| 摘要 |
PURPOSE:To execute the correction so that the surface inclination is brought close to zero by detecting a variation of a position in the sub-scanning direction of a luminous flux brought to deflection scan by a detecting means, detecting the surface inclination of the reflecting surface of a rotary deflector, and executing a control by outputting a signal to a surface inclination correcting means by a control means which inputs this detecting signal. CONSTITUTION:A light source part 36 of the upper part of an optical case 35 on a substrate 34 emits a laser beam L to a pyramidal mirror 32. In this state, when the mirror 32 rotates and write to a photosensitive body 31 is executed, a photodetector 39 placed in the outside of a write scanning area detects a variation of a position in the sub-scanning direction of the laser beam L and detects the surface inclination quantity from an original desired inclination position of the reflecting surface 32a of the mirror 32. When a housing 40 is brought to temperature rise and expands due to a temperature variation and heating of a motor 43, etc., and the surface inclination quantity of the reflecting surface 32a of the mirror 32 exceeds an allowable value, the photodetector 39 outputs a detecting signal corresponding to the surface inclination quantity to a controller 46, applies a voltage to one of lamination type piezoelectric actuators 45, inclines an axis of the mirror 32 by a difference of the expansion to the other of the actuator 45 and corrects the surface inclination quantity of the reflecting surface to zero. |
