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. 01, 1986
Filed:
May. 31, 1983
Shigeki Inoue, Toyokawa, JP;
Takao Arai, Yokohama, JP;
Yukio Fukui, Yokohama, JP;
Takashi Takeuchi, Fujisawa, JP;
Harushige Nakagaki, Toyokawa, JP;
Masafumi Nakamura, Yokohama, JP;
Tatsuo Baba, Aichi, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A servo circuit for a signal reproducing apparatus for reproducing signals from a record medium such as a disc utilizing an optical pickup, wherein a variable gain amplifier is arranged in a servo loop between a pickup and an actuator so that the pickup is caused to track a signal track in accordance with a servo error signal produced by the variable gain amplifier. A playback condition of a disc is discriminated by detecting the number of errors in a signal reproduced from a recorded signal on the disc by the pickup, and a gain of the variable gain amplifier is controlled by the discrimination output so that the variation of the servo error signal caused by a difference in reflectance between individual discs is eliminated and a loop gain appropriate to an individual disc is automatically set.