| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device for developing an electrostatic latent image on an image carrier, in which the fogging of a background part is prevented and sharpness is increased while securing a sufficient developing toner amount. SOLUTION: A 1st developing roller 62, a 2nd developing roller 64 and a 3rd developing roller 66 are disposed in order from a downstream side in the rotating direction of the image carrier 20 in the developing device 26. Predetermined AC bias is applied from an AC power source 82 to the 2nd developing roller 64 and the 3rd developing roller 66 on an upstream side in the rotating direction of the image carrier 20. Thus, the developing amount of the toner becomes large to be adaptive to speeding-up. Then, predetermined DC bias is applied from a DC power source 80 to the 1st developing roller 62 on the most downstream side in the rotating direction of the image carrier 20 to prevent the fogging of the background part and improve the sharpness. COPYRIGHT: (C)2006,JPO&NCIPI |
