Abstract: Touch mapping method and apparatus locate a touch to an unpatterned and continuous layer of selected electrical conductivity in response to the incremental electrical charge which the conductive layer draws at one or more known positions, in response to electrical excitation, and relative to the charge which layer draws in the absence of the touch condition. The measurement of electrical charge provides touch location for a variety of touch impedances and other impedences coupled with the selectively conductive layer.

Abstract: An improved touch-panel and method of increasing the percentage of useful area of a touch-sensitive panel include electrode elements in electrical communication with an electrically conductive layer of known spatial impedance characteristics. The touch-panel structure incorporates improved electrode structure and electrode to impedance layer interfacing elements which impart a more linear mapping function within an expanded touch-sensitive region of the resistive layer. The touch-panel can be utilized in a general touch-mapping system without resort to extensive mapping coordinate correction apparatus of earlier systems.

Abstract: A display device locates a touch anywhere on a conductive display faceplate by measuring plural electrical impedances of the faceplate conductive coating. The impedances are at electrodes located on different edges of the faceplate. A touch locating circuit determines the location of a touch using known pulsed signals and, in another embodiment, using a tuned measuring signal.

Abstract: A touch terminal identifies a single user-selectable, touch-responsive pad element on the display screen for user communication with a data processing system. The terminal makes the identification in response to the durations of pulse signals which vary according to the touch-selection condition of the pad elements. A multiple-step technique of repetitively measuring the signal durations relative to reference values attains essentially error-free pad selection. The operation includes the updating of the reference values of the pulse-signal durations.