| 摘要 |
PURPOSE:To read black information which is dropped out by a high-speed scanning, by switching the subscanning speed from a high speed to a normal speed and reversing the subscanning for a required time at a black information detection point. CONSTITUTION:The subscanning is performed in a high speed till a black information detection point. When black information is detected, a black signal is outputted, and therefore, a picture signal detecting circuit 11 operates a rotation speed switching circuit 12 for a pulse motor for subscanning to switch the pulse motor 9 for subscanning to a normal speed. Simultaneously, a rotation direction switching circuit 14 for the pulse motor is driven to rotate reversely the pulse motor 9 during the set time of a timer circuit 15, and the scanning is reversed. After that, the pulse motor 9 is rotated normally to perform the scanning in the normal speed. When a reader 7 outputs a white signal, the pulse motor 9 is switched to a high-speed scanning again through the rotation speed switching circuit 12. |
