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. 07, 1981
Filed:
May. 14, 1979
Masayuki Hongu, Kawasaki, JP;
Masaharu Tokuhara, Tokyo, JP;
Sony Corporation, Tokyo, JP;
Abstract
An automatic fine tuning loop in a television receiver is controlled by phase comparison between a video intermediate frequency signal and a reference oscillator signal. The reference oscillator signal is used in synchronous detection of the video intermediate frequency signal. The frequency of the reference oscillator is controlled by a phase locked loop, of which it is a part, and which includes a low-pass filter having selectable high and low cut-off frequencies. A lock-out detector selects the high cut-off frequency for rapid correction when lock-out is detected and selects the low cut-off frequency for frequency stability when lock-in is detected. An AFT disable switch disables the automatic fine tuning loop during manual tuning. In one embodiment, a disable switch ganged with the AFT disable switch selects the high cut-off frequency in the low-pass filter to prevent hunting.