SENSOR DEVICE USING PHOTOCOUPLER

摘要

PURPOSE:To correct the quantity of light emitted from a light emitting element in a simple circuit constitution. CONSTITUTION:A microcomputer 15 performs the ON control of a switch SW1 when a power supply is turned on. Thus the DC voltage Vcc1 and a current set by a current control circuit 20 flow to an LED 13. At the same time, a current flows to a phototransistor 14 in response to the quantity of light received from the LED 13. Then the voltage V1 set by the current to the phototransistor 14 is fly backed to the control voltage input terminal of the current control circuit 20. Thus the circuit 20 stores the data on the voltage V1 and sets a resistance level to keep a proper quantity of light emitted from the LED 13 based on the stored data. Thus the current flowing to the LED 13 is controlled. As a result, the quantity of light emitted from the LED 13 can be corrected in a simple circuit constitution.