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. 21, 1991
Filed:
Dec. 29, 1989
Koichi Sunada, Osaka, JP;
Hiroshi Sato, Osaka, JP;
NEC Home Electronics Ltd., Osaka, JP;
Abstract
A keyed type synchronization wave detecting circuit comprises a phase wave detector for synchronizing and wave detecting a composite video signal responsive to a signal for wave detection. A synchronizing signal generator provides a horizontal synchronizing signal controlled by the frequency of a horizontal synchronizing signal of the composite video signal. A keying pulse generator provides a keying pulse signal from the synchronizing signal of the synchronizing signal generator. A phase controller outputs a phase difference signal in accordance with the difference in phase between the signal for wave detection and a carrier of the composite video signal such that the phase difference approaches a predetermined level, the phase controller having a comparator for performing a keying outputting operation of the phase difference signal by the input of the keying pulse signal, and a filter for removing the high frequency component of the phase difference signal and forming a control signal. A lock detector controls the output of at least the keying pulse signal to the phase controller when it is detected that the signal for wave detection is phase-locked to the carrier. Means are provided for generating the signal for wave detection synchronized with the carrier based on the control signal.