JPH04212593A - Video disk, video disk recording device and video disk reproducing device - Google Patents

Abstract

PURPOSE:To provide the video disk of long recording time and the video disk recording device which can prepare such video disk. CONSTITUTION:The one channel signal of the two channel signals formed by subjecting the brightness signal and two pieces of color difference signals of a high-grade television signal to time base conversion processing and multiplex processing is recorded on the front surface and the other channel signal is recorded on the rear surface. A time base conversion means 5a which executes the time base expansion of the brightness signal of the high-grade television signal, selects the respective color difference signals in each of respective horizontal scanning periods and executes the time base compression of these signals to provide the same band as the band of the brightness signal after the time base expansion, a multiplex means 5b which multiplexes the brightness signal and two pieces of color difference signals subjected to the conversion of the time base to two channel signals and a recording means are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video disc for high-definition television signals, a video disc creation device, and a video disc playback device.

[Prior Art] For example, in the high-definition television signal proposed by the Japan Broadcasting Corporation, the bandwidth of the luminance signal is 21 MHz, the bandwidth of each color difference signal of red (PR) and blue (PB) is 6 MHz,
It is significantly wider than the current NTSC television signal.

If you try to record such wide-bandwidth television signals on a video disc, you will need to take measures such as increasing the rotational speed of the video disc, shortening the wavelength of the recording laser light, and narrowing the track pitch. . However, practical technology for implementing such countermeasures is still insufficient.

Therefore, a recording method has been proposed to achieve good image quality within the currently available bandwidth (Japanese Patent Laid-Open No. 2-10
Publication No. 4095).

In this method, the band is reduced by time axis extension processing for the luminance signal, and for each color difference signal, the time axis compression processing is performed on the color difference signal using the signal for each horizontal scanning period. equal to the band of the luminance signal after decompression processing,
These luminance signals and two color difference signals are multiplexed to obtain two-channel signals, and these two-channel signals are respectively recorded on double spiral tracks of a video disk.

[Problems to be Solved by the Invention] However, the conventional method has a problem in that the recording time for one video disc is short. For example, in the case of constant angular velocity rotation method (CAV method), it is about 8 minutes, and in the case of constant linear velocity method (CLV method), it is 15 minutes.
It was about a minute.

This is because, although the recording band is reduced, the band cannot be significantly reduced when image quality is taken into account since a high-quality television signal is recorded. Furthermore, since recording is performed using a double helix, the track pitch is limited by the arrangement of the optical system and the like. Furthermore, in order to achieve a safe track pitch when obtaining two beams and realizing a double helix, it is necessary to increase the angle between the two beams, which requires increasing the wavelength. This is because the amount of recording is limited.

The present invention has been made in consideration of the above points, and aims to provide a video disc with a long recording time, and further provides a video disc creation device that can create such a video disc. This is what we are trying to provide. Furthermore, the present invention seeks to provide a video disc playback device capable of playing such video discs.

[Means for Solving the Problems] In order to solve the problems, the video disc according to the first aspect of the present invention performs time axis conversion processing and multiplexing on a luminance signal and two color difference signals in a high-definition television signal. One of the two channel signals formed by processing is recorded on the front side, and the other channel signal is recorded on the back side.

Moreover, the video disc creation device according to the second invention includes:
In order to create a video disc according to the first aspect of the present invention, the luminance signal in a high-definition television signal is time-axis expanded, and each color difference signal is selected for each horizontal scanning period, time-axis compressed, and after time-axis expansion. a time axis conversion means for converting one channel signal into a two-channel signal; A recording means is provided for recording the signal on the front side of the video disc and recording the other channel signal on the back side of the video disc.

In this case, the recording means includes a first master creation means for creating a front master disc, a front disc creation means for creating a front video disc from a front master disc created by this creation means, and a back disc creation means for creating a front video disc from the front master disc created by this creation means. a second master creation means for creating a master disk for
It is preferable that the apparatus is comprised of a back side disc creating means for creating a back side video disc from the back side master disc created by this creating means, and a pasting means for pasting the front side video disc and the back side video disc together.

In order to play the video disc according to the first invention, the video disc playback device according to the third invention includes a front side pickup means for picking up channel signals recorded on the front side of the video disc, and a front side pickup means for picking up channel signals recorded on the back side of the video disc. a back side pickup means for picking up the channel signals that have been picked up; a demultiplexing means for distributing the picked up two-channel signals into a luminance signal and two color difference signals; and time axis conversion means for time axis expansion and interpolation of each color difference signal.

[Function] In the first aspect of the present invention, signals are distributed and recorded on both the front and back sides of a video disc in order to prolong the recording time of high-definition television signals. In this case, time axis conversion processing is performed to equalize the bands of the luminance signal and the two color difference signals in the recording signal. Furthermore, in order to record on both the front and back sides, multiplex processing is performed to convert the luminance signal and two color difference signals into two-channel signals.

In the second aspect of the present invention, the time axis conversion means time axis expands the luminance signal in the high-definition television signal, selects each color difference signal for each horizontal scanning period, compresses the time axis, and expands the time axis. The multiplexing means multiplexes the luminance signal whose time axis has been converted and the two color difference signals into a two-channel signal, with the band being the same as that of the subsequent luminance signal,
The recording means records one channel signal on the front side of the video disc and records the other channel signal on the back side of the video disc, thereby realizing the above video disc.

In the third aspect of the invention, the front side pickup means picks up the channel signals recorded on the front side of the video disc, and the back side pickup means picks up the channel signals recorded on the back side of the video disc, and demultiplexes the channel signals recorded on the back side of the video disc. The plex means divides the picked up two-channel signal into a luminance signal and two color difference signals, and the time axis conversion means compresses the divided luminance signal in time axis and expands each divided color difference signal in time axis. , and interpolated to obtain the original luminance signal and color difference signal.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail in the order of a video disc creation device and a video disc playback device with reference to the drawings.

FIG. 1 shows the configuration of the production device.

At the recording site, a high-definition television signal captured by a video camera 1 for high-definition television signals is given to a digital videotape recorder 2. For example, the luminance signal Y has a bandwidth of 30 MHz, and each red and blue signal is The color difference signals PR and PB are each recorded on a video tape with a bandwidth of 15 MHz.

The video tape is loaded into a digital video tape recorder 3 installed at a video disc production site and played back. The reproduced luminance signal Y and two color difference signals PR and PB are given to a low-pass filter circuit 4, where the luminance signal Y is band-limited to 21 MHz, and each color difference signal PR
, PB are each band-limited to 6 MHz. The luminance signal Y and two color difference signals PR and PB passed through the low-pass filter circuit 4 are applied to a two-channel circuit 5.

The two-channel conversion circuit 5 is functionally the time axis conversion circuit 5.
a and a multiplex circuit 5b, and under timing control by a timing control circuit 6, converts the input luminance signal Y and two color difference signals PR and PB into two-channel signals.

FIG. 2 is an explanatory diagram of two-channel conversion. Here, FIG. 2 (A1) to (A3), (B1) and (B2) represent the luminance signal Y and two color difference signals PB and PR.
) to (C3).

In this embodiment, a luminance signal Y and two color difference signals PR
, PB are converted into two-channel signals every two horizontal scanning periods.

The luminance signal (Y1,
Y3,...) is expanded by the time axis to 7/4 (compressed to 4/7 in terms of band) by the time axis conversion circuit 5a, and then converted to the first signal shown in FIG. 2 (B1) by the multiplex circuit 5b. It is inserted into the latter 7/4 horizontal scanning period of the next two horizontal scanning periods in the channel signal. On the other hand, the luminance signals (Y2, Y4,...) of the rear horizontal scanning period within the two horizontal scanning periods of the input luminance signal are time-axis expanded to 7/4 by the time-axis conversion circuit 5a, and then multiplexed. The second half 7/ of the next two horizontal scanning periods in the second channel signal shown in FIG. 2 (B2) is controlled by the circuit 5b.
4 horizontal scanning periods.

On the other hand, regarding the input blue difference signal shown in FIG. 2 (A2), the signals (B1, B3, ...) of the front horizontal scanning period in the two horizontal scanning periods are selected by the time axis conversion circuit 5a. After that, the time axis is compressed to 1/2 (expanded to 2 times in terms of bandwidth), and then the multiplex circuit 5b
This is inserted into the first half horizontal scanning period of the next two horizontal scanning periods in the first channel signal shown in FIG. 2 (B1). Furthermore, regarding the input red difference signal shown in FIG.
After being selected by a, the time axis is compressed to 1/2, and then the multiplex circuit 5b performs the first half horizontal scanning period of the next two horizontal scanning periods in the second channel signal shown in FIG. 2 (B2). inserted.

In this way, the first
and a second channel signal are obtained and output from the two-channel circuit 5.

Here, the reason for converting to a 2-channel signal is as follows.
This is because both sides of the video disc are used in this embodiment, and each channel signal becomes a recording signal for each side.

In addition, for the luminance signal, the time axis is expanded and the band is 4/4.
7 (therefore, 12MHz), and for the color difference signal, the signal is selected every horizontal scanning period, and then the time axis is compressed to double the band (therefore, 12MHz).
This is to align the recording bands for the luminance signal and color difference signal.

Note that the common recording band for luminance signals and color difference signals is 12M.
The reason for choosing Hz is as follows. Considering the current level of practical technology, the band of recording signals is 23 MHz or less due to restrictions due to optical systems and the like. Since a band of 3 MHz or less is used for audio signals, the recording signal band for video signals is 3 to 23 MHz. Since this much band is required as the recording signal band after FM modulation, which will be described later, each channel signal is required to be narrower than this. Here, if the band of the channel signal is selected so that both sidebands are sufficient, the band of the channel signal will be narrow and the image quality will deteriorate. On the other hand, if the entire band from 3 to 23 MHz is allocated to the single-side band, reproduction of low frequency components, which poses a particular problem in terms of image quality, will be insufficient. Therefore, as mentioned above, the band of each channel signal is set to 12M.
Hz was selected.

FIG. 3 shows the spectrum of the recording signal with respect to the channel signal.

Each channel signal output from the two-channel conversion circuit 5 is given to a front side output circuit 7 and a back side output circuit 8, respectively.

The audio signal reproduced by the digital video tape recorder 3 described above is applied to the audio PCM modulator 9 and modulated, and then distributed into two channels and applied to the front side output circuit 7 and the back side output circuit 8.

The front side output circuit 7 and the back side output circuit 8 synthesize a channel signal for a video signal and a channel signal for an audio signal, and further synthesize various control signals (address signals) given from the timing control circuit 6. After that, FM modulation is performed and recording amplification processing is performed to limit the band to a predetermined band, and the resulting recording signals of each channel are provided to the corresponding recording optical systems 10 and 11.

The front master disk 12 is rotated clockwise by a motor 13, while the rear master disk 14 is rotated counterclockwise by a motor 15, and receives laser beams from recording optical systems 10 and 11, respectively. Record each channel recording signal. Note that both motors 13 and 15 are controlled to rotate synchronously by a synchronous driver circuit 16 that receives a control signal from a timing control circuit 6 and controls the rotation.

Surface master disk 1 created with the above configuration
A well-known method can be applied to create a front video disc and a back video disc from the master disc 2 and the back master disc 14, and the explanation thereof will be omitted here.

The front video disc and the back video disc thus created are pasted together to form a final video disc.

FIG. 4 shows a reproducing apparatus for a video disc formed in this manner, and the reproducing configuration will be described below with reference to FIG. 4.

A video disk 21 rotated clockwise by a motor 20 is provided with two optical heads 22 and 23 adjacent to it. One optical head 22 is provided facing the surface of the video disc 21 and picks up a channel recording signal recorded on the surface. The other optical head 23 is provided facing the back side of the video disc 21 and picks up the channel recording signal recorded on the back side. Note that, when viewed from the back side optical head 23, the video disc 21 is rotating counterclockwise.

Each picked-up channel recording signal is amplified via a corresponding reproduction preamplifier 24, 25, and then given to a corresponding FM demodulator 26, 27 for FM demodulation.

Each channel signal containing video signal, audio signal and control signal components obtained in this manner is transferred to a corresponding drive control signal separation circuit 28, 29.
given to. Each drive control signal separation circuit 28, 29
decodes the track number included in each channel signal and provides it to the drive synchronous controller section 30, and also detects the burst signal and provides it to the drive synchronous controller section 30.

The drive synchronous controller section 30 controls the drive of the motor 20 based on these signals, and controls the drive of the optical head 22.
and control the radial drive of 23.

Each channel signal that has passed through each drive control signal separation circuit 28, 29 is given to a two-channel decomposition circuit 31. The two-channel decomposition circuit 31 includes a video/audio separation circuit 31a, a demultiplex circuit 31b, and a time axis conversion circuit 31c.

The video/audio separation circuit 31a separates the video signal and audio signal included in each channel signal, and demultiplexes the two-channel video signal (see FIG. 2 (B1) and (B2)). 31b, and the two-channel signal of the audio signal is sent to the audio P.
It is applied to the CM demodulator 32.

The audio PCM demodulator 32 demodulates the two-channel audio signal to obtain and output the original audio signal.

The demultiplex circuit 31b separates a luminance signal and two color difference signals from each channel video signal and supplies them to the time axis conversion circuit 31c.

The time axis conversion circuit 31c compresses the time axis of the luminance signal to 4/7 (expands it to 7/4 in terms of band), and converts the compressed luminance signal from the first channel signal into the next one. The compressed luminance signal from the second channel signal is inserted into the latter half of the next two horizontal scanning periods, and the original luminance signal is reproduced and output. For each color difference signal, its time axis is expanded by 2 times (bandwidth: 1
/2), and the expanded color difference signal is repeatedly inserted into each of the first and second half of the next two horizontal scanning periods to reproduce and output the color difference signal.

Therefore, according to the above embodiment, the luminance signal and the two color difference signals are converted into two-channel signals, and each channel signal is recorded and played back on both the front and back sides of the video disc. The recording time can be approximately doubled compared to the conventional method.

In addition, since each side of the video disc can have a single helical track, it is not necessary to install two optical systems close to each other facing each other on one side of the video disc, so the track pitch can be reduced compared to the conventional method. This also makes it possible to lengthen the recording time.

Furthermore, since it is not recorded using a double helix like in the past,
No need for a diffraction grating to separate the laser beam into two,
Since the wavelength of the laser beam is not restricted by the diffraction angle, the wavelength can be made as short as possible, and from this point of view as well, the recording time can be lengthened.

In the above embodiment, two master disks, one for the front side and one for the back side, were created, but the recording optical system of each channel could be placed opposite to each other on both the front and back sides of one master disk. Alternatively, a two-channel signal may be recorded. In this way, the influence of uneven rotation caused by the motor can be made equal on both the front and back sides of the video disc.

Further, the method of forming a two-channel signal from a luminance signal and two color difference signals is not limited to that of the above-described embodiment. FIG. 5, which corresponds to FIG. 2, shows a two-channel method according to another embodiment.

[Effects of the Invention] As described above, according to the present invention, a two-channel signal is obtained by performing time axis conversion processing and multiplex processing on a luminance signal and two color difference signals in a high-definition television signal. Since each channel signal is distributed and recorded on both the front and back sides of a video disc and then played back, the recording time can be longer than in the past.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration for creating a video disc according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a two-channel conversion method, FIG. 3 is a spectrum diagram of a recording signal according to the above embodiment, and FIG. The figure is a block diagram showing the playback configuration of the video disc according to the above embodiment, and FIG. 5 is an explanatory diagram of another two-channel conversion method. 5...2-channel conversion circuit, 5a...time axis conversion circuit, 5b
...Multiplex circuit, 12... Master disk for front side, 13... Master disk for back side, 21... Video disk, 31... 2 channel decomposition circuit, 31b... Demultiplex circuit, 31c... Time axis conversion circuit. patent applicant

Claims (4)

[Claims] Claim 1: Of two channels of signals formed by performing time axis conversion processing and multiplex processing on a luminance signal and two color difference signals in a high-definition television signal, one channel signal is A video disc characterized in that the signal of the other channel is recorded on the reverse side. Claim 2: Expanding the luminance signal in a high-definition television signal on the time axis, and compressing the time axis by selecting each color difference signal for each horizontal scanning period so that the band becomes the same as the band of the luminance signal after time axis expansion. a time axis converting means for converting the time axis, and a multiplexing means for multiplexing the luminance signal and two color difference signals whose time axes have been converted into a two-channel signal; A video disc creation apparatus for creating the video disc according to claim 1, comprising: recording means for recording a channel signal on the back side of the video disc. 3. The recording means comprises: first master creation means for creating a front master disc; front disc creation means for creating a front video disc from the front master disc created by the creation means; a second master creation means for creating a rear master disc; a rear disc creation means for creating a rear video disc from the rear master disc created by the creation means; the front video disc and the rear video disc; 3. The video disc creation apparatus according to claim 2, further comprising a pasting means for pasting the discs together. 4. A front side pickup means for picking up a channel signal recorded on the front side of the video disc according to claim 1; a back side pickup means for picking up a channel signal recorded on the back side of the video disc; The picked up 2-channel signal is converted into a luminance signal and a 2-channel signal.
A high-definition television set comprising demultiplexing means for distributing into individual color difference signals, and time-base conversion means for time-base compressing the distributed luminance signals, time-base expansion and interpolation of each distributed color-difference signal. 1. A video disc reproducing apparatus characterized in that the apparatus reproduces a luminance signal and two color difference signals in a video signal.