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. 18, 1989
Filed:
Sep. 29, 1986
Sadayuki Narusawa, Hamamatsu, JP;
Abstract
A circuit in a video disc playback device for detecting a state in which a disc motor rotation speed is double a normal rotation speed comprises a counter for counting a signal occurring at a timing intermediate between windows established for a timing at which a horizontal synchronizing signal is expected to occur and a double speed judgement circuit receiving a count by this counter and produces a double speed detection signal when the count has reached a predetermined value within a certain fixed period. The double speed detection signal is utilized for preventing an erroneous switching between AFC and PLL in the disc motor control such as an erroneous switching from AFC mode to PLL mode with phase locking in a double rotation speed.