| 摘要 |
PURPOSE:To control the specific charge of a toner to a proper value to improve the transfer efficiency by changing and applying a discharging current having the same polarity as the toner in accordance with the change of the speed of an image carrier before a latent image is transferred from the image carrier. CONSTITUTION:The electrostatic latent image of an original 0 is formed on a photosensitive body 1, which is rotated in the direction of an arrow, through an optical system by a mirror 31 and is developed in a developing part 6. The DC of a high DC power source 12 or a low DC power source 13 is superposed to the AC of an AC power source 10, and the discharging current having the same polarity as the toner is applied by a discharger 9. The speed of a motor is switched between unmagnification image formation and m-magnification (m<1) image formation, and the speed of the motor is made lower in the latter case. Simultaneously, the applied voltage is switched to the low DC power source 13 by a changeover switch 14. The quantity of light with which the photosensitive body is exposed by a lamp 15 is switched to a low voltage side 17 when the speed of the motor is lower. Thus, the specific charge of the toner is controlled to a proper value even if the speed of the image carrier is changed by the change of the image forming mode, and the transfer efficiency is improved. |
