JPH0584985B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reproducing apparatus for a video disc on which television video signals are recorded.

[Conventional technology]

Recently, disks that record information at high density have been developed and commercialized. Typical examples are video disks and digital audio disks.
There are several types of methods, but in the case of optical video discs, the spectrum is as shown in FIG. In other words, by frequency modulating the carrier wave so that the television image signal has a sync chip level of 7.6 MHz and a white level of 9.3 MHz, the accompanying audio signals such as left and right stereo signals and bilingual signals can be adjusted to 2.3 MHz. It is recorded by frequency modulating carrier waves of MHz and 2.8MHz, respectively. On the other hand, the spectrum of the EFM signal of the PCM-converted left and right stereo audio signals in an optical digital audio disk occupies a band of approximately 2 MHz or less, as shown in FIG. As mentioned above, on video discs, the band below 2 MHz is almost empty, so such EFM signals can be frequency division multiplexed and recorded on video discs. The spectrum in this case is as shown in FIG. 8, and it can be seen that both signals can be sufficiently separated.

FIG. 9 shows a block diagram of such a video disc recording device. That is, a television video signal whose high frequency components have been pre-emphasized by a pre-emphasis circuit 1 is frequency-modulated by an FM modulator 2 and input to an adder 3.
The audio signals of the two channels are pre-emphasized by pre-emphasis circuits 4 and 5, frequency-modulated by FM modulators 6 and 7, and input to an adder 3. Furthermore, the audio signals of the two channels are converted into digital (PCM) by PCM encoder 8, and then converted into digital (PCM) by EFM encoder 9.
After being subjected to EFM modulation and having unnecessary high-frequency components removed by a low-pass filter 10, the signal is input to an adder 3 via a pre-emphasis circuit 11. Therefore, in the adder 3, the FM signal of the video signal and the 2
The FM signal of the audio signal of the channel and the EFM signal of the audio signal of the two channels are added, multiplexed by the limiter 12, and then supplied to the optical modulator 13. As a result, the laser beam output from the laser light source 14 is modulated in accordance with the signal, and is irradiated via the objective lens 15 onto the recording master disk 17 rotated by the motor 16, thereby recording the signal. Since the technique for forming a disk from such a recording master 17 is well known, detailed description thereof will be omitted.

FIG. 10 shows a block diagram of a disc playback apparatus constructed in this manner. A disk 22 rotated by a motor 21 is irradiated with a laser beam emitted from a pickup 23 via an objective lens 24, and the reflected light is received by the pickup 23 via the objective lens 24, and a reproduced signal is output. . The reproduced RF signal is outputted via the amplifier 25, of which the video signal
The FM carrier wave component passes through the bandpass filter 26 and is supplied to the FM demodulator 27, where it is demodulated.
It is output via the de-emphasis circuit 28.
Furthermore, the FM carrier wave components of the audio signals of the two channels are supplied to FM demodulators 31 and 32 via bandpass filters 29 and 30, respectively, where
After FM demodulation, the de-emphasis circuit 33,
34. Further, the EFM signal component is separated by a low-pass filter 35 and sent to an EFM decoder 37 via a de-emphasis circuit 36.
The signals are further supplied to a PCM decoder 38, where they are subjected to EFM demodulation and PCM demodulation, respectively, and output as analog signals. Therefore, the viewer can select and listen to a higher-fidelity audio signal as desired along with the video signal.

[Problem that the invention seeks to solve]

By the way, it is conceivable to record a digital data signal instead of an audio signal as such an EFM signal. Since digital data signals, unlike audio signals, are not necessarily continuous signals, it may be advantageous to have a block structure.

When digital data signals are recorded in a block structure as described above, interleaving is generally performed to prevent burst errors that occur successively.

Simply put, interleaving divides digital data signals in time, gives periodic delays to each divided group, reassembles them, and interleaves the order of the signals. Even if errors occur continuously on the digital data signal, the errors are dispersed when viewed on the original signal.

When performing the above interleaving,
Even if the original digital data signal can be recorded within the recording time of a certain frame or field of television video signal, the interleaved digital data signal
Even if the recording start position is the same as when no interleaving is performed, the recording may end up exceeding the recording time of the television video signal of the corresponding frame or field.

Therefore, in such a case, if you try to reproduce the frame or field television video signal as a still image and simultaneously reproduce the corresponding digital data signal, synchronization will not be achieved, so it is necessary to properly match the two and reproduce them. It was difficult.

Therefore, an object of the present invention is to convert the digital data signal into a television video signal even if the digital data signal after interleaving is recorded beyond the television video signal recording time of the corresponding frame or field. An object of the present invention is to provide a playback device capable of playing back still images.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a system in which a television video signal and a digital data signal are frequency-divided and multiplexed onto the same track, the digital data signal is divided into blocks each having a predetermined number of bits, and The length after interleaving is longer than the corresponding frame or field of the television video signal, and the beginning of one block corresponding to a certain frame or a certain field or the beginning of a plurality of blocks corresponding to a certain frame or a certain field Reproducing a video disc recorded discretely such that the recording start position at the beginning of the first block is timing-wise located near the position where the vertical synchronization signal at the beginning of the corresponding frame or field is recorded. The playback device includes filter means for separating a modulation signal of the television video signal and a modulation signal of the digital data signal from the playback signal of the video disc, and a filter means for reproducing a digital data signal from the modulation signal of the digital data signal. a digital data reproducing means that records a modulated signal of the television video signal in the vicinity of a position corresponding to the beginning of the one block or the beginning of the first block of the plurality of blocks of the digital data signal; a first detection means for detecting the vertical synchronization signal, and a second detection means for detecting a predetermined position after the end of the one block or a predetermined position after the end of the last block of the plurality of blocks; , when the predetermined position is detected by the second detection means, a frame or field whose recording start position is the vertical synchronization signal recording position detected by the first detection means based on the modulation signal of the television video signal; still image reproducing means for reproducing the television video signal as a still image.

[Effect]

According to the present invention, the filter means separates the modulation signal of the television video signal and the modulation signal of the digital data signal from the reproduction signal of the video disc, and the filter means separates the modulation signal of the television video signal and the modulation signal of the digital data signal, and the filter means separates the modulation signal of the television video signal and the modulation signal of the digital data signal,
The digital data signal is outputted to the second detection means and the still image reproduction means, and the digital data signal is outputted to the digital data reproduction means.

Thereby, the digital data reproducing means reproduces the digital data signal from the modulated signal of the digital data signal.

On the other hand, the first detection means detects a vertical synchronization signal recorded in the vicinity of a position corresponding to the beginning of one block of the digital data signal or the beginning of the first block of a plurality of blocks from the modulation signal of the television video signal. Detect the signal. Further, the second detection means detects a predetermined position after the end of one block or a predetermined position after the end of the last block of a plurality of blocks.

As a result, when the predetermined position is detected by the second detection means, the still image reproduction means sets the vertical synchronization signal recording position detected by the first detection means based on the modulation signal of the television video signal as the recording start position. The frame or field of the television video signal is reproduced as a still image.

Therefore, even if the length of a block of digital data signals after interleaving is longer than the frame or field of the corresponding television video signal, still images can be reproduced in a reliable manner.

〔Example〕

Next, preferred embodiments of the present invention will be described with reference to the drawings.

First, before explaining the playback device of the present invention, the video disc recording device and the recording state of the video disc will be explained.

Figure 1 shows the block of the recording device.
Components corresponding to those in FIG. 9 are designated by the same reference numerals, and detailed description thereof will be omitted. In the case of FIG. 9, the 2
The audio signals of the two channels are sent to the EFM encoder 9.
However, in the present invention, the digital data signal is input to the EFM encoder 9 via the memory 41 (of course, a changeover switch etc. is provided so that either the audio signal or the digital data signal can be selectively input). ). Reference numeral 42 denotes a position detecting means, which detects a predetermined position of the video signal and controls the memory 41. Other video signal pre-emphasis circuit 1, FM modulator 2, adder 3, 2
pre-emphasis circuits 4 and 5 for audio signals of two channels, FM modulators 6 and 7, a low-pass filter 10 in the signal path of the EFM encoder 9, a pre-emphasis circuit 11, a limiter 12 arranged in the signal path from the adder 3, The configuration of the optical modulator 13, laser light source 14, objective lens 15, motor 16, recording master disk 17, etc. is the same as that in FIG. 9.

Next, the operation will be explained. The video signal and the audio signals of the two channels are sent to pre-emphasis circuits 1, 4,
5. The frequencies are modulated by the FM modulators 2, 6, and 7 and the adder 3, and then added, as in the case described above. In the present invention, the position detection means 42
detects a predetermined position of the video signal.

This detected position may be any vertical synchronization signal position, but for example, the fifth position of each vertical synchronization signal.
The position may be indicated as s in the figure. In Figure 5, the arrow indicates that one frame (two fields) of video signal is recorded in one rotation.
On a CAV disk, this indicates the position where the pick-up can jump for still image playback.
In the case of a normal television video signal, there is an odd field (A ₁ , B ₁ , C ₁ , D ₁ , E ₁ , F ₁ ) followed by an even field (A ₂ , B ₂ , C ₂ , D ₂ , E ₂ , _F2 )
Since one screen is configured by
Diagram a). On the other hand, a movie film with 24 frames per second,
When a television video signal is obtained by so-called 3-2 pulldown, the portion where the same screen is recorded in two consecutive fields (a ₁ , a ₁ , c ₁ ,
c ₂ , e ₁ , e ₂ ) and the part where the same screen is recorded for three consecutive fields (b ₁ , b ₂ ,
b ₃ , d ₁ , d ₂ , d ₃ , f ₁ , f ₂ , f ₃ ), and the position where you can jump for still image playback is the same screen as the two fields before and the one field before. (Figure 5b). Therefore, the position s detected by the position detecting means 42 is the position of the synchronization signal one frame (two fields) before the position of the jumpable synchronization signal indicated by this arrow.
In a portion where the same screen is recorded for three fields, there are two positions s, and one of them is selected.

When the position detection means 42 detects the position s,
The memory 41 outputs the digital data signal that has been accumulated and stored up to that point. This digital data signal is supplied to the EFM encoder 9, subjected to processing such as interleaving, and then passed through the low-pass filter 1.
0, adder 3 via pre-emphasis circuit 11
and is added to the frequency-modulated video and audio signals. Therefore, the beginning of the digital data signal is placed and recorded near the position corresponding to the position s of the video signal.

By the way, the length of one block of a digital data signal can be set to any value such as 1 kilobyte or 2 kilobytes, but for example, the length of an audio signal block (98 frames) before EFM modulation in an optical digital audio disk (1
If one block is a digital data signal of 2.352 kilobytes (=24 x 98), or 1.816 kilobits, and the length before interleaving is approximately 13.3ms, then optical digital audio disk
Since the dispersion due to interleaving of the EFM encoder spans a length of approximately 14.7 ms, the length of one block after interleaving is approximately 28 ms. The interval between vertical synchronization signals (length of one field) is approximately
Since it is 16.7ms, the length of one block before interleaving is shorter than the vertical synchronization signal interval (length of one field), but the length after interleaving is longer than the length of one field and shorter than the length of one frame. Become. Therefore, for example, when two blocks of digital data signals are made to correspond discretely to a video signal of a certain frame, more specifically, the fourth block of digital data signals is
Video signal of frame A and frame B shown in figure a
When the digital data signals D _a1 and D _a2 and the digital data signals D _b1 and D _b2 are made to correspond discretely to the video signal of FIG. 4, as shown in FIG. 4 c, as shown in FIG. The first block of the digital data signal after interleaving as shown.
The beginnings of D' _a1 and D' _b1 are recorded at a timing corresponding to the vicinity of the recording position of the immediately preceding vertical synchronizing signal (see FIG. 4 f) corresponding to each frame A and B.

In this case, in item 4e, the blocks of the digital data signal after interleaving are drawn diagonally to schematically show the recording (distribution) range after interleaving of each block corresponding to the video signal. More specifically, by interleaving, the digital data constituting each block is rearranged randomly between adjacent blocks and within a block, and recorded in an intertwined (weaved) state. Therefore, for example, the recording ranges of the blocks of digital data signals D _a1 and D _a2 corresponding to frame A overlap with each other, and the recording (distribution) range is longer than when interleaving is not performed. , is recorded over the video signal recording range of the next frame B, which does not necessarily correspond in content. Furthermore, the recording range of the digital data signal D _a2 also overlaps with the recording range of the digital data signal D _b1 corresponding to the next frame B. This is shown in Figure 4e.

Furthermore, when one block of digital data signal is made to correspond discretely to the video signal of a certain field, more specifically, the field shown in FIG.
When digital data signals D _a1 and D _a2 are made to correspond discretely to the video signal of A ₁ and the video signal of field A ₂ , as shown in FIG. 4 b, the result is shown in FIG. 4 d. The first block of the digital data signal after interleaving as shown.
The beginnings of D' _a1 and D' _a2 are recorded at a timing corresponding to the vicinity of the recording position of the immediately preceding vertical synchronizing signal (see FIG. 4f) corresponding to each field A ₁ and A ₂ .

In this case, the reason why the blocks of the digital data signal after interleaving are drawn diagonally in FIG. 4d is because the recording (distribution) of each block corresponding to the video signal after interleaving is similar to FIG. 4e. This is to schematically show the range. Than,
Specifically, by interleaving, the digital data constituting each block is rearranged randomly between adjacent blocks and within the block, and is recorded in an intertwined (weaved) state. Therefore, for example, the recording range of the block of digital data signal D' _a1 corresponding to field _A1 overlaps with the block of digital data signal D' _a2 of field _A2 , and is compared with the case where no interleaving is performed. The recording (distribution) range is getting longer. Furthermore, recording will be performed over the recording range of the video signal of the next field _A2 , which does not necessarily correspond in content.

Furthermore, since it is preferable that jumpback occurs during playback in the vertical retrace interval, it is preferable not to record digital data signals within the vertical retrace interval that includes the vertical synchronization signal.

Next, a reproducing apparatus which is an embodiment of the present invention and which reproduces a video disc recorded by the above-mentioned recording apparatus will be described.

FIG. 2 shows a block diagram of the reproducing apparatus, in which parts corresponding to those in FIG. 10 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the playback device according to the present invention,
The output of the EFM decoder 37 is sent to the data decoder 52 or PCM decoder 38 via the switch 51.
It is now being supplied to The switch 51 responds to commands from a microcomputer (not shown) or the like to the PCM decoder 38 side if an audio signal is recorded as an EFM signal, or to the data decoder 52 side if a digital data signal is recorded. It is possible to switch between the two. Of course, in digital data signals as well.
If the PCM decoder 38 can be shared, the data decoder 52 may be omitted and the switch 51 may be provided on the output side of the PCM decoder 38. 53 is a switch that squelches the video signal from the de-emphasis circuit 28. 54 is an equalizer 55 to which a tracking error signal is input, a tracking servo loop loop switch 56, and an adder 5.
7 and a drive amplifier 58 for driving a tracking actuator (not shown). The video signal output from the de-emphasis circuit 28 is input to a synchronization separation circuit 59 and further to a vertical synchronization separation circuit 60, where a vertical synchronization signal is separated and detected. The detection signal of the vertical synchronization signal is a jump pulse generation circuit 61.
and is supplied to the squelch control circuit 62. 63 is a memory control circuit that controls the memory (RAM 75 in FIG. 3) of the data decoder 52. A jump command signal, a squelch command signal, and a memory control signal are output from the microcomputer to the jump pulse generation circuit 61, squelch control circuit 62, and memory control circuit 63, respectively.

Next, the operation will be explained.

The effect when the EFM signal is not a digital data signal is the same as the case described above, so it will be omitted.
Only the case where it is a digital data signal will be explained. For example, frame A or digital data
Search commands for D' _a1 and D' _a2 are issued from the microcomputer, the loop switch 56 is opened, and frame A or digital data is searched.
The search operation for D′ _a1 and D′ _a2 is started, and
The squelch control circuit 62 opens the switch 53 and squelches the video signal. When frame A or digital data D' _a1 , D' _a2 is retrieved, the loop switch 56 is closed, the tracking control device 54 is operated, and normal reproduction operation is started. Of the reproduced signals from the amplifier 25, the EFM signal is input to the EFM decoder 37 via a low-pass filter 35 and a de-emphasis circuit 36.
EFM demodulated. The EFM demodulated signal is input to the data decoder 52 via the switch 51.
The data is stored in a predetermined memory and processed in response to a signal from the memory control circuit 63.

On the other hand, as shown in Figure 4d or Figure 4e,
Regardless of whether the digital data signal is recorded discretely in field units or frame units, the 2-digit data signal corresponding to frame A is When the storage operation of the block D' _a2 recorded later among the two blocks is completed, a jump command is issued to the jump pulse generation circuit 61. Then, the jump pulse generation circuit 61 generates a jump pulse to the adder 57 at the next timing when the vertical synchronization signal is detected by the vertical synchronization separation circuit 60.
(Of course, if the jump pulse is generated immediately after reading of the subsequent block Da2' is completed, there is no need to wait until the next vertical synchronization signal is detected). Therefore, the tracking actuator is driven, and the pickup 23 moves from the vicinity of the vertical synchronizing signal between the first field _B1 and the second field _B2 of frame B to the first field of frame A.
Jump back one track (one frame) near the vertical synchronization signal between _A1 and the second field _A2 . Then, a jump pulse is generated again in the vicinity of the vertical synchronization signal immediately after the second field _A2 , and the signal jumps back one track (frame) to the vicinity of the vertical synchronization signal immediately before the first field _A1 . After that, after playing frame A, the operation of jumping back one track is repeated, and then frame A is played back.
A still image is played back (see Figure 4g). On the other hand, the squelch control circuit 62 closes the switch 53 to cancel the squelch when the frame A first jumps back to a position near the vertical synchronization signal immediately before it. Therefore, the user only sees the still image of frame A (FIG. 4h). When the processing of the digital data signal is completed, this still image reproduction operation is also canceled and the next operation is started.

FIG. 3 shows a more detailed block diagram of EFM decoder 37 and data decoder 52 (switch 51 between them is omitted). In other words, in the EFM decoder 37, the input
The EFM signal is waveform-shaped by a waveform shaping circuit 71,
The signal is demodulated by an EFM demodulator 72, temporarily stored in a RAM 73 of, for example, 16 kilobits, and after processing such as deinterleaving, an error detection and correction circuit 74 detects and corrects errors. Further, in the data decoder 52, digital data is temporarily stored in the RAM 75, and the digital data is stored in the memory control circuit 6.
From 3 onwards, processing such as reading is performed by control signals, and error detection and correction is performed by an error detection and correction circuit 76. For example, if the capacity of RAM 75 is approximately 38 kilobits, which is equivalent to 2 blocks, image 1
Although it is possible to capture digital data for one page at a time, it is also possible to capture approximately 19 kilobits for one block. In this way, the length of the series of digital data recorded on the disk is
If the memory capacity of the RAM 75 exceeds the capacity that can be stored at one time (of course, it may not exceed the capacity), the data from the vicinity of the vertical synchronization signal immediately before the first block D' _a1 and immediately after the block D' _a2 immediately after the first block D' a1 will be stored. The jump-back operation is repeated from the vicinity of the vertical synchronization signal to the vicinity of the vertical synchronization signal immediately before the first block D' _a1 (regardless of the path), and after the processing of the stored digital data is completed, the next block is executed. It is also possible to store and process them sequentially.

In addition, in the embodiment shown in FIG. 4, the video signal is squelched until all the digital data has been read, but as mentioned above, the RAM 75 can store the length of a series of digital data recorded on the disk at one time. If the same image is recorded over multiple frames that exceed the length of the series of digital data, if the length of the series of digital data is exceeded, the series of digital data can be It is possible to cancel the squelch of the video signal before completing the processing of all the digital data constituting the video signal. In other words, the field or frame to be squelched can be arbitrarily selected within the plurality of frames. For example, it is possible to store the same image in frames A, B, etc., and reproduce it as a still image at all times during the jump repetition operation.

The start and end points for repeating the playback operation and jumpback operation are, for example, near the vertical synchronizing signal immediately before the first block D' _a1 , as shown in Fig. 4g'.
Frame B where the end of the subsequent block D′ _a2 is located
(solid line in the same figure), or near the vertical synchronization signal one field before the field where the beginning of the first block D' _a1 is located, and at the end of the subsequent block D' _a2 . It can be placed near the immediately following vertical synchronization signal (dashed line in the figure). In these cases, the playback operation and the two frame (two track) jump back operation are repeated.

When the length of digital data is 1 block, the length after interleaving of 1 block, which is the minimum unit, is shorter than 1 frame, and the beginning can be jumped as described above instead of the position of all vertical synchronization signals. By setting the position s of the vertical synchronization signal one frame (one rotation) before the position, the squelch of the video signal can be canceled at the time when the position s is searched, and the squelch time can be shortened. Furthermore, regarding the jump position, it is possible to ensure compatibility with ordinary video discs that are already commercially available.

〔effect〕

According to the present invention, when the recording position of the vertical synchronization signal is detected by the second detection means, the still image reproduction means detects the vertical synchronization signal detected by the first detection means based on the modulation signal of the television video signal. Since the television video signal of a frame or field whose recording position is the recording start position is reproduced as a still image, the length of the block of the digital data signal after interleaving is longer than the corresponding frame or field of the television video signal. Even if there is a problem, static playback can be performed with certainty.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the recording apparatus of the present invention, and FIG.
Figure 3 is a block diagram of the playback device, Figure 3 is a more detailed block diagram of a part of the playback device, Figure 4 is a timing chart during recording and playback, and Figure 5 is a field diagram of the television video signal. Schematic plan view, Figure 6 is a spectrum diagram of an optical video disc, Figure 7 is a spectrum diagram of an EFM signal, Figure 8 is a spectrum diagram of an optical video disc recording an EFM signal, and Figure 9 is a spectrum diagram of a conventional video disc. FIG. 10 is a block diagram of a recording device for an optical digital audio disk, and FIG. 10 is a block diagram of a reproducing device thereof. 1, 4, 5, 11... pre-emphasis circuit,
2, 6, 7...FM modulator, 3...adder, 8...
...PCM encoder, 9...EFM encoder, 1
0...Low pass filter, 13...Light modulator, 1
4... Laser light source, 15, 24... Objective lens,
17...recording master, 22...video disc, 2
3...Pickup, 25...Amplifier, 26,2
9, 30...hand pass filter, 27, 31,
32...FM demodulator, 28, 33, 34...De-emphasis circuit, 37...EFM decoder, 3
8...PCM decoder, 41...memory, 42...
...Position detection means, 51, 53...Switch, 52
...Data decoder, 54...Tracking control circuit, 61...Jump pulse generation circuit, 73,
75...RAM.

Claims (1)

[Scope of Claims] 1. A television video signal and a digital data signal are frequency-divided and multiplexed onto the same track, the digital data signal is divided into blocks each having a predetermined number of bits, and the length after interleaving is is longer than the corresponding frame or field of the television video signal, and is the beginning of a block corresponding to a certain frame or a certain field, or the beginning of a plurality of blocks corresponding to a certain frame or a certain field. A playback device that plays back a video disc recorded discretely such that the recording start position at the beginning is timing-wise located near the position where the vertical synchronization signal at the beginning of the corresponding frame or field is recorded. filter means for separating the modulation signal of the television video signal and the modulation signal of the digital data signal from the reproduction signal of the video disc; and a digital data reproducing device for reproducing the digital data signal from the modulation signal of the digital data signal. means, and the vertical synchronization is recorded in the vicinity of a position corresponding to the beginning of the first block of the digital data signal or the beginning of the first block of the plurality of blocks from the modulation signal of the television video signal. a first detection means for detecting a signal; a second detection means for detecting a predetermined position after the end of the one block or a predetermined position after the end of the last block of the plurality of blocks; Television video of a frame or field whose recording start position is a vertical synchronization signal recording position detected by the first detection means based on a modulation signal of the television video signal when the predetermined position is detected by the detection means. A reproducing device comprising: still image reproducing means for reproducing a signal as a still image;