Light spot position-to-pulse width converter

摘要

A converter for providing an electrical signal according to the status of a light spot applied thereto, comprises: a sensor for sensing the light spot and generating a position current according to the position of the light spot sensed thereat; and an operating circuit for providing the sensor with an operating current when the light spot is sensed by the sensor and for outputting a status current corresponding to the operating current. The sensor comprises two electrodes each providing a current with magnitude determined according to the distance between it and the position of the light spot sensed thereat. The position current is obtained by subtracting the first electrode current from the second electrode current. A pulse width modulator characterized by a narrow pulse generator is further included to output a sequence of pulses each with pulse width determined according to the position current and with cycle period determined according to the period of a sequence of narrow pulses generated by the narrow pulse generator.