| 摘要 |
PURPOSE:To reduce variation in reflection factor by correcting the variation in reflection factor affected by variation in the angle of incidence of a laser beam on a rotary polygon mirror in rotation. CONSTITUTION:The oscillation frequency of a laser oscillator 10 itself is made optionally controllable and then the influence of the variation in the angle of incidence of the beam on the rotary polygon mirror on the reflection factor is corrected. Namely, the reflection factor of the rotary polygon mirror 4 has characteristics which vary with the wavelength of the laser beam when the angle of beam incidence is made constant. The incidence angle of the incident laser beam B, therefore, varies as the rotary polygon mirror 4 rotates, and consequently even if the reflection factor of the rotary polygon mirror 4 varies, the frequency of the laser beam B is controlled by the laser oscillator 10 to minimize the variation in the reflection factor. Consequently, a latent image of high quality which has small light-shade variation is formed on a photosensitive drum to obtain a produced image with uniform density. |
