JPH0554389A - Video disk reproduction device - Google Patents

Abstract

PURPOSE:To improve the output speed of a picture by synthesizing a regenerative signal from both pickups without performing the rotation phase control of a disk when a video signal split-recorded on both sides of the disk. CONSTITUTION:In the case of high-speed reproduction, each pickup on both sides of the disk is track-jumped, and an address is detected in the position. Next, whether or not each pickup position is a track of the picture signal of the same frame is judged. In case it is not, the position of each pickup is moved so as to reproduce the picture signal of the same frame. On the other hand, when the pickup position is correct, a regenerative signal from each pickup is synthesized, to be outputted as a video signal. In this case, even when pictures of the current frame and the former frame coexist in one picture, the video signal has the timewise correlation so that this influence will not be particularly noticeable, thus outputting much more pictures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video disc reproducing apparatus.

[0002]

2. Description of the Related Art As a method of recording a wideband signal such as a high-definition video signal on a video disk or the like, a 2-channel T for dividing the video signal into two to lower the recording signal band.
There is a CI recording method. For example, the luminance signal is divided for each line and expanded on the time axis, the color difference signal is line-sequentially compressed on the time axis, and they are time-division multiplexed.

The applicant of the present invention records each channel of a two-channel video signal on both sides of a video disk,
We have developed a playback device that plays back both sides simultaneously with one pickup, and has already applied for a patent (see Japanese Patent Application No. 2-114077).

FIG. 4 shows the recording apparatus. The high-definition VTR 1 is an analog VTR for reproducing and deriving a baseband high-definition video signal recorded on a video tape by using the crystal oscillation circuit 2 as a reference signal.
It consists of a luminance signal Y of 20 MHz and two color signals P _R and P _{B of} 10 MHz.

From the high-definition VTR 1, in addition to the high-definition video signal, the address code signal of the frame period recorded in the control track is reproduced and derived, and the oscillation output (48.6 MHz) of the crystal oscillation circuit 2 is also derived. To be done. The signal obtained from the high quality VTR 1 is input to the recording encoder 3. The two color signals P _R and P _B are input to the line sequential circuit 4, the luminance signal Y is input to the time division multiplexing circuit 5, and the address code is input to the address detection circuit 6.

The line-sequentializing circuit 4 alternately selects the color signals P _R and P _B in a line cycle in synchronization with the address code and the synchronizing signal to form and derive a line-sequential color signal. The line-sequential color signal is input to the time-axis compression circuit 7 and 3 times during the horizontal blanking period of the luminance signal in which both ends of each line are partially removed.
Time axis compression is doubled. The line-sequential compressed color signals are time-division multiplexed in the time-division compression / multiplexing circuit 5 to be MUSE.
The signal is converted into a line-sequential high-definition color video signal of which the arrangement is almost the same as that of the signal and is input to the signal selection circuit 8.

The signal selection circuit 8 selects a line-sequential high-definition color video signal every other line in accordance with the recording surface designating signal, and time-division-multiplexes an address code on a specific line in the vertical blanking period. Note that, as a result of this selection, only the signal lines in which the same color signal is compressed and multiplexed according to the recording surface designation signal are selected, and the same color information is recorded on the same surface.

The selected signal is time-doubled in the time-axis expansion circuit 9 and is input to the frequency multiplexing circuit 10 as a signal in the band of about 12 MHz. The frequency multiplexing circuit 10 frequency-multiplexes the pilot signal generated by the burst signal generation circuit 12 on the back porch of the horizontal synchronizing signal by dividing the period by 6 cycles. Burst signal generation circuit 12
Generates a pilot signal of 8.1 MHz by dividing the crystal oscillation output by 1/6.

The frequency multiplex output has an FM shift range of 15.4.
The signal is input to the FM modulation circuit 11 which is set to 3 to 17.17 MHz and is FM-modulated. The FM modulation output is supplied as a recording signal to the optical video disk recorder 15. Further, the recording encoder 3 clearly identifies the reference signal generating circuit 13 for changing the frequency of the reference signal according to the address code to keep the recording linear velocity constant, and the recording end of the recording track on the disc record. The end signal generating circuit 14 for

The reference signal specifies the rotational angular velocity of the disc in accordance with the address code. As a result, when the front and back sides of the pasted discs are simultaneously reproduced, the recording tracks of the same address are recorded. The linear velocities will always match.

The end signal generating circuit detects the end of recording from the address code and sends the end signal to the reference signal generating circuit 13 and the video disk recorder 15. The reference signal generation circuit 13 fixes the reference signal frequency after the end signal is input.

The movement control means 16 in the video disk recorder 15 defines the optical recording means 17 at the innermost circumference of the disk in the initial state, and when the recording is started, the optical recording means 17 is moved at a speed inversely proportional to the PG pulse period. Move it along the guide rail in the outer peripheral direction. Further, the movement control means 16 also detects the positional information in the radial direction by the built-in decoder, and compares the detected positional information with the address code to correct the moving speed.

The recording means 17 optically modulates the recording signal during the recording period to form a recording track, and activates the mark signal generating circuit 19 at the recording end signal generation timing.
The mark signal generation circuit 19 detects a period from the final PG pulse generation timing to the end signal generation timing, delays the subsequent PG pulse generation timing by that period, and intermittently generates a mark signal of a predetermined frequency for a certain period. To do. Therefore, the optical recording means 17 forms a visible end mark outside the recording end of the disc.

The disk motor 20 rotates the disk at a predetermined angular velocity in the initial state. The reference signal supplied at the start of recording and the FG pulse derived from the disk motor 20 are input to the phase comparison circuit 21 to perform phase comparison. The phase comparison output is the motor drive circuit 22.
And the rotation of the disk motor 20 is controlled according to the reference signal frequency. The motor drive circuit 22 is
The polarity of the drive voltage is inverted based on the recording surface designation signal, and the rotation direction of the disk is inverted according to the recording surface designation signal.

When the first disc is mounted and a surface designation signal is generated, the disc motor 20 is rotationally driven in the clockwise direction to form recording tracks in the counterclockwise direction from the inner side to the outer side, and the recording end is formed. An end mark is formed on the outside. The recorded signals are the luminance signal and the P _R signal for every other line.

Next, when the second disc is mounted and a rear surface designation signal is generated, the disc motor 20 is rotationally driven in the counterclockwise direction, and recording tracks are formed in the clockwise direction from the inner side to the outer side. , An end mark is formed outside the recording end. The recorded signals are the luminance signal and the P _B signal for every other line.

The disc on which the recording is performed in this manner and the duplicate disc thereof are adhered and fixed so that the reproduction surfaces thereof are outside. Then, the signals are read by the two pickups from both outer surfaces of the disc thus created. The disc is a combination of discs that are cut separately for each channel, and there is a time difference between the signals read from the two pickups depending on the laminating error. Therefore, in the reproducing apparatus that the applicant has already developed, the memory absorbs this time difference.

That is, as shown in FIG. 5, Ach and B
The reproduced signal of 2 channels with ch is the A / D conversion circuit 3
In 1 and 41, the signals of the two channels which are A / D converted and have a time difference are once written in the memories 32 and 42. Then, the time difference between the signals read from the two pickups due to the disc bonding error is absorbed, the video signal is read out from the memory with a delay required for decoding the video signal, and both channels are read by the synthesizing circuit 33. The video signals of are combined. Then, the D / A conversion circuit 34 performs D / A conversion.

FIG. 6 shows the video signals of both channels, and FIG. 7 shows the relationship between the writing and reading timings in the memories 32 and 42. If the phase difference between the read timing and the write timing is inappropriate, normal image reproduction cannot be performed. When this phase difference is appropriate over the entire circumference of the disk, the phase is said to have locked. In the CLV disk (constant linear velocity), the time difference between channels becomes larger toward the outer circumference. Therefore, the phase difference at the outermost periphery of the disk is always locked to prevent the phase relationship of the timing signals in FIG. 7 from being destroyed. That is, the phase is always locked by the phase difference at the time of the maximum permissible error of the disc (the maximum bonding error defined by the standard. The time difference of the recording signals at the outermost circumference of the disk).

Therefore, in this case, since writing to the memory always precedes reading, the output video signal is always that of the current frame.

[0021]

When a video signal recorded on two sides of a disk is reproduced at high speed, the two pickups arranged on both sides simultaneously jump several tracks (tracks). Jump), after playing the disc, jump a few tracks again to play the disc. High-speed reproduction is realized by repeating this operation. However, in order to play back the disc by causing the pickups to track-jump in this way, normal playback of images cannot be performed unless the pickup positions on both sides are aligned and the phase of the read timing to the memory is locked.

FIG. 8 shows a processing procedure of the reproducing apparatus already developed by the applicant.

When performing high-speed reproduction (step 11), the pickups on both sides of the disk are caused to jump to a track (step 12), and address detection is performed at that position (step 13). From the next detected address,
It is judged whether or not the position of each pickup is the track of the image signal of the same frame (step 14). If they are different, the position of each pickup is moved so that the image signal of the same frame is reproduced from each pickup (step 15).

On the other hand, when the pickup is at the correct position, the phase difference between the memory read timing and the read signal from the disk changes each time the jump occurs, and the memory read timing and the read signal from the disk are locked to lock the phase. So that the time difference is within the allowable range,
Disk rotation control processing is performed (step 20). That is, the time difference between the channels is detected (step 1
6) It is determined whether or not the detected phase difference is within the allowable range (step 17). If the phase difference is not within the allowable range, the disk rotation speed is controlled so that the phase difference is within the allowable range (step 18).

If the phase difference is within the allowable range, the reproduced signals from the respective pickups are combined and output as a video signal in step 19).

As described above, in the case of the CLV disc, the control for the phase lock is required every time the pickup jumps the track, and unnecessary time loss occurs. This causes deterioration of the image output speed during high-speed reproduction and a limitation on the number of updated images.

It is an object of the present invention to provide a video disc reproducing apparatus capable of improving the image output speed during high speed reproduction.

[0028]

A video disk reproducing apparatus according to the present invention is a video disk reproducing apparatus for reproducing video signals divided and recorded on both sides of a disk simultaneously by using two pickups. In a video disc reproducing apparatus equipped with a disc rotation phase control means for keeping the phase difference of the timing of read / write to the memory provided for correcting the time axis signal of each surface of In playback mode,
The feature is that the reproduced signals from both pickups are combined without controlling the rotational phase of the disc.

[0029]

In the high speed reproduction, the image is output without performing the phase lock. Therefore, during high-speed reproduction, the time required to lock the phase is reduced, the image output speed is increased, and the limitation on the number of updated images is also improved.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the video disc reproducing apparatus according to the present invention is the same as that shown in FIG. In the video disc reproducing apparatus according to the present invention, the reproduction processing procedure is different from that shown in FIG.

FIG. 1 shows a reproduction processing procedure in the video disc reproducing apparatus according to the present invention.

When high-speed reproduction is performed (step 1), the pickups on both sides of the disk are caused to jump to a track (step 2), and address detection is performed at that position (step 3). Next, it is judged from the detected address whether or not the position of each pickup is on the track of the image signal of the same frame (step 4). If they are different, the position of each pickup is moved so that the image signal of the same frame is reproduced from each pickup (step 5).

On the other hand, if the pickups are in the correct position, the reproduced signals from the pickups are combined (step 6) and output as a video signal. If it is not the high-speed reproduction, the same processing as the processing after steps 13 to 19 in FIG. 8 is performed (step 7).

During high speed reproduction, steps 1 to 5 above
When the reproduction process is performed, an adverse effect may occur that an image of the current frame and an image of the previous frame are mixed in one image. (For example, in the color difference signal, P _R is the current frame, P _B is changed from the middle line to the data of the previous frame, and regarding the luminance signal, the odd line is changed to the current frame and the even line is changed to the data of the previous frame. This is because the phase lock is not performed as in step 20 of FIG.

In the case of a CLV disc, this phase relationship is
The phase relationship of the timing signals for writing and reading to and from the memory changes every track jump. Since the method according to the present invention does not perform the phase lock, it may not be as shown in FIG. 7 but may be as shown in FIGS. 2 and 3. In this method, this phase relationship changes every time the pickup jumps a track, and it is not constant which of the relationships shown in FIG. 7, FIG. 2 and FIG.

When the phase relationship between the timing signals for writing and reading in the memory is as shown in FIG. 7, the video signal of the current frame is always output as described above. Further, in the case where the phase relationship is as shown in FIG. 3, since the reading from the memory precedes the writing, the output video signal is Ac
The video signals of the previous frame are output from both h and Bch, and then the video signals of the current frame are output simultaneously from the lines in the middle. The image is adversely affected by the image of the previous frame at the top and the image of the current frame at the rest.

Further, when the phase relationship is as shown in FIG.
In ch, writing to the memory precedes reading, and B
In ch, the reading from the memory precedes the writing, so that the Ach always outputs the video signal of the current frame, and the Bch outputs the video signal of the previous frame. Therefore, in the image, the color difference signal Pr is the current frame, Pb
, The upper line changes from the middle to the current frame in the previous frame, and the luminance signal becomes an image in which the odd line is the current frame and the even line is the upper line from the middle to the current frame in the previous frame, and the image is adversely affected. ..

However, since the video signals are temporally correlated, this effect is not noticeable during high speed reproduction. Since high-speed playback is used as a search function, this effect has a greater merit of being able to output more images faster than high-speed playback rather than causing a problem.

[0039]

According to the present invention, in a double-sided simultaneous reproduction video disk reproducing apparatus, phase locking is not performed during high speed reproduction, so that more images can be output faster.

[Brief description of drawings]

FIG. 1 is a flowchart showing a reproduction processing procedure according to an embodiment of the present invention.

FIG. 2 is a time chart showing the relationship of timing signals to a memory when phase locking is not performed.

FIG. 3 is a time chart showing a relationship of timing signals to a memory when phase locking is not performed.

FIG. 4 is a block diagram showing a video disk recording device that the present applicant has already developed.

FIG. 5 is a block diagram showing a signal processing circuit of a video reproduction signal in a video disc reproducing apparatus which has already been developed by the applicant.

FIG. 6 is a time chart showing a video signal.

FIG. 7 shows a relationship of timing signals to a memory when phase locking is performed.

FIG. 8 is a flowchart showing a reproduction processing procedure in the video disk reproducing apparatus that the applicant has already developed.

[Explanation of symbols]

 31 A / D conversion circuit 32 Memory 33 Compositing circuit 34 D / A conversion circuit 41 A / D conversion circuit 42 Memory

Claims (1)

[Claims] 1. A video disc reproducing apparatus for reproducing video signals dividedly recorded on both sides of a disc by using two pickups at the same time, the time axis correction of signals on each side of the disc. In a video disk reproducing apparatus equipped with disk rotation phase control means for keeping the phase difference between read / write timings in the provided memory within an allowable range, in the high speed reproduction mode, without performing disk rotation phase control. , A video disk playback device characterized by synthesizing playback signals from both pickups.