| 摘要 |
PURPOSE:To set exactly the exposing position on a photosensitive body, and to prevent a shift of a multiple transfer by stopping a color separation filter at a reference position, and thereafrer, displacing it in accordance with a correction quantity. CONSTITUTION:A filter provided between a photosensitive body and a lens is displaced by an angle theta clockwise or counterclockwise, corrects an overdelay or an overadvance of scanning, and prevents the generation of a shift of an image. A correction quantity X of an image shift on the photosensitive drum is derived. from a correcting angle theta displaced from the reference position of the filter and a thickness (t) of the filter. When a refractive index of air in the optical path, and a refractive index of the filter are denoted as n0 and n1, respectively, the correction quantity X is derived from an expression ( I ). theta' in the expression ( I ) is determined by an expression (II). This X corresponds to a shift generated in the incident position to the filter and an emitting position from the filter on the basis of displacing the filter by an angle theta from the reference position, and the image shift can be prevented by selecting an angle Q in accordance with a position variation of the scanning system and the photosensitive drum, etc. |
