JPH0374877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for recording and reproducing color video signals on a disc-shaped record carrier.

(Conventional structure and its problems) In recent years, with the development of high-output, semiconductor lasers and highly sensitive recording materials, color video signals are transmitted using laser beams by forming concentric or spiral guide grooves with a pitch of about 1.5 μm. A new type of video signal recording and reproducing apparatus has been proposed that records and reproduces video signals (hereinafter abbreviated as tracks) on a pre-configured disc-shaped recording medium.

This type of recording/playback device can easily record one frame per rotation, allowing for time-lapse and continuous shooting, and because it is a non-contact method using a laser beam, there is no deterioration during playback, and it can instantly record tracks. Compared to a VTR that uses magnetic tape as a recording medium, it is possible to perform slow-motion and quick-motion playback without a nozzle, and to search recorded information on the screen in an instant. It has many excellent features, and is expected to find applications in fields such as image files and computer graphics, which have been difficult to use with VTRs.

In the above-mentioned color video signal recording and reproducing device, the NTSC color video signal to be recorded is
The luminance signal component is separated into a luminance signal component and a color difference signal component, and the luminance signal component is frequency modulated and occupies a relatively high frequency band, and the color difference signal component is converted to a lower frequency and added to the frequency modulated luminance signal component. , a composite signal is obtained by frequency multiplexing. The recording laser beam obtained by modulating the output intensity of the semiconductor laser with this composite signal is irradiated onto a guide groove (hereinafter referred to as a track) formed in advance on the disc-shaped record carrier, and the recording laser beam is Causes a change in reflectance.

Further, a number is added to this track for each round, and by searching for the number, recording can be performed from any position.

In the case of reproduction, by irradiating a reproduction laser beam with a constant low intensity and reading the change in reflectance caused by the recording laser beam, the FM-modulated luminance signal and the color difference that has been frequency-converted to a low frequency are detected. It detects the signals, restores the original NTSC color video signal from these signals, and supplies it to the TV receiver.

The disk-shaped record carrier is rotated at 1800 rpm, and one frame of video signal is recorded per rotation. Therefore, images can be searched frame by frame using the address signal indicating the number added every round.

In addition, the pre-formed address signal is
Although it interferes with the video signal to be recorded later, it is configured so that it exists only during the vertical retrace period of the video signal, which is located at two points per rotation, so as not to cause interference on the screen.

The recording density of the video signal recording and reproducing device configured as described above is determined by the track pitch (hereinafter referred to as track pitch), but if this pitch is made too narrow, crosstalk from adjacent tracks will occur and the screen cause interference. The amount of crosstalk varies not only by the track pitch but also by the wavelength of the semiconductor laser used and the NA of the objective lens.

In addition, the degree of interference due to crosstalk differs between the luminance signal component and the color difference signal component, and the luminance signal component is frequency-modulated and recorded, so it is less susceptible to interference due to crosstalk, but the color difference signal component is recorded using a low-frequency conversion recording method. Therefore, it is susceptible to interference due to crosstalk.

Therefore, if crosstalk in color difference signal components can be eliminated, the track pitch can be narrower and the recording density can be increased.
As mentioned above, in a recording/reproducing device using a disk-shaped record carrier, only one semiconductor laser is used for recording, and two recording heads are used like in a home VTR, and the heads record different phase forms. By recording and reproducing color difference signal components,
It is difficult to increase the recording density because it cannot be configured to remove crosstalk components.

(Object of the Invention) In view of the above-mentioned drawbacks, the present invention makes it possible to make the phase forms of color difference signal components different in adjacent tracks even in recording with a single semiconductor laser, and to remove crosstalk components of color difference signal components during reproduction. The present invention provides a color video signal recording and reproducing device with greatly improved recording density.

(Structure of the Invention) In order to achieve this object, in the color video signal recording and reproducing apparatus of the present invention, tracks are classified into two types, odd tracks and even tracks, depending on whether the track numbers are odd or even numbers, and low frequency conversion is performed. The phase of the color difference signal is processed and recorded differently for odd-numbered tracks and even-numbered tracks. When playing, the track number is used to determine whether it is an odd track or an even track, the phase of the color difference signal is restored based on the result, and crosstalk from adjacent tracks is eliminated by adding it to the signal that has passed through the 1H delay line. The ingredients are made to cancel each other out.

When recording as described above, it is necessary to read the address signal using a recording laser beam, but unlike a reproduction laser beam, the recording laser beam is a beam modulated by the video signal to be recorded, so it is difficult to read the address signal. Easy to cause errors. Therefore, in the embodiment of the present invention, one rotation of the disk-shaped record carrier is detected, and the phase processing of the low-frequency converted color difference signal to be recorded is switched based on this result.

When reproducing a disc-shaped record carrier recorded in this way, if the phase of the color difference signal is restored only from the results of reading the address signals recorded at two locations on one track as described above, slow motion or quick motion may occur. When a track is skipped to the previous or next adjacent track to perform special playback of the color difference signal, the color difference signal cannot be restored correctly until the next address signal is read. Therefore, in the embodiment of the present invention, the phase processing of the color difference signal component is switched every time a track is skipped.
The color difference signal components are always restored correctly.

(Description of Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a recording block diagram of a color video signal recording and reproducing apparatus according to an embodiment of the present invention. In the figure, an NTSC color video signal to be recorded is input to a terminal 1, and is supplied to a Y/C separator 2 and a sync separator 3. A sync separator 3 separates a horizontal sync signal from the video signal, and this signal is supplied to a multiplier circuit 4 and a PS processing circuit 5. In the multiplier circuit 4, the frequency of the horizontal synchronization signal is, for example,
A signal multiplied by 160 is generated, and this signal is supplied to the PS processing circuit 5. The PS processing circuit 5 divides the frequency multiplied signal from the multiplier circuit 4 by 4, and uses the control signal S ₁ from the PS control circuit 6 to change the phase by 90% every horizontal period (hereinafter referred to as 1H) on odd-numbered tracks. For even-numbered tracks, the phase is delayed by 90 degrees every 1H, and this signal is supplied to the frequency converter 7 as a color subcarrier for low frequency conversion. The frequency converter 7 converts the color subcarrier in the NTSC system and the PS supplied from the crystal oscillator 8.
From the color subcarrier for low frequency conversion from the processing circuit 5,
A signal of the sum of these frequencies is synthesized, and this signal is supplied to the frequency converter 9.

On the other hand, the NTSC color video signal supplied to the Y/C separator 2 is separated into a luminance signal component and a color difference signal component.The luminance signal component is sent to a frequency modulator 10, and the color difference signal component is sent to a frequency converter 9. is supplied to The color difference signal component supplied to the frequency converter 9 is converted by the low frequency conversion signal from the frequency converter 7.
The frequency is converted, and a low-pass converted color difference signal is obtained with a frequency that is 40 times the horizontal synchronization signal frequency, and whose phase advances by 90 degrees every 1H on odd-numbered tracks, and whose phase lags 90 degrees every 1H on even-numbered tracks. Adder 1
1. In the adder 11, this low-pass conversion color difference signal is added to the luminance signal component modulated into an FM signal with a carrier frequency of 5.2 to 6.7 MHz in the frequency modulator 10, and this added signal is sent to the semiconductor laser drive circuit. 12. The semiconductor laser drive circuit 12 amplifies this added signal and supplies it to the optical pickup 13. In the optical pickup 13, the semiconductor laser is driven by this drive signal to generate a recording laser beam, and the recording laser beam is placed on the track of the disk-shaped record carrier 15 which is being rotated at 1800 revolutions per minute by the disk motor 14. A light beam is irradiated and a color video signal is recorded.

Further, the address signal detected by the optical pickup 13 is amplified by a preamplifier 16 and supplied to an address signal reading circuit 17. The address signal reading circuit 17 reads address information indicating the track address from the address signal and supplies an even/odd signal S ₂ to the PS control circuit 6. The PS control circuit 6 is also supplied with a rotation signal _S3 indicating the rotation of the disc-shaped record carrier 15 by a rotation detection circuit 19, and the address signal is determined by an even number track where the address signal is an even number and an odd number track where the address signal is an odd number. , the phase of the low-pass converted color difference signal component to be recorded.
A PS control signal _S1 is generated to switch the direction of rotation by 90 degrees every 1H.

The operation of generating the PS control signal _S1 will be explained using the signal waveform diagram in FIG. In the figure, the recording start track number is 1, and the _1st address is being reproduced before the recording start time t1, so the even/odd determination result is an odd number, and the even/odd signal _S2 becomes "0". Due to this even/odd signal S ₂ , the PS control signal S ₁ is also “0”
becomes. At the same time as recording starts, the constant intensity laser beam used to read the address signal is modulated in intensity by the signal to be recorded, so the address signal cannot be read accurately, and the even/odd signal _S2 is no longer correct. Since this is an accurate signal, after recording address 1, the PS control signal _S1 is inverted in accordance with the rotation signal _S3 . By doing this, when the track number is an even number, the PS control signal _S1 becomes "1", and when the track number is an odd number, the PS control signal _S1 becomes "0".

As described above, according to this embodiment, it is possible to stably record color difference signal components whose phases rotate in opposite directions by 90 degrees every 1H on even-numbered tracks and odd-numbered tracks.

FIG. 3 shows a reproduction block diagram of a color video signal recording and reproduction apparatus according to an embodiment of the present invention. In the figure, a signal recorded on a disc-shaped record carrier 15 is detected by an optical pickup 13 using a semiconductor laser which is oscillated at a constant output by a semiconductor laser drive circuit 12, and is supplied to a preamplifier 16. The preamplifier 16 amplifies the detected signal and supplies it to a high-pass filter 20 , a low-pass filter 21 , and an address signal reading circuit 17 . The high-pass filter 20 removes color difference signal components in the low frequency range and supplies only the luminance FM signal in the high frequency range to the FM demodulator 22 . FM demodulator 2
2, the luminance FM signal is demodulated to obtain a luminance signal component, and this signal is supplied to the adder 23.

Furthermore, the low-pass filter 21 removes the luminance FM signal from the signal amplified by the preamplifier 16 and supplies a low-pass converted color difference signal to the frequency converter 24 . The frequency converter 24 converts the frequency of the low-pass converted color difference signal to obtain a color difference signal component based on the NTSC system, and this color difference signal component is passed through the comb filter 2.
5. In the comb filter 25, the crosstalk component from the adjacent track is canceled by adding it to the signal delayed by 1H to obtain a color difference signal component from which the crosstalk component has been removed, and this color difference signal component is sent to the burst gate circuit 26. It is supplied to an adder 23. The adder 23 adds the color difference signal component from which the crosstalk component has been removed and the FM demodulated luminance signal component, and outputs a color video signal based on the NTSC system to the adder 29 .

On the other hand, the luminance signal component obtained by the FM demodulator 22 is supplied to the sync separator 3, where the horizontal sync signal component is separated. is supplied to The multiplier circuit 4 and the PS processing circuit 5 generate a low-frequency conversion subcarrier wave whose phase is rotated by 90 degrees every 1H, and this carrier wave is supplied to the frequency converter 7, as in the case of recording. Further, the burst gate circuit 26 extracts the burst signal component from the color difference signal component, and supplies this burst signal to the phase comparator 27. A phase comparator 27 compares the phase of the burst signal with a signal from a crystal oscillator 8 that generates an NTSC subcarrier, and the error signal is supplied to a variable frequency crystal oscillator 28. The variable frequency crystal oscillator 28 generates a signal with a frequency corresponding to the phase error signal, and this signal is supplied to the frequency converter 7. The frequency converter 7 converts the low frequency converted subcarrier from the PS processing circuit 5 and the variable frequency crystal oscillator 28
A signal for restoring a low-pass converted color difference signal whose phase is rotated by 90 degrees every 1H into a constant phase color difference signal component based on the NTSC system is synthesized from the signals from the NTSC system, and is supplied to the frequency converter 24.

Further, the reproduction signal from the disc-shaped record carrier 15 amplified by the preamplifier 16 is transmitted to the address signal reading circuit 1.
7, the address signal is read, and this signal is supplied to an even/odd discrimination circuit 18. The even/odd discrimination circuit 18 discriminates whether the read address information is an even number or an odd number, and supplies an even/odd signal S ₂ to the PS control circuit 6. In the PS control circuit 6, this even/odd signal
PS control signal S1 is generated from track jump pulse _S2 and track jump pulse _S4 supplied from terminal 30, and is supplied to PS processing circuit ₅ , which changes the phase of the low frequency conversion subcarrier every 1H according to the track number to be reproduced. The direction of rotation is changed by 90 degrees.

The operation of generating the PS control signal _S1 will be explained using the signal waveform diagram in FIG. In FIG. 4, the address signal recorded in one rotation is read at time _t2 , and as a result of the even/odd determination, the even/odd signal becomes "1", and this even/odd signal _S2 Based on this, the PS control signal _S1 becomes "1". At time _t3 after one round, the next address signal is read, so the even/odd signal _S2 becomes "0" and therefore the PS control signal _S1 also becomes "0". Then at time t ₄ ,
Track jump pulse is used for special playback.
When a track is skipped by _S4 and the next track is played back, the even/odd signal _S2 remains in the previous state "0" until time _t3 when the next address signal is read, but the PS control signal S ₁ is track jump pulse S ₄
As a result, each time the track jumps to the next track, it is inverted and becomes "0".

As described above, according to this embodiment, even when a track is skipped to perform special playback, it is possible to generate the PS control signal _S1 according to the playback track, and the recorded color difference signal components can be correctly adjusted. It can be restored.

In the embodiment of the present invention, as a method for removing crosstalk components from adjacent tracks, the phase of the color difference signal component is rotated in opposite directions for even and odd tracks by 90 degrees every 1H.
(Phase Shift) method, but it goes without saying that it is also possible to record color difference signal components of a constant phase on even-numbered tracks, and record the color-difference signal components with the phase reversed by 180 degrees every 1H on odd-numbered tracks. stomach.

(Effects of the Invention) As described above, the present invention provides color difference signals of color video signals between even and odd tracks formed on a disc-shaped record carrier so that crosstalk components from adjacent tracks can be removed during reproduction. By recording the components in different phase formats and switching the phase format of the color difference signal components to be recorded using the rotation signal of the disc-shaped record carrier, it is possible to record correctly even when the address signal cannot be read, and playback is possible. Sometimes, it is determined whether the track address is an even number or an odd number, and the processing of the color difference signal component is switched, and after determining whether the track address is even or odd, the next number signal is used to determine whether the track address is even or odd. in front,
When a track being played back is skipped to an adjacent track, the processing of the color difference signal components is switched each time one track is skipped, so that the phase forms of the color difference signal components recorded on the odd and even tracks are different as described above. Therefore, crosstalk interference from adjacent tracks of color difference signal components can be significantly reduced during playback, and the recording density of the disc-shaped record carrier can be reduced accordingly. can be improved, and its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is a recording block diagram of a color video signal recording and reproducing apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a signal waveform diagram for explaining the recording block diagram of FIG. FIG. 5...PS processing circuit, 6...PS control circuit, 17
... Address signal reading circuit, 18 ... Even/odd discrimination circuit, 19 ... Rotation detection circuit.

Claims (1)

[Claims] 1. In an apparatus for recording a color video signal consisting of a luminance signal component and a color difference signal component on a disc-shaped record carrier in which a numbered guide groove is formed for each rotation, recording is started. The phase form of the color difference component at the start of recording is set to be different depending on whether the number of the guide groove to be recorded is even or odd, and thereafter, the rotation of the disc-shaped record carrier is detected, and based on the rotation signal, A color video signal recording and reproducing device characterized in that the phase form of the color difference signal component is switched and recorded every round. 2. When reproducing a disc-shaped record carrier on which a color video signal is recorded, it is determined whether the number of the guide groove formed on the disc-shaped record carrier is an even number or an odd number, and the reproduced color difference signal is processed. At the same time, after determining whether the number is even or odd, and before determining whether the number is even or odd based on the number of the next guide groove, when jumping over the guide groove being played to the adjacent guide groove, 2. The color video signal recording and reproducing apparatus according to claim 1, wherein the processing of the reproduced color difference signal is switched every time one groove is skipped.