| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical scanner in which the curvature of an image field and a distortion aberration in a main scanning direction, and the curvature of an image field and the fluctuation of a magnification in the vertical scanning direction or the like are excellently corrected, so that the optical scanner is suitable for a highly definite printing with a compact structure, and to obtain an image forming apparatus using the optical scanner. SOLUTION: The optical scanner comprises: a light source means; a rotating polygon mirror which deflects and scans a luminous flux emitted from the light source means; an incidence optical means for causing luminous flux emitted from the light source means to be incident on the deflecting face of the rotating polygon mirror; and a focusing optical means which focuses the luminous flux deflected and scanned on the deflecting face of the rotating polygon mirror onto a face to be scanned. In the above-described optical scanner, when the fθcoefficient of the focusing optical means is defined as k and the effective scanning width thereof is defined as W, the condition of k/W≤0.6 is satisfied. The shapes of the incident face and the emitting face of a first lens arranged on the deflecting means side and of a second lens arranged on the side of the face to be scanned, which constitute focusing optical means, are appropriately set. COPYRIGHT: (C)2007,JPO&INPIT |
