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:
Dec. 14, 1993
Filed:
Oct. 29, 1992
Applicant:
Inventor:
Yuzo Ono, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369110 ; 369 4423 ; 369 4442 ; 369112 ; 369120 ;
Abstract
An optical head comprises a grating lens for diffracting light beam separated from the light beam path. The grating lens is composed of a plurality of regions having different focal length and diffraction direction so that the light beam is divided into a predetermined number of light beams. Therefore, a conventional beam splitter or polarizing beam splitter is replaced by a grating lens so that the optical head can be smaller and lighter, and the precision of detecting a track and focus errors is improved.