COLOR IMAGE FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To correct color misregistration on a single picture element basis in a subsidiary scanning direction, provide an inexpensive rotary polygonal mirror requiring less assembly man-hours and maintain the compatibility of a laser beam scanning unit in a tandem color image forming device equipped with a plurality of rotary polygonal mirrors. SOLUTION: The color image forming device has a position detection means to detect a writing position in a main scanning direction, a phase difference detection means of a writing position detection signal in a main scanning direction, a PLL driving means to perform the PLL control of the rotating speed of each rotary polygonal mirror and a phase control means to change the phase of a reference clock to be supplied to the PLL driving means to control the phase of each rotary polyhedron mirror. The device corrects a color misregistration in a subsidiary scanning direction by using the phase control of the rotary polygonal mirror after making a phase difference between a writing position detection signal in a main scanning direction to be a reference and a writing position detection signal in the other main scanning direction below a specified interval by the phase control means and the detection of a phase difference. COPYRIGHT: (C)2005,JPO&NCIPI