Instant-on circuit for a television receiver

Claim 1

In a supply circuit for powering the filament of a cathoderay kinescope of a television receiver of the type including a horizontal oscillator and a horizontal deflection system including first and second switching means operable between conductive and non-conductive states for providing trace and retrace portions of developed horizontal deflection currents to said cathode-ray device and for generating such high voltages as are necessary for the reproduction of transmitted image signals applied to said device via included signal processing stages within said receiver, the combination comprising: a source of alternating voltage; first means coupling said voltage source to energize said horizontal oscillator to provide oscillation output signals to said second switching means of said horizontal deflection system for alternatively operating it and said first switching means of said deflection system in their conductive and nonconductive states in providing said deflection retrace and trace currents, respectively; second means coupled to said second switching means for providing energizing potentials for said cathode-ray filament to power said kinescope, said potentials being of a magnitude dependent upon the relative conduction time of said second switching means in providing said retrace current as compared to that of said first switching means in providing said trace current; third means coupled to said voltage source for providing energizing potentials for said signal processing stages for developing said image signals for reproduction; said third means including third switching means for energizing said signal processing stages when it is desired to enable image reproduction by said television receiver and for deenergizing said signal processing stages when it is desired to disable said image reproduction, with said third switching means being additionally coupled to inactivate said first switching means providing said trace portion of horizontal deflection current when image reproduction is disabled, to alter the relative conduction times of said first and second switching means in a direction to reduce the magnitude of energizing potential continuing to be applied to said cathoderay filament via said second switching means and said horizontal oscillator continuing to provide oscillation output signals thereto, even though said receiver is switched to its non-operative condition.