| US 7,616,364 B2 | ||
| Scanning optical system, optical scanner, and image forming apparatus having a biconvex lens having a change of curvature of the toric surface in the cross section in the sub-scanning direction along the main scanning direction is asymmetric with an optical axis of the lens | ||
| Kenichiroh Saisho, Kanagawa (Japan); and Kohji Sakai, Tokyo (Japan) | ||
| Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
| Filed on Jan. 27, 2006, as Appl. No. 11/340,646. | ||
| Claims priority of application No. 2005-044661 (JP), filed on Feb. 21, 2005; application No. 2005-091795 (JP), filed on Mar. 28, 2005; and application No. 2005-138243 (JP), filed on May 11, 2005. | ||
| Prior Publication US 2006/0187294 A1, Aug. 24, 2006 | ||
| Int. Cl. G02B 26/08 (2006.01) | ||
| U.S. Cl. 359—207.1 [359/207.6] | 12 Claims |
| 1. A scanning-optical system that converges, with a single lens, a divergent luminous flux, which is deflected in a main scanning
direction by an optical deflector, on a surface of a scan target, the scanning optical system comprising:
a lens configured to have two surfaces in a biconvex shape in both the main scanning direction and a sub-scanning direction,
wherein
the surfaces are anamorphic surfaces,
at least one of the surfaces of the lens configured to have two surfaces in a biconvex shape in both the main scanning direction
and a sub-scanning direction is a toric surface in which a line that connects, on a cross section in the main scanning direction,
centers of curvature in a cross section in the sub-scanning direction is nonlinear, and
a change of the curvature of the toric surface in the cross section in the sub-scanning direction along the main scanning
direction is asymmetric with an optical axis of the lens.
|