| 摘要 |
PROBLEM TO BE SOLVED: To measure the light beam main scanning time between two points with high precision by an inexpensive arrangement. SOLUTION: In the image forming apparatus for forming an electrostatic latent image on a photosensitive drum 4 by irradiating the photosensitive drum 4 with a laser beam a modulated based on image data h while polarizing in the main scanning direction, when the scanning time after the laser beam a is detected by a first BD sensor 5 until being detected by a second BD sensor 6 is measured by counting a reference clock signal d and a PWM modulation clock signal e obtained by multiplying the frequency of the reference clock signal d 16 times, a component having a scanning time longer than one period of the reference clock signal d is measured by counting the reference clock signal d, and component having a scanning time shorter than one period of the reference clock signal d is measured by counting the PWM modulation clock signal e. COPYRIGHT: (C)2006,JPO&NCIPI |
