US 4,396,948 A · Dual mode horizontal deflection circuit

Abstract

A horizontal deflection turn-on circuit operates in the absence of trigger pulse normally derived by an AFPC loop. Under normal operation, the AFPC loop generates the trigger pulses based on a synchronized phase relationship with sampled flyback pulses. During receiver start-up, the flyback pulses are not present and no trigger pulses are generated. The turn on circuit provides auxiliary pulses which occur later in time than the normal occurrence of the trigger pulses. Means are provided for applying the auxiliary pulses to the horizontal deflection circuit only in the absence of normal trigger pulses.

Claims7

Dependent claims

In a television receiver having means for providing drive signals to a horizontal deflection circuit in a predetermined frequency and phase relationship with external synchronizing signals, said drive signals normally provided in response to horizontal rate signals generated in response to trigger pulses occurring at a horizontal deflection rate, said trigger pulses derived from a feedback signal from said deflection circuit, a horizontal deflection circuit turn-on means operating in the absence of said feedback signal comprising:

a source of horizontal rate pulses occurring during each horizontal deflection interval and later in time during a given horizontal deflection interval than said trigger pulses;
means coupled to said horizontal rate pulse source and responsive to said horizontal rate pulses only in the absence of said trigger pulses for applying horizontal rate signals to said horizontal drive signal providing means.

Dependencies are inferred from the claim text.

Dual mode horizontal deflection circuit

Life of this patent

Dual mode horizontal deflection circuit

Life of this patent

Abstract

Claims7