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:
Feb. 08, 1994
Filed:
Jul. 20, 1992
Masahiro Takasago, Odawara, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
It is intended that the relative head speed for a track in seeking is detected precisely without being influenced by track swing due to eccentricity of a disk. To this end, the current (proportional to the acceleration of an optical head) for a voice coil motor for driving an optical head is previously detected while track following control is executed and the detected data are stored in memory. In seeking, the sum of a detected current (representative of the acceleration of the head for a fixed component) and the data supplied from the memory is integrated to provide the relative speed of the head for a track. The relative speed signal is added to the differential signal of a pulsated signal of the track traversing signal of the head. The addition output represents the precise relative speed signal in consideration of track swing. If the voice coil motor is controlled so that this relative speed coincides with a target speed signal, the head speed can be controlled without being influenced by the track swing.