Touch panel and method for controlling same

A touch panel adapted to be connected to a host computer comprising:

• a display area having a defined perimeter;
• a plurality of beam emitter-detector pairs disposed around at least a portion of said perimeter of said display area;
• said emitter-detector pairs each comprising an emitter adapted to be actuated to direct an energy beam, and a detector positioned across said display area opposite from said emitter for receiving said energy beam in response thereto;
• central processor means separate from said host computer connected to said emitter-detector pairs;
• computer program means within said central processor means for causing said central processor means to control the actuation and deactuation of said emitter-detector pairs one at a time sequentially to create a plurality of energy signals each of which comprises an actuated portion and a deactuated portion;
• said computer program means being adapted to cause said central processor means to create a modulation signal for causing said actuated portions of said energy signals to be modulated at a predetermined frequency, whereby said emitters will emit a modulated energy beam during the time that they receive said modulation signal;
• said detectors each being adapted to sense said modulated energy beam and create a first electrical beam signal whenever said modulated beam passes unobstructed from each of said emitters to each of said detectors, said detectors each creating a second electrical beam signal different from said first beam signal whenever there is an obstruction of said modulated beam between said emitter and said detector during said predetermined period of time;
• blockage detection means connected to said detectors, and said central processor means for sending a blockage signal to said central processor means in response to said blockage detection means sensing said second signal;
• said computer program means causing said central processor means to generate an output signal indicative of the location of said obstruction on said display area in response to receiving said blockage signal from said blockage detector means.