| 摘要 |
PURPOSE:To form a fine picture with a simple constitution and to reduce the load of a photosensitive body cleaning device and the deterioration of toner by using developing rollers also as latent image potential detecting electrodes. CONSTITUTION:The developing rollers 12, 13 to which a bias voltage is applied from a bias device 19 on the basis of a developing solution supplied from a developing solution feeding port 28 develope a latent image formed on a photosensitive drum 1. The rollers 12, 13 are used also as potential detecting electrodes, about 90% the potential of the latent image formed on the drum 1 is detected through the developing solution and a developing bias potential level approximately equal to an average latent image potential is supplied to the rollers 12, 13 by an inpedance converting FET, transistors (TRs) Q1, Q2, TRs Q3, Q4 for amplification ''1'', Zenner diodes Z1, Z2, etc. in the bias device 19. Consequently, a fine picture faithful to the density of an original picture and having no dirt on its surface is formed with simple constitution. On the other hand, a switch 20 is turned off at a time other than a developing processing time and the potential difference between the drum 1 and the rollers 12, 13 is regarded as a low level, so that the load of the photosensitive body cleaning device and the deterioration of toner are reduced. |
