POSITION DETECTING DEVICE BY PHOTOSENSOR

摘要

PROBLEM TO BE SOLVED: To obtain the position detecting device which can have its circuits simplified by using one input interface circuit although input interface circuits as many as photosensors were needed before and can also greatly decrease the number of pins and wires of connectors. SOLUTION: Photosensors P1 to P3 are connected in series and the series circuit has its one terminal connected to a power source E and the other terminal connected to one input interface circuit IF; and voltage dropping resistances R1 to R3 which have mutually different resistance values are connected to phototransistors T of the respective photosensors P1 to P3 in parallel. The voltage at a point (c) which varies with a phototransistor turned on is converted by an A/D converter IC of the input interface circuit IF from data on an analog quantity to data on a digital quantity and the data is sent to a processor such as a CPU.