Patent ID: 8774658
Filing Date: 2014-07-08
Classification: G03G

Abstract:
1. An image forming apparatus for forming an image on a medium, having a monochrome printing mode and a color printing mode, the image forming apparatus comprising: a first photosensitive drum used in the monochrome printing mode; a second photosensitive drum used in the color printing mode; a third photosensitive drum used in the color printing mode, the first photosensitive drum, the second photosensitive drum and the third photosensitive drum being aligned sequentially in this order from an upstream side of a moving direction of the medium; charger devices provided so as to correspond respectively to the first to third photosensitive drums for charging the photosensitive drums; transfer devices provided so as to correspond respectively to the first to third photosensitive drums for transferring developer images on the photosensitive drums to the medium fed by a moving unit; and a control unit configured to control charging biases applied to the charger devices and transfer biases applied to the transfer devices, wherein the control unit executes, in the monochrome printing mode, an energy saving control in which an absolute value of a charging bias applied to the charger device corresponding to the third photosensitive drum is smaller than an absolute value of a charging bias applied to the charger device corresponding to the third photosensitive drum in the color printing mode and is smaller than an absolute value of a charging bias applied to the charger device corresponding to the second photosensitive drum in the color printing mode, wherein in executing the energy saving control, the control unit makes smaller an absolute value of a transfer bias applied to the transfer device corresponding to the third photosensitive drums.