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:
Oct. 14, 1980
Filed:
May. 25, 1979
William R Weissmueller, Wildwood, IL (US);
Zenith Radio Corporation, Glenview, IL (US);
Abstract
A two-mode digital vertical synchronization system is described for controlling the phase synchronization of vertical scan in a television receiver. In one mode, the system searches for incoming vertical sync pulses which occur during a wide sync 'window'. Sync pulses received during that window are utilized to initiate vertical scan. When the received sync pulses are in time-coincidence with an internal control signal generated at a standard line/frame rate, the system switches to a narrow window mode of operation. Vertical sync pulses received during a narrow sync window continue to initiate vertical scan. When a lack of time-coincidence between received vertical sync pulses and the control signal occurs for a predetermined interval, the system reverts to its wide window mode. Preferably, the locally generated control signal has a time duration sufficient to permit detection of coincidence between itself and a typical non-standard vertical sync pulse to hold the system in the narrow window mode, thus preventing oscillation between the narrow and wide window modes.