| 摘要 |
PURPOSE:To ensure exact synchronism of optical scanning means with a photosensitive drum, by controlling speed of the scanning means using information read out with a photodetector fed back as a detected speed value. CONSTITUTION:Black and white successive pattern 20a repeated at the same pitches is printed on one side border of a contact glass 20 surface in the scanning direction. This pattern 20a is optical scanned at the same time as original 3 is scanned, and the reflected light reaches photosensitive drum 9 through the same path as the light reflected from original 3, and it is read out with photodetector 21. This black and white pattern information read out is that of the scanning speed, and fed back as a detected speed value, thus permitting scanning speed to be controlled. |
