JPH0195681A - Time base correcting circuit for video disk player - Google Patents

Abstract

PURPOSE:To correct the time base of a regenerative MUSE signal even when the S/N of a regenerative pilot signal is deteriorated by correcting the time based on the phase fluctuation of the regenerative pilot signal and the phase fluctuation of the regenerative horizontal synchronization signal. CONSTITUTION:A synchronization phase error detecting signal, which is a D/A conversion output, is removed from a band area compression decoder, inputted into a video disk player, and supplied through a switch 19 to an adder circuit 17. The switch 19 is closed by the generation of the synchronization detecting signal derived from a frame synchronizing detector circuit 27. Consequently, when a horizontal synchronization pulse is correctly derived on a band area compression decoder side, the synchronization phase error detecting signal is inputted to the adder circuit, and based on each phase error between the regenerative pilot signal and the horizontal synchronization signal, a jitter is corrected. Thus, even when the S/N of the pilot signal is deteriorated, the time basis correction of the regenerative band area compression video signal (the regenerative MUSE signal) is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an improvement in a time axis correction circuit for a video disc player that reproduces high-quality video signals.

(B) Prior art A band compressed video signal (MUSID signal) obtained by band compressing a high-quality video signal using a multiplex sub-Nyquist sampling encoding method forms a horizontal synchronizing signal of positive polarity, and is in an analog state. Synchronous separation is not easy.

Therefore, Japanese Patent Application Laid-Open No. 1989-191589 (H04N9
/81), when recording a MUSE signal on a video disc record, a constant frequency pilot signal is frequency multiplexed onto the FM modulated MUSE signal, and the phase fluctuation of the reproduced pilot signal is detected during playback to record the video disc record. Time axis correction has been made.

Vl Problem to be Solved by the Invention However, in the case of the above-mentioned prior art, the pilot signal level to be multiplexed is
It is set to 20 dB or less with respect to the FM-MUSE signal so as not to cause beats in the reproduced output. Therefore, focusing on the fact that the band compression decoder connected to the reproduction pilot signal disc player detects the horizontal synchronization signal, the time axis correction of the reproduction MUSE signal is performed based on the reproduction horizontal synchronization signal.

B) Means for Solving the Problems Therefore, the present invention provides a first phase comparison means for detecting phase fluctuations of a reproduced pilot signal, and a second phase comparison means for detecting phase fluctuations of a reproduced horizontal synchronization signal obtained from a band compression decoder. The present invention is characterized in that it includes a comparison means and a jitter correction circuit that performs time axis correction based on the outputs of both phase comparison means.

(e) Operation According to the present invention, time axis correction is performed based on the phase fluctuation of the reproduced pilot signal and the phase fluctuation of the reproduced horizontal synchronization signal.

(f) Example Hereinafter, the present invention will be explained according to an illustrative embodiment.

First, FIG. 1 shows a circuit block diagram of the video disc player of this embodiment. As is clear from this figure, the pickup (3) that optically plays back the disc record (1)
) is input to a bypass filter (5) K via an equalizer (4), where a reproduced FM band compressed video signal is separated and derived. This bypass output is connected to the FM demodulation circuit (6
), the signal is input to a de-emphasis DO path (8) via a low-pass filter (7), and is output as the output of the video disc player.

On the other hand, a low-pass filter (9) Fi inputting the pickup output □ separates and derives the reproduced pilot signal component, and the reproduced biloft signal is further waveform-shaped in the subsequent pilot detection circuit Q□. The waveform-shaped reproduced pilot signal is sent to the PLL that constitutes the disk servo circuit.
The first phase comparator circuit Q that constitutes the circuit plane and the time axis correction circuit
[Each is input. Disk servo circuit FiPLL
By dividing the output in the frequency dividing circuit (2), the frequency divided output is used as a comparison input of the frequency comparison circuit (α), and by using a fixed base value, a frequency comparison result is formed.

This frequency comparison output is input to the motor driver circuit to rotate the disk motor (2) 11i1Ja.

In addition, the first phase comparison circuit member is the reference signal generation circuit 03)
A first phase comparison output is formed by using the output of the reference input as a reference input and using the waveform-shaped regenerated pilot signal as a comparison input. This first phase comparison output is input to the jitter mirror driver α0 via the adder circuit (14), and is input to the pickup (3).
) is driven to perform time axis correction. The configuration described above is a well-known configuration for a video disc player.

The playback band compression video signal derived from the video disk player mentioned above is input to the band compression decoder shown in FIG. This band compression decoder first inputs the band compression video signal into the AD conversion circuit and performs AD conversion. ) is entered. The still image processing circuit (2) Fi forms still image data using the successive data of frame memory 0 and AD conversion data, and the moving image processing circuit Q2 forms moving image data from the AD conversion data. Mixing circuit (241II'i) Changes the mixing ratio of moving image data and still image data according to the movement of the screen and forms mixed data.TO decoding circuit Wt-t that inputs the mixed data, color component and luminance component The signals are derived simultaneously and converted into analog signals in the next-stage DA conversion circuit (2), thereby converting them into the original surface quality video signals.

On the other hand, the ADi conversion data is also input to the frame synchronization detection circuit and the horizontal synchronization detection circuit (support). The horizontal synchronization detection circuit @ forms and derives horizontal synchronization pulses corresponding to each horizontal synchronization timing based on the frame synchronization detection output,
This horizontal synchronization pulse is supplied as a reference input to the second phase comparison circuit. Also, this second phase comparator circuit i#-tP
It constitutes a part of the LL circuit, and the divided output of the frequency divider circuit (to) is input for comparison and fed back. Further, the second phase comparator circuit digitally counts and derives the phase difference between the horizontal synchronizing pulse and the branch output, and latches the count output of the next stage latch circuit. Latch data is D
After A conversion, the oscillation frequency of the voltage controlled oscillation circuit Q is controlled. Note that this oscillation output is used as a timing clock for the digital signal processing described above.

In the configuration described above, the features of this embodiment are as follows. That is, in this embodiment, the synchronous phase error detection signal, which is the DA conversion output, is extracted from the band compression decoder, inputted into the video disc player, and supplied to the adder circuit Roku via the switch a9. The circuit is closed by the generation of a synchronization detection signal derived from the frame synchronization detection circuit.

Therefore, according to this embodiment, when the horizontal synchronization pulse is correctly derived on the band compression decoder side, the synchronization phase error detection signal is input to the adder circuit, and the jitter is calculated based on each phase error between the reproduced pilot signal and the horizontal synchronization signal. , a correction is made.

(G) Effects of the Invention According to the present invention, even if the SN of the pilot signal deteriorates, time axis correction using the horizontal synchronization signal is possible, and the effect is significant.

4. Fl! The explanatory diagrams on page J each show one embodiment of the present invention, with FIG. 1 showing a circuit block diagram of a video disc player, and FIG. 2 showing a circuit block diagram of a band compression decoder.

α■...First phase comparison circuit, ■...Second phase comparison circuit.

Claims (1)

[Claims] (1) FM-modulate a band-compressed video signal obtained by band-compressing a high-quality video signal using a multiplex sub-Nyquist sampling encoding method, and play a video disc record by frequency-multiplexing recording of a fixed-frequency playback pilot signal. In a high-definition video playback system that includes a video disc player and a band compression decoder that inputs the playback output of the video disc player and regenerates a high-definition video signal, detecting phase fluctuations in a playback pilot signal. a first phase comparison means for detecting a phase fluctuation of a horizontal synchronization signal obtained from a horizontal synchronization separation circuit in the band compression decoder; A time axis correction circuit for a video disc player, comprising: jitter correction means for correcting the time axis of a reproduced signal based on the output of the phase comparison means.