Patent ID: 8144179
Filing Date: 2012-03-27
Classification: B41J,G02B,H04N

Abstract:
1. An image forming apparatus, comprising: a laser beam source; a plurality of photoconductive members respectively corresponding to a plurality of colors; a modulation drive unit configured to subject image data of each of the colors to pulse width modulation by an image clock having a cycle of a pixel length of the image data, and drive the laser beam source; a single piece of polygon mirror whose reflection surfaces are disposed in a rotation direction thereof with a plurality of different inclination angles respectively corresponding to the plurality of colors, and via a plurality of different optical paths respectively corresponding to the inclination angles, the polygon mirror scanning the photoconductive members with a light coming from the laser beam source sequentially for each of the colors in a main scanning direction; a plurality of beam detectors respectively corresponding to the plurality of photoconductive members, each disposed adjacent to and on an upstream side of the corresponding photoconductive member in the main scanning direction; and an image clock/data switching unit configured to generate the image clock of a frequency varying with the colors for making the same a color-based image magnification defined by an optical path length of each of the optical paths of the colors, and switch at least either the image clocks generated for each of the colors or the image data of each of the colors in synchronization with a detection signal coming from the beam detector, the image clock/data switching unit further configured to, when first, second, third, and fourth colors are switched in a sequential manner: