JPH0732495B2 - Time axis error correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a time axis error correction apparatus suitable for use in reproducing a CD-V disc.

[Outline of Invention]

In the present invention, the time axis error signal generated from the color burst signal is equalized so that the coking components of the motors that drive at least two types of recording media having different inertias are suppressed, and the time axis error signal generated from the horizontal synchronization signal is equalized. It is added to the error signal.

[Background technology]

FIG. 3 is a block diagram of a conventional time axis error correction device. The pickup 3 reproduces a recording signal from the disk 2 which is rotated and driven by the motor 1. The output of the pickup 3 is input to the demodulation circuit 4 and frequency demodulated, for example. The demodulated video signal of the demodulation circuit 4 is output via the CCD 5 as the first correction circuit for correcting the time base error and the correction circuit 6 as the second correction circuit.

The separation circuit 7 separates the horizontal sync signal from the output of the CCD 5.
The detection circuit 8 compares the output of the separation circuit 7 with the fixed horizontal synchronization signal output from the oscillation circuit 9 to detect the time axis error signal. The time axis error signal generated by the generation circuit including the detection circuit 8 and the oscillation circuit 9 is input to the equalizer 10,
Equalized to a predetermined characteristic. The output of the equalizer 10 is input to the VCO 12 via the adder circuit 11, and the VCO 12 outputs a signal (clock) having a frequency and a phase corresponding to the time axis error. The output of VCO12 is supplied to CCD5, and CCD5 corrects the time base error of the video signal corresponding to the signal from VCO12.

On the other hand, the separation circuit 13 separates the color burst signal from the output of the CCD 5. The output of the separation circuit 13 is input to the detection circuit 14. The detection circuit 14 compares the output of the separation circuit 13 with the phase of the reference color signal output by the oscillation circuit 9, and outputs a signal corresponding to a time axis error that cannot be corrected by the CCD 5. The time axis error signal is amplified by the amplifier circuit 15 and then supplied to the correction circuit 6. The correction circuit 6 corrects the phase (residual time axis error) of the color signal corresponding to the signal from the amplification circuit 15.

A part of the output of the amplifier circuit 15 is input to the equalizer 16.
The equalizer 16 uses an eccentric component (for example, frequency) of the disk 2.
The output of the amplifier circuit 15 is equalized so that the gain of the servo loop of 30 Hz component) increases. Equalizer 16
Is output to the adder circuit 11, is added to the output of the equalizer 10, and is supplied to the VCO 12. Ie equalizer 10
Is set to the characteristic shown by the solid line in FIG. 4, but the output of the equalizer 16 is added to the output of the equalizer 10, so the characteristic of the output of the adder circuit 11 becomes as shown by the broken line in the figure. . As a result, the eccentric component is sufficiently suppressed.

However, this device has a drawback that it takes time to stabilize the phase of the color signal at the time of scanning.

Therefore, there is an apparatus configured as shown in FIG. In this example, the detection circuit 14, amplification circuit 15 and VCXO17
The L circuit is configured, and the phase of the color signal is controlled by the output of the amplifier circuit 15 that controls the phase of the oscillation signal of the VCXO 17.

[Problems to be solved by the invention]

As described above, in the apparatus of FIG. 5, the CCD 5 corrects the time base error due to the horizontal synchronizing signal rate. As a result, when the disc 2 is a video disc having a relatively large inertia, there is almost no problem. However, when the disc 2 is a CD-V disc having a relatively small inertia, a rotation unevenness component (hereinafter referred to as a coking component) due to the coking of the motor 1 is caused. The time axis error cannot be sufficiently suppressed, and color unevenness appears.

Therefore, the present invention is capable of sufficiently suppressing color unevenness due to the cogging component of the motor that rotationally drives at least two types of recording media having different inertias.

[Means for solving problems]

The time-axis error correction device of the present invention includes a motor that rotationally drives at least two types of recording media having different inertias at a predetermined number of rotations corresponding to each recording medium, and a horizontal synchronization signal from a video signal reproduced from the recording medium. A first separation circuit that separates the first time axis error signal, a first generation circuit that generates a first time axis error signal from the output of the first separation circuit, and a first generation circuit that equalizes the first time axis error signal. An equalizer, a second separation circuit for separating a color burst signal from the video signal, a second generation circuit for generating a second time base error signal from the output of the second separation circuit, and the inertia As the servo loop gain of the rotation unevenness component due to the coking of the motor with respect to the predetermined rotation speed of the recording medium having the smallest inertia among the recording media increases,
A second equalizer for equalizing the second time axis error signal, an adder circuit for adding the output of the first equalizer and the output of the second equalizer, and the adder circuit corresponding to the output of the adder circuit. First to correct time-axis error signal of video signal
And a second correction circuit for correcting the time base error of the video signal in correspondence with the second time base error signal.

[Action]

At least two types of recording media having different inertias such as disks are driven by the motor. The first separating circuit separates the horizontal synchronizing signal from the reproduced video signal of the recording medium.
The first generation circuit generates a first time base error signal from the output of the first separation circuit. The first time axis error signal is equalized to a predetermined characteristic by the first equalizer.

On the other hand, the second separation circuit separates the color burst signal from the reproduced video signal, and the second generation circuit generates the second time base error signal from the output of the second separation circuit. The second time axis error signal is equalized by the second equalizer so as to increase the gain of the servo loop of the coking component of the motor.

The output of the first equalizer and the output of the second equalizer are added by the adder circuit, and the first correction circuit corrects the time base error of the video signal corresponding to the output of the adder circuit. Further, the second correction circuit corrects the time base error of the video signal in response to the second time base error signal.

In this way, the occurrence of color unevenness due to the cogging of the motor that rotationally drives at least two types of recording media having different inertias is prevented.

〔Example〕

FIG. 1 is a block diagram of a time axis error correction apparatus according to the present invention, and portions corresponding to those in FIGS. 3 and 5 are designated by the same reference numerals. In the time axis error correction device of the present invention, part of the output of the amplifier circuit 15 is input to the adder circuit 11 via the equalizer 21 and added to the output of the equalizer 10. Other configurations are the same as those in FIG.

The equalizer 21 is set to have a characteristic that the gain of the servo loop with respect to the cogging component of the motor 1 increases. For example, when the equalizer 10 is set to the characteristic shown by the solid line in FIG. 2, the characteristic of the equalizer 21 is set so that the characteristic of the output (input of the VCO 12) of the adder circuit 11 becomes as shown by the broken line in the figure. . In this way, not only the time axis error due to the eccentricity component centered on 10 to 30 Hz but also the frequency f ₁ (for example,
The gain of the servo loop for the time axis error of 360 Hz) to f ₂ (for example, 540 Hz) due to the coking component of the motor 1 also increases. As a result, not only the eccentricity component but also the time axis error caused by the coking component is sufficiently suppressed. Since the operation in that case is the same as that described above, the description thereof will be omitted.

It is theoretically possible to omit the equalizer 21 and change the equalizer 10 itself to the characteristic shown by the broken line in FIG. However, if the equalizer 10 is redesigned in such a manner, a phase rotation of the servo loop also occurs, and its configuration becomes complicated in order to suppress it. So the equalizer
It is preferable to increase the gain of the servo loop by adding 21.

The present invention is suitable for use when a video disk and a CD-V disk are driven by a common motor 1, but can also be applied when reproducing other recording media.

[Effect] As described above, the present invention equalizes the low-frequency component of the time-axis error signal generated using the color burst, and eliminates the time-axis error due to the cogging component of the motor that drives at least two types of recording media having different inertias. Since it was suppressed, the CD-CD as well as the video disc can be used with a simple structure.
It is possible to reproduce an image without color unevenness from a V disc.

[Brief description of drawings]

FIG. 1 is a block diagram of a time axis error correction device of the present invention, FIG. 2 is a characteristic diagram of its equalizer, FIG. 3 is a block diagram of a conventional time axis error correction device, and FIG. 4 is a characteristic diagram of its equalizer. FIG. 5 is a block diagram of another conventional time axis error correction device. 1 ... Motor 2 ... Disk 3 ... Pickup 4 ... Demodulation circuit 5 ... CCD 6 ... Correction circuit 7 ... Separation circuit 8 ... Detection circuit 9 ... Oscillation circuit 10 ... Equalizer 11 ... Addition circuit 12 …… VCO 13 …… Separation circuit 14 …… Detection circuit 15 …… Amplification circuit 16 …… Equalizer 17 …… VCXO 21 …… Equalizer

Claims (1)

[Claims] 1. A motor for rotationally driving at least two types of recording media having different inertias at a predetermined number of revolutions corresponding to each recording medium, and a first for separating a horizontal synchronizing signal from a video signal reproduced from the recording medium. Separation circuit, a first generation circuit for generating a first time-axis error signal from the output of the first separation circuit, a first equalizer for equalizing the first time-axis error signal, and the video A second separating circuit for separating a color burst signal from the signal, a second generating circuit for generating a second time-axis error signal from the output of the second separating circuit, and a recording medium having different inertia. The second time axis error signal is equalized so that the servo loop gain of the rotation unevenness component due to the coking of the motor with respect to the predetermined rotation speed of the recording medium having the smallest inertia increases. A second equalizer, an adder circuit for adding the output of the first equalizer and the output of the second equalizer, and a time axis error signal of the video signal is corrected corresponding to the output of the adder circuit. A time-axis error correction device comprising: a first correction circuit; and a second correction circuit that corrects a time-axis error of the video signal in response to the second time-axis error signal.