| 摘要 |
<p>A circuit for controlling and detecting infrared light beams arrayed in front of a visual display to form a "touchscreen" is provided. Infrared light emitting diodes (2001) arrayed in front of the visual display are sequentially selected for a selection period and activated for a pulse period. Each infrared diode has associated with it a light sensitive phototransistor (2002) which is also selected for the selection period. If there is no obstruction between the selected infrared diode and its associated phototransistor, a signal is generated by the phototransistor and processed by the circuit, and a flip-flop is set. If there is an obstruction, no signal is generated, and the flip-flop is reset.</p> |
