| 摘要 |
PURPOSE:To perform clear printing, by setting higher the synchronizing signal which controls the modulation starting time and ending time of the laser beam which scans on the photosensitive drum by printing pattern information. CONSTITUTION:An unmodulated laser beam generated from a laser device (not shown in the diagram) is received by a photodiode 6 and added to the 1st delay circuit 13 and an inverting circuit 14 through an amplifier 8. The output of the inverting circuit 14 is added to the 2nd delay circuit 16 through an attenuating circuit 15 which attenuates the output at a prescribed rate. Even when the laser beam receive signal of the photodiode 6 fluctuates due to the inclination of the surface of a rotary polyhedral mirror (not shown in the diagram) for scanning, the output of a combining circuit 17 will become one having the same width and a highly accurate square wave signal (synchronizing signal) is obtained at a waveform converting circuit 9 by appropriately selecting the delay time of the delay circuits 13 and 16 and the attenuation ratio of the attenuating circuit 15. |
