| 摘要 |
PURPOSE:To prevent the development of a nonelectrified part in synchronization with the start of an image forming device even in a contact electrification system by employing a contact electrification power source as a source supplying current to a constant voltage circuit. CONSTITUTION:A constant voltage power source 15 is used as the power source for contact electrification. The power source 15 is connected to an electrification roller 14 and also connected to a Zener diode 8, composing the constant voltage circuit, via a resistor 6. One of the terminals of the Zener diode 8 is connected to the conductive base of a latent image carrier 11 which is downstream from the roller 13 and the other of the terminals is grounded. At the same time the image forming device operates, the electrification power source 15 is turned on. At the same time the latent image carrier 11 starts to move, current flows in the Zener diode 8. Thus, during the switching of bias between the latent image carrier 11 and the developing roller 17a to zero for the prevention of unnecessary sticking of toner, a development preventing electric field is generated to prevent toner from unnecessarily sticking to a nonelectrified area. After the non-image area passes through a developing part, the development can be normally carried out. |
