| 摘要 |
PURPOSE:To increase the image density of image, by selectively directing corona ions generated by discharge of a corona charger to a toner on a donor by electric field generated in accordance with a print signal. CONSTITUTION:When the surface of a toner roller 1 fitted with a toner 2 goes out from a hopper 13, the toner is uniformly positive-charged with a doctor blade electrode 3. A voltage controlled for the polarity in accordance with a print signal is selectively applied to the toner layer in positive charge via a control electrode 5, allowing to selectively give negative corona ions via a corona charger 4, and the toner only give with the ions is charged to negative. A copying paper 11 is carried between the roller 1 and a copying roller 12 in the synchronization with image forming, and only the toner with negative charge is copied through the application of the positive voltage. Thus, the copying can be made while keeping the charged potential sufficiently and the image density of image can be increased. |
