| 摘要 |
PROBLEM TO BE SOLVED: To prolong the life of a photosensitive drum by shortening the time of application of a charging bias from a charging roller to the photosensitive drum. SOLUTION: An electrostatic latent image on the photosensitive drum is developed by applying developing biases V2 and V3 to developing sleeves 41 and 42 by developing high-voltage power sources 25 and 26. When the front end of an image formation region on the photosensitive drum 1 reaches a development section 41a, the V2 is applied to the developing sleeve 41 first, and the V3 is applied to the developing sleeve 42 y/v later, provided that (y) is the length between the developing sleeves 41 and 42 and (v) is the peripheral speed of the photosensitive drum 1. Further, when the rear end of the image formation region reaches the development section 41a, the V2 is turned off and the V3 is turned off y/v later. Consequently, the application time of the charging bias to the photosensitive drum 1 can be shortened. COPYRIGHT: (C)2006,JPO&NCIPI |
