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 acoustic touch position sensor is shown in which a transducer coupled to a side of a substrate imparts a shear wave into the substrate for propagation along a first axis. A reflective array disposed along the first axis reflects portions of the shear wave along a plurality of parallel paths extending across a touch surface of the substrate to a second reflective array the axis of which is parallel to the first axis. The second reflective array reflects the shear waves incident thereto a receiving transducer mounted on the side of the substrate. A touch on the substrate results in perturbation in the shear wave which is sensed to determine the axial position of the touch on the substrate. A laminated touch panel is provided such that a back plate of any desired thickness is bounded onto the substrate. A non-shear wave coupling adhesive may be used to bond the back plate to the substrate.

Abstract: A touch input device which continuously samples and digitally stores ambient light readings and compares these with previously stored readings is taught. Briefly stated, a phototransistor is turned on before, during and after an LED emitter energization. An ambient value is calculated which is subtracted from the value obtained during LED firing so as to develop a signal indicative of the presence or absence of the LED pulse, irrespective of ambient light fluctuations. The ambient level is stored for comparison purposes during the next sampling of the associated phototransistor.

Abstract: A low profile opto-device panel assembly suitable for use in an input detection apparatus used as an input device in conjunction with a visual display is disclosed. Arrays of light emitting devices and light detecting devices are juxtaposed along the internal edge of a peripheral frame printed circuit board to reduce the overall height of the panel assembly. Alignment housings surrounding each of the arrays of opto-devices are attached to the printed circuit board and extend inwardly of the sides of the peripheral frame printed circuit board. The opto-devices disposed in the alignment housings along the internal edge of the printed circuit boards are mechanically and electrically interconnected to the printed circuit board by bent leads which extend along the upper surface of the printed circuit board and into conventional printed circuit board holes.

Abstract: An infrared touch input system is taught. Briefly stated, the system comprises a four-sided frame having an infrared transparent bezel along the inside thereof and having infrared emitters along the top and one side of the frame with infrared detectors along the sides opposite the emitters. Darlington transitor arrays are used as source and sink drivers for driving the LED's in an array. The I/O lines of a microprocessor in conjunction with the source and sink drivers are used to selectively energize each LED. Additional I/O lines of the microprocessor in conjunction with BCD decoders are used to selectively energize corresponding infrared detecting phototransistors before, during and after LED turn-on. A host computer supplies a clocking signal for the microprocessor with programming in the microprocessor thereby automatically performing the selection and deselection of emitters and detectors.

Abstract: A current injection compensation circuit for dynamically compensating for the effect of ambient conditions on phototransistor output is disclosed. An output voltage is maintained at a nominal reference voltage level independent of ambient light input to allow use of a large output for a detected signal. Phototransistor current is a function only of ambient conditions, especially incident ambient light and is unaffected by compensation current injection. The ambient compensation current injection network can be employed with interactive touch input devices, such as infrared touch entry systems used with video displays.

Abstract: A touch entry system employing arrays of emitter and detector opto devices located around the periphery of an irradiated field detects intrusion of an opaque element such as a stylus within the field. The detector analog output is converted to a digital signal for input into a microprocessor. Digital signals input into the microprocessor can vary due to inconsistencies in conventional opto devices. A programmable amplifier responsive to the microprocessors preconditions the analog signals prior to analog to digital conversion to bring all digital signals corresponding to the unblocked emitter beam condition within a normalized range before input into the microprocessor.

Abstract: An infrared touch input system having bezel glare compensation via power profiling is taught. Briefly stated, a touch input system is utilized having a four-sided frame and having an infrared transparent bezel along the inside thereof and having infrared emitters along the top and one side of the frame with infrared detectors along the sides opposite the emitters. The optical power used with emitter-detector pairs adjacent the corners of the bezel is reduced with respect to emitter-detector pairs approaching the center of the bezel. In this manner, light which is reflected after striking the side of the bezel adjacent the emitter-detector pair and which is received by the emitter is of low intensity or is ignored.

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.