Abstract: An acoustic wave touch panel is shown for use with a non-active stylus. The acoustic wave touch panel includes an acoustic wave touch position sensor with an elastomeric substrate 20 overlying the touch position sensor and further including a stiff substrate overlying the elastomeric substrate. When a non-active stylus contacts a surface of the stiff substrate exerting a Z-axis force thereon, the Z-axis force is transmitted through the stiff substrate to the elastomeric substrate. The elastomeric substrate deforms in response to the Z-axis force and transmits the force to the acoustic wave touch sensor, the deformation of the elastomeric substrate absorbing or damping acoustic wave energy like a finger touch on the acoustic wave touch sensor.

Abstract: A controller for an acoustic wave touch panel includes a signal conditioning circuit that can generate X-axis and Y-axis burst drive signals for a touch panel as well as receive and process X-axis and Y-axis sense signals from a touch panel that can be configured with either one or two transducers per sense axis. The signal conditioning circuit includes a differential amplifier to which simultaneously received X-axis and Y-axis sense signals are applied to provide common mode rejection. The signal conditioning circuit includes a resonant circuit, in each of the X and Y channels, that forms a series resonant circuit through which a burst signal is applied to generate the transducer drive signal. The resonant circuit further forms a parallel resonant circuit of high impedance.

Abstract: An opto-matrix touch input device which samples and compares beam readings is taught. Briefly stated, phototransistor readings which sample ambient light as well as light from an associated light emitting diode are compared with preset values. If the readings from the phototransistor are below a certain level, then the phototransistor/LED pair are flagged as bad. If the readings are within preset limits, yet below nominal values, then the phototransistor/LED pair are flagged as indicating a marginal beam. In this manner a trouble report may be generated for the purpose of repair or investigation as well as providing a vehicle for keeping a history of the opto-matrix frame condition and thereby a method of early fault detection.