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. 06, 1999
Filed:
Sep. 26, 1996
Akitomo Ohba, Tokyo, JP;
NEC Corporation, , JP;
Abstract
A tracking error detecting unit outputs a tracking error signal for two types of optical disks having different recording densities. The tracking error detecting unit includes a diffraction grating for generating first- and second-order beams and a photodetector having detecting sections for receiving zero-, first- and second-order beams to generate reproduced signal, first pair of detected signals and a second pair of detected signals, respectively. The tracking error detecting unit outputs a difference between the first pair of detected signals in the case of a high density disk and outputs the difference between the second pair of detected signals in the case of an ordinary density disk to output a tracking error signal.
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