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. 01, 1999
Filed:
Oct. 08, 1997
Akira Minami, Kawasaki, JP;
Shigeyoshi Tanaka, Kawasaki, JP;
Michio Matsuura, Tokyo, JP;
Hiromichi Kuwano, Yokohama, JP;
Kazuyuki Tamanoi, Hayami-gun, JP;
Fujitsu Limited & Texas Instruments Japan, Kawasaki, JP;
Abstract
A positioning control system for performing recording/reproducing operations by irradiating an optical beam to a predetermined position on an optical recording medium, e.g., magneto-optical disk. The control system includes a photo-detector constituted by at least two-divisional units, and a servo-error signal generating circuit which can generate at least one servo-error signal in accordance with a difference between the detection currents. Preferably, the servo-error signal generating circuit includes at least one division circuit that has two pairs of transistors, two emitters in each pair of transistors being connected together into a common emitter, bias voltages of a direct current type being applied to the respective bases of transistors on one side, and the respective collectors of the transistors on one side being connected to a common connecting portion via resistors. The common connecting portion is connected to a power supply, and the respective bases of transistors on the other side are connected together into a common base. An integrating capacitor which integrates a difference between the current flowing through the common connecting portion and the reference current, is connected to the common base of the transistors on the other side.