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:
Aug. 13, 2002
Filed:
Oct. 24, 2000
Noritaka Akagi, Osaka, JP;
Tsutomu Kai, Katano, JP;
Shuichi Yoshida, Osaka, JP;
Kiyoshi Masaki, Amagasaki, JP;
Teruyuki Naka, Izumi, JP;
Yasuo Kashiwagi, Saijo, JP;
Isao Takemoto, Saijo, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
In order to correct the change in the offset and amplitude of a tracking error signal because of the change in the position of an object lens from the center of an optical pickup, the offset amount and amplitude value of the tracking error signal with respect to the displacement amount of the object lens from the center of the optical pickup are checked beforehand, and the displacement amount of the object lens is estimated on the basis of a tracking correction signal by using an object lens displacement observer. An offset detection section and an amplitude detection section detect the offset amount and amplitude value of the tracking error signal respectively, and the tracking error signal is corrected by an offset correction circuit and an amplitude correction circuit on the basis of the offset amount and amplitude value having been checked beforehand so that the offset amount and the amplitude value of the tracking error signal become identical to those obtained when the displacement amount of the object lens is zero. In addition, the offset of the tilt error signal depending on the movement direction of the optical pickup is detected and recorded beforehand, and the tilt error signal is corrected on the basis of the above-mentioned recorded offset when a rotation direction detection section detects the moving direction of the optical pickup.