COLOR MARK SENSOR

摘要

PURPOSE:To increase a control range together with high control accuracy by controlling reference light with an aperture diaphragm and at the same time dividing the output level of a reference light receiving element into plural steps of reference values at a prescribed rate. CONSTITUTION:An aperture diaphragm is provided between a light source and a reference light receiving element 12 and controlled so that the output level of the 1st comparator circuit 41 is set at H or L when the detection level of a signal light receiving element 20 exceeds that of the receiving element 12. The output currents of the receiving elements 20 and 12 are converted into voltages by current/voltage converting circuits 31 and 32 and applied to comparators 41 and 42 respectively. Here the output voltage of the circuit 32 is divided by variable resistors 331-33n connected in series with each other. The outputs of these resistors serve as the reference value of multi-stage comparators 01-40n respectively. In such constitution, the comparators 401-40n turn on the corresponding LED1-LEDn only when the detection level of the signal light is kept between the upper and lower limit levels of the reference value. This attains the discrimination of multiple colors as well as multiple stages.