| 摘要 |
PURPOSE:To steadily and accurately prevent color slippage and to obtain a high quality image by mowing and adjusting an exposure device in such a maker that the intensity of laser beams reflected from or transmitted through a reference pattern on an image forming body becomes a set value. CONSTITUTION:When the intensity of the laser beams transmitted through the reference pattern for a resist mark 102 is detected by a photosensor FS1, a microprocessor 37 calculates a S/N value, drives a moving means 38, via a correction circuit, to obtain the set value, and focuses the laser beams of a writing system unit 19. Then, focusing is repeatedly carried out for all the laser-writing units 19-22. Subsequently, the units 19-22 are directed in the sub- scanning direction by the sub-scanning correction circuit, and time lags between the resist signals are obtained to correct displacements. Thereafter the surface of a photosensitive body is irradiated with the laser beams. Thus, focusing can be steadily and accurately carried out, and high picture quality free of color slippage can be obtained. |
