Automatic gain control circuit.

摘要

An automatic gain control (AGC) circuit for use in an optical code reader which eliminates error caused when regular reflecting light is directly incident on the detector element of the optical code reader. The AGC has a variable gain amplifier which receives a signal from the detection element and outputs a signal to a peak-holding circuit. The output from the peak-holding circuit is used to control the gain of the variable gain amplifier. A reset circuit resets the output of the peak-holding circuit either when the output reaches a predetermined level, or at regular intervals during the operation of the optical code reader. The output of the variable gain amplifier is fed to a binary circuit. <IMAGE>