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. 20, 2005
Filed:
Feb. 24, 2003
Sadayuki Takaba, Osaka, JP;
Minoru Hirashima, Osaka, JP;
Sadayuki Takaba, Osaka, JP;
Minoru Hirashima, Osaka, JP;
Funai Electric Co., Ltd., Osaka, JP;
Abstract
A focus error signal which is a differential signal indicative of a difference between a sum of amounts of reflected light detected by photodetector elements A and C of a four-split photodetector, and that of amounts of reflected light detected by photodetector elements B and D is measured. The level of the focus error signal at a timing when the amount of reflected light from the optical disc and detected by the four-split photodetector is at the maximum is set as a reference level. The gains of amplifiersandare individually adjusted so that the maximum and minimum values of the focus error signal are substantially symmetrical about the reference level. According to the configuration, the focus control can be performed by using the balance-adjusted focus error signal, and therefore can be stably conducted.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile