The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 18, 1991
Filed:
Jul. 10, 1989
Akira Arimoto, Kodaira, JP;
Susumu Saito, Hachioji, JP;
Yoshito Tsunoda, Tokyo, JP;
Shigeo Moriyama, Tama, JP;
Takeshi Mochizuki, Mito, JP;
Hitachi, Ltd., Tokyo, JP;
Hitachi Koki Co., Ltd., Tokyo, JP;
Abstract
An optical scanning apparatus has a scanning lens with a rotationally asymmetric aspheric surface having individual curvature radii in the main scanning direction and in the sub-scanning direction. The curvature radius in the sub-scanning direction is asymmetrically increased in the lateral direction with the distance from the optical axis. A field curvature aberration which may be generated in the sub-scanning direction on the scanning surface due to an oblique incident of optical beams on the rotating polygonal mirror or the movement of the reflective surface caused by rotation of the rotating polygonal mirror is compensated for by the scanning lens and the focusing properties of the system can be kept at a level of high resolving power.