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:
Feb. 24, 2009
Filed:
Feb. 26, 2002
Applicant:
Fumio Isshiki, Kokubunji, JP;
Inventor:
Fumio Isshiki, Kokubunji, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B 7/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
An indirect semiconductor laser having an indirect semiconductor used as the material of an active layer is used, instead of a conventional direct semiconductor laser so as to obtain a reproducing optical source, in order to reduce optical interference noise of the laser caused in the optical head in an optical disc apparatus, and to eliminate the necessity of high frequency wave convolution, thereby it is possible to reduce the cost.