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. 29, 1998
Filed:
Apr. 05, 1996
Yoshitaka Takahashi, Yokohama, JP;
Masami Emoto, Yokohama, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An optical pickup device includes an optical system which forms a main spot and a set of sub-spots on an optical disk by a beam of light passing the optical system. A photodetector unit outputs first signals in response to a reflection beam from the main spot, and outputs second signals in response to reflection beams from the sub-spots. A tracking error detector includes a first detection circuit designed to output a first tracking error signal for a first track pitch, and a second detection circuit designed to output a second tracking error signal for a second track pitch different from the first track pitch. A switch selectively connects one of the first detection circuit and the second detection circuit to an output of the tracking error detector in response to a track pitch of the optical disk, so that one of the first and second tracking error signals appropriate for the track pitch of the optical disk is output.