JPH02141081A - Video disk recording/reproducing device - Google Patents

Abstract

PURPOSE:To reduce the linear velocity of a video disk and to decrease the burden of a motor by dividing a video signal into two channels, and recording them on two adjacent tracks on a disk. CONSTITUTION:A switching circuit 3, which time-shares the television video signal into two signals at every two lines, time base extending circuits 4 and 5 to respectively extend the time base of the time-shared signals, line inserting circuits 6 and 7, which insert a vertical synchronizing signal to the signal not to have the vertical synchronizing signal out of the two time base extended signals and insert a new line to the other line, a pilot carrier multiplexing circuit 15, frequency-multiplexes the pilot carrier to be synchronized with the video signal to one channel, and a voice multiplexing circuit 13 to frequency multiplex a PCM sound signal to the other channel are provided. The video signals are divided into two channels at every two lines, and recorded and reproduced on the two adjacent tracks on the disk at approximately the same linear velocity of that of the current video disk. Thus, the linear speed of the disk is reduced, and the design of a spindle motor is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a recording and reproducing apparatus for video discs.

BACKGROUND OF THE INVENTION NHK has proposed the MUSE method, which compresses high-definition video signals into a band of approximately 8 MHz, which provides higher definition images than the current standard television method. This method is used not only for satellite broadcasting but also for video discs and VT.
It can be used for package media such as R.

However, since the MUSE signal uses a positive synchronization signal, synchronization cannot be detected using simple methods such as amplitude separation.
In a video disc, a pilot carrier is frequency-multiplexed onto the MUSE signal and recorded, and during playback, this pilot carrier is used to control the disc rotation and correct the time axis (for example, Ninomiya et al. Optical video disc rPA73-8).

Problems to be Solved by the Invention The MUSE signal is an analog video signal with a maximum frequency of 8.1 MHz, and has a band approximately twice that of the current television signal. When recording and reproducing this MUS[E signal with FM modulation on a video disc, a linear velocity approximately twice that of current video discs is required, and in order to use the inner periphery of the disc with a small radius, the number of revolutions must be increased significantly. have to raise
The load on the motor is heavy.

Furthermore, the bandwidth of the signal amplification circuit needs to be about twice as large, making it difficult to design. Therefore, in order to reduce the rotational speed of the motor and narrow the signal band, a method can be considered in which the MUSE signal is divided into two channels and recorded.

By the way, it is generally known that even when crosstalk occurs between adjacent tracks on a disk, the effect will be reduced if adjacent signals have a correlation. Since the color difference signal of the MUSE signal is line sequential, if the signal is allocated to two channels in units of two lines, color difference signals of the same type will be adjacent to each other when recorded.

Therefore, it is convenient to use pJ for 2 channels every 2 lines. However, if we simply divide every two lines into two channels, the number of lines will be an odd number, so the signal division pattern will have a period of 4 frames, as shown in Figure 4, and will be defined as line numbers 1 and 2. There are also four patterns of frame pulse distribution.

Furthermore, in the synchronous playback method for MUSE-based discs, the signal is first sampled using a clock synchronized with the MUSE signal played from the pilot carrier, and then,
A procedure in which vertical synchronization is established by extracting the frame pulse, which is the vertical synchronization signal, using clock and line-by-line correlation, and then the horizontal synchronization signal is extracted while counting the sample clock with a counter, and horizontal synchronization is also established. It will be held in Therefore, even when divided into two channels, frame pulses are required for synchronous reproduction of the MUSE signal.

Therefore, when recording and reproducing the MUSE signal by dividing it into two channels, there are problems in that the circuit scale for synchronous reproduction becomes considerably large and the synchronous pull-in speed becomes slower than in one-channel recording.

However, as another problem, there is a method of frequency multiplexing the PCM audio signal in the lower frequency range of the pilot carrier in order to record a separate system of PCM audio signals in addition to the audio signal time-axis multiplexed on the MUSE signal. There was a problem in that the audio signal and the pilot carrier caused mutual interference, leading to deterioration in playback quality and increase in jitter.

The present invention has been attempted in view of the problems of the prior art described above, and an object of the present invention is to provide a video disc recording and reproducing apparatus that records and reproduces a high-definition MUSE signal divided into two channels.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a switching circuit that time-divides a television video signal into two signals every two lines, and a switching circuit that time-divides a television video signal into two signals every two lines. two time axis expansion circuits that extend each axis, and a vertical synchronization signal is inserted into the signal that does not have a vertical synchronization signal among the two signals that have been time axis expanded by the time axis expansion circuit, and at least A line insertion circuit that inserts a new line into one signal, a pilot carrier multiplexing circuit that frequency multiplexes a pilot carrier synchronized with a video signal on one channel, and an audio multiplexing circuit that frequency multiplexes a PCM audio signal on the other channel. In order to do so, recording is performed on a disc using a video disc recording device that is characterized in that a video signal is divided into two channels and recorded on two adjacent tracks on the disc.

In order to reproduce the disc, two sets of reproducing means obtain respective reproduction signals from two adjacent tracks on the disc, and a clock that separates the frequency of a pilot carrier from one of the reproduction signals and synchronizes it with the frequency. A clock reproducing circuit for reproducing, two synchronized reproducing circuits for independently performing synchronized reproduction on each channel using the vertical synchronization signal of each reproduced signal and the clock, and two synchronous reproducing circuits for compressing the time axis of the synchronized video signal. and a signal mixing circuit that alternately switches the two signals compressed by the time axis compression circuit in units of two lines and restores them to a continuous one-channel video signal. Use a video disc playback device.

Operation The present invention uses the above-mentioned means to convert the video signal into two lines every two lines.
The disc is divided into channels and recorded and played back on two adjacent tracks on the disc at a linear speed similar to that of current video discs. At this time, since each of the divided video signals has a vertical ijl signal, each channel can be independently and synchronously reproduced. Furthermore, since a video signal normally has an odd number of lines, if a new odd number of lines is inserted to equalize the number of lines in the two channels, control signals etc. can be recorded on the added lines.

In addition, since the video signal is divided into two lines each having two lines, if the color difference signal is line sequential, the two signals have a correlation, and the effects of crosstalk are reduced by recording on two adjacent tracks on the disk. .

Furthermore, by multiplexing the pilot carrier on one of the two divided recording signals and multiplexing the PCM audio signal on the other, mutual interference between the pilot carrier and the PCM audio signal does not occur.

Example The configuration and operation of an embodiment of the present invention will be described below.

Note that in this embodiment, a MUSE signal is used as the video signal.

First, an embodiment of a video disc recording apparatus for recording MUSE signals on a disc will be described with reference to FIGS. 1 and 3. The MUSE signal to be recorded is converted into a digital signal by an A/D conversion circuit 1, and a synchronization reproducing circuit 2 performs synchronization detection, clock reproduction, and various timing generation. The MUSE signal here can be expressed as shown in FIG. 3(a). In FIG. 3, the horizontal axis indicates the time axis of the signal, and the numbers in the figure are the line numbers of the input MUSE signal. The synchronized digital MUSE signal is time-divided by the switching circuit 3 into two channels every two lines. Here, let us assume that in FIG. 1, the upper side after the switching circuit 3 is the A channel, and the lower side is the B channel. The time-divided A channel signal is shown in FIG. 3(b), the B channel signal is shown in FIG. 3(c), and the shaded area is a no-signal state. Next, each signal is manually inputted to the time axis expansion circuits 4 and 5, and the time axis is expanded, so that the A channel signal becomes as shown in FIG. 3(d), and the B channel signal as shown in FIG. 3(e). . Here, the numbers in the figure indicate the line numbers of the time-axis expanded signal. In the case of this embodiment, each time-axis expanded signal has 564 lines and l 125
This means that the time axis has been expanded 1564 times. Next, A
In the channel, the line insertion circuit 6 inserts the frame pulse line defined by the 1st and 2nd lines of the MUSE signal into the no-signal portion of the 1st and 2nd lines, and in the B channel, the line insertion circuit 7 inserts the frame pulse line defined by the 564th line Insert a line with a control signal written into the line. As a control signal, it is possible to write a frame number, a time code, etc.

The signal into which additional information has been inserted by the line insertion circuits 6 and 7 is
The result will be as shown in Fig. 3 (f) and (g). However, human power M
There is no 1126 line in the USE signal, and for convenience of explanation B
I wrote 1126 on the 564th line of the channel.

With the above procedure, the MUSE signal is divided into two channel signals each having a frame pulse.

Below, the two signals are converted into analog signals by D/A conversion circuits 8 and 9, frequency modulated by FM modulation circuits 10 and 11, and PCM audio encoded by an encoder 12 into the A channel. The signal is low-frequency multiplexed by the audio multiplexing circuit 13,
For the B channel, pilot carriers synchronized with the input MUSE signal generated by the pilot carrier generation circuit 14 are multiplexed by the pilot carrier multiplexing circuit 15, and E10
The modulators 16 and 17 turn the laser beam on and off to write pits on two adjacent tracks on the disk.

Next, an embodiment of a reproducing apparatus for a video disc created as described above will be described with reference to FIGS. 2 and 3. Note that, similarly to the embodiment described above, the upper side before the signal mixing circuit 32 in FIG. 2 is assumed to be the A channel, and the lower side is assumed to be the B channel.

The signals reproduced from two adjacent tracks on the disk are amplified by amplifier circuits 18 and 19, and the audio signal is separated from the A channel signal on which the PCM audio signal is multiplexed by an audio signal separation circuit 20. A decoder 21 demodulates the audio. On the other hand, B where pilot carriers are multiplexed
Pilot carrier separation circuit 22 from channel signal
The pilot carrier is separated and the clock regeneration circuit 23
Regenerates a clock synchronized with the playback video signal. This clock is used for synchronized playback and jitter correction.

The 2-channel reproduction m from which the low-frequency components have been removed is F.
The M demodulation circuit 24.2'5 demodulates the signal, and the A/D conversion circuit 26.27 samples the signal using the clock and converts it into a digital signal.

The two-channel video signal converted to a digital signal is
The A channel signal is shown in FIG. 3(f), and the B channel signal is shown in FIG. 3(g). As explained in the above embodiment, since frame pulses are recorded in the signals of each channel, this is used to
In the same manner as the USE signal, synchronous reproduction circuits 28 and 29 independently perform synchronous reproduction on each channel. Furthermore, the synchronous reproducing circuit 29 can read out the control signal inserted into the 564th line during recording. The synchronized video signals are subjected to time axis compression circuits 30 and 31 in which jitter caused by rotational unevenness of the disk is removed and the time axis is compressed. The A channel of the time-axis compressed two-channel signal is shown in FIG. 3(b).

The B channel is represented as shown in FIG. 3(c), and in the case of this embodiment, the time axis is compressed to 564/1125. Next, the signal mixing circuit 32 switches the two signals every two lines and restores them to one MUSE signal. The restored MUSE signal is expressed as shown in FIG. 3(a), which has the same signal form as the MUSE signal before recording.

Finally, the MUSE signal combined into one channel is D
/A conversion circuit 33 converts it into an analog signal, M t
Sent to JSE decoder.

In this embodiment, the MUSE signal is used as the video signal, but the present invention is not limited to this, and the present invention can be applied to a case where the video signal is divided into two channels and recorded together with a pilot carrier. Further, although the number of lines to be inserted is three in this embodiment, it is not limited to this, and any odd number of lines may be used. In this case, as a matter of course, it is necessary to also change the signal compression ratio.

Effects of the Invention According to the present invention, since the video signal is recorded and reproduced by dividing it into two channels, the linear velocity of the disk is reduced and the design of the spindle motor is easy.

Furthermore, the bandwidth of the reproduced signal is narrowed, making circuit design easier.

Moreover, in addition to simply dividing the video signal into two channels, each divided channel is provided with the same vertical synchronization signal as the original signal, so the synchronization speed is not inferior to that of one-channel recording. A synchronous regeneration circuit can be realized by only partially changing the conventional synchronous detection circuit.

Furthermore, since a new line is provided, control signals unique to the disc, such as frame numbers and time codes, can be recorded and reproduced without substituting lines that are already in use.

Furthermore, when the color difference signal of the video signal is line sequential, 2
Since each line is divided into two channels and recorded on two adjacent tracks on the disc, adjacent color difference signals on the disc have a correlation and crosstalk during reproduction is less noticeable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a video disc recording device in one embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a video disc playback device in this embodiment, and FIG. 3 is a block diagram showing the configuration of a video disc reproducing device in this embodiment. Fig. 4 is a schematic diagram showing the signal format processed in the conventional example, and Fig. 4 is a schematic diagram showing the channel-divided MUSE signal in the conventional example. Circuit, 15...Pilot carrier multiplex circuit, 2
3... Clock regeneration circuit, 28, 29... Synchronous regeneration circuit, 30.31... Time axis compression circuit, 32... Signal mixing circuit.

Claims (3)

[Claims] (1) A device for recording television video signals on a disk, which includes a switching circuit that time-divides the video signal into two signals every two lines, and expands the time axes of the signals time-divided by the switching circuit. two time axis expansion circuits,
A line insertion circuit that inserts a vertical synchronization signal into the signal that does not have a vertical synchronization signal among the two signals whose time axis has been expanded by the time axis expansion circuit, and also inserts a new line into at least one of the signals. 1. A video disc recording device comprising: a video disc recording device which divides a video signal into two channels and records the divided video signals on two adjacent tracks on the disc. (2) A device that divides a television video signal into two channels and records them on a disk, which includes a pilot carrier multiplexing circuit that frequency multiplexes a pilot carrier synchronized with the video signal on one channel, and a pilot carrier on the other channel.
A video disc recording device comprising: an audio multiplexing circuit that frequency multiplexes CM audio signals. (3) A reproducing device for a video disc recorded with the video disc recording device according to claim 1 or 2, comprising two sets of reproducing means for obtaining respective reproduction signals from two adjacent tracks on the disc. , a clock regeneration circuit that frequency-separates a pilot carrier from one of the reproduced signals and reproduces a clock synchronized with the pilot carrier, and independently performs synchronized reproduction on each channel using the vertical synchronization signal of each reproduced signal and the clock. two synchronized playback circuits, two time-base compression circuits that compress the time-base of synchronized video signals, and the two signals compressed by the time-base compression circuits are alternately switched in units of two lines to produce a continuous one. A video disc playback device comprising: a signal mixing circuit for restoring channel video signals.