PHOTOELECTRIC SWITCH CIRCUIT

摘要

PURPOSE:To improve the reliability for detection an object with a photoelectric switch circuit by producting an object detecting output from an AND between a detection signal obtained based on the photodetecting signal quantity and another detection signal based on the distance information to the object to be detected. CONSTITUTION:Detection currents I1 and I2 supplied from a position detecting means 15 such as a semiconductor position detecting element PSD, etc. are converted into voltage forms by photodetecting circuits 17 and 18 respectively and then amplified to be converted into voltage V1 and V2. Logarithm amplifier circuits 19 and 20 amplify the V1 and V2 after logarithmic compression. These amplified voltages are turned into the input of a comparator 22 through the next arithmetic circuit 21 and compared with the reference voltage. This reference voltage can be varied by a means such as a variable volume VR which sets a detection area, etc. Thus the detecting distance is set for a photoelectric switch.