| 摘要 |
PURPOSE:To eliminate the misregistration of rasters by the surface inclination of a rotary polygonal mirror by dicontinuously writing the rasters on a recording material by using the rotary polyhedral mirror which has the inclinations varying from each other with respect to a revolving shaft and by continuing the many rasters by the same specular surfaces of the rotary polyhedral mirror. CONSTITUTION:A polygonal mirror 14 is designed to deflect a laser beam 26 in one-dimensional direction and has the plural specular surfaces. Since these specular surfaces are mounted at the angles varying from each other with respect to the mirror 14 and the revolving shaft 30, the mirror is rotationally driven at a prescribed sped by a driving source. The rasters formed by the rotation of the mirror 14 have, therefore, spaced intervals from each other and the writing sequence of the rasters is discontinuous. Since n-pieces of the rasters by the same specular surface can be continued on the recording material A in this way, the space period in one rotation of the mirror 14 is apparently increased and the period of the fluctuation in the density generated by the rotation of the mirror is increased. The rasters are thereby so positioned as to lower the visibility of the unequal densities in the human visual sensation. The misregistration of the rasters by the surface inclination is thus lessened. |
