Coded data generation or conversion – Bodily actuated code generator
Patent
1991-12-20
1997-08-12
Swarthout, Brent
Coded data generation or conversion
Bodily actuated code generator
341 33, 324686, G08C 2100
Patent
active
056570120
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to finger-operable control devices for controlling equipment such as computers or position-controlled devices and the like.
BACKGROUND INFORMATION
Control devices such as mouse, trackball, or joystick are used to control such equipment but all these have moving parts and in the case of a mouse a level table surface is needed. Joysticks and trackballs are bulky and require robust mounts and all are protrusive. Touch-plate switches are known, but these are simple on/off devices.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a finger-operable control device having at least some of the following characteristics, that is a device which: substantial lag between operation by the operator and response by the instrument.
According to the present invention a finger operable control device (such as a joystick emulator or mouse) comprises a sensor having a central electrically conductive plate, a first pair of electrically conductive plates on a first axis and spaced from opposite edges of the central plate to form a first pair of capacitors therewith having substantially equal capacitance, a second pair of electrically conductive plates on a second axis different from the first and spaced from opposite edges of the central plate to form a second pair of capacitors therewith having substantially equal capacitance and is characterised in that at least one of the plates is connected to a detector circuit arranged to sense capacity imbalance between at least the first pair of capacitors induced by the presence of a finger or finger operable earthed object placed on or near the conductive plates when the finger or object is disposed asymmetrically along the first axis with respect to the central plate.
The plates may be formed as a matrix of copper conductors on a printed circuit board. In some embodiments of the invention one or more of said conductive plates may be driven by alternating signals, and in others, the plates are connected to phase-sensitive detectors.
The amount of signal detected is normally small, being due to stray capacity between conductors of the matrix which is balanced by design to give a very low zero residual signal. The presence of a grounded object such as the operator's fingertip intercepts some of the electrical flux and unbalances the stray signals. The phase and amplitude of the imbalance depends on the precise position of the fingertip, i.e., whether it is to the left or right of the axis of symmetry of the matrix, or above or below the centre-line. Sensitivity to angular direction and distance of finger movement is determined by the design of the matrix.
The detector output is passed to logic circuits which convert the output into a form suitable for transmission to a computer or other indicating device so as to control for example the position of a cursor on a display screen by slightly varying the position of the operator's finger located on the sensitive area of the device.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which;
FIGS. 1A-F show five embodiments of a sensor matrix,
FIGS. 2A-C show a perspective, a cross-section on line B--B of FIG. 1A and a side view of a device according to the invention,
FIGS. 2D and E show a side cross-section and an elevation of a device similar to that of FIGS. 2A-C according to the invention.
FIG. 3a shows a single-axis device with a balanced drive and an unbalanced detector,
FIG. 3b shows a single axis device with the drive applied to the central plate and a balanced detector coupled to the other plates,
FIG. 3c shows a 2-axis sensor with a quadrature squarewave drive and phase sensitive detectors using D-registers,
FIG. 4 shows a joystick emulator embodying a device according to the invention.
FIG. 5 shows a Quadrature-Mouse emulator embodying a device according to the invention,
FIG. 6 shows a combined Joystick/Mouse emulator embodying a device accordin
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patent: 4016490 (1977-04-01), Weckenmann et al.
patent: 4168464 (1979-09-01), Coulson et al.
patent: 4264903 (1981-04-01), Bigelow
patent: 4305007 (1981-12-01), Hughes
patent: 4755634 (1988-07-01), Pepper, Jr.
patent: 4873400 (1989-10-01), Rapp et al.
Hill A. M.
Swarthout Brent
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