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. 08, 2014
Filed:
May. 22, 2007
Applicants:
Kenya Nakai, Tokyo, JP;
Masahisa Shinoda, Tokyo, JP;
Nobuo Takeshita, Tokyo, JP;
Inventors:
Assignee:
Mitsubishi Electric Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11B 7/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
When using an optical disc medium that includes pit trains having their widths narrower than a diffraction limit, it is difficult to detect a tracking error signal and take a tracking-servo control while increasing pit density in a direction orthogonal to a pit-train extension direction. Information pit trains are arranged spirally or concentrically and formed in a structure in which their depths are changed periodically at a pitch radially along the optical disc medium, so that the tracking error signal can be obtained by push-pull detection of diffraction light from the structure.