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:
Jun. 24, 1997
Filed:
Nov. 02, 1995
Tatsuya Murata, Tokorozawa, JP;
Teac Corporation, Tokyo, JP;
Abstract
A first servo unit controls a rotational speed of an optical disc using a reproduced signal obtained as a result of reading a signal previously written on the optical disc. A second servo unit controls rotation of the optical disc using a rotation detection signal obtained as a result of measuring a rotational speed of a disc motor which drives the optical disc. A determining unit determines that the second servo unit is to perform a disc-rotation-speed control operation when it is determined that a disc-rotation-speed control operation performed by the first servo unit is not possible. The determining unit determines that the first servo unit is to perform the disc-rotation-speed control operation when the rotation speed of the optical disc is a predetermined one. The optical disc has a plurality of recording regions, the plurality of recording regions having different recording modes for recording signals therein such that a polarity of the reproduced signal relevant in a tracking control operation is different in response to a change of a currently scanned recording region among the plurality of recording regions. The determining unit further changes the polarity of the reproduced signal relevant in the tracking control operation when it is determined that the disc-rotation-speed control operation performed by the first servo unit is not possible.