| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent generation of streaks when a surface exposure and a spiral exposure are carried out. SOLUTION: The phase of a light deflector is synchronized with the rotation of a drum by a drum starting point detection signal generated once every time the drum rotates once, and a two-dimensional image of one frame formed by a light source group arranged in two dimensions is made still relatively on a recording medium to expose one frame. Then, an optical system is vertically scanned and moved by an amount of an integral multiple of a pitch of pixels which form the one frame. At the same time, the angle of the light deflector is deflected by an amount of one frame in a horizontal scanning direction. An amount of one rotation of the drum is exposed. At an exposure time by the amount of a next rotation of the drum, if there is brought about a deviation in the vertical scanning direction, a vertical scanning moving speed is changed in a non exposure time zone before the exposure by the amount of the next rotation of the drum, whereby the deviation in the vertical scanning direction is corrected.</p> |
