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:
Mar. 21, 1989
Filed:
Sep. 10, 1986
Shinzi Aoshima, Hamamatsu, JP;
Sadayuki Narusawa, Hamamatsu, JP;
Yamaha Corporation, Hamamatsu, JP;
Abstract
In one aspect of the invention, a disc motor control circuit in a disc playback device comprises a rotation detection circuit for detecting the rotation speed of a disc motor and producing a rotation detection signal, a first control circuit for controlling the rotation speed of the disc motor by comparing the rotation detection signal with a reference clock, a second control circuit for controlling the rotation speed of the disc motor by comparing a synchronizing signal taken out of a reproduced signal from the disc with a reference clock, a window circuit for establishing a window for an expected timing of a next synchronizing signal on the basis of the synchronizing signal taken out of the reproducing signal, a state detection circuit for detecting a state of rotation of the disc motor by counting the number of the synchronizing signal entering the window and a mode switching circuit for selectively operating one of these control circuits in accordance with the result of counting in the state detection circuit.