METHOD OF DETECTING POSITIONAL DEVIATION IN LASER SCANNING ON PHOTORECEPTOR, METHOD OF CORRECTING IT, AND LASER COLOR IMAGE FORMING DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent a color slurring from occurring because the distance between a laser scanner and a photoreceptor is dispersed in respective colors due to an attaching error and temperature fluctuation in a laser color image forming device. SOLUTION: A horizontal synchronizing signal detector 18 detects the start of laser scanning and outputs a horizontal synchronizing signal pulse. A pattern generator circuit 4 generates an image pattern for detecting positional deviation in printing while setting such a pulse as reference. A laser driver 6 drives the laser scanner 8 including a laser based on an image signal from the circuit 4. A reflection density sensor 1 detects the difference of the density of a printing positional deviation pattern formed on a photoreceptor belt 10 and inputs it in a CPU 9. The CPU 9 calculates the positional deviation in printing in a main and sub scanning directions, calculates the frequency of a clock to be outputted from a clock generator circuit 5 and laser scanning start timing and sets the values in the circuit 5. Thus, the color slurring on the photoreceptor is eliminated.