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:
May. 30, 1989
Filed:
Dec. 14, 1987
Keiji Nakatsu, Amagasaki, JP;
Shigeo Hayashi, Amagasaki, JP;
Masaharu Ogawa, Amagasaki, JP;
Osamu Itou, Amagasaki, JP;
Isao Watanabe, Amagasaki, JP;
Kunimaro Tanaka, Amagasaki, JP;
Abstract
A device for driving and controlling an optical head by forming a spot of a light beam on an optical disk having a plurality of tracks and detecting light from the spot reflected on the optical disk by a pair of optical detectors disposed in the head. This device has: a head actuator for moving a movable portion of the optical head in the radial direction of the disk; a speed detector for detecting the track-crossing speed of the spot from outputs from the optical detectors; a reference speed generator for generating, while accessing to a target track, a reference moving speed signal in accordance with the distance to the target track obtained from the outputs from the optical detectors, the movable head portion being moved on the basis of the reference moving speed signal so that the speed of the movable portion decreases at a position near the target track before the light beam spot reaches this track; a speed error detector for obtaining the difference between outputs from the reference speed generator and the speed detector; and a magnification change circuit adapted for amplifying the outputs from the reference speed generator and the speed detector by a predetermined multiplying factor when the distance between the light beam spot and the target track, or the crossing speed of the spot, becomes smaller than a predetermined value, the magnification change circuit also being adapted for outputting the difference obtained by the speed error detector after multiplying it by the reciprocal of the multiplying factor. The head actuator is driven on the basis of the output from the error detector so as to control the speed of the movable head portion.