frequency is preferred.

Independent pickups offer one approach to identify the vibration frequencies of each string while multiple strings are being played. With a single prior art magnetic pickup, the output signal is a composite signal comprised of all of the vibrating strings, so it is difficult or impossible to determine the vibrations of any one string. However, with independent pickups, the output from a single pickup represents the vibrations of an individual string, primarily. Once the

fundamental vibrating frequency, or vibration frequency profile, is determined it can be used to adjust the control logic for the string for the note being played or for subsequent notes that will be played. An algorithm that continually monitors the vibration frequency profile of each string and continually adjusts tension to play the desired frequency profile would result in a well-tuned and well-intonated instrument.

Another embodiment for determining vibration frequency includes a vibration sensor on each string. This may be attached inline with a string, affixed to the tension adjusting lever, string pulley, mechanism, or other mechanical element of each or select strings, and may be separate from, or work with, the pickup(s). Optionally, each vibration sensor can include an electronic filter that is designed to exclude unwanted frequencies from the output signal from the vibration sensor. Because each string will have a limited range of possible fundamental frequencies, it is preferred that the electronic filter is designed to eliminate as many frequencies outside of this range as possible. The vibration sensors may comprise a piezo-electric element, an audio element (such as a microphone), an optical detector and/or emitter, and/or other suitable devices.

For an optical emitter and detector pair, or other vibration sensor, it may be advantageous to locate them near the midpoint of the vibrating string. This will eliminate the first harmonic frequency (2x the fundamental frequency) because the midpoint of the vibrating string represents a non-vibrating node for the first harmonic. This may be important because the first harmonic frequency is closest to the fundamental frequency and may not be fully eliminated by an electronic filter.

Alternatively, or in combination with the vibration sensor, a force sensor, load sensor, load cell, or other type of force gauge may be included in line with the string or along one of the mechanical elements of the tension adjustment linkage such that the amount of force applied to a string can be determined. For example, if the force sensor is in line with the string, it will measure the actual force applied to the string. If the load sensor is connected to the motor drive arm, it will measure the force prior to any mechanical gear or leverage and will thus measure the force applied reduced by the multiple of the gear and/or leverage ratio. Vibration frequencies of the connected string will also be detected by these sensors and used to determine the vibration frequencies as discussed above for other sensor types.

In one embodiment, the control system determines the difference between the fundamental frequency of a played string and the desired fundamental frequency that the microprocessor intended to achieve for that given string. The microprocessor will store this frequency deviation data for a predetermined number of intended notes and/or for a predetermined time period and generate an average frequency deviation. The microprocessor then compares the average frequency deviation to a predetermined value and determines if an adjustment in the tension is required, if the average frequency deviation is greater than some predetermined level (e.g., 2 Hz). Preferably, an adjustment is made if the average frequency deviation is greater than 10 Hz, more preferably if it is greater than 5 Hz, and most preferably is greater than 2Hz. This type of 'delayed feedback' control scheme is important for many embodiments because an instant type feedback control scheme (where the frequency of a played note is determined while the control system uses this information to adjust that played note) may not occur fast enough to reliably control each played note, especially when a fast set of notes is played. A delayed feedback control scheme requires a system that can accurately achieve desired notes between control system adjustments. System designs based on servo motors is preferred for such embodiments.

Inputs & Note(s) and/or Chord Selection

In one embodiment, a set of chord input buttons is included with the instrument. The buttons may be located on the instrument or may be separate from the instrument. In one embodiment, the buttons are located along the neck of the guitar along a movable rail that can be easily folded back or removed from the instrument so that the instrument can be played with the player's fingers.

The instrument may comprise many different sensor types. For example, a series of sensors placed along the neck of the instrument may be used to determine the finger placements of the player's fingers. This may be used, for example, as a means to determine the desired notes so that the microprocessor can adjust the tension on a string if the intended frequency differs by some predetermined value from the frequency being played. The instrument may include a second neck or a neck that is wider than that required for the number of strings on the instrument. This allows the strings to be tensioned by the instrument, while the player uses traditional or modified finger positions on the portion of the neck, or on the second neck, where the strings are not located. In this way, the strings can vibrate and will not be interrupted by the player's fingers.

In one embodiment, a variable input is used instead of the discrete inputs such as the on-off buttons described in other embodiments herein. Variable inputs may be used along or in conjunction with discrete input devices. One example of a variable input device is a linear sliding potentiometer. This device increases or decreases the resistance across two electrical leads of the device as a sliding mechanism is slid from one end to the other. A microprocessor can be programmed to adjust the string tension for a unique set of preprogrammed notes for a predetermined number of positions of the slider along the length of the potentiometer. When the slider is in between two preprogramed positions, the control system may be programmed to adjust tension to notes in between the notes programmed for each of the 2 preset positions. It may be programmed to further adjust depending on the proximity of the slider to each of those 2 positions, or in some alternative manner. In this way, a musician may use the slider to crease a unique sound as the strings are strummed and the slider is slid from position to position for each string. Optionally, the potentiometer may include a set of soft stops or other means that provides a player the ability to recognize each of the preset locations along the sliding rail. This may also be accomplished through an optical means by illuminating an LED or set of LEDs as the slider reaches various locations along the length of the potentiometer. Other aids to help the player know when they have located a preset position on the variable input may be used as well.

Various types of variable inputs may be used as well, including rotating potentiometers, foot pedals with variable outputs as a function of pedal position (a foot pedal may incorporate a linear or rotating potentiometer), optical elements that have a variable output in relation to some adjustable element, such as a hand casting a shadow onto a photo sensor, and others. Electronically Controlled Tremolo (Whammy Bar/Wobble Bars)

A device that allows someone playing an instrument to quickly change tension of the set of strings is common in the prior art. Such a device is called a tremolo and also referred to as a 'whammy bar,' 'wobble bar,' and other names and can be found on many electric guitars. These devices include a handle (the bar) that provides the leverage needed for the player to slightly apply additional tension to each string or slightly reduce the applied tension to each string. This is accomplished mechanically by slightly reducing or increasing the length of each string, which slightly increases or decreases the applied tension, respectively. When actuated during play, a frequency shift centered around the base note of each string being played is heard. Prior art tremolos can be used with the present invention. In addition, the present invention provides for a new type of sound modifier, that can closely replicate the effect provided by the mechanical tremolo, if desired. It can create new sounds not possible with a traditional tremolo, as well. This is accomplished electronically. In one embodiment of an electric wobble bar, a handle is included and attached to the base or neck of the guitar as desired. An electronic sensor near the attachment point of the handle detects the movement of the handle. This information can be interpreted by a microprocessor, which can then provide output signals for each of the tension motors for tension adjustments in some programmed manner. One benefit of an electronic wobble bar is that the scale of adjustment is easily controlled through the use of a dial or other adjusting device known in the art. For example, the electronic wobble bar may provide an adjustment to the base frequency being played by a fraction of one hertz, or by one or more hertz while the position of the adjustment device is set near the low end of a scale. When adjusted to near the high end of the scale, it may provide an adjustment to the base frequency being played of many hertz. It may adjust a full note up or down, or a full octave up or down, for example, when the handle is moved to its limits in each direction. An electronic tremolo of the present invention provides for more complex inputs by the player.

In one embodiment, the handle is allowed to move in multiple directions. For example, it may be moved left, right, forward, backwards, into the base and out from the base, and all positions in between the extents. The electronic sensor near the attachment point of the handle detects the complex movement of the handle and is converted by a microprocessor to output signals for each of the tension motors, as determined by the programmed algorithm. In one embodiment, one direction set (e.g., left to right movement around a center point) determines how much adjustment is applied to string tension (resulting in an adjustment of string vibration frequency) and another direction (e.g., forward to backward movement around a center point) determines which strings will be adjusted. For example, when in full forward position, only the string 1 is adjusted and moving towards the center causes an additional string to be adjusted. When at the center point of front to back motion, all of the strings are equally adjusted and as the handle is moved toward the reverse position, only the higher strings (string 6, 5 etc.) will be adjusted with only string 6 being played when in full backward position. The third axis of movement (g., into and out of the base of the instrument around a center point) may be used to control the scale of adjustment, instead of, or in combination with the adjustment dial described earlier herein. This would allow a player to adjust the scale more quickly giving the output a new type of sound effect. Many other combinations or effects may be incorporated into this design.

Learn to Play

A series of lights such as LEDs can be included at various positions along the fretboard. For example, one LED may be positioned under each string at every fret. The microprocessor can then switch on individual LEDs to instruct the player where the fingers should be positioned during play. Optionally, multicolored LEDs may be used, such as red and green LEDs, such that green will be turned on to indicate a finger position and red would be turned on to indicate a string should not be played for the given chord/set of notes. The control system may also properly adjust tension of one or more strings while it is providing illumination for equivalently placed finger positions, or it may allow the player to manually depress the string at the appropriate illuminated finger position for one or more strings.

Similarly, one embodiment can include LEDs or other illumination elements under one or more strings at the point on the base where strumming/plucking/other string actuation occurs. The microcontroller may illuminate the LED under each string that should be strummed, and may use intensity to indicate how hard a string should be strummed or plucked. For example, a dimly lit LED under a string would indicate that the string should be strummed lightly, while a brightly lit LED would indicate that the string should be strummed firmly.

This learn-to-play aspect of the present invention may be combined with a business method that allows a player to download pre-programmed songs into the instrument controller so that the player can learn to play a particular song. Prior to making the song available for download, a program would be developed that properly sequences each element of tensioning, lighting, and other aspects of play. The player could select which elements to turn on or off and either automatically play the song, learn to play the song using the illuminated fretboard and/or strumming indicators, or play some other combination of available features.

Combining independent pickups and the ability to eliminate the output signal from a string or strings with an auto strumming device that is capable of strumming the strings with proper timing for a melody allows someone learning to play the guitar to focus solely on finger positioning. This could be combined with a foot switch or other input device to allow the user to control when the strumming occurs.

Given the capabilities of the entire device presented herein, independent pickups and the ability to eliminate the output signal from a string or strings can be used by someone learning to play to focus on learning one string at a time, with the instrument playing each relevant string except one or more, as desired. In part, this may be important for learning disabled or for those with phy si cal handi cap s .

Example Embodiment

Referring now to Figs. 7 through 16, one embodiment of an automatic playing electric guitar 1000 will be described.

Figure 7 shows three views of the automatic playing electric guitar 1000, including FIG. 7(A) a isometric view generally towards the front portion 1090 of the automatic playing electric guitar

1000, FIG. 7B a plan view of the bottom side of the automatic playing electric guitar 1000, and FIG. 7C an isometric view generally towards the back portion 1100 of the automatic playing electric guitar 1000. The automatic playing electric guitar 1000 is comprised of a body 1010, neck 1020, on which includes a series of frets called a fretboard 1030, head 1040, and tuning pegs 1050, where each of six strings 1060 terminate. The body 1010 further comprises a top portion 1070, a bottom portion 1080, a front portion 1090, and a back portion 1100. The transition between the body 1010 and the neck 1020 occurs at the neck transition 1110 where the neck 1020 is typically bolted or otherwise secured to the body 1010. The transition between the neck 1020 and the head 1040 occurs at the nut 1120 which is the final fret of the fretboard 1030. Included on the front portion 1090 are adjusting knobs 1130, pickup interfaces 1140, two lever support posts 1150 that support a lever rod 1160 onto which six tensioning levers 1170 are secured, and a saddle 1180 on which each of the strings 1060 rest. Included on the back portion 1110 are six servo motors 1190 fixed to the guitar 1000 with each connected to one of the six tensioning levers 1170 though a set of mechanical linkages 1200. The guitar 1000 also includes electrical connectors 1210 not shown, and a set of internal elements within the body 1010 including a battery 1220 not shown, a microprocessor 1230 not shown, and connecting wires 1240 between each of these elements not shown.

Figure 8 shows an enlarged front view of a portion of the body 1010 of the automatic playing electric guitar 1000, including the strings 1060 which are comprised of string 1 1061, string 2

1062, string 3 1063, string 4 1064, string 5 1065, and string 1066. Only string 1 1061 and string 6 1066 are labeled for ease of reading. The strings 1060 are numbered for convenience in sequence from the bottom to the top. Also shown are adjusting knobs 1130, pickup interfaces 1140, the saddle 1180 on which each of the strings 1060 rest, and two lever support posts 1150 that support a lever rod 1160 onto which six tensioning levers 1170 are secured. For increased detail, the tensioning levers 1170 are denoted tensioning lever 1 1171 through tensioning lever 6 1176 to match the set of six strings 1060. In this way, tensioning lever 1 1171 is connected to string 1 1061, tensioning lever 2 1172 is connected to string 2 1062, and so forth. Each string 1060 runs through its mating tensioning lever 1170 though a hold that is drilled through each tensioning lever 1170. A knot in each string 1060 or other type of stop as known in the art of instrument strings, prevents each string from sliding completely through the tensioning levers 1170.

Figure 9 shows an enlarged isometric view of a portion of the body 1010 of the automatic playing electric guitar 1000 generally from the top-front. The FIG. includes the strings 1060 which are comprised of string 1 1061 though string 6 1066, Only string 1 1061 and string 6 1066 are labeled for ease of reading. Also shown are adjusting knobs 1130, pickup interfaces 1140, the saddle 1180 on which each of the strings 1060 rest, and two lever support posts 1150 that support a lever rod 1160 onto which six tensioning levers 1170 are secured.

Figure 10 shows an enlarged back view of a portion of the body 1010 of the automatic playing electric guitar 1000. The back portion 1110 includes six servo motors 1190 each fixed to the guitar 1000. For convenience, the servo motors 1190 are denoted as servo motor 1 1191 thought servo motor 6 1 196, with each number correlating with the that of the string number to which it is connected. In a similar fashion, the mechanical linkages 1200 are too denoted as mechanical linkage 1 1201 through mechanical linkage 6 1206 with each number correlating with the that of the string number, tension lever number, and servo motor number to which it is connected. For clarity, an example is servo motor 1 1191 connected though mechanical linkage 1 1201, which is then connected to tension lever 1 1171, which is connected to string 1 1061.

Figure 11 shows an enlarged isometric view of a portion of the body 1010 of the automatic playing electric guitar 1000 generally from the back. The FIG. includes the servo motors 1 1191 through servo motor 6 1196, as well as the mechanical linkages 1200 and tensioning levers

1170.

Figure 12A shows an enlarged front view of a portion of the body 1010 of the automatic playing electric guitar 1000 and a reference line C-C that indicates the location of the cross section cut view which is shown in FIG. 12B. Figure 12B shows an enlarged cross sectional view of the section indicated in FIG. 12A. Figure

12(B) shows servo motor 4 1194 though servo motor 6 1196 as well as the connected mechanical linkage 4 1204 through mechanical linkage 6 1206, and tensioning lever 4 1174 through tensioning lever 6 1176. In the cross section, the pickup interfaces 1140 are shown as well as the pickups - including the first pickup 1141 and the second pickup 1142. Also shown is the saddle 1180, one support post 1150, the lever rod 1160, as well as the sectioned body 1010 and strings 4 1064 though string 6 1066. This view also shows the motor shafts 1250 including motor shaft 4 1254, motor shaft 5 1255, and motor shaft 6 1256. For convenience, the motor shafts are numbered to match each of the other drive elements, such that motor shaft 1 1251 is the shaft of servo motor 1 1191, and so on. Figure 13 shows the enlarged cross sectional view of FIG. 12B with some elements removed so that a single motor and drive train can be highlighted. In FIG. 13, servo motor 5 1195, mechanical linkage 5 1205, tension lever 5 1175, and string 5 1065 have been removed. Also removed are servo motor 6 1196, mechanical linkage 6 1206, tension lever 6 1176, and string 6 1066. In the embodiment of this example, tension of strings is adjusted through the tensioning levers 1170, that are connected to the servo motors 1190 which are mounted to the back side of the guitar body 1010. The servo motors 1190 are connected to the tensioning levers 1170 through mechanical linkages 1200. The servo motors 1190 provide the energy required to tension the strings 1060 by applying a torque to the motor shafts 1250 that is converted to a linear force applied to the tensioning levers 1170 by the mechanical linkage. In this example embodiment, the amount of force applied to each of the strings is independently controlled with an electronics control system that includes a microcontroller board. The servo motors are designed to accurately rotate to a predetermined position when a corresponding signal is sent to the motor. In use, after a desired position is determined by the microprocessor, the microprocessor sends appropriate command information to the servo motor which then rotates until the position is achieved. Torque is applied to the motor output shaft as required to reach said predetermined position, up to the torque limit of the motor.

Analysis with Schematic Line Drawings

Figure 14 is a line schematic representation 2000 of a portion of a drive mechanism of the present embodiment for a single string including the lever rod 2160, tensioning lever 2170, saddle 1180, and the string 2061. For convenience, the last three digits of the indicating numbers represent the like components shown in the example above, as shown in Figs. 7 - 13; that is, the schematic drawing of the lever rod 2160 represents the lever rod 1160, the schematic drawing of the tensioning lever 2171 represents the tensioning lever 1171, the schematic drawing of the saddle 1180 represents the saddle 1180 at the point where the string makes contact, and the schematic drawing of the portion of the string 2061 represents the string 1061. The line schematic allows a clearer description of certain geometrical features that will be described herein. Also shown are a series of reference lines 2300 used to help indicate the distance between certain elements as well as an enlargement area circle 2400 within which is an enlarged view of the elements near the schematic lever rod 2160.

Figure 15 is the line schematic representation 2000 of FIG. 14, except the location of the tensioning lever 2171 is at the midway position within its range of motion.

Figure 16 is the line schematic representation 2000 of FIG. 14 and 15, except the location of the tensioning lever 2171 is at the full-rearward position within its range of motion. In the line schematics of Figures 14 through 16, the following terminology is used:

L = Horizontal distance between point of rotation on lever and saddle restring point, when the tensioning lever 2171 is at the middle position;

H = Vertical distance between point of rotation on lever and saddle restring point, when the tensioning lever 2171 is at the middle position; d = Distance between point of rotation on lever and String connection point on lever;

L string = length of string between string connection point on lever and saddle restring point; a = the angle of rotation of the tensioning lever 2171 about the lever rod 2160; d_L = the horizontal component of distance change between the point of string contact on the tensioning lever 2171 when the tensioning lever 2171 is positioned midway compared to the tensioning lever 2171 being positioned full-forward or full-rearward; and d_H = the vertical component of distance change between the point of string contact on the tensioning lever 2171 when the tensioning lever 2171 is positioned midway compared to the tensioning lever 2171 being positioned full-forward or full-rearward.

Figures 14 through 16 provide a means to predict the full stretch of the string as a result of the varying amount of force applied to the string during use. This is because the length of the string between the saddle 2180 and the location where the string terminates at the head 1040, such as on one of the tuning pegs 1050, is a fixed distance; therefore, this portion of string does not need to be considered when evaluating how much the string will elongate when the mechanical system of this example embodiment applies tension. When tensioned, the entire string will contribute to the stretching of the string by slightly reducing its diameter, as is known in the art of solid body mechanics, but the linear expansion can be measured by simply observing the point at which the string is connected to the tensioning lever. Changes in the length of the string can be calculated using geometrical relationships. For both positive and negative (counterclockwise and clockwise, respectively, if using a clockwise- negative notation) rotation angles, a, we find: d_L = sin(a) * d [10] d_H = d - (cos(a) * d) [11]

L String = Square Root of ((H + d_H) ^A 2 + (L + d_L) ^A 2)) [ 12]

For analysis, it is important to be consistent in describing the rotation of the Tensioning Lever 2171. For this analysis, we observe from the direction such that the Tensioning Lever 2171 rotates -30 Degrees about the lever rod 2160 to reach the Full Forward Position, shown in FIG.

8, and the Tensioning Lever 2171 rotates +30 Degrees about the lever rod 2160 to reach the Full Rearward Position, shown in FIG. 10.

In some embodiments, the vertical distance between the string 2061- tensioning lever 2171 connection point when the tensioning lever 2171 is at the middle position, H, is minimized. It is preferred to design a system such that H is less than 12 mm, more preferably such that H is less than 8 mm, and most preferably H is less than 3 mm. In some cases, such as when H is zero and the range of rotation of the tensioning lever 2171 is limited to +/- 30 degrees, the full forward position results in the shortest string length, since the string - tensioning lever 2171 connection point is closest to the saddle in this position. Full forward position will thus require the least amount of tension. The full rearward position results in the longest string length, since the string

2061- tensioning lever 2171 connection point is furthest from the saddle in this position. Full rearward position will thus require the largest amount of tension.

Equations [10], [11], and [12] can be used to determine the instrument limited string elongation (defined as the distance the instrument is capable of elongating a string) if the relevant information about the design are known. For demonstration, instrument limited string elongation and required tension will be calculated using an example case where H is zero, the range of rotation of the tensioning lever 2171 is limited to +/- 30 degrees, L_string is 5 cm when the tensioning lever 2171 is at the middle position, and d is 5 mm. L string is found to be 47.5 mm when the tensioning lever 2171 is in the full forward position and L string is found to be 52.5 mm when the tensioning lever 2171 is in the full rearward position. Subtracting the shortest string length from the longest, we find the instrument limited string elongation to be 5.0 mm. The tension required to accomplish the full elongation of the string can now be determined if certain information about the string is known, as well as the tuning tension, which is the tension on the string when the position of the tensioning lever 2171 is in the full forward position. For a 0.5 mm diameter string with a total length of 70 cm when the position of the tensioning lever 2171 is in the full forward position (this is the total length of the string subject to the applied tension), made from maraging steel with properties as shown in Table 1 and a tuning tension of 5 Newton, using Eq. [5], an elongation of 5.0 mm is found that requires an additional force of 257 Newton, for a total force requirement of 262 N. Equation [6] should be reviewed to ensure that this force is not above the maximum applied tension.

The flow diagram 2100 shown in FIG. 17 provides a depiction of some of the features of control logic for this example embodiment. After the processor has been initialized, it proceeds to the cycle start 2101 portion of the instructions, where it begins control logic. First, at block 2102 the processor receives note input data from chord input data block 2103 that includes the desired note to be played on each string and whether or not each string will contribute to the musical output signal. This data will represent a traditional musical chord if 3 different notes are played simultaneously. It should be noted that the term chord is used for convenience and that one or more notes can be generated; the control system is not limited to generating 3 or more notes in order to make a traditional chord. The processor stores this data into memory as referred to here as chord input data (CID). The chord input data (CID) contains the desired notes or vibration frequency to be played on each string and the strings that will be selected and/or excluded from contributing to the musical output signal. CID may be input by a user through input buttons or by other means as described herein, and/or it may be pre-generated and downloaded to the control system before or during play, and/or it may be generated randomly and/or by other means.

At block 2104, the processor correlates (or compares) stored chord information and the CID data to determine the desired play frequency (DPF) for each string. Next, at block 2105, the processor uses stored chord data indicating the required position of each servo motor needed to achieve the DPF for each string and determines an output command for each servo motor and strings that should be selected and/or excluded from contributing to the musical output signal. At block 2106, the processor performs instructions and transmits output signals to each servo motor such that the proper position of the output shaft is achieved, and/or the required tension is developed in the string, such that the DPF is played for each string, as determined at block 2105. Data indicating the proper position of the output, and/or the required tension, to reach one or more played frequencies (i.e., notes) on each of the strings is stored in memory so that the processor can access this information quickly; this position-frequency and/or tension-frequency data can be determined in numerous ways: it can be calibrated by applying various amounts of tension to a played string and measuring and recording the resulting frequencies; and/or it can be estimated from computational estimates using equations and relationships described herein; and/or it can be estimated based on the calibration of an identical or similar instrument, and/or other methods that provide sufficiently accurate data.

At block 2107, the processor performs instructions and transmits switching signals for all strings such that strings selected to play the musical output signal will contribute to the musical output signal and strings selected to be excluded from the musical output signal will not contribute to the musical output signal. Next, at block 2108, the program returns to the cycle start at block 2101 to perform another loop.

The flow diagram 2200 shown in FIG. 18A and FIG. 18B provides a depiction of some of the features of an alternative control logic for this example embodiment. After the processor has been initialized, the processor proceeds to the full cycle start 2201 portion of the instructions, where the processor begins control logic. First, at block 2202 the processor determines frequency deviation data by receiving data from stored memory and/or a user input interface 2203 that may be a dial selector, buttons, user keypad or other input device allowing the user to enter certain data. At block 2202 the processor stores this data as average deviation value (ADV) data, and proceeds to the next instruction or set of instructions. At block 2204, stored memory and/or a user data is again received this time from block 2205 and includes cycle count data that is stored by the processor into memory as cycle count value (CCV) data.

Next, the processor proceeds to a new chord cycle 2210, which designates a break point in the instructions that will be used as a program loop beginning. At block 2211, the processor receives stored memory and/or a user data from input 2212 comprising chord input selection data and stores this data into memory as chord input data (CID). At block 2213, the processor compares stored chord information and the CID data to determine the desired play frequency (DPF) for each string. In some cases, this information will include instructions that select one or more strings to be included in the musical output signal, as described earlier herein. This may be accomplished by a DPF of zero for such strings, or any other convenient indicator. Next, at block 2214, the processor uses stored data identifying the required position of each servo motor needed to achieve tension in the corresponding strings connected to each of the servo motors to generate the frequencies or notes (chords) with the DPF for each string and determines an output command for each servo motor and corresponding string(s), if any, that should be excluded from the musical output signal. At block 2215, the processor performs instructions to transmit output signals to each servo motor such that the DPF is reached for each string. At block 2216, the processor performs instructions to transmit switching signals to select or deselect each string for the musical output.

The processor then receives data at block 2217 from a played frequency sensor (PFS) 2218 for each string, interprets the data according to instructions, and stores this data to memory as actual played frequency (APF) data for each string. After block 2218 and 2220 which indicate a transition from FIG. 18A to FIG. 18B, the processor calculates the difference between DPF and APF for each string and stores this into memory as DPF-APF data at block 2221. Next, at block 2222 a counter variable COUNT is set to increase by a count of 1. At block 2223, COUNT is then compared to CCV; if COUNT is less than or equal to CCV, the program returns to new cord cycle start at block 2210; if COUNT is greater than CCV, COUNT is then set to zero at block 2225 and instructions progress as follows. At block 2226, the average of DPF-APF for each string is calculated for the total number of cycles performed, which in this case is equal to COUNT +1 (since count begins at 0), and stores this data as A VG DPF - APF . At block 2227, A VG DPF - APF is compared to ADV; if AVG DPF-APF is less than or equal to ADV for all strings, the program returns to full cycle start at block 2201; if AVG DPF-APF is greater than ADV for at least one string, the program performs an adjustment to the output correlation for those strings which AVG DPF-APF is greater than ADV such that subsequent outputs to the servo motors will more accurately achieve the desired played frequency. Next, the program returns to full cycle start at block 2201.

Applications of Select Embodiments of the Present Invention

In one embodiment, the present invention comprises a guitar with six strings arranged with a 9 gauge wire string as the thinnest string, followed by an 11 gauge wire string, a 16 gauge wire string, a 24 gauge wire string, a 32 gauge wire string, followed by a 42 gauge wire string as the thickest string. The embodiment further comprises six DC gear motors secured to the headstock with the output shaft of each gear motor fixed to a 1cm diameter pulley. The pulleys are arranged such that each of the six strings aligns generally with one of the pulleys, such that a set of 6 pulley-string are formed. The guitar further comprises a set of chord buttons located on the neck of the guitar that can be depressed by someone playing the instrument. Preferably, there is at least one button, more preferably there are at least 2 buttons, and most preferably there are at least 6 buttons. Each motor is connected to an electronic DC motor control board that allows for fast control of applied voltage and applied polarity, as is well known in the art of electronics and DC motor control. Each DC motor controller is connected to a microcontroller board, such as the Arduino Mega 2560. The microcontroller is programmed such that each chord button corresponds to a set of notes that forms a desired chord.

In another embodiment, a handheld device includes a set number of buttons and is used to control the set of notes/chords played by the instrument. For example, a device with 4 buttons numbered 1 through 4 programmed such that the depression of one of the buttons and depression of a combination of buttons results in the production of a set of notes generated by the six pulley-strings form a desired chord. For example, when button 1 is depressed, the notes of an E chord are formed. When button 3 is depressed, the notes of an F# chord are formed. When button 4 is depressed, a single note of one of the strings may be formed. When buttons 1 and 3 are depressed simultaneously, the notes of a G chord are formed. This type of chord, or note, generator is limited by the number of unique combinations of depressed buttons. If more chord and/or note combinations are desired, the number of available buttons can be increased.

Preferably, there are at least 3 buttons, and more preferably there are at least 4 buttons. During use, this handheld device may be coupled to the neck of the guitar where one of a musician's hands is typically found. Instead of playing the cords on the fretboard as is done in a traditional guitar, the musician plays the notes and chords by depressing the buttons as described above. In one embodiment, the handheld device can be slid up and down the neck of the guitar, allowing the musician to simulate the movement of a hand as played on a traditional guitar.

Another embodiment of the present invention comprises a guitar with eight strings arranged with a 9 gauge wire string as the thinnest string, followed by an 11 gauge wire string, a 16 gauge wire string, a 24 gauge wire string, a 32 gauge wire string, a 42 gauge wire string, a 46 gauge wire string, followed by a 49 gauge wire string as the thickest string. A guitar, or other instrument, with more than six independent strings (some instruments include pairs of strings, as in a 12 string guitar) is rare and may not be easily played in a traditional manner due to the limited number of digits on a musicians hand. The embodiment further comprises eight DC gear motors secured to the headstock with the output shaft of each gear motor fixed to a 1cm diameter pulley. The pulleys are arranged such that each of the six strings aligns generally with one of the pulleys, such that a set of 8 pulley-string are formed. The guitar further comprises a set of 5 chord buttons located on the neck of the guitar that can be depressed by someone playing the instrument. Each motor is connected to an electronic DC motor control board that allows for fast control of applied voltage and applied polarity, as is well known in the art of electronics and DC motor control. Each DC motor controller is connected to a microcontroller board, such as the Arduino Mega 2560. The microcontroller is programmed such that the depression of one of the buttons and/or depression of a combination of buttons results in the production of a set of notes generated by the 8 pulley-strings form a desired note or chord, as described above.

In another embodiment, the instrument disclosed in the previous paragraph uses a set of tuning machines and coupled turning pegs as seen on a typical prior art guitar, and instead of using a pulley, the gear motors are connected to the tuning pegs to provide adjustment.

In another embodiment, the present invention comprises a guitar with six strings arranged with a 9 gauge wire string as the thinnest string, followed by an 11 gauge wire string, a 16 gauge wire string, a 24 gauge wire string, a 32 gauge wire string, followed by a 42 gauge wire string as the thickest string. The embodiment further comprises six DC gear motors secured to the headstock with the output shaft of each gear motor fixed to a 1cm diameter pulley. The pulleys are arranged such that each of the six strings aligns generally with one of the pulleys, such that a set of 6 pulley-string are formed. The guitar further comprises a single chord button located on the neck of the guitar that can be depressed by someone playing the instrument. Each motor is connected to an electronic DC motor control board that allows for fast control of applied voltage and applied polarity, as is well known in the art of electronics and DC motor control. Each DC motor controller is connected to a microcontroller board, such as the Arduino Mega 2560. The microcontroller is programmed to sequentially play a set of notes/chords, wherein each note or chord is triggered, or played, after the depression of the single button and held for the duration of the button depression, such that a well-known song is played by simply depressing and releasing the button with the proper timing. Thus by tapping the button at the proper rhythm, the player can properly play a complex song possibly comprised of complicated notes and chords.

In another embodiment, the instrument disclosed in the previous paragraph includes a set of additional chord buttons to complement the single chord button, such that additional notes and/or chords can be played in addition to the programed notes.

One embodiment of the present invention comprises a guitar with six strings arranged in a common arrangement with a 9 gauge wire string as the thinnest string, followed by an 11 gauge wire string, a 16 gauge wire string, a 24 gauge wire string, a 32 gauge wire string, followed by a 42 gauge wire string as the thickest string. The embodiment further comprises six DC gear motors secured to the headstock with the output shaft of each gear motor fixed to a pulley.

Preferably, the pulley has a diameter of less than 6 cm and more preferably less than 2 cm. The pulleys are arranged such that each of the six strings aligns generally with one of the pulleys, such that a set of 6 pulley-string are formed. Each motor is connected to an electronic DC motor control board that allows for fast control of applied voltage and applied polarity, as is well known in the art of electronics and DC motor control. Each DC motor controller is connected to a microcontroller board, such as the Arduino Mega 2560. The microcontroller is programmed such that the output from the microcontroller board independently controls each of the six DC motor control boards, indicating the applied polarity and voltage for each, which controls the tension applied to each string thus determining the resonant frequency, or note played, of each string. A program is written for the microcontroller board that continually changes, at some predetermined rate or rates, the applied voltage and polarity to each motor, to generate a set of notes and/or chords that form a tune or melody. In one embodiment, the notes and chords of a well-known song can be programed into the microcontroller board so that a musician can easily play the song by simply strumming and/or picking the correct strings at the correct time. In another embodiment, the instrument disclosed in the previous paragraph is combined with a mechanical device that is programmed to strum the strings of the guitar. When the timing of the strumming is set to match the creation of notes performed by the microcontroller board along with the gear motors, an entire song can be played automatically, without the need for a musician. This type of instrument results in a fully automated string instrument that could play a pre-programed song similar to a playing piano. The instrument is shown in FIG. 6. In another embodiment, the instrument disclosed in the previous paragraph uses an electromagnetic system to generate vibration in the strings. In one embodiment, the strings are made from a magnetic material, such as steel and/or certain grades of stainless steel and/or alloy steel and/or specific alloys developed for their magnetic properties, as is well known in the art of metallurgy. In one embodiment, the timing of the electromagnetic pulses used to induce vibration of the vibrating strings is set to match the creation of notes by the microcontroller board along with the gear motors, an entire song can be played automatically, without the need for a musician.

In another embodiment, the instrument disclosed in the first paragraph of this section includes a set of chord buttons that is numbered and/or colored so each button has a unique number and/or color. The instrument is further combined with a video gaming system. When played, the video game displays the button or buttons that should be depressed by the player while strumming the guitar or while using an automated strummer. When the chord buttons are depressed correctly, the video game records a correct match. In one embodiment, the button or set of buttons displayed on the video game screen is continually changing, such that when a player

successfully matches each button or set of buttons displayed on the video game screen by depressing the matching button or set of buttons on the instrument, a song is produced by the player. In one embodiment, the actual music played by the player can be analyzed by the gaming computer by use of an input microphone and rated for performance. In another embodiment of the present invention, the video gaming system disclosed in the paragraph above is used to train a musician to play an instrument designed and built according to the present invention.

In another embodiment, an automated string instrument is designed to be operated by a musician through a foot pedal. Because the tension in a string will remain near constant when a player depresses a string at a fret, on a guitar for example, numerous embodiments of the present invention can be employed while the musician continues to work the fretboard with their fingers, as done during traditional play. Coupled with a foot pedal controller, for example, a musician can control octaves of individual some, or all of the strings, for example, while continuing to play the instrument as typical. Figure 19 shows a frequency map of a guitar of one embodiment of the present invention for the instrument as typically tuned as recommended by the string and/or guitar manufacturer (FIG. 19 A) and frequency map of the same guitar after a connected foot pedal is depressed and tension is applied to each of the strings such that the resonant frequency of each string is twice that of the previously tuned guitar (FIG. 19B). This results in the guitar generating a similar set of notes but will be one octave higher than the previous tuning.

In another embodiment, an automated string instrument is designed to automatically tune the instrument periodically, such that the instrument remains in tune over the course of playing, time, and variations in the temperature of the instrument and strings and temperature and humidity of the atmosphere. In another embodiment, a harp is modified to include a set of DC sear motors, each coupled to a pulley. Some of the strings of the harp are attached to a pulley at one end of the string. The DC gear motors can be controlled as described elsewhere in this section. This would give the musician the ability to modify notes of strings on a harp during play, essentially creating a new instrument. In another embodiment, an automated string instrument is designed with large diameter gear motors to control a set of six strings, and the output shaft of each gear motor is connected through a flexible drive cable to a pulley mounted on the headstock corresponding to one of the six strings. This externally mounted motor design is useful in order to keep the instrument light for ease of playing and the large motors allow for very fast adjustment of tension over a broad range.

In yet another embodiment of the present invention, an automated string instrument, including a microprocessor controller system, is coupled with an optical scanner and character recognition system, as is well known in the art of optical character recognition, to convert a sheet of music into instructions that are automatically played by the string instrument. Although the present invention has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present invention may be made without departing from the spirit and scope of the present invention. Hence, the present invention is deemed limited only by the appended claims and the reasonable interpretation thereof.