Abstract

A circuit for adjusting the sensitivity of an optical character reader in which light is applied to an information-recorded material by an LED array and the information is read by a line sensor. The optical character reader is switched to a sensitivity adjusting mode. It reads a reference material having uniform reflectivity on the surface. The read signal is A/D converted and the microcomputer 10 detects a discrepancy between the amounts of light depending on the different portions of the line sensor. Based upon the detection, the microcomputer sets the applying time of driving currents to the respective LEDs so that the light is uniformly applied to the reference material. The set value is stored in a memory. Thereafter, since the amounts of light from the LEDs of the LED array are adjusted according to the set value, the amount of the reflected light to the line sensor 5 can be uniform. Thus, a series analog voltage accurately responding to the darkness and brightness of the information can be obtained.