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:
Apr. 29, 1997
Filed:
Sep. 27, 1993
Applicant:
Inventors:
Takeshi Maeda, Kokubunji, JP;
Masahiko Takahashi, Kodaira, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01D / ;
U.S. Cl.
CPC ...
3461351 ; 346 742 ;
Abstract
A recording mark having width (disk radius direction) larger than length (disk rotation direction) is formed by using the light intensity modulation method. The recording mark is ring-shaped. The ring part differs in optical characteristic from a part surrounded by the ring part. In order to form a ring-shaped mark, laser light having predetermined intensity is continuously radiated onto the recording medium. By modulating the intensity of the laser light, information is overwritten. The ring-shaped mark is set to have a width based upon the intensity of radiated laser light and the characteristic of the recording film.