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:
Jul. 16, 2002
Filed:
Oct. 13, 1998
Takeshi Mizuno, Kanagawa, JP;
Sony Corporation, Tokyo, JP;
Abstract
An optical device having an irradiated portion formed of an optical recording medium in which a pit is formed on a reflection surface, a semiconductor unit in which a semiconductor laser, a semiconductor structure and a photo-detection element are formed on the same semiconductor substrate, and a converging device for converging a light emitted from the semiconductor laser and irradiating the same of the irradiated portion and further converging a returned light reflected from the irradiated portion. The semiconductor structure is formed near the confocal of the converging device and includes at least three reflection surfaces. The photo-detection element includes a first detection element for receiving a returned light reflected on the second reflection surface and a second detection element for receiving the returned light reflected on the third reflection surface. A first detection signal which results from detecting a diffracted light from one pit edge of the pit by the first detection element and a second detection signal which results from detecting the diffracted light from one pit edge of the pit by the second detection element are obtained. The first and second detection signals are computed to generate a tracking error signal.