Abstract: A method, computer readable medium, and touch sensor system for reducing the effects of contaminants on an acoustic touch sensor. Acoustic energy is transmitted across the touch sensor substrate. Any perturbations in the acoustic energy induced by environmental events, such as valid touches or contaminants, are sensed and analyzed. If the perturbation exhibits a monotonic growth over a time period, it is considered to be a valid touch. If the perturbation exhibits a non-monotonic growth over the time period, it is considered a contaminant.

Abstract: Touch input systems for use with information display systems and methods distinguishing multiple touches overlapping in time. The touch input systems and methods analyze and optimize data collected on the X axis over time independently from that collected on the Y axis, and for each (X, Y) pair corresponding to a potential touch location, calculate correlation values between X magnitudes and Y magnitudes. The touch input system determines valid touch locations based on the correlation values. Because the touch input systems and methods of the present invention can process multiple concurrent touches, they can be used in applications for multiple users, such as games, and in other applications requiring the processing of concurrent touch inputs.

Abstract: A method, computer readable medium, and touch sensor system for reducing the effects of contaminants on an acoustic touch sensor. Acoustic energy is transmitted across the touch sensor substrate. Any perturbations in the acoustic energy induced by environmental events, such as valid touches or contaminants, are sensed and analyzed. If the perturbation exhibits a monotonic growth over a time period, it is considered to be a valid touch. If the perturbation exhibits a non-monotonic growth over the time period, it is considered a contaminant.

Abstract: A method and apparatus for adapting an acoustic touchscreen controller to the operating frequency requirements of a specific touchscreen are provided. The adaptive controller can either utilize look-up tables to achieve the desired output frequency or the it can use a multi-step process in which it first determines the frequency requirements of the touchscreen, and then adjusts the burst frequency characteristics, the receiver circuit center frequency, or both in accordance with the touchscreen requirements. In one embodiment, the adaptive controller compensates for global frequency mismatch errors. In this embodiment a digital multiplier is used to modify the output of a crystal reference oscillator. The reference oscillator output is used to control the frequency of the signal from the receiving transducers and/or to generate the desired frequency of the tone burst sent to the transmitting transducers.

Abstract: An improved touch sensor having a resistive surface and simplified corner electrodes for introducing electrical potentials into the resistive surface. Improved positional accuracy is achieved by selectively energizing the touch sensor transversely (either vertically or horizontally) and diagonally, in either direction. As a result, equipotential lines formed in this manner are nearly perpendicular to each other (from the two energizations) throughout a larger area of the touch sensor so that increased accuracy of position coordinates is achieved over this larger area. Provision is made to determine the quadrant of touch and to optimize the energization to achieve the increased accuracy in that particular quadrant of touch.

Abstract: A projection television system which adapts automatically between from screen projection and rear screen projection upon insertion of the projector into a rear screen cabinet. A compact projection unit has a quick-disconnect electric connector and optical aligner which mate with connection elements in a projection cabinet upon insertion of the projector into an opening in the front of the cabinet. The cabinet has a two-mirror optical relay which inverts the projected picture. Upon completion of insertion, the electric connections automatically invert the image being projected by the projector. In another embodiment, insertion also automatically connects to audio equipment in the rear screen cabinet.