Background of the Invention

Field of Invention

This invention relates generally to computer input devices, and more particularly to directional and velocity controlled input devices which are compact and which can be operated with a single finger.

Description of Prior Art

There are a variety of devices for providing input into a computer: keyboard, joystick, mouse, lightpen, etc. Some of these devices, e.g., mouse and joystick, position a cursor on the screen based on the direction in which the input device is moved. For example, when an input mouse is moved to the right along a flat surface, the cursor on the computer display moves to the right. The speed with which the cursor moves on the computer display is a function of how quickly the input mouse is moved along the flat surface. Most of these input devices are independent from the computer keyboard. A mouse for example is a separate piece of hardware that can be moved independently of the keyboard.

Prior art in computer input devices does not accommodate use with portable computer equipment such as laptop computers. In a portable computer environment there are often space limitations, e.g., using a laptop computer on an airplane tray table, which restrict or prohibit the use of an independent hardware device such as

a mouse. In addition, having to carry extra pieces of hardware is an inconvenience and results in a portable computer being less portable.

A significant portion of current software can be operated using a mouse-type input device. Laptop computer users either have to forego using the mouse interface with such programs or carry along a separate mouse input device.

With the advent of portable or laptop computers, it would be desirable to have an input device similar to a mouse, but which would be an integral part of the keyboard, which would occupy the approximate space of a key cap and which could be operated with a single finger. In view of the foregoing, it is an object of this invention to provide a computer input device incorporated within the computer keyboard in the approximate space occupied by a typical key cap and switch, which can be easily operated with a single finger.

Another object of this invention is to provide a computer input device that uses both direction and velocity input information for cursor positioning on the computer display.

Still another object of this invention is to provide a computer input device that may incorporate an electronic switch that is activated by pressing down on the key cap input device regardless of the horizontal position of the key cap.

Summary of the Invention

This invention was evolved with the general object of providing a mouse-like computer input device which is housed in the space that approximates the space used by a conventional computer keyboard key cap and switch and which can be operated with one finger.

The invention, called a finger mouse, employs a key cap device that can be displaced in the horizontal plane (horizontal will be used to describe the plane

perpendicular to the normal stroke of a key board key and does not limit the use of the finger mouse in terms of its orientation) .

Displacement of the key cap in the horizontal plane is detected by a transducer or transducers. With a position sensing transducer the possible displacement of the finger mouse key cap is greater than with a force sensing transducer in which the key cap displacement is virtually unnoticeable to the user who simply applies lateral force to the key cap.

The output from the transducer is converted to a signal used by the computer's cursor control logic to control cursor movement on the computer's display. When the finger mouse key cap is moved or pressed forward, the cursor moves in an upward direction on the display. When the finger mouse key cap is moved or pressed backward, the cursor moves in a downward direction. Similarly, when the finger mouse key cap is moved or pressed to the left or right, the cursor moves left or right respectively on the display screen. The cursor on the computer display will move in the same direction that the finger mouse key cap is being moved or pressed. The amount of force or degree of displacement applied by the user to the finger mouse key cap is translated into velocity of cursor movement; the more force or displacement, the faster the cursor will move.

The finger mouse may include an electronic switch which can be activated by pressing down on the key cap or applying downward force (with no key movement) on the key cap, regardless of the location of, or lateral force on, the key cap. This switch provides the "clicking" action found in conventional computer input mice. The switch action of a conventional one, two and or button mouse can be emulated by the invention with multiple presses of the key cap switch or with a combination of a keyboard key and "click" of the finger mouse key cap, or by the use of an independent keyboard key preferably adjacent to the finger mouse key cap.

Brief Description of the Drawings

FIG. 1 is a cross-sectional view of the computer input device in accordance with the principles of the invention. FIG. 2 is a diagram showing various positions of the common capacitor top plate in reference to the bottom plates of the variable capacitors.

FIG. 3 is a flow chart of the operation of the finger mouse control program.

Detailed Description of the Preferred Embodiments

Referring now to the drawings, therein like numerals represent like or corresponding elements throughout the several views, there is shown in FIG. 1 a cross-sectional diagram of the finger mouse computer input device. The invention employs transducers which are used to determine the position of, or the force being applied to, the key cap 10. Such transducers include strain gauges, optical detectors, capacitors, inductors, multiple contacts, change coupler devices, or any conventional transducer which can be activated by position or force. Position sensitive transducers such as capacitors or optical detectors require that the key cap 10 be capable of horizontal movement. If a force sensitive transducer, such as a strain gauge is used, the key cap would not move or travel as in the case of a position sensitive transducer, but would be displaced only to the extent necessary to activate the strain gauge transducers. The following description of the invention describes the use of three variable capacitors as the transducer element, but any other conventional transducer could be used in place of the capacitors.

The key cap 10 is connected to the position puck 12 which sits directly below the key cap 10. The lower surface of the position puck 12 is the common top plate 14 for the variable capacitors.

The key cap 10 and position puck 12 assembly is held in place with a centering and tension spring 16. The centering and tension spring 16 is a coil-type spring. The purpose of the centering and tension spring 16 is to position the key cap 10 and position puck 14 to a centered or neutral position in the horizontal plane within the finger mouse housing 30 when no force is being applied to the key cap. One end of the centering and tension spring 16 is attached to the key cap 10 and position puck 12 assembly; the other end of the centering and tension spring 16 is fixed to the housing 30.

The key cap 10 can be moved in any direction in a horizontal plane from the centered position. The amount of displacement in any given direction is limited by the centering and tension spring 16 and the finger mouse housing 30.

Located below the capacitors common top plate 14 is a common dielectric material 18. Located below the dielectric material 18 are at least three capacitor bottom plates 20, 22, 24. The bottom plates are of equal size and together form a circle which is larger than the area of the common top plate 14.

The capacitance of each capacitor is measured by means of conventional capacitance circuitry. The capacitance in each of the variable capacitors is a function of the area of the bottom plates 20, 22,24 covered by the common top plate.

Located below the capacitors bottom plates 20, 22, 24 is a switch actuator 26. An electronic switch 28 can be activated by pressing down on the finger mouse key cap 10. Downward pressure in the key cap 10 creates downward pressure on the actuator 26 which in turn activates the switch 28. The actuator 26 enables the switch 28 to be activated regardless of the position of the finger mouse key cap 10 in the horizontal plane. The actuator is spring loaded with actuator springs 32 which are compressed when the key cap 10 is pressed down and

which decompress when the key cap 10 is released returning the actuator 26 to its original position.

Activating the switch 28 is equivalent to "clicking" a switch on a convention single switch mouse. Multiple switch mouse conventions can be replicated by multiple "clicks" of the finger mouse switch, or through a combination of pressing a keyboard key and "clicking" the finger mouse switch.

FIG. 1 shows the finger mouse switch as an integral part of the finger mouse assembly. It need not be located in the finger mouse assembly, but could be an independent keyboard key preferably located adjacent to the finger mouse.

FIG. 2 shows several possible positions of the common top plate 14 with respect to the bottom plates 20, 22, 24. When in the centered position 36, the common top plate 14 covers equal portions of each of the bottom plates 20, 22, 24 yielding an equivalent capacitance for each of the capacitors. As the finger mouse key cap is moved forward and to the left, the common top plate is moved to a position such as position A 38 over the bottom plates 20, 22, 24. While in position A 38, the capacitance of the capacitor with bottom plate 20 is greater than the capacitance of the capacitor with bottom plate 22, which is in turn greater than the capacitance of the capacitor with bottom plate 24.

If the key cap is moved backwards and to the right so that the common top plate 14 is in position B 40, the capacitance of the capacitor with bottom plate 24 is greater than the capacitance of the capacitor with bottom plate 22, which is in turn greater than the capacitance of the capacitor with bottom plate 20. For every possible position of the finger mouse key cap 10 in the horizontal plane, a unique capacitance profile will result based on the respective capacitance of the variable capacitors.

When the finger mouse key cap 10 is moved, the capacitance in the variable capacitors changes. The

capacitanσe in the variable capacitors is constantly measured through the capacitance measuring circuitry 34. The result of the capacitance measurement is used in the finger mouse control program which converts the capacitance profile for a given key cap position to direction and velocity information which controls the movement of the cursor on the computer display.

FIG. 3 is a flow chart which describes the finger mouse control program. The control program is described with reference to a capacitor type transducer. The control program would be the same if another type of transducer is used - the control program converts the output from the transducer into position and velocity information used by the computer's cursor control logic to move the cursor on the computer's display.

Referring to FIG. 3, the capacitance of the of the variable capacitors is simultaneously measured and a capacitance profile is calculated. Step 201. The capacitance profile is then translated into a cursor direction value and a cursor velocity value. Step 202. There is a direction and velocity value for each capacitance profile.

The direction value and velocity values are then converted to a cursor input signal which is sent to appropriate cursor control logic in the computer. Step 203. The result of the signal is cursor movement on the computer display. Step 204. Capacitance values translated to directional information are linear so that movement of the finger mouse key cap causes similar direction movement of the cursor on the computer display. Capacitance values translated to velocity information are non linear; the further the finger mouse key cap is moved from the centered position, the faster the cursor will move on the computer display. When the finger mouse key cap reaches the limits of its outer movement, the maximum cursor velocity is achieved.

The process repeats itself until the finger mouse key cap returns to the centered position. Step 205.