| 摘要 |
PROBLEM TO BE SOLVED: To realize an optical scanner where a spot diameter deviation of the main scanning luminous flux is small on a surface to be scanned. SOLUTION: In the optical scanner, a light source 1, a light source driving means to light up the light source 1 according to the image information, a deflecting means 5 to deflect the luminous flux from the light source 1 and scan focusing optical systems 7 and 8 conducting the luminous flux from the deflecting means 5 to the surface to be scanned are provided. In this case, the following conditions: 1. deflecting angleϕby the deflecting means is not varied in conformal speed, 2. on the assumption that the deflecting means is moved at conformal speed, the linearity deviation in a range within an effective writing width is <=10% are satisfied. That is, by using the deflecting means where the deflecting angleϕis not varied by conformal speed, banding due to oscillation, the rise in temperature, noise and increase in consumed energy can be reduced and by making the linearity deviation <=10% when being deflected at conformal speed in the range within the effective writing width, the deviation in the beam spot diameter of the main scanning luminous flux can be reduced.
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