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:
Aug. 25, 1992
Filed:
Dec. 04, 1990
Takashi Shiraishi, Tokyo, JP;
Ken Omura, Tokyo, JP;
Naruhito Yoshida, Yokohama, JP;
Masao Yamaguchi, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In an optical unit used for a laser beam printer, a laser beam generated by a laser diode is converted by a group of conversion lenses into a laser beam having a predetermined-size cross section. The laser beam is directed toward a photosensitive body by a scanner, so as to scan the photosensitive body at a constant speed. A focusing lens allows the rotating angle of the reflecting faces of the scAnner to correspond to a desirable point on the surface of the photosensitive body. In other words, the rotating angle is made to correspond to the distance between the optical axis center determined with respect to a main scanning direction and a point to which the laser beam is irradiated for scanning. The focusing lens is arranged between the scanner and the photosensitive body and shapes the laser beam reflected by the scanner such that the laser beam has a desirable diameter. The focusing lens has a toric surface which is formed on the side closer to the scanner than the other and which is rotation-symmetric with reference to an axis extending in the main scanning direction. The cross sectional shape of the focusing lens is concave in a plane expanding in the main scanning direction and is convex in a plane expanding in a sub-scanning direction.