PHOTOELECTRIC SENSOR AND LIGHT RECEIVING UNIT OF PHOTOELECTRIC SENSOR

摘要

PROBLEM TO BE SOLVED: To provide a photoelectric sensor and a light receiving unit of the photoelectric sensor capable of maintaining detection accuracy of an object even if the amount of light received varies by using a general-purpose photo IC in which a function to deal with variation of the amount of light received is not provided and a threshold value is fixed.

SOLUTION: In the inside of a general-purpose photo IC 11: a light receiving element 5 receives light entering from a detection area and outputs a signal with a size corresponding to the amount of light received; an amplifier 6 amplifies the signal output from the light receiving element 5; a threshold output part 4 outputs a threshold signal with a fixed size; a signal comparison part 8 compares the amplified signal with the threshold signal; and a first output terminal 12 outputs the amplified signal outside. In the outside of the general-purpose photo IC 11: an A/D conversion part 21 acquires the amplified signal from the first output terminal 12; and a light transmission amount control part 22 sends to the light transmission unit 30 a light transmission amount control signal to vary a light transmission amount of the light transmission element 1 based on the amplified signal so that the amount of light received in the light receiving element 5 can be within a predetermined range.

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