| 摘要 |
PURPOSE:To cause scanning speed of an optical system to exactly follow the peripheral speed of a photosensitive drum, by using a pulse signal corresponding to the peripheral speed of the drum as a reference input, and a pulse signal obtained from an encoder, corresponding to the scanning speed as a feedback signal. CONSTITUTION:Binary discrimination marks 12 on a photosensitive drum 7 are detected with a photosensor 8, and this pulse detected with the photosensor 8 is delivered to a phase comparator 14 as a reference input. The output of this comparator 14 is amplified in a power amplifier 15, and a driving motor 16 and an optical system 4 are drived. A linear type encoder 5 is provided along the main scanning route of the optical system 4, and a photosensor 11 detects output of the encoder 5 to feed back a pulse signal to the comparator 14, thus permitting the scanning speed of the optical system 4 to exactly follow the peripheral speed of the drum 7. |
