Time-axis correcting circuit for recorded data reproducing device

A time-axis correcting circuit for a recorded data reproducing device, comprising:

• means for extracting a baseband video signal from an optical signal provided from a video disc to be reproduced;
• a first separating circuit receiving said base band video signal for separating a horizontal synchronizing signal from said baseband video signal;
• a reference signal generator;
• a first phase comparator receiving as inputs an output of said first separating circuit and a reference signal produced by said reference signal generator;
• a phase correcting circuit having an input coupled to an output of said first phase comparator, an output of said phase correcting circuit being applied to control a motor rotating said video disc;
• a first variable delay circuit receiving as an input said baseband video signal;
• a second separating circuit having an input coupled to an output of said first variable delay circuit for extracting a horizontal synchronizing signal from an output signal of said first variable delay circuit;
• a second phase comparator having a first input coupled to an output of said second separating circuit;
• a first voltage-controlled oscillator having an input coupled to an output of said second phase comparator and an output coupled to a second input of said second phase comparator;
• a second voltage-controlled oscillator having an input coupled to said output of said second phase comparator;
• a first drive circuit having an input coupled to an output of said second voltage-controlled oscillator and an output coupled to a delay control input of said first variable delay circuit;
• a second variable delay circuit having an input coupled to said output of said first variable delay circuit;
• a third separating circuit having an input coupled to an output of said second variable delay circuit for separating a color burst signal from an output signal of said second variable delay circuit;
• a third phase comparator having a first input coupled to an output of said third separating circuit;
• a third voltage-controlled oscillator having an input coupled to an output of said third phase comparator and an output coupled to a second input of said third phase comparator;
• a fourth voltage-controlled oscillator having an input coupled to said output of said third phase comparator;
• and
• a second drive circuit having an input coupled to an output of said fourth voltage-controlled oscillator and an output coupled to a delay control input of said second variable delay circuit, said first voltage-controlled oscillator and said second phase comparator forming a sub servo loop having an open-loop oscillation frequency at least close to a lowest frequency of a dominant time-axis error component to be suppressed, and said third voltage-controlled oscillator and said third phase comparator forming a sub servo loop having an open-loop oscillation frequency at least close to a highest frequency of said dominant time-axis error component to be suppressed.

A time-axis correcting circuit comprising:

• means for extracting a baseband video signal from an optical output signal from a video disc to be reproduced;
• a first separating circuit for separating from said baseband video signal a horizontal synchronizing signal;
• a first phase comparator having a first input coupled to an output of said first separating circuit;
• a first voltage-controlled oscillator having an input coupled to an output of said first phase comparator and an output coupled to a second input of said first phase comparator;
• a phase correcting circuit having an input coupled to said output of said first phase comparator and an output applied to control a tangential mirror for controlling a tangential position of an illuminating beam upon said video disc;
• a second phase comparator having a first input coupled to said output of said first separating circuit;
• a reference signal generating circuit having an output coupled to a second input of said second phase comparator;
• a signal summing circuit for summing an output of said phase correcting circuit and an output of said second phase comparator;
• a second phase correcting circuit having an input coupled to an output of said summing circuit and an output applied to control a motor rotating said disc;
• a variable delay circuit having an input receiving said baseband video signal;
• a second separating circuit for separating a color burst signal from an output signal of said variable delay circuit;
• a third phase comparator having a first input coupled to an output of said second separating circuit;
• a second voltage-controlled oscillator having an input coupled to an output of said third phase comparator and an output coupled to a second input of said third phase comparator;
• a third voltage-controlled oscillator having an input coupled to said output of said third phase comparator;
• and
• a drive circuit having an input coupled to an output of said voltage-controlled oscillator and an output applied to a delay time control terminal of said variable delay circuit, an open-loop oscillation frequency of a sub servo loop formed by said first voltage-controlled oscillator and said first phase comparator being at least close to a lowest frequency of a dominant time-axis error component to be suppressed, and an open-loop oscillation frequency of a sub servo loop formed by said second voltage-controlled oscillator and said third phase comparator being at least close to a highest frequency of said dominant time-axis error component to be suppressed.