| 摘要 |
PURPOSE:To obtain a fog-free good black and red image in a two color electrophotographic method, by setting potential on a photoreceptor after forming an electrostatic latent image, the bias potential of black and red developing machines in accordance with the potential of the photoreceptor especially white areas as a standard. CONSTITUTION:A photosensitive drum is subjected to primary negative electrostatic charging with a primary charging corotron 1. Then, it is subjected to secondary positive charging with a secondary charging corotron 3 at the same time as it is imagewise exposed through a blue filter 9. Next, it is imagewise exposed through a red filter 10, and the surface potential is detected with an electrometer 45. A fog-free good black and red two color image is obtained by applying the optimum bias to black and red developing machines using this potential as a standard. In this process monitoring the standard potential, each bias voltage can be changed in accordance with this standard value, thus permitting perfect prevention of inferior development. |
