| 摘要 |
PROBLEM TO BE SOLVED: To suppress a deterioration in the image quality of a laser beam scanning unit of a multibeam system. SOLUTION: The absolute value of difference between a beam pitch calculated in a step 125 and a preset beam pitch P0 (=25.4/D×(1-Δθ×M×N/(4×π)))is judged to be equal to or smaller than a threshold valueΔP (1μm, for example) (S127), wherein D stands for the resolution (dpi) in a subscanning direction,Δθ(rad) stands for the angle between adjacent laser beams, M stands for the number of faces of a polygon mirror, and N stands for the number of light sources. When the value is judged not to be equal to or smaller than the threshold valueΔP (=larger than the threshold valueΔP) (NO in S127), a wedge prism is turned into the direction in which the beam pitch P approaches the beam pitch P0 (S129), the process is returned to a step 123, the processes of the step S123 and the following steps are repeated. When the value is judged to be equal to or smaller than the threshold valueΔP (YES in S127), the process is terminated. COPYRIGHT: (C)2008,JPO&INPIT
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