Fast recovery squelch circuit for a video disc player

A squelch circuit for use in a video disc player of the kind including a video signal processing circuit and a video signal correction servo responsive to said processing circuit for producing video signal error correction signals over a given control range, said squelch circuit comprising:

• player control means responsive in a first operating mode for producing a squelch signal and responsive in a second operating mode for terminating said squelch signal;
• loss-of-carrier detector means in said video signal processing circuit for producing a loss-of-carrier output signal in response to the absence of an FM carrier input signal and terminating said loss-of-carrier output signal in response to the presence of said FM carrier input signal;
• a squelch memory circuit having first and second states;
• means for placing said memory circuit in said first state in response to the simultaneous occurrence of said squelch input signal and said loss-of-carrier input signal and for placing said memory circuit in said second state in response to the termination of said loss-of-carrier signal;
• means responsive to said squelch signal for preconditioning said video signal correction servo system to the center of its control range, and responsive to the first state of said squelch memory circuit for maintaining said video signal correction servo system in its preconditioned state.

In a video disc player the apparatus comprising:

• a video FM detector for producing a video signal;
• a defect masking circuit operable in a first mode for coupling said detected video signal to an output terminal thereof and in a second mode for supplying a substituted signal to said output terminal thereof;
• a phase-lock loop servo system having a phase comparator for comparing a component of said video signal with an output of a reference oscillator to produce an error voltage, a sample and hold circuit for storing said error voltage on a holding capacitor and means responsive to said error voltage for feeding back at least one correction signal to a point in said video disc player in a sense to minimize the error voltage on said capacitor;
• means for producing a squelch signal;
• means responsive to said squelch signal for preventing application of said video signal to said defect masking circuit and substituting therefore a non-video signal;
• and
• means responsive to said squelch signal for clamping said holding capacitor to a predetermined reference voltage, said reference voltage being of such a value as to place said servo system in the center of its control range.