| 摘要 |
PROBLEM TO BE SOLVED: To reduce the quantity of toner transferred to a photoreceptor from a developing roller by making the output of the application of developing bias supply variable and controlling the output of the application of the developing bias supply, in accordance with the total rotational time of the developing roller. SOLUTION: When the potential difference between a developing bias potential and the surface potential of the photoreceptor 1 is made small, the quantity of the toner stuck to the photoreceptor 1 is reduced. At this time, an MPU 22 monitors the rotational time of the developing roller 9 clocked by a timer 23 and controls the output of bias supply 21, so that the potential difference between the developing bias potential and the surface potential of the exposed photoreceptor 1 is made small based on the monitored result, so that the quantity of the toner stuck to the photoreceptor 1 is reduced. Thus, the developing bias potential is controlled to always keep a dot diameter constant regardlessly of the increase of the quantity of the toner on the developing roller 9 with the lapse of time and stable gradation can be obtained. |
