JPS61240478A - Disc-servo circuit for high quality video-disc player - Google Patents

Abstract

PURPOSE:To attain synchronized pull-in even for a large variation in revolution by changing the variable frequency division ratio when the revolution of a disc record goes out of a narrow phase control range, and by supplying a revolution control output to the disc motor based on the frequency division output. CONSTITUTION:The oscillation frequencies of the first, second, and third oscillation circuits 6-8 are fixed at one 2<1/2>-times of that of the pilot signal and at one 1/2<1/2>-times likewise. A comparator circuit 12 outputs a comparison output when the first rectification output is larger than the third one. A discriminatory circuit 13 outputs a discrimination output when the second rectification circuit level exceeds a threshold. When the rotation of the disc lowers, a control voltage is supplied to the third control terminal T3 of a variable frequency division circuit 15 in order to extend the period of the frequency division output long enough even if a PLL circuit 14 shows a wrong oscillation frequency. But when the rotation excessively rises, the control voltage is supplied to the first control terminal T1, and the period is made shorter. The output from the circuit 15 is supplied to a frequency control circuit 16 to drive the disc motor by frequency control driving at the time when the motor is being at a speed other than the normal one.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention relates to a disc servo circuit for a high-definition video disc player.

(b) Conventional technology Regarding a method for optically recording and reproducing a high-quality video signal using a 1TcI multiplexed subsampling method and band-compressed MUSE signal on an entire disk, the applicant previously filed a patent application filed in 1986-47.
In No. 764, a method was proposed in which a constant frequency pilot signal is frequency multiplexed and recorded on recording information obtained by modulating the MUSE signal 7F'M. According to this method, jitter correction can be performed without detecting all the horizontal synchronization signals in the MUSE signal.

Furthermore, in Japanese Patent Laid-Open No. 59-238115, the applicant displaces the elivic up to the phase comparison output of the regenerated pilot signal and the reference signal, and the frequency-divided output of the regenerated pilot signal and the frequency-divided output of the reference signal. We have proposed a structure to control the rotation of a disk motor using the phase comparison output of .

According to this method, even if the disc record is a constant linear velocity recording type, it can be reproduced.

→ Problems that the invention aims to solve In the conventional example described above, the level of the reproduced pilot signal is set to -20 dBa degrees in order to prevent the generation of beats between the reproduced pilot signal and the recorded information. When extracting , it is advantageous to use a resonant circuit with a high Q value. However, the tracking range of the resonance circuit for the injected playback pilot signal is narrow, and when rotational fluctuations occur in the video disc record, the resonance circuit may resonate at a frequency other than the playback pilot signal, and the rotational state of the disc record may be affected. It becomes difficult to check the ninth time when it cannot be detected correctly.

2) Elaborate means for solving the problem Therefore, the present invention provides a first resonant circuit that resonates at a frequency higher than the regular pilot signal frequency, and a @2 resonant circuit that resonates at a frequency that matches the regular pilot signal frequency. and 2 resonates at a frequency lower than the regular pilot signal station wave number! 3 resonant circuits, 2 comparison circuits that compare the respective levels of the first resonance c6 and the third resonance output, a discrimination circuit that detects that the level of the second resonance output exceeds a predetermined level, and the second A variable frequency divider circuit inputs a resonance output circuit, sets a frequency division value to a predetermined value when the discrimination output is generated, and changes the frequency division value completely according to the comparison output when the discrimination output is deactivated; 2. A phase control circuit that compares all phases of the output and reference signals and supplies a phase control output to the disc motor; and (2) a frequency control circuit that supplies all of the frequency control outputs to the disc motor based on the frequency division output when the discrimination output is deenergized. and? , each one should be arranged! -Characteristics.

(E) Effect Therefore, in the present invention, if the rotation of the disk record is outside the narrow phase control range, 1! The comparator circuit identifies all rotational discrepancies, switches the variable frequency division ratio, and supplies rotation control output to the disc motor based on the frequency division output, making it possible to synchronize even a large rotationally passive motor. .

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

In this embodiment, the present invention is applied to a video disc player that optically uses a video disc record that is made by recording an FM-MUSK signal and a pilot signal in a full frequency multiplexed manner. 9 is shown, and FIG. 2 is an explanatory diagram of the joint gripping characteristics.

In this embodiment, the playback output obtained from the pickup (11) is amplified by the preamplifier (21) and input to the 1 bus filter + 31 draw pass filter (4).The playback FM obtained by the bypass filter + 31Jc!II
- The MUSE signal is FM demodulated by the next stage FM demodulation circuit (51) and supplied to the MUSE decoder. On the other hand, the reproduced pilot signal obtained from the low-pass filter is sent to the first, second and third resonant circuits +6H70R1. is input.

The second resonant circuit (7) has its resonant frequency set to the full regular pilot signal frequency of 2,27585 MH2, and the first resonant circuit (61) has its resonant frequency set to 5 times (-3) the regular pilot signal frequency. ,21854MH2)(
f 1 )<, Furthermore, @3 resonant circuit (8:
> times (-1,60927MHz).

Therefore, the empathic output characteristics of each empathetic circuit are A in fa2 diagram,
Venus will have the characteristics shown in B and C1. Therefore,
1st, 2nd, 3rd resonance output? 1st, 2nd, 3rd input
The rectifier circuit f9 derives the rectified output according to the resonance output level by detecting each resonance output.The comparator circuit fi21 inputs the first rectified output and the third rectified output and compares them. , and when the first rectified output is larger, an Irepel comparison output is derived. That is,
In the range (a) in Figure 2, no comparative output is derived, and the range (
In b), comparative deba is derived. '! 7? :, the discrimination circuit a3 inputted with the M2 rectified output is 1[2'! A determination output is derived when the outflow level exceeds the threshold level (θ). That is, the discrimination output is derived only in range (d) in FIG. In addition, the range (d) is.

This is the range in which the @22 resonance path (7) can sufficiently follow the fluctuations of the reproduced pilot signal. On the other hand, the second resonant circuit (71
The output of
14 and is converted into a continuous oscillation output with no dropout. This PLL output is used as a counting input of the variable frequency divider circuit 19. This variable frequency divider circuit changes the frequency division value to 1/
and 17 and "1st, 2nd, and 288"
The f85 control terminals (T1) (T2) (T3) are completely blinded, and when a 1 discrimination output is generated, the full control voltage is applied to the second control terminal (T2) and the frequency division value is set to the normal "ra4".

Also, both the discrimination output and the comparison output are in a deactivated state.

When the rotational speed of the disc record decreases, the control voltage is applied to the third control terminal (T3) and the frequency division value is set to t"288. Therefore, when the reproduction pilot signal frequency is within the range (0) Even if the PLL circuit σ core erroneously exhibits the nine-engine frequency, the period of the divided-by-2 frequency output will be longer than that.Furthermore, the discrimination output is deactivated and a comparison output is generated, causing a disc and the rotation of the code. When the voltage rises too much, the control voltage is input to the first control terminal (T1) and the 1 frequency division value becomes 17.
It is set to 72. Therefore, when the reproduced pilot signal frequency is within the range (θ), even if the PLL circuit a1 erroneously sets the oscillation frequency, the period of the 1-frequency output will be more than that. The output of the variable frequency divider circuit (15) is input to the 1 frequency control circuit 1e and the phase control circuit aη.The phase II'IJ8 circuit αη is supplied with a reference signal equal to the regular frequency division period to the reference oscillation circuit. 0919 is manually operated.The frequency control output and the phase control output are input to the switching circuit a9.This switching circuit (IQ) uses the discrimination output as the control input.
When the discrimination output is generated, the phase control output t- and when the discrimination output is deactivated, the frequency control output is input to the disk drive circuit (2).

Therefore, the disk motor is driven by phase control in a steady rotation state, and is driven by frequency control in other states.

(g) According to the present invention, even when the reproduced pilot signal frequency deviates significantly from the original frequency 19 at the time of start-up or rotational fluctuation, and the second resonant circuit cannot follow it, the servo system can be activated. It is possible to quickly enter the synchronous pull-in state.

[Brief explanation of the drawing]

The first @ is a circuit block diagram showing one embodiment of the present invention, the second @ is a circuit block diagram showing an embodiment of the present invention.
The figure shows an explanatory diagram of the frequency characteristics of each common grip circuit. (6)...First resonance circuit, (7)...Second resonance circuit, (8)...Third resonance circuit, (17j...Comparison circuit, (13...Discrimination circuit, ( 15... variable frequency divider circuit,
αe: Frequency control circuit, αη: Phase control circuit.

Claims (1)

[Claims] (1) In order to play back a video disc record that is made by converting a high-quality video signal into a MUSE signal using the TCI multiplex sub-sampling method and frequency-multiplexing recorded information that is FM-modulated and a pilot signal of a constant frequency. In a high-definition video disc player that controls the rotational phase of the disc motor by comparing the phase of the divided pilot signal and the reference signal, the reproduced pilot signal is input and resonates at a higher frequency than the regular pilot signal frequency. a second resonant circuit that receives the regenerated pilot signal and resonates at a frequency that matches the regular pilot signal frequency; and a third resonant circuit that receives the regenerated pilot signal and resonates at a frequency that is lower than the regular pilot signal frequency. a resonant circuit; a phase comparator circuit that compares the output of the first resonant circuit with the output of the third resonant circuit; and a determination device that derives a determination output when the output level of the second resonant circuit exceeds a predetermined level. a variable frequency dividing circuit that inputs the output of the second resonant circuit, sets a regular frequency division ratio when the discrimination output is generated, and changes the frequency division ratio according to the comparison output when the discrimination output is deactivated; , a phase comparison circuit that supplies a phase comparison output between the frequency division output and a reference signal to the disk motor when the discrimination output is generated; and a phase comparison circuit that supplies a frequency control output based on the frequency division output to the disk motor when the discrimination output is deactivated. A disk servo circuit consisting of a frequency control circuit and a frequency control circuit.