摘要 |
PURPOSE:To control a developed image to constant density and to improve its picture quality by varying a bias voltage applied to a developing means synchronously with areas on a photosensitive body which are charged electrostatically for transfer and not charged when a positive image is formed from an original negative image. CONSTITUTION:A driving circuit 21 applies driving voltage HV-, HV+, and HAC to a charger 2, charger 5, and developing sleeve 4a and blade 4b under the command to a microcomputer 20. A waveform shaping circuit 22 shapes the waveform of the signal of a sensor 8 which detects whether a transfer material P is present or not and sends the waveform-shaped signal to the microcomputer 20. A bias voltage setting circuit 23 divides a constant voltage Vcc through a resistance Ra, variable resistance VR, and resistance R2. When its relay RY1 is on, the divided voltage is outputted as it is as a remote signal VREM through the contact of the relay and the developing bias voltage VDC is varied to adjust image density. |