| 摘要 |
PURPOSE:To obtain an excellent image without back soiling of an image receiving paper by impressing the same polarity voltage to a coloring powder body on a transfer roller and actuating an exposure means when the image receiving paper does not exist between an electrostatic latent image carrier and a transfer roller. CONSTITUTION:The surface of a photoreceptor 1 is electrostatically charged to be negative by using a corona discharge device 2 and a latent image by the surface charge of the photoreceptor 1 is developed by a developing device 4 by an exposure device 3. Since a developing electrode 4a holding toner on the surf ace is opposed to the photoreceptor 1 where the latent image is formed and an approximate developing bias to the surface potential of the photoreceptor 1 is impressed on a power source 4b, the latent image is developed by attaching the toner 12 electrostatically charged to negative polarity on a part exposed by the exposure part 3'(the surface potential of the photoreceptor is low) (reversal developing method). Then, the image receiving paper 10 is supplied to a contact part between the photoreceptor 1 and the transfer roller 5 at the same time as the photoreceptor 1 reaches the contact position with the roller 5. Since constant current of opposite polarity to the toner 12 is impressed on the roller 5, the toner is transferred on the paper 10 by electrostatic force. |
