JPS6411839A - Image recording apparatus of laser scanning type - Google Patents

Abstract

PURPOSE:To correctly determine the reference light amount by an output of a semiconductor laser without any influences of streaking phenomenon, by controlling the operation of the semiconductor laser of a timer which is started operating at the starting time of the forcible light emission, after the lapse of a predetermined time including the time before the semiconductor laser generates a stationary output. CONSTITUTION:A semiconductor laser 4a overshoots its output owing to the thermal characteristics thereof for a predetermined time immediately after the generation of a laser beam B. Therefore, if an output controlling circuit 11 operates while the semiconductor laser 4a overshoots, the controlling circuit 11 erroneously determines the reference light amount by a higher output of the semiconductor laser 4a than the stationary value. As such, a sample & hold signal generating circuit 12 is provided so as to control the output controlling circuit 11 to operate after the output of the semiconductor laser 4a reaches the stationary value. The sample & hold generating circuit 12 is arranged to receive an operation timing signal concurrently with a laser driving device 3 from a timing generating circuit 13 on the basis of an SOS signal from a waveform shaping circuit 10, with a sample & hold signal being added to the output controlling circuit 11.