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. 03, 1979
Filed:
Jun. 02, 1977
Judson A Hofmann, Schaumberg, IL (US);
Zenith Radio Corporation, Glenview, IL (US);
Abstract
A television receiver has a tuner, an intermediate frequency amplifier, and a detector for recovering a composite signal including horizontal and vertical display synchronization components and picture information. Horizontal display means produce a long-duration trace signal and short-duration retrace signal and a coincidence gated AGC system which is responsive to coincidence of the horizontal retrace signal and horizontal synchronization signal controls the gain of the intermediate frequency amplifier. A combination synchronizing signal separation and AGC lock-out defeat circuit comprises a transistor, having an input electrode DC coupled to the detector, a common electrode coupled to a charge-discharge circuit such that the input-to-common electrode junction of the transistor and the charge-discharge circuit cooperate to establish a bias voltage dependent upon the occurrence and amplitude of the display synchronization signals, and an output electrode DC coupled to the AGC system. An override system response to said bias means overcomes the coincidence requirement of the AGC system to render said AGC operative solely in response to the occurrence of horizontal retrace signals when the bias indicates prolonged absence of sync pulse signals.