TECHNICAL FIELD

This application relates to medical headlamps. More specifically, this application relates to medical headlamps employing a high efficiency light source, and which includes batteries mounted on the headband that supports the headlamp.

BACKGROUN D ART

A medical headlamp assembly is a critical part of the surgeon's suite of tools, as it is of great importance that a surgeon can clearly see in the operating theater. The ideal headlamp would be easily portable, light and comfortable to wear for at least four hours. Further, it would have battery power, mounted on the headstrap, sufficient to last four hours from one charge, thereby eliminating the necessity of waist mounted battery pack and cables connecting this pack to the lamp, which are uncomfortable and complicate antiseptic protocol. Further the ideal headlamp assembly would create a bright beam of light that was homogenous and uniform in brightness and color, from edge-to-edge, directly along the surgeon's line of sight, without obscuring his or her line of sight. Also, it would be entirely silent, easily adjustable in position and would not be susceptible to infection by mold or any other sort of organism.

Unfortunately, these criteria are not only difficult to meet, but are also frequently at odds with each other. For example, although it is better to have a bright light, this creates more heat, which must be safely expressed from the lamp. It is helpful in the elimination of heat to make the lamp bigger, but doing so is likely to cause it to obscure the surgeon's line of sight and add unbearable weight. Another option for expressing heat would be to provide a fan, but this creates a sound which may be difficult for the surgeon to tolerate. To permit longer battery life it would be helpful to have higher capacity batteries, but doing so makes the assembly heavier and more difficult for the surgeon to tolerate for a long period of time. The batteries could be placed in a waist pack, but doing so requires an electrical line extending from an aseptic area, about the waist underneath the scrubs (anything under the neck is a "sterile" area), to a non-sterile area, on the surgeon's head. This arrangement complicates aseptic protocol. There is a currently available headlamp assembly that mounts batteries on the headband and that has batteries that can be swapped out, one at a time, for extended surgical periods. The light produced by this headlamp is on the order of 166 lumens in intensity. For many types of surgery, for example where a deep cavity that has been opened up inside a patient requires illumination, a higher intensity lamp is desirable.

DISCLOSURE OF THE INVENTION

The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above- described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

In a first separate aspect, the present invention may take the form of a battery headlamp assembly that includes a light engine bezel, and adjustable linkage supporting the bezel and including an electrically conductive system terminating at the bezel. Also, a headband assembly supports the adjustable linkage and includes inner assembly. The inner assembly has a strip of flex circuit having two longitudinally opposed ends and defining a set of conductive traces. Also, a pair of circuit boards, each one electrically and physically connected to one of said two longitudinally opposed end, each bear a network of electrical components and include a set of battery contacts. The conductive traces connect both the networks to each other to permit communications between the networks. In addition, a further electrically conductive element, electrically connects at least one conductive trace of the flex circuit to the electrically conductive system of the adjustable linkage, to permit the bezel to be powered from the battery contacts. A housing of flexible material substantially encloses the inner assembly and the further electrically conductive element and supports the linkage. In a particular

embodiment, the flex circuit and circuit boards are integrated together into one continuous piece of rigid-flex circuit. In a particular embodiment, the housing of flexible material defines a battery slot on each end of the rigid-flex circuit. In a particular embodiment, the flexible material is unitary and homogeneous. In a particular embodiment, the flexible material ensheathes at least a portion of the inner assembly, directly touching it. In a particular embodiment, the battery contacts are a component of both circuit boards and are at the end of each circuit board farthest from the linkage. In a particular embodiment, the inner assem bly further includes a set of cans covering the electrical networks and the flexible material substantially ensheathes the inner assemble, except the battery contacts and a conductive portion of the further electrically conductive element, to permit it ito be electrically connected to the electrically conductive system. In a particular embodiment, the D Shore durometer rating of the flexible material is between 45D and 70D. In a particular embodiment, the D Shore durometer rating of the flexible material is between 50D and 60D. In a particular embodiment, the D Shore durometer rating of the flexible material is between 55D and 60D. In a particular embodiment, the band extends past the inner assembly, thereby forming side-extension located behind and above the batteries, that may be joined together to form a portion extending around the back of a user's head. In a particular embodiment, the side extensions have a shore durometer rating that is different from the shore durometer rating of the flexible material covering the rigid-flex circuit. In a particular embodiment, the band includes two portions extending perpendicularly from the portions sheathing the inner assembly, these extensions being joinable to form a portion extending around the top of a user's head. In a particular embodiment, the further electrically conductive element includes a jack connected to at least one of the traces, and the electrically conductive system includes a mating plug. In a particular embodiment, the further electrically conductive element includes an additional jack connected to at least one of the traces and a permitting mating plug for transmitting electricity to the battery contacts, for recharging batteries connected to the contacts. In a particular embodiment, the jacks are positions side by side about the linkage and are ensheathed by the polymer material to create a pair of forward protrusions, which resist vertical flexure of the headband assembly during linkage adjustment. In a particular embodiment, the flexible material is a polymer material. In a particular embodiment, the electrically conductive system and the further electrically conductive element comprise an insulated wire, connected to a rigid-flex circuit trace and to the bezel, where the wire in the headband assembly constitutes the further electrically conductive element and where the linkage constitutes the electrically conductive system.

In a second separate aspect, the present invention may take the form of a method of making a headband for an electrical device to be supported and supplied with electricity by the headband, that utilized an inner assembly, including an electrically conductive assembly, including a terminal to permit connection to the electrical device and two networks of electrical components each supported by and electrically connected together, to one of the battery contacts and to the electrical terminal by the electrically conductive assembly, and protective cans placed over the networks. The rigid-flex circuit assembly is suspended inside a mold, which is filled with a curable resin, thereby substantially covering the inner assembly with the resin and the resin is permitted to cure. In a particular embodiment, the electrical terminal is at the center of the inner assembly. In a particular embodiment, the electrically conductive assembly includes a longitudinal extent of flex circuit that supports as well as electrically connects the networks. In a particular embodiment, the terminal is a jack supported by the flex circuit. In a particular

embodiment, the curable resin is a polymer resin. In a particular embodiment, the curable resin is a styrene-ethylene/butylene-styrene block copolymer.

In a third separate aspect, the present invention may take the form of a battery headlamp assembly that includes a light engine bezel and an adjustable linkage supporting the bezel, and including an electrically conductive system terminating at the bezel. A headband assembly supports and provides an electrical connection to the adjustable linkage and includes battery contacts and battery slots extending rearwardly from the adjustable linkage, for accepting batteries having electrical contacts matching the headband battery contacts and positioning the batteries so that the electrical contacts mate to the battery contacts. Finally, the battery contacts are positioned at least a 14 cm distance from the adjustable linkage, so that on a user of average head size the batteries are positioned mostly behind the user's ears. In a particular embodiment, the batteries are at least 14 cm from the linkage, as measured from the closest portion of each battery to the linkage, along the headband as it curves about a user's head. In a particular embodiment, the batteries are at least 14.5 cm from the linkage, as measured from the closest portion of each battery to the linkage, along the headband as it curves about a user's head.

In a fourth separate aspect, the present invention takes the form of a lamp having a front surface from which light is emitted and that includes a high efficiency light source assembly producing a beam having a 3 dB beamwidth of greater than 100°, and which includes a substrate, a high efficiency light source supported by the substrate; and a dome-lens that contains the high efficiency light source. Also, an optical assembly is positioned to receive light from the light emitting diode assembly and produce a headlamp light beam emitted from the front surface of the lamp. Further, an annular light block defines an annulus and is placed about the lens, so that the lens protrudes through the annulus, thereby creating a sharp boundary for the output light beam. In a particular embodiment, the high efficiency light source is a light emitting diode. In a particular embodiment, the lens is made of silicone. In a particular embodiment, the annular light block is supported by the lens. In a particular embodiment, the optical assembly includes a lens having a rear surface defining a concavity into which the light emitting diode assembly protrudes. In a particular embodiment, the headlamp light beam has a circular edge wherein light intensity decreased by 20 dB over 0.5° from a position inside the headlamp light beam to a position outside the headlamp light beam. In a particular embodiment, the lamp has a mass of less than 30 grams. In a particular embodiment, the electrical conductor is connected to a one amp current source, uses about 3.15 Watts of electricity and produces a beam of greater than 300 lumens from the front surface.

In a fifth separate aspect, the present invention takes the form of a lamp having a light source and an annular light block positioned to block an annulus of the light produced by the light source, the annular light block being thinner than 75 μ. In a particular embodiment, the annular light block is thinner than 40 μ. In a particular embodiment, the light source is an LED assembly. In a particular em bodiment, the LED assembly includes a dome lens encasing an LED. In a particular embodiment, the annular light block is located within 1 cm of the light source. In a particular embodiment, the lamp produces a light beam having an edge wherein the light intensity diminishes by 20 dB over 0.5 degrees from inside the edge to outside the edge.

In a sixth separate aspect, the present invention takes the form of a lamp having a front surface from which a beam of light is emitted and that includes a housing, and a high efficiency light source assembly, having a high efficiency light source covered by a lens, supported within the housing, an optical assembly, supported by the housing and having a front surface that is coincident with the front surface of the lamp and positioned to accept light from the high efficiency light source assembly and to emit the light from the front surface, and having a rear surface that defines a concavity; and wherein the high efficiency light source lens protrudes into the concavity. In a particular embodiment, most of the light produced by the high efficiency light source assembly is emitted from the front surface of the lamp. In a particular embodiment, the high efficiency light source is a light emitting diode (LED). In a particular embodiment, the optical assembly includes a prime lens, which defines the concavity and accepts light from the high efficiency light source, and an exit lens, which accepts light from the prime lends and define the front surface of the optical assembly and the lamp. In a particular embodiment, the lamp further has an annular light block placed about the light source assembly at the concavity.

In a seventh separate aspect, the present invention may take the form of a medical headlamp having a front surface from which a lamp light beam is emitted. The headlamp has a high efficiency light source producing a beam having a 3 dB beam width of greater than 100° and an annular light block, defining an annulus and placed immediately in front of the high efficiency light source, a light beam extending from the light block. Also, an optical assembly is positioned to receive light from the high efficiency light source assembly and produce a lamp light beam emitted from the front surface of the lamp. Further, a housing supports the light source and the optical assembly and an electrical conductor connects to the light source, for supplying electricity to the light source. Finally, the optical assembly includes an adjustable iris assembly including a user accessible actuator and an iris that is adjustable by the actuator, to be retracted away, thus leaving unaffected the light beam from the light block, or to be tightened to block a portion of the light beam from the annular light block, thus producing a thinner lamp light beam. In a particular embodiment, the high efficiency light source is a light emitting diode. In a particular embodiment, the optical assembly includes a prime lens and an exit lens. In a particular embodiment, the exit lens is moved backward or forward in response to the user accessible actuator, over at least a portion of the actuator's range. In a particular embodiment, a portion of the actuator's range moves the iris to block a variable portion of the light beam from the light block, and over that portion of the actuator's range the exit lens is not moved. In a particular embodiment, a portion of the actuator's range moves the iris over a range that does not block the light beam from the light block, and over that portion of the actuator's range the exit lens is moved forward or backward by the actuator. In a particular embodiment, when the iris is expanded to leave the light beam unaffected, the light beam has a circular edge wherein light intensity decreases by 20 dB over 0.5° from a position inside the light beam to a position outside the light beam.

In an eighth separate aspect, the present invention may take the form of a medical headlamp having a front from which light is selectively emitted. The headlamp includes a beam origination portion that produces a light beam and an iris assembly, positioned in front of the beam origination portion, having a user accessible actuator and an iris, responsive to the actuator to block a user selectable portion of the light beam. The iris is also responsive to the actuator to block none of the light beam, for maximum efficiency, when a user so selects. In a particular embodiment, the headlamp further includes an exit lens that can be controlled to move forward or backward. In a particular embodiment, the exit lens is greater than 20 mm in diameter and the beam spreads out from it in greater than 3 degrees in all directions as the beam advances, when the exit lens is focused and the iris is actuated to block none of the light beam. In a particular embodiment, the iris and the exit lens are controlled in tandem, by a single manual actuator. In a particular embodiment, the beam origination portion includes a light source and an annular light block that is thinner than 100 μηη. In a particular embodiment, when the iris blocks none of the light, the headlamp emits a beam of greater than 90 lumens, per watt of power consumed. In a particular embodiment, the headlamp emits a beam of greater than 100 lumens, per watt of power consumed. In a particular embodiment, the beam has a light intensity of more than 110 lumens per watt of power consumed. In a particular embodiment, the beam of light has a color rendering index of greater than 60.

In a ninth separate aspect, the present invention may take the form of a lamp having a front from which light is selectively emitted. The lamp includes a beam origination portion, which produces a light beam and a beam modification portion, which can be controlled to block a selectable portion of the light beam and can also be controlled to block none of the light beam, for maximum efficiency. Further, when the beam modification portion is controlled to block none of the light beam, the lamp produces a beam of more than 90 lumens per watt of electrical power delivered to the lamp. In a particular embodiment, the headlamp emits a beam of greater than 100 lumens, per watt of power consumed. Ina particular embodiment, the beam has a light intensity of more than 110 lumens per watt of power delivered to the lamp. In a particular embodiment, the beam of light has a color-rendering index of greater than 60.

In a tenth separate aspect, the present invention may take the form of a medical headlamp assembly has a headband subassembly, including an electrical network, including a battery and an electrical jack and a headlamp mount. An electrical headlamp subassembly, has a mounting element that is matingly and removably engaged to the headlamp mount, and an electrical plug that is matingly and removably engaged to the jack and an electrical headlamp, electrically connected to the plug. In a particular embodiment, the electrical headlamp subassembly also includes a second electrical headlamp subassembly, having a mounting element capable of removably mating to the headlamp mount and an electrical plug capable of removably mating to the jack and and electrical headlamp, electrically connected to the plug. In a particular embodiment, the second electrical headlamp subassembly is different in design from the first electrical headlamp subassembly. In a particular embodiment, both the first and second electrical headlamp subassemblies each require an electrical current source at the electrical plug, and the electrical current source required by the second electric headlamp subassembly is different from the electrical current source required by the first electrical headlamp subassem bly. In a particular embodiment, the electrical plug of the first and second electrical headlamp subassemblies are physically identical, each having a set of pin elements which are mutually electrically isolated from one another and the pin elements of the electrical plug for the first electrical headlamp subassembly are connected to the first electrical headlamp

subassembly and the pin elements of the electrical plug for the second electrical headlamp subassembly are connected to the second electrical headlamp subassembly. In a particular embodiment, the electrical plugs are audio plugs, each having a single longitudinal element which is divided into mutually electrically isolated pin elements. In a particular

embodiment, the headlamp subassembly further includes an adjustable mechanical linkage, permitting adjustment of the elevation angle of the electrical headlamp. In a particular embodiment, the headlamp mount is a guide rod and the mounding element is a slider. In a particular embodiment, the headband subassembly is shaped to be worn on a human head in a predetermined manner, and when the head is vertically oriented, the guide rod is substantially vertical, thereby permitting adjustment of the vertical position of the electrical headlamp.

In an eleventh separate aspect, the present invention may take the form of a method of switching out a medical headlamp that makes use of a medical headlamp assembly having a headband assembly, including a mounting element, an electrical jack and a power supply assembly electrically connected to the electrical jack. A first headlamp assembly is removably engaged to the mounting element and including a conductor terminating in a plug that is plugged into the jack; and a second headlamp assembly removeably engageable to the mounting element and including a conductor terminating in a plug that is engageable to the jack. The method includes removing the first headlamp assembly from the mounting element and unplugging the first headlamp plug from the jack and mounting the second headlamp on the mounting element and plugging the second headlamp plug into the jack. In a particular embodiment, the second headlamp has different illumination characteristics from the first headlamp. In a particular embodiment, the second headlamp has different electrical power requirements from the first headlamp. In a particular embodiment, the second headlamp plug makes a different electrical connection to the jack, compared to the electrical connection formed by the first headlamp plug to the jack. In a particular embodiment, the electrical power supply supplies electrical power having different characteristics to the second headlamp, compared to the characteristics of the electrical power delivered to the first headlamp. In a particular embodiment, the power supply assembly includes a network of resisters that the return from the headlamp connects into at a different point, depending on the plug, and includes a power sense resister that drives a DC-to-DC converter, which is driven differently depending on the point in the resistive network where the return from the headlamp is connected. In a particular embodiment, the electrical plugs are audio plugs, each having a single longitudinal element which is divided into mutually electrically isolated pin elements. In a particular embodiment, the headlamp subassembly further includes an adjustable mechanical linkage, permitting adjustment of the elevation angle of the electrical headlamp. In a particular embodiment, the headlamp mount is a guide rod and the mounting element is a slider. In a particular embodiment, the headband subassembly is shaped to be worn on a human head in a predetermined manner, and when the head is vertically oriented the guide rod is substantially vertical, thereby permitting adjustment of vertical position of the electrical headlamp.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. BRIEF DESCRIPTION OF TH E DRAWI NGS

Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

FIG. 1 is an isometric side-top view of a medical headlamp assembly according to the present invention, configured to be received onto a user's head.

FIG. 2 is an isometric side-top view of the assembly of FIG. 1, but without the tightness adjustment elements, and with elements extended outwardly, in a plane.

FIG. 3 is a front view of the assembly of FIG. 2.

FIG. 4 is an isometric side-top view of a rigid-flex circuit element of the assembly of FIG. 2.

FIG. 5 is a front view of the rigid-flex circuit element of FIG. 4.

FIG. 6 is a section view of the assembly of FIG. 3, taken along view line 6-6 of

FIG. 3.

FIG. 7 is a section view of the assembly of FIG. 3, taken along view line 7-7 of FIG. 3.

FIG. 8 is a cross-sectional view of a lamp for use in a medical headlamp assembly such as that of FIG. 1.

FIG. 9 is an exploded view of the lamp of FIG. 8.

FIG. 10 is a diagram of the lens system of a prior art headlamp, showing the outer light rays when the system is in operation.

FIG. 11 is a diagram of the lamp of FIG. 8, showing the outer light rays when the system is in operation.

FIG. 12 is a graph of light intensity values from a spot formed on a white background formed 45.7 cm (18 inches) in front of the front surface of the headlamp, according to a preferred embodiment, using 1 Amp of current and a 3.4 Volt, from battery, voltage drop. The intensity values are taken along a diameter of the light spot.

FIG. 13 shows an exploded view of a medical headlamp, according to an alternative preferred embodiment of the present invention.

FIG. 14 shows a sectional view of the medical headlamp of FIG. 13.

FIG. 15 is an illustration of the effect of the barrel adjustment on the light beam diameter, for the lamp of FIG. 13. FIG. 16 shows an isometric view of a medical headlamp assembly, having an attached medical headlamp of a first type.

FIG. 17 shows an isometric view of a medical headlamp assembly, having a detached medical headlamp of the first type.

FIG. 18 shows an isometric view of a medical headlamp assembly, having an attached medical headlamp of a second type.

FIG. 19 shows an isometric view of a medical headlamp assembly, having a detached medical headlamp of the second type.

FIG. 20 shows an isometric view of a medical headlamp assembly, having an attached medical headlamp of a third type.

FIG. 21 shows an isometric view of a medical headlamp assembly, having a detached medical headlamp of the third type.

FIG. 22 shows an audio plug and the scheme of use of the poles of the audio plug that is used in a preferred embodiment of the present invention.

FIG. 23 shows a simplified schematic of the electrical network of the medical headlamp assembly of FIGS. 16-21.

BEST MODES OF CARRYING OUT TH E I NVENTION DEFINITIONS:

For the purposes of this application, a "high efficiency light source" is an electrically powered light source having a light emitting surface area of less than 50 mm ² that produces light at a rate of greater than 50 lumens per watt of input power and at a rate greater than 30 lumens per square millimeter of light emitting area. This term does not include packaging or a lens. If these items are included the phrase used is "high efficiency light source assembly".

A light emitting diode (LED), as used in the application, refers to a solid state electrical device and does not include any lens or packaging. This element is sometimes referred to as a "die," by others. A light emitting diode assembly, includes packaging and a lens.

The term "most" as used in this application, means more than 50%.

The term "light" as used in this application refers to visible light. The "front" of the medical lamp is the side from which light is emitted. The

"longitudinal dimension" extends from front to back.

In this application the terms "headlamp" and "light engine bezel" are used interchangeably and are synonymous.

Referring to FIGS. 1 and 2, in a preferred embodiment of the present invention is a medical headlamp assembly 10, having a light engine bezel 12, an adjustable bezel support linkage 14 , a headband assembly 16, defining a pair of battery sockets 18, bearing batteries 20, each in contact to a rigid-flex circuit insert 30 (FIG. 4). The charge remaining in batteries 20 is indicated by a set of battery charge indicator lights 21. A head-top strap 22 and a head-back strap 23 form a part of headband assembly 16. As shown in FIG. 2 straps 22 and 23 are both formed from a pair of arms (26, 28) each having a serrated elongated opening 25. The two arms of the head-top band are drawn together by tightness adjust 27 which engages the serrations to adjust the length of the coupled arms, and the two arms of the head-back strap 23 are drawn together by tightness adjust 29. A brightness control knob 24 is also supported by headband assembly 16.

Referring now to FIG. 3-7 a rigid-flex circuit 30 is embedded into the center portion of headband assembly 16. Rigid-flex circuit is an industry term that describes a structure having both rigid and flexible portions, constructed by laminating together rigid and flexible layers and then removing the rigid layers in areas where flexibility is desired. In this application, the term "flex circuit" encompasses rigid-flex circuit, so that rigid-flex circuit is a type of flex circuit. Rigid-flex circuit 30 includes right and left-side rigid portions that support a right hand electrical network 32, and a left hand electrical network 34, respectfully. The electrical components of network 32 and 34 are connected together by a first set of conductive traces (not shown) that are internal to rigid-flex circuit 30. These traces are configured in a pattern designed to effect a predetermined scheme of connection. Rigid-flex circuit includes an additional rigid portion, right at the location where the linkage 14 connects to headband assembly 16.

The right hand network 32 is kept in an air pocket, protected by a right hand top can 35 (FIG. 6) and a right hand bottom can 37 (FIG. 6), both made of stainless steel that is .15 mm thick. The top can 35 is 4.5 mm high, whereas can 37 is 1.5 mm high. During the molding process, these cans 35 and 37 prevent the polymer material from contacting the components of network 32. Although bottom can 37 does create an area of some rigidity to the outside of strap assembly 16, it is covered by a 0.3 mm thick covering of relatively soft polymeric material 36, which greatly ameliorates this condition. A round indent (not shown) in can 37, which defines a hole (not shown) at its center, provides a seat for the head of a shaft (not shown) for the brightness control knob 24. On the left hand side, only a top can 41 (FIG. 6), having similar dimensions to and made of the same material as the top right hand top can 35, is required, due to a smaller component set, confined to the top of rigid-flex circuit 30.

Electrical networks 32 and 34 are electrically connected together and to bezel 12 by a second set of conductive traces 40, each of which extends either across the center of rigid-flex circuit 30 or from one of the electrical networks 32 and 34 to either a first jack 42 or a second jack 44. In a preferred embodiment first jack 42 accepts a plug 46 that supplies bezel 12 and second jack 44 accepts a plug (not shown) from a voltage source, for recharging batteries 20. Plug 46 and the wire attached to it may be considered an electrically conductive system of linkage 14, whereas first jack 42 may be considered a further electrically conductive element of headband assembly 16. Bezel 12 could be electrically connected to headband assembly 16 by a simple wire, in which case the portion of the wire in the linkage could still be considered an electrically conductive system and the portion in the headband could be considered a further electrically conductive element.

In an alternative preferred embodiment, rigid-flex circuit 30 is replaced by a longitudinal flex circuit or a longitudinal rigid-flex circuit having a circuit board electrically and physically connected to either end, a right hand circuit board supporting and electrically connecting network 32 and a left had circuit board supporting and electrically conecting network 34. In alternative preferred embodiments the pair of circuit boards are connected by a cable harness or a ribbon cable.

In a preferred embodiment, rigid-flex circuit 30 (together with jacks 42 and 44 and networks 32 and 34) is encased in a sheathing of polymer material 36 that also forms the top arms 26 and side arms 28. To produce the headband assembly 16, rigid-flex circuit 30 is suspended in a mold by shafts that extend through apertures for battery charge indicator lights 21. Polymer material in liquid phase is forced into the mold and after it has been allowed to cure, the shafts are withdrawn and the headband assembly 16 is ejected.

In a preferred embodiment sheathing polymer material 36 may be Styrene-

Ethylene/Butylene-Styrene Block Copolymer or similar material, preferably having a shore durometer rating of between 50 and 60 in its cured state. In one preferred embodiment, the shore durometer rating is 55. The 100% modulus is preferably between 1800 and 2500 psi. The mold injection temperature is between 180°C and 240°C. These materials are available from United Soft Plastics of Lawrenceville, Georgia.

In prior art, battery bearing headbands, the battery sockets have been separated from the material contacting the user's head by a space for circuitry, whereas in the preferred embodiment, the circuitry has been placed in front of the battery, as opposed to a position interposed between the battery and the head. Also, the battery sockets 18 have been moved farther back on the head, relative to prior art headbands, so that the closest portion of the batteries 20 to the linkage is 153 mm from the linkage as measured along the headband as it curves about the head, or stated in a slightly different but equivalent manner, measured as it would be if the headband assembly were laid out flat. For most wearers, this places the forwardmost part of the batteries at a position just above the ears, so that a portion of batteries may extend in backward direction at the place where the head curves inwardly toward the back, thereby avoiding contact between the batteries and the head, and providing a greater balance in weight, yielding greater comfort.

There are a number of advantages to the resulting headband. First, as it is constructed as a unitary piece, there are no seams that in other systems provide a foothold for the growth of fungus, and seepage of users' cleaning fluid into interior cavities, which can potentially damage electrical networks 32 and 34. Also, in one prior art system the two pieces that were joined to form the band for the back of the head also formed the panels separating the batteries from the head. This piece was made of a harder polymer material than other portions of the headband, in part to resist the tendency of the batteries, which extended further from the head because of the interposed electrical network, to torque with the top being pulled by gravity downwardly, which could easily translate to away from the head. The use of a harder polymer, however, can result in discomfort over the hours required to complete some surgeries. In headband 16, the use over the entire assembly of polymer material 36 which in a preferred embodiment has a shore durometer reading of 55 is more comfortable, even over long periods of time. In addition, the traces 40 that link networks 32 and 34 permit communication that permits these networks to cooperate. In one preferred embodiment, the battery delivering power to the bezel 12 shifts periodically, for example as the voltage of the active battery passes below a threshold, the load of the optical assembly is shifted to the other battery 20, so that the batteries drain at the same rate, over time. Also, those traces leading from networks 32 and 34 to the jack for supplying bezel 12 make external wires unnecessary. Such wires can present a snagging hazard.

A pair of parallel front-center vertical ridges 50 are created by the encasement of jacks 42 and 44. The valley 52 between these ridges form an elongated seat for post 54, which is part of support linkage 14. When arms 56 (also part of linkage 14) are rotated, post 54 is torqued and in turn torques headband assembly 16. The structure of post 54 and ridges 50, however, help to diffuse this torque and material 36 helps to cushion the forehead from the torque, so that the operation of rotating arms 56 is not as uncomfortable to the wearer of headlamp assembly 10 as it would otherwise be.

It is highly desirable, but very difficult, to produce a large, clear, sharp round light spot for a surgeon, using LED technology that is powered by head-mounted batteries. To do this it would be beneficial to use an LED assembly that produces a cone of light having a 3dB beam width of greater than 90°, but there is no such LED assembly available that produces a beam that has a sharp edge while still being efficient enough to provide the brightness necessary to do a deep cavity surgery. The Oslon Square™ LED assembly provides a beam width of 120°, and although bright enough was considered unusable in this application due to the slow tapering off of the beam edges, which if not corrected would create a spot of light having a fuzzy boundary, when an aspheric lens system is used, as is typical. This detracts from the tight focus on a specific area that the medical light is intended to provide and can cause distracting reflections of the metal instruments used in surgery.

Referring to FIGS. 8, 9 and 11, in a preferred embodiment, of an optical assembly 12, an LED assembly 212, including a domed silicone lens 214, and producing a light beam having a 3dB beamwidth of 120°, has a 25 μ (1 mil) thick annular light block 220 fitted around LED assembly 212, with the domed silicone lens 214 extending through the annulus of the light block 220. The beam exiting light block 220 has a beamwidth of 120° but with a much sharper edge then the beam from LED assembly 212. This contrasts with prior art systems in which an adjustable iris light block is placed entirely in front of the light source, resulting in a greater portion of the light being blocked and lost to beneficial use. Because this permits the use of the otherwise unusable 120° beam width assembly, this assembly permits a larger spot of light for the surgeon using the optical assembly 12. The placement of the light block 220 together with its 25 μ thickness, creates a sharp boundary about the light, and ultimately creating a sharp spot of light, at the typical 80-100 mm (16- 18 in) working distance. Lens 214 is fit into a concavity 216 formed in the back of an aspheric prime optic lens 218. Table 1 shows the LED assembly 212 characteristics for four differing embodiments. In an alternative preferred embodiment an LED assembly is used that is similar to the Oslon Square LED assembly, but includes more than one LED die, and in another preferred embodiment more than one LED assembly is used.

In front of prime optic lens 218, an exit lens 222 has a convex rear surface 224, thereby better directing the captured light back to create a beam of constant illumination over area. The equation for the surface is: · Z=(CR ² )/(1+SQRT(1-(1+K)C ² R ² ));

Where Z is the distance of the surface away from the apex of the rear surface 224 of the exit lens 222, in the longitudinal dimension, toward plane 226 (see FIG. 11), where:

R = radial distance from center in mm; and where C=0.05479 mm ^"1 , and K= - 14.954 (unitless).

More generally, the curve described by the above equation has the characteristic that for every 0.5 mm chord connecting two points along the curve the perpendicular distance ("sagitta" or "sag") from the chord to the curve, at the chord midpoint, is at least .025 mm.

As noted in the background, prior art systems included an adjustable iris aperture in front of the light source to permit adjustment of light spot size and create a sharply defined edge and homogeneous brightness and color from edge to edge. Although this permitted flexibility with respect to spot size, the movable elements of the iris required the iris aperture to be positioned further in front, the light source resulting in more light being blocked. Also, the need to have moveable leaf elements that fit together could impart a noncircular shape to the beam and the spot of light produced by the beam. Even when an iris was not used, as illustrated by FIG. 10, prior art systems, such as optical arrangement 300, would lose light by placement of the prime lens 310 far ahead of the light source 312. By contrast, a preferred embodiment has a set aperture size created by the 25 micron - 100 micron (1 to 4 mils) thick annular light block 220. This novel arrangement creates a far sharper light-spot boundary, due to the extremely thin circular aperture wall, resulting in virtually no light reflecting from the inner surface of annulus. This light block 220 is positioned around dome 214 of LED assembly 212, thereby blocking a smaller portion of the light produced by assembly 212.

The LED assembly 212 is driven by a 750 milliamp or greater current. A one (1) amp current at a typical battery voltage of 3.45 Volts results in a voltage drop through the LED assembly of about 3.15 Volts, due to some voltage drop through a rheostat, which is used to adjust light intensity, in the headstrap 16. This creates about 3.15 Watts of power that must be dissipated as heat from the LED assembly 212. The LED assembly 212 is driven by traces 242 that extend through a sheet of flex circuit 240 that is mounted behind prime lens holder 250 (FIGS. 8 and 9). Annular light block 220 fits into a round recess 260 in the center of holder 250. A layer of the flex circuit 240 is made of copper (except for channels where the copper has been removed to separate the traces 242 from the rest of the copper covering), which efficiently conducts heat away from assembly 212. Light is reflected from this conductive layer, which is close to the front, and at most covered with a transparent coating. This light is re-reflected back by the annular light block, preventing this yellowish light from entering the beam of light produced by assembly 10.

As illustrated in FIGS. 8 and 9, the exit lens 222 is held in a lens holder 270 that has a slot-follower 272 which is fitted into a curved slot 282 in an aft barrel 280. An outer ring 290 includes a straight internal longitudinal slot 292, and is mounted about aft barrel 280, so that when outer ring 290 is rotated, lens holder 270 is also rotated as slot- follower 272 is forced to stay in straight slot 292. This rotation forces slot-follower 272 to rotate within curved slot 282, which in turn causes slot-follower 272 and lens holder 270 to be moved either forward or backward in aft barrel 280. This either focuses or defocuses the light beam, creating a larger or smaller spot of light. The aft barrel 280 is made of aluminum and has a high thermal conductivity, whereas lens holder 270 and outer tube 290 are made of hard, black acrylonitrile butadiene styrene (ABS) polymer. Aft barrel 280 has a length 300 of 49.36 mm, and a height 320 of 38.61 mm. The front of aft barrel 280 has an outer diameter 330 of 27.26 mm._The other parts shown in FIGS. 8 and 9 are shown at the same scale as the aft barrel. The optical assembly 12 has a mass of 43 grams. The entire assembly 10, including batteries 18, has a mass of 340 grams. Table 1: LED Assemblies Used in Various Embodiments

The effect of the above detailed design is a medical headlamp assembly 10 with batteries 18 mounted on the headstrap assembly 16, and without a fan to provide forced air cooling, but which produces a brighter beam than previously available headlamp assemblies of this sort. The beam produced, in one preferred embodiment, has a light volume of 413 lumens with a color rendering index of at least 65. The beam is emitted relatively evenly from the 23 mm diameter front surfaces of the exit lens 222, and spreads out by 4.19 degrees in all directions as the beam advances. Referring to FIG. 12, a one (1) Amp lamp, as described above, where the voltage drop from the batteries is 3.4 Volts, produces a spot of light at 45.7 cm (18 inches) as shown. With a bright central area, about 52 mm wide at all above 50,000 lux at a color rendering index (CRI) of greater than 65. This is surrounded by a ring of about 10 mm width, where the light intensity declines from 50,000 lux to 25,000 lux. At the edges of the light beam, the brightness drops off by 20 dB in 0.5°. The lamp is operable in an ambient temperature of up to 30° Celsius, with no fan to cool the lamp.

This brightness is achieved by two improvements, with respect to prior art assemblies. First, the electric power applied to the LED assembly 212 is greater than in the prior art. Second, the proportion of light produced by the LED that is emitted in the beam is greater. The greater electric power of 2.5875 Watts creates a problem of successfully expressing the heat produced. It is highly advantageous to do this without the use of a fan, which would drive up electric power usage and create an unwanted noise. Accordingly, no fan is used in the preferred embodiment. The need to express the heat produced, is addressed by a longer aft barrel 280 which is made of aluminum and acts as a heat radiator, without blocking the surgeon's view. Also, the copper surface of flex circuit 240 conducts heat away from the LED assembly 212 and toward the bezel housing. A greater proportion of light produced by the LED is emitted in the light beam because: 1) the distance between the LED assembly 212 and the prime lens is shortened to virtually nothing, as the LED assembly 212 protrudes into a concavity 216 in the prime lens 218; 2) the adjustable iris, present in many prior art systems has been eliminated; 3) the annular light block 220 sits on the lens of the LED assembly 212, so that it is so far back that it blocks only a small proportion of the light. In one preferred embodiment 70% of the light produced by LED assembly 212 is emitted from the exit lens 222 as a light beam. Alternative preferred embodiments emit anywhere from 50% to 70% of the light produced by the led assembly 212 out of exit lens 222. This compares favorably with prior art systems where less than 45% of the light produced by the light source is emitted in the beam. In a preferred embodiment the light beam produced from exit lens 222 has a volume of 114 to 161 lumens for every watt of power applied to LED assembly 212. In one alternative preferred embodiment this figure ranges from 90 lumens of output light per watt to 161 lumens of output light per watt. This device greatly eases the task of the surgeon, who may now have an adequately bright and wide spot for deep cavity surgery, without the need for the distracting noise and cumbersome extra weight of a fan and without the need of any power cable traversing from a sterile to a nonsterile zone.

Referring to FIGS. 13 and 14, a high-efficiency medical headlamp 310 is shown, of the type that could be attached to a head strap assembly and used by a surgeon to light the surgical theater, or by a medical professional, in general, to illuminate an area of interest. This headlamp 310 is very efficient, producing a relatively high volume of light for the amount of electrical power consumed, thereby permitting the use of batteries mounted on the headband assembly, as opposed to mounted on a waist pack, with electrical cabling connecting the battery to the lights.

The headlamp 310 includes an aft barrel 312, which houses a round piece of flex circuit 314, upon which are defined conductive traces 316, adapted to drive a light emitting diode (LED) assembly 318, more generally termed "a high efficiency light assembly." Aft barrel 312 defines a channel 20 (FIG. 14) for an electrical wire to pass through, to connect a supply of electricity to traces 316.

A portion of LED assembly 318 extends through an aperture 322 in a prime lens holder 30, and also extends through an aperture 324 in an annular light block 32, which has a thickness on the order of 25 μηη and which blocks the peripheral light produced by assembly 318, thereby creating a crisp outline for the spot of light produced by headlamp 310. In front of and surrounding the portion of the high efficiency light source 318 that protrudes through aperture 324 is a prime lens 334 having a convex rear surface (FIG. 14). Immediately in front of prime lens 334 an iris 336 acts to permit an adjustment by actuator 338, to create a thinner light beam, which will be described in more depth, below. In front of iris 336 is an exit lens holder 350, containing an exit lens 352. An outer ring 354 surrounds exit lens holder 350.

The iris actuator 338 fits through a circumferential groove 360 defined in aft barrel 312 and further extends into straight forward and backward groove 362, defined in outer ring 354. Similarly, a groove follower 364 on exit lens holder 350 protrudes through a groove 366 on aft barrel, and also extends into groove 362 in outer ring 354. The result of this arrangement is that as outer ring 354 is rotated, both actuator 338 and groove follower 364 are moved circumferentially. In addition, over part of the travel of outer ring 354, groove follower 364 is moved forward or backward, as slot 366 is diagonal. This changes the focus of the light beam produced by headlamp 310. Over the remainder of the travel of outer ring 354, groove follower 364 is only moved circumferentially, which has no effect on the optical characteristics of headlamp 310.

Referring to FIG. 15, in configuration 370 outer ring is at the clockwise end of its travel, which causes actuator 338 to be at the extreme right end of groove 360 (from the perspective of an observer looking at groove 360). This causes iris 336 to be in its narrowest aperture state, creating a very thin light beam 380. Groove follower 364 is also at the extreme right hand side of groove 366, causing exit lens 352 to be at the extreme far forward extent of its range of motion. This option is sometimes required, particularly by ear, nose and throat specialists. In configuration 372, both actuator 338 and follower 364 are at the mid-range of their circumferential motion. This increases the aperture defined by iris 336 enough so that the beam width is defined by annular light block 324. At the same time, exit lens is maintained in its far forward position, defocusing the beam to create a wider, although less well focused light spot 382. Finally, in configuration 374, the actuator 338 and follower 364 are at the extreme left hand extent of their travel, causing iris to be definitively not affecting the beam 384, which is shaped entirely by annular light block 324. The exit lens 352, however, is brought back in to create a tight, well-focused beam with sharp boundaries. Accordingly, a full range of beam widths are permitted, while removing the iris entirely from engagement with the light beam for the wide beam geometries, thereby resulting in a more efficient system, when it is needed most, for the illumination of deep cavity surgery.

The effect of the above detailed design is a medical headlamp 310, that can be incorporated into an assembly with batteries mounted on the head strap assembly, and without a fan to provide forced air cooling, but which produces a brighter beam than previously available headlamp assemblies of this sort, and is also adjustable.

When iris 336 is opened up so that it does not block any of the light from LED 318, the proportion of this light that is emitted in the light beam from the exit lens 352 is greater than in prior art systems. This is because: 1) the distance between the LED assembly 318 and the prime lens 334 is shortened to virtually nothing, as the LED assembly 318 protrudes into a concavity in the prime lens 334; 2) the annular light block 332 sits on the lens of the LED assembly 318, sufficiently far back that it blocks only a small proportion of the light. In one preferred embodiment, 70% of the light produced by LED assembly 318 is emitted from the exit lens 352 as a light beam. Alternative preferred embodiments emit anywhere from 50% to 70% of the light produced by the LED assembly 318 out of exit lens 352. This compares favorably with prior art systems where less than 45% of the light produced by the light source is emitted in the beam. In a preferred embodiment the light beam produced from exit lens 352 has a volume of 114 to 161 lumens for every watt of power applied to LED assembly 318. In one alternative preferred embodiment this figure ranges from 90 lumens of output light per watt to 161 lumens of output light per watt. Many prior art systems include an iris but do not include any part analogous to light block 332, so that the iris is always blocking a portion of the light beam produced by the light source. Incorporating both the annular light block 332 and the iris 336, makes it possible to create a very high intensity beam, with minimum battery drain when the iris is opened up wide enough so that it blocks no light, but also to have a thin beam, when warranted.

The same lamp described above may, in its narrow beam state of adjustment, be used by an ear, nose and throat specialist.

Referring to FIGS. 16-21, in a further preferred embodiment, a medical headlamp assembly 410 includes a headband 412, supporting a mounting column 414. A low intensity headlamp assembly 416 includes a low intensity headlamp 418, a linkage 420, a slider 422. Also included is an electrical conductor 426 terminating in a four pole audio plug 428, which plugs into a four pole audio jack 430.

As shown in FIG. 17, when a user decides that he would like to remove assembly 416 from mounting column 414, he pulls assembly 416 upwardly to disengage slider 422 from column 414 and unplugs plug 428 from jack 430. He may do this simply to replace a worn out assembly 416, or (referring to FIG. 18) to install an assembly having different characteristics, such as medium intensity assembly 416', having medium intensity light 418' and plug 428' which is plugged into jack 430. Referring to FIGS. 20 and 21, in like manner assembly 416' can be switched out and assembly 416" having high intensity light 418" and plug 428", can be installed onto with slider 422 on column 414, and with plug 428" plugged into jack 430.

Referring to FIG. 22, although plugs 428, 428' and 428" appear identical, each one has a different active pin (longitudinally arranged electrical contact) that is electrically connected to the light emitting diode (not shown) of lamp 418, 418' or 418", respectively, and serving as the return, with the current being delivered into lamp 418, 418' and 418" in all cases through the ground. Pin 1 of plug 428 serves as the LED return for lamp 418, pin 2 serves as the LED return for lamp 418' and pin 3 serves as the LED return for lamp 418". Pin 1, pin 2 and pin 3 of plug 428 connects to pin 2, pin 3 and pin 4 of jack 430, respectively. Pin 1 of jack 430 connects to the ground of pl ug 428.

Referring to FIG. 23, a DC-to-DC converter 450 acts as a power supply to whichever one of lamps 418, 418' or 418" is connected to jack 430. A feedback loop is formed by the output of converter 450 powering the LED line, all of the current in which flows to the LED return line, and at least a portion of which pass through a current sense resister Rl, which in turn drives the feed back pin FB of converter 450. (The modification of the voltage at feedback pin FB through a voltage increase circuit 454 is described below.) The output of converter 450 increases if the voltage of feedback pin FB is below 0.5 volts and decreases if the voltage of feedback pin FB is a bove 0.5 volts, thereby setting that voltage at pin FB at 0.5 volts. Accordingly, when the voltage increase circuit 454 is not active, the voltage across resister Rl is set at 0.5 volts, and accordingly, / _R i = Rl/0.5 VDC. For the 800 mAmp lamp, for which the return current exits at Pin 2 of the jack 430, a few equations apply:

/RI = 800 mAmps - / _R2 /RI = 800 mAmps *( R ₂ + R^ + RA)

RI*( R ₂ + R ₃ + R ₄ +l)

For the 1.1 Amp lamp (from jack 430 pin 3) these equations become: /R2,RI - 1.1 mAmps - /R3 _; R4

/R2,RI = 1.1 mAmps *( R ₃ + R4)

( Ri+R ₂ )*(R ₃ +R4+1)

For the 1.4 Amp lamp (from jack 430 pin 4) these equations become: /R3,R2,RI = 1.4 mAmps - / _R4

/ _R3 ,R2,Ri = 1.4 mAmps *(R ₄ )

(R ₁₊ R ₂ +R ₃ )*( R4+1) In addition, for no lamp 418, 418' or 418" may the voltage drop through the lamp and the resistive network composed of Ri, R ₂ , R3 and R ₄ must not exceed a maximum, that in one embodiment is about 3.4 volts. In addition, the power consumption of this resistive network must be minimized for all the lamps, leading to low values for all of the resistors, on the order of a little more than an ohm.

The voltage output of the brightness adjust rheostat 440 is fed into a pin of a microprocessor 456, resulting in a periodic waveform having a duty factor that is related to the rheostat output voltage, appearing on an output pin of the microprocessor 456. When the rheostat 440 is moved to a "dim" setting, this causes microprocessor 456 to produce a waveform that causes voltage increase circuitry 454 to amplify the voltage at its input, thereby reducing the current (and voltage) out of the DC-to-DC converter 450, and reducing the current through resister R5. In an alternative preferred embodiment voltage increase circuitry is set to always amplify its input signal, thereby permitting a lower value for the voltage drop across Ri, when the lamp 418, 418' or 418" is not being dimmed. This permits a lower value of resistance for Ri, and lower power loss through Ri and through the entire resistance network Ri, R ₂ , R3 and R ₄ . For dimming positions of rheostat 440, this

amplification is increased.

When the brightness adjust knob 440 is set at its maximum, causing a voltage increase circuit 454 (described below) to pass the voltage from a current sense resister RI, unchanged, then the voltage through the current sense resister RI is forced to 0.5 volts by the feedback loop implemented by the converter 450 feedback pin FB (driven directly or indirectly by the current sense resister RI, and the converter 450 output powering the lamp 18, 18' or 18", with the LED return line powering resister RI. IN DUSTRIAL APPLICABILITY

The present invention finds industrial applicability in the manufacture of headlamp assemblies, and more particularly in the manufacture of medical headlamp assemblies.

While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.