Abstract

A cursor control device (10) is provided which has a touch pad (14) formed of individual conductive plates (16) forming sectors of a circle. A user's touch on a dielectric layer (18) overlying the plates (16) is detected by individually charging and discharging each of the sector plates in a sequential manner to determine the increased capacitance, if any, of each sector plate. A microprocessor assigns each of the sector plates a relative X and Y weighting as a function of its angular position in the touch pad which are combined with the individual plate capacitance readings to calculate the relative X and Y position of the touch with respect to the origin (28) of the touch pad. Cursor control signals proportional to the relative X and Y values, plus a Z value proportional to the area of touch, if desired, are provided to the keyboard (12) of a displaying computer. The touch pad (14) can be effectively integrated into a computer keyboard by positioning it immediately beneath the space bar (25) of the keyboard so that it can be accessed by the thumb of the user without requiring the user to move his or her hand from the keyboard.

Other References

• IBM Technical Disclosure Bulletin, "Keyboard Scanned Capacitive Joy Stick Cursor Control", J. E. Foy, vol. 23, No. 8, Jan. 1981, pp. 3831-3834