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:
Sep. 01, 1992
Filed:
Mar. 01, 1991
Applicant:
Inventors:
Teruo Mozume, Yokohama, JP;
Isao Ohbu, Hachioji, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B / ;
U.S. Cl.
CPC ...
369 4414 ; 369 4412 ; 369109 ; 369112 ;
Abstract
An optical head using a refractive index distribution changeable lens by which light focused on a recording surface of an optical disc is precisely and positionally controlled. The refractive index distribution of this refractive index distribution changeable lens is changed by changing an electric field applied thereto so as to precisely displace the position of the focus point of the emitted light on the recording surface of the optical disc.