JPH0271401A - Disk reproducing device - Google Patents

Abstract

PURPOSE:To eliminate discontinuity of reproducing signals when a disk reproducing face is switched and to smoothly reproduce both sides continuously by providing a device to process and reverse a signal time-axially so as to output one part of information recorded on a disk before information fetched after. CONSTITUTION:The title device consists of a video disk 1, a disk rotating motor 2, pick-ups 3 and 4 for an A-face and a B-face, a time axis reversing circuit 13, etc. The information of the face opposite to the face being reproduced is read and demodulated while the first face is reproduced and it is outputted as soon as the information of the face being reproduced is finished. Since, at this time, the disk on the side read newly rotates in a direction opposite to a normal rotational direction, the front and rear of a demodulated signal is reversed. By reversing this signal time-axially and outputting it by the device which outputs previously the information fetched after, it is made into the same signal at the time of a normal rotation. Thus, the discontinuity of the reproducing signals when the disk reproducing face is switched is eliminated and both the sides can be smoothly reproduced continuously.

Description

[Detailed Description of the Invention] [Industrial Field of Application J] The present invention relates to a double-sided fluoroplastic disk device, and particularly to a device for shifting to playback on the opposite side without changing the rotational direction of the disk when switching between top side playback and bottom side playback. The present invention relates to a disc device that eliminates discontinuity in the reproduction signal due to reverse rotation and the time required for its verification, and is capable of smooth continuous reproduction of both sides.

[Prior art] Conventional devices are disclosed in Japanese Utility Model Application No. 61-98292 and Japanese Utility Model Application No. 61-98292.
As described in publications such as No. 101889, when information on the disc is read using two sensors on both the upper and lower surfaces of the disc, the direction of rotation must be changed in accordance with the reproduction of the upper and lower surfaces respectively.

[Problem to be solved by the invention]

In the above-mentioned prior art, when the reproduction surface of the disk changes from the upper surface to the lower surface or from the lower surface to the upper surface, it is necessary to change the direction of rotation of the disk according to each reproduction surface.

For this reason, normal high-speed reproduction could not be performed during the period required for the 8th speed for reversing the disc when switching the disc reproduction surface, and the reproduction signal became discontinuous, making it impossible to perform smooth continuous reproduction on both sides.

The purpose of the present invention is to make it possible to obtain the same playback signal even when the disk is rotating in the reverse direction as when the disk is rotating in the forward direction, thereby eliminating the need to reverse the rotation direction when switching the playback surface, and to eliminate the discontinuity of the playback signal when switching between playing the disk. It is an object of the present invention to provide a disc playback device that can perform smooth continuous playback on both sides by eliminating the problem.

[Means to solve the problem]

The above purpose is to read and demodulate the information on the side opposite to the side being played initially while the first side is being played, and output it as soon as the information on the side being played runs out. !
l) Be accomplished. At this time, since the disk on the side to be newly read is rotating in the opposite direction to the normal rotation direction, the demodulated signal has the front and back reversed. By reversing the time axis and outputting this signal using a device that first outputs the information captured later, it is possible to make the same signal as during normal rotation.

[Effect]

Because of this reverse rotation, the information to be read from a new VC that is rotating in the opposite direction will be read from the end of the information toward the beginning. For this reason, the information is inverted to produce the same reproduction signal as in the normal rotation state, but reading and inverting the entire one side at once requires a huge amount of memory. Therefore, in order to reduce memory, a part of the information on the disk, for example, is divided into frames, is read from the end of the frame to the beginning, and then reversed by the time axis reversal device to send signals from the beginning of the frame to the rear. Restore to. Therefore, the memory capacity can be covered by one frame.

Furthermore, in order to read the next frame, the sensor for reading the signal is moved to the end of the next frame and read toward the beginning, and the reproduced signal is restored by the time axis reversing device. Repeat this operation to read the disk that is rotating in the opposite direction.

The movement of this sensor is based on a constant angular velocity (CAV) disk.
In this case, if you move in the radial direction after one rotation, you can move to the end of the next frame, but if the linear velocity is constant (Ct, V
), depending on the position of the disk, it takes time to move the sensor to the last point of the second frame.

In order to eliminate this time difference, it is necessary to compress the time axis of the time axis reversing device. The above constant linear velocity type (ci, v)
The specific time compensation method will be explained in the implementation section.

As described above, it is possible to reproduce the same signal as in normal operation from a disk rotating in reverse.

[Embodiments of the invention]

Hereinafter, an embodiment of the present invention will be explained with reference to FIG.

In Fig. 1, 1 is a video disc, 2 is a disc rotation mode, 3 is an AFfi pickup, 4 is a B open pink-up, 5 and 6 are preamplifiers, 7 and 8 are FM demodulators, 9 and 1o are 11 and 12 are jitter servo circuits, 13 is a time axis inversion circuit,
14 is a spindle servo, 15 and 16 are changeover switches, and 17 is an output terminal.

In the video disc 1, image signals and audio signals are frequency-multiplexed and FM-recorded on both sides of a disc-shaped recording medium. The video disk 1 is rotated by the moder 2, and the recorded FM signal can be read out by the pickup 3. In the video disc 1, signals are recorded in the same format on sides A and 8 on the premise that after playing back side A, the disc is turned over and playing back side 8 is performed. FIG. 2 explains the process by which the big amplifier 3 reads out signals from the video disc 1. In FIG. 2, the solid lines indicate the tracks of the video disc 1, and the broken lines indicate the process in which the pickup 3 traces the tracks. In an actual device, the pickup moves in the radial direction of the disk, causing the disk to rotate.

In the following, an example in which side A is read out by the big amplifier 3 in FIG. 1 will be explained. The signal read out by the big amplifier 3 is amplified by the preamplifier 5, then demodulated by the J unit 7 into a baseband video signal. This baseband video signal is separated into a horizontal synchronization signal by a synchronization separation process shown in FIG. Spindle servo circuit 1
4, the speed of the moder 2 is controlled by comparing the reference horizontal synchronizing frequency generated by the crystal generator with the horizontal synchronizing signal inputted through the synchronizing separation circuit 9.

The jitter servo circuit 11 uses the horizontal synchronization signal input to the synchronization separation circuit 9 to extract the following from the baseband video signal.
Extracting the color burst signal, comparing the phase with the basic color burst signal from the crystal oscillator, controlling the delay amount of the variable delay line by the CCDIC, and outputting the signal that has passed through the variable delay line. This outputs a video signal that maintains the phase continuity of the color burst signal.

The process of reading side A with the pickup 3 described above is a method well known to those skilled in the art.

Continuation, read side B with pickup 4? 11 will be explained.

Since signals are recorded on the B side in the same format as on the A side, it is possible to process signals in the usual way by reversing the rotation direction of the video disc 1. It takes a long time (more than 10 seconds) to reverse the rotation.Therefore, in this embodiment,
How to play BIfi without changing the rotation direction of the video disc.

FIG. 3 shows the movement process of the pickup 4 when playing back side B without changing the rotational direction. In FIG. 83, the solid line shows the track of the disk, and the broken line shows the locus traced by the pickup. Note that FIG. 6 describes an example of a CAV (constant angular velocity) disk.

In normal playback, when the pickup traces the track, it moves to the outer circumference of the disc, but this time it moves to the inner circumference. Therefore, when the disk rotates once, it jumps toward the outer circumference by two trunks, and further vC1
When it rotates, it repeats the same jumping motion on the outer periphery for two tracks, resulting in the wake shown in Figure 3 being drawn. The above track jump is a video signal played back.
This is done within the vertical blanking period so as not to affect the lJ plane. In the case of a CAv disk where the inner and outer circumferences of the disk are equal and a video signal of 1 frame/1 rotation is recorded, the track jump point is 1 point in the radial direction on the disk, as shown in Figure 3. You will have to wait in line.

When the pickup 4 reads out data along the trajectory shown in FIG. 3, the frames are read out in the correct order, but signals whose time axes are reversed within the frame are read out. This signal is amplified through the preamplifier 6.1. Input to FM demodulator 8. Since the FM signal is correctly detected even if the time axis is reversed, a baseband video signal with the time axis reversed can be obtained.

Approximately 65 μs of the normally reproduced video signal shown in Figure 4 α)
I) shows an example of a video signal whose time axis is reversed, which is the output of the F'M demodulator 8. The output of the FM demodulator 8 is input to a synchronization separation circuit 10 and a jitter servo circuit 12. The synchronization separation circuit 10 extracts the horizontal periodic signal and inputs it to the changeover switch 15 and the jitter servo circuit 12. In the jitter servo circuit 12.

Although there is a difference in whether the burst position is the front porch or the bank porch, the jitter servo circuit 11 performs the same operation as the jitter servo circuit 11, and generates a baseband signal in which the phase continuity of the color bar 281 is guaranteed.

By inputting this signal to the time axis inversion circuit 13 and inverting the time axis for each frame and outputting it,
No. 14: It is possible to obtain a normal baseband video signal on both the time axis within the frame.

FIG. 5 shows the concept of the operation of the time axis inverting circuit 13 in the form of a time chart. After storing the input signal for one frame,
This is a circuit that continuously performs an operation of reversing the time axis within a frame and outputting the output, and the specific open circuit method will be described later.

FIG. 6 shows a timing chart when switching from A-side playback to Brki playback. 81! In figure 6, signal 1
is the output signal of the FM demodulator 7, and the key code 2 is the FM demodulator FJ
! 48, signal 3 is the output signal of the time axis counter-axis circuit 13, and signal 4 is the output signal of the output terminal 17.

Time 1. , the changeover switch 15 is connected to the synchronous separation circuit 9
is switched from the output side of the synchronization separation circuit 10 to the output side of the synchronization separation circuit 10, and the reference of the spindle servo is switched from the reproduction signal of the A side to the reproduction signal of the B side. Since the positional relationship of the synchronization signals on the disk between side A and B is arbitrary, the operation of the time axis inversion circuit starts at time t, which is later than time t1, and the operation of the time axis inversion circuit starts at time t, which is delayed from time t1. Output begins. Changeover switch 16
is time t.

jitter servo circuit 11 at any position from to time t.
is switched to the time axis inversion circuit 13aIl from the output side of the time axis inversion circuit 13aIl. Therefore, signal 4 is at time 1. Until then, the signal of side A is output, and after time t, the signal of side B is output. Further, it is preferable to apply kneening to the output signal 4 during the period from time t to time t.

The configuration described in this embodiment allows a smooth switching operation from the A side to the B side without turning the disc over.

FIG. 7 is a block diagram showing one embodiment of the time axis inversion circuit 13, in which 101 is an input terminal, 102 is an A/D converter that converts an analog signal into a digital signal, 103 is a memory circuit, and 104 is a memory. A control circuit 105 controls the circuit 103, and a control circuit 105 converts the digital signal into an analog signal Kf.
/AK converter, 106 is an output terminal. In the same figure, the signal inputted from input terminal jQj is sent to A/D converter 102.
The analog signal is converted into a digital signal at
The output signal is written to the memory circuit 103. Next, the digital signal read and suspended from the memory circuit 103 is
) / A f converter 105 converts it into an analog signal, and outputs it from the output terminal 106. Furthermore, writing and reading to and from the memory circuit 103 are performed by control signals from the control circuit 104.

Next, the operation of reversing the time axis will be further explained using FIG. 8. FIG. 8 shows the memory circuit 10 shown in FIG.
6, and A1-A100 shown in the figure are addresses indicating individual storage locations.

The memory circuit 103 has a storage capacity capable of storing a digital signal for one frame of a video signal, but the 8th
In the figure, for convenience of explanation, it is assumed that a digital signal for one frame of a video signal can be stored at addresses A1 to A100.

First, in the wJZ diagram, the digital signal output from the A/DK converter 102 is written into the memory circuit 103, which is written at addresses A1, A2, A3, .・・・
. . , and finally, when address A100 is written, the video signal for one frame is stored in the memory circuit 103.

Next, the written data is stored at addresses A100 to A99.
A98... is read in reverse, and the read digital signal is converted into an analog signal by the D/A converter 105!
A signal is output from the output terminal 106. That is, in the memory circuit 103, by switching the writing order and the reading order, the time axes of the video signal input from the input terminal 101 and the video signal output from the output terminal 106 are reversed. Further, in FIG. 8, after performing the reverse VcR reading from address A100 described above, there is no need to save the contents of the memory. Therefore, after reading data, it is necessary to read the data of the other frame, that is, always read data from one address, and move from address A1 to A100 and from A100 to A1 while performing a flavoring operation. Therefore, the memory circuit 105 has 1
With the storage capacity for one frame, it is possible to invert the axis of the video signal between f\P for each frame.

Next, Figure 8g9 is a block diagram showing another embodiment of the time axis inversion circuit 13, and 107 and 112 are switches;
108, 109, and 110 are memory circuits, and 111 is a field discrimination circuit. In FIG. 7, the same components or components having the same function are given the same reference numerals, and the explanation thereof will be omitted.

@9 In Figure 9, the digital signal output from the A/D 7 & converter 102 is switched by the switch 107 and sent to one of the memory circuits 108, 109, 110 (
written. One of the digital signals read from the memory circuits 108, 109, and 110 is selected by the switch 112 and supplied to the D/A converter 105, and the field discrimination circuit 111 receives the video signal input from the input terminal 101. Determine the field of and switch 1
Controls the switching timing of 07°112.

In FIG. 9, the higher the sampling frequency when converting into a digital signal in the A/D converter 102, the higher the resolution of the video signal, and the more finely the t expression can be transmitted. However, in the circuit shown in FIG. 7, the memory circuit 103 performs reading/writing at one time, so the A/D
The sampling frequency at converter 102 cannot be increased if the read/write speed of the memory circuit is slow.

Therefore, if the memory speed is slow, the problem can be solved by using a time axis inversion circuit shown in FIG. In FIG. 9, memory circuits 108, 109, and 110 have a capacity that can store one field's worth of video signals. So now A/D converter 1
The signal from 02 is sent to memory circuit 1 by switch 107.
Written in 08.

When the signal for one field is written, the switch 107
Accordingly, the signal for the other one field is written into the memory circuit 109. Therefore the memory circuit 108.109 K
This means that the signal for one frame is stored.

a Ic l Mo IJ circuit 108.109 VC#
The obtained data is read out from the memory circuit 109 in the reverse order of writing in the same manner as explained in FIG. . While reading from this memory circuit 109, the deviation for the next one field is written to the memory circuit 110 by the switch 107, and when the writing to the memory circuit 110 is completed, the previously described memory circuit 109 ends at the same time. Therefore, reading is then transferred to the memory circuit 108, and writing is transferred to the memory circuit 109 from which the reading has been performed. In this way, the memory circuit 108.109.110 ff:Soreso t-Li
If the time is shortened by performing either tll or read operation -1, and if the time required for read and 8 write is the same, then the circuit shown in Figure 9 will be faster than the one shown in Figure 7. The A/D converter 102 can be operated at twice the sampling rate. Conversely, if the sampling frequency is the same in FIG. 7 and FIG. 9, the memory circuit of the embodiment shown in FIG.
It has the advantage that it can be used at 1/2 the operating speed of 3.

In addition, the field discrimination circuit shown in FIG.
The memory circuits 108, 109, and 110 for each field detect the fields of the video signal that is inputted from the outside.
:t@Switch the input/read signal switch 10
7.112.

The arrow shows an example of a CLV (constant linear velocity) video disc. Figure $10 shows the movement of the pickup on the back side, on the reverse rotation side.

300 is the direction of rotation of the track 325 of the CLV disk. Further, FIG. 11 shows the relationship between the track position and the video and audio signals that are reversed in time from the pink-up signal.

In this embodiment, the CLv disk rotates at one or more times the original rotation speed. For example, a case is shown in which the CLV disk rotates twice during the period of one frame of the video signal.

It is assumed that track jumping on the CL and V disks is performed at a position where the pickup crosses the radial line segment 320. Assuming that the pickup is at the trunk position 11301, the pickup is read two revolutions to the track position 302 during one frame period of the video signal without performing a track jump at the track position [1305] as shown in FIG. 11 fal. When this is extracted as a video signal, it includes 311 between frames and 310 between frames as shown in Figure 11 tbl. Therefore, the frame ffJ1311. Between frames 31
The video signal between 0 and 0 can be output seamlessly. Next, the pickup located at the track position 302 moves three tracks as indicated by an arrow 303 to a track position 304. Therefore, the video signal is read for one frame period, and as shown in FIG. 11, the signal is read up to track Qfi 305 without performing track skipping at the track position 301. When this is extracted as a video signal, the video signal between the frames 312 and between the frames 311 can be seamlessly extracted.

Next, the pickup at track position #305 moves to track position 307 as indicated by arrow 306, and similarly moves to the front d
The pit track fftt3o1 is read, and signals between frames 313 and between the frames 312 of the video signal can be extracted. In this way, for one set, the frame 1iJ
between I311.310 and 312.31 between said frames.
Since the video signal between 10 darkness and the frame interval 313.3120 can be read out for one frame period without any break, it can be played back as a continuous video signal by performing time axis inversion processing and then time axis correction. becomes. Further, although the explanation is given in units of frames of the video signal, the same applies to units of fields.

W. FIG. 12 shows a block diagram of the CLV disk shown in FIG. 10 during reproduction when rotating in reverse. In order to obtain a seamless frame as shown in FIG.
Timing detection Lt1 circuit 330 detects the synchronization signal issued by
The input interval of the synchronization signal is manually compared, and if the interval corresponds to the original frame period, the time axis inversion circuit is controlled as a continuous frame signal. Thereafter, the time axis correction circuit 331 corrects the original time axis.

This action is normal! Get a signal. Also,
When two frames or more of uninterrupted frame signals are inputted consecutively, the time axis inverting circuit inverts the two frames or more of consecutive signals. FIG. 13 shows an example of the outer periphery where one frame can be read seamlessly by one rotation of the CLV disk. FIG. 14 shows the relationship between the track position and the temporally reversed video and audio signals extracted from the big amplifier. Similarly to the 101st side, the CLV disk rotates at more than one time the original rotation speed. Now, the pickup is a truck (q lt3 A
1, two revolutions 1 f to track position 342;
= 35 le between frames without time break, 353.352.3
You can capture 3 frames of 51. Said track (ff t
3'1 to track position 3 as shown by arrow 34!1
Move to 44. Said track position 3 A A f) h
35 between frames when rotated twice from to trunk position 345
6.355.354.353 frames can be captured.

This relationship is shown in Figure 14, but if only the unbroken frames of fbl and ldl are connected, the frame will collapse.
Fields 354 and 353 overlap. Therefore, if the timing detection circuit shown in FIG. 12 detects that 3 frames can be taken in 2 rotations, the difference between the frames of ldl is 654.353? :
Skip to content. This operation is performed using the time axis correction circuit 3 in Figure 12.
31 to correct the time axis so that it becomes the original time axis.

〔Effect of the invention〕

According to the present invention, since it is possible to reproduce the normal rotating state from a disc that is mown in a reverse rotational manner, when the disc is continuously played back on both sides, the disc rotates when switching from the side that is being played initially to the opposite side. Even if you do not know the direction, playback can be performed even if the previously played side has not finished playing and is rotating in the opposite direction to the newly read side, so when switching the disc playback side, 4. There is no discontinuity in Satoru Gogo.
Tx allows smooth continuous playback on both sides.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the movement of the sensor when the disk is rotating in the II direction, and Fig. 3 is an explanatory diagram showing the movement of the sensor when the disk is rotating in the opposite direction. 4 is an explanatory diagram showing the reproduced video signal, FIG. 5 is a time chart of the time axis inversion circuit, FIG. 6 is a time chart when switching the reproduction signal, and FIG. 7 is the time axis inversion circuit. 8 is an explanatory diagram showing the memory map of the circuit in FIG. 7, FIG. 9 is a block diagram showing another embodiment of the time axis inversion circuit, and FIG. 10 is a CLV
An explanatory diagram showing the movement of a sensor on a disk. Figure 11 is the time chart of Figure 10, and Figure 12 is the CL.
V f (Block diagram showing Kazumi!M example by Sufu,
FIG. 13 is an explanatory diagram showing the movement of the sensor on the CLV disk, and FIG. 14 is a time chart of FIG. 12. 1... Disk, 4.3... Big amplifier, 13.
...Time axis inversion circuit, 7.8...FM demodulator, 15.
16... Selector switch, 11, 12... Jitter servo, 9.10... Synchronous separation circuit, 102... Al1
) converter, 105...D/Ai converter, 300...C
1, V disk trunk, 311-315... track position, 330... timing detection circuit, 331
...Time axis correction circuit, 351-358...Between tracks, 3A1-347-) Rack position W0 th surface ヰ(α) CI)) fig. t, tZ fig. Cb) th Fig. ■ t7 frame period No. 1

Claims (1)

[Claims] 1. Sensors for reproducing information recorded on both the upper and lower surfaces of the disk are installed at upper and lower positions sandwiching the disk placed on the turntable for rotating the disk, and both sensors are arranged in a straight line in the radial direction. A signal that causes at least some of the playback systems in a double-sided playback disc device that can freely move back and forth to reverse the time axis of some of the information recorded on the disc so that the information captured later is output first. A disc playback device characterized by having a device for performing processing.