Patent ID: 6222182
Filing Date: 2001-04-24
Classification: G06F

Abstract:
An input device including an opto-mechanical encoding system comprising:a light source;a phototransistor having a collector, an emitter, and a base arranged to receive light from the light source to charge the base;a moveable encoder structured so as to periodically vary light flux from the light source at the phototransistor base with motion of the encoder;a microcontroller for controlling and sampling the phototransistor,wherein the microcontroller turns on the phototransistor when the light source is on and prior to sampling the phototransistor, by changing the potential difference across the collector and emitter from zero or near zero to a state in which the collector/base junction is back biased and the base/emitter junction is forward biased, therein providing an essentially immediate peak response from the phototransistor.