JPH1051726A - Video disk reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce non-linear reproduction with one head, to miniaturize a whole device and to reduce cost by speeding up disk rotary speed compared to that at regular reproduction time and speeding up the acquirement of data at the time of non-linear reproduction. SOLUTION: At the time of non-linear reproduction, the decoder 14 of a synchronizing signal generation part 7A outputs a reference track synchronizing signal Sr of a period when rotary speed becomes W when it recognized regular reproduction by a reproduction mode signal. When it recognizes non-linear reproduction, it outputs the reference track synchronizing signal Sr of the period when rotary speed becomes 'W*(Nmax+Ns)/Ns'. Thus, 'Nmax+Ns' rotation is realized at the time of Ns rotation in regular reproduction and data for Ns tracks can be obtained. The maximum value of the number of rotations until track jump is executed and data can be obtained is set to be Nmax and continuous track reproduction is to be executed for more than Ns rotations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video disk reproducing apparatus, and more particularly to a video disk reproducing apparatus for reproducing digital image data from a disk medium having a substantially constant recording length per bit.

2. Description of the Related Art A video disk reproducing apparatus reproduces digital image data from data recorded on a disk medium. In this case, the recording form of digital data is such that a recording angle per bit is constant. In some cases, the recording length per bit is constant.

When reproducing digital image data from a disk medium having a substantially constant recording length per bit, it is desirable to be able to perform non-linear reproduction with one head.

[0004]

2. Description of the Related Art There are the following two types of digital image data recorded on a disk medium from the viewpoint of the form of digital data on the disk medium. That is, a recording angle per bit (angle viewed from the center of the disc) is constant, and a recording length per bit is constant.

A CAV (Constant Angular V) having a constant recording clock frequency and a constant rotational angular velocity.
(e.g., location) recorded in the former method,
CLV (Constant Linear) with constant linear velocity
(Velocity) method is the latter. In this case, video data is often recorded in the latter form because the latter can increase the amount of recorded data.

[0006] When reproducing a disc having a fixed recording length per bit, there are a method of reproducing by the CLV method and a method of reproducing at a constant angular velocity.

The latter is, in particular, MCAV (Modified)
This is called an “Angular Linear Velocity” method, and the reproduction clock frequency changes in proportion to the distance from the center of the disk to the access position.

On the other hand, in the case of the former CLV system, since the rotation cycle is not constant, the phase relationship between the track synchronization signal and the field synchronization signal is not constant. Also, the latter MCA
In the case of the V system, since the data amount per track is not constant, the phase relationship between the timing of reading data for one field from the disk and the timing of outputting the data is not constant.

Therefore, in both the CLV system and the MCAV system, a buffer memory is required to absorb the difference between the timing of reading from the disk and the output timing.

In this case, since the capacity of the buffer memory is finite, the data rate read from the disk must be equal to the data rate output from the device.

The use of such a buffer memory is disclosed in, for example, JP-A-63-56082. The CLV described in JP-A-63-56082 is disclosed.
It is disclosed that a video disk reproducing apparatus includes a memory for storing at least approximately one field of a video signal, and writes at least one field into the memory after a track jump.

Further, Japanese Patent Application Laid-Open No. 63-287278 discloses that a CLV disc is reproduced by performing track jump.
It is disclosed that a discontinuous reproduction video signal is intermittently written in a field memory, read out at a constant field cycle and made continuous to realize special reproduction of a CLV disc.

Means for correcting the data rate when the disk rotation control is faster than normal is disclosed, for example, in Japanese Patent Application No. Hei 6-117779. According to this document, when the data stored in the buffer memory exceeds a predetermined amount, the writing to the buffer memory is interrupted, and the head is traced again to the same track, whereby the rotation of the disk is faster than normal. When the rotation speed is lost, the rotation speed difference is absorbed and the data is reproduced.

In order to record digital video data, processing such as data compression and shuffling is performed. These data processing units are of various types, such as one field unit, one frame unit, or several frame units, depending on each system. Hereinafter, description will be made assuming that the recording processing unit is one field. In other words, the data read from the disc will be described as being subjected to reproduction processing and output in units of one field, but the same applies to the case of frames.

FIGS. 4 and 5 are diagrams showing an example of a relationship between tracks on a disk and field data, showing an example of a format in which the recording length per bit is substantially constant.

As shown in FIGS. 4 and 5, all 72 tracks are divided into nine equal parts to form a set of eight tracks (hereinafter, this set is referred to as a clock block). Then, in order from the inner circumference to the outer circumference, the clock block number “0”
From “8”.

In the clock block 0, the data amount per track is defined as one field. Hereinafter, as the clock block number increases by 1, the data amount per track increases by "0.125 fields". In the block, data for "2 fields" is recorded per track.

Here, a description will be given of a conventional example in the MCAV system in which data on a disk is reproduced in an arbitrary order in such a format, that is, in a case of performing non-linear reproduction.

For example, in FIGS. 4 and 5, fields 65, 66, 67, 68, 28, 29, 30, 31, 3,
Consider the case of reproducing in the order of 2, 33, 80, 81, 82, 83.

In this case, there is no problem in the order of the tracks in the fields 65 to 68,
When going from 8 to 28 and from field 33 to 80, a large track jump occurs. At this time, once tracking is lost, data cannot be acquired until tracking is stabilized again at the track jump destination.

To solve this problem, a plurality of heads are prepared. Here, it is assumed that heads A and B are provided. The fields 65 to 68 are reproduced by the head A, the fields 28 to 33 are reproduced by the head B, and the fields 80 to 83 are reproduced by the head A again. After reproducing the head A to the field 68, the head A jumps to the field 80, during which the head B reproduces from the field 28.

At this time, the head A (B) jumps,
The time required for the servo to stabilize depends on the other head B (A)
In the case of reproducing a continuous track, the reproduced output image is not interrupted.

In the case of the CLV system, the rotational speed differs depending on the access position, and the rotational inertia of the disk is large, so that the desired rotational speed cannot be obtained immediately. I can't do that.

Next, a description will be given of a conventional example in the case of quick reproduction in the MCAV system.

As shown in FIGS. 4 and 5, the format is such that the data amount of the innermost track is equal to one field.
In the case of normal reproduction by the MCAV method, the time for one rotation is 1
It should be equal to the time of the field.

In the n-times fast playback, the head is moved in a range of "n * i fields" on the disk in a time corresponding to i fields, or the head is moved while the disk rotates j times. It can be realized by moving by “n * j tracks”.

For example, in the case of triple-speed playback,
This will be specifically described with reference to FIGS.

It is assumed that one turn is made until the head data of the track can be read with the servo stabilized after the track jump. Tracks 12 and 13 are accessed, tracks 14 to 20 are skipped, and tracks 21 and 22 are accessed.
And skips tracks 23 to 29, play fields 13, 24 during six revolutions,
The head moves 18 tracks. That is, data for one field is obtained in three fields.

In this case, since the data of two fields out of the three fields is insufficient (dropped frames), the same data is covered by continuously outputting the three fields.

The case of the quick playback in the MCAV system among the quick playback has been described above. The same applies to the case of the CLV system. For example, Japanese Patent Application Laid-Open No. 63-56 mentioned above
Japanese Patent Application Laid-Open No. 082 discloses a configuration in which a special reproduction such as a quick look is performed by detecting a rotation cycle of a disk, generating a track jump pulse, and changing a timing cycle for performing a track jump and the number of tracks. Done C
Although the video disk reproducing apparatus of the LV system is disclosed, in this case also, data cannot be obtained from the disk until the servo disturbed by the track jump stabilizes again, so that a frame drop occurs similarly.

Next, a conventional example in which output images are reproduced in reverse order will be described. For example, in the format shown in FIGS. 4 and 5, a case in which reproduction is performed in the reverse direction from the field 33 will be described.

First, the track 28 is accessed to acquire data from the beginning of the field 33, and then the track 29 is accessed to acquire data until the end of the field 33. Next, jump to the track 27 to obtain the data of the field 32 from the tracks 27 and 28.

Here, the jump from the tracks 29 to 27 requires a jump of two tracks. It is assumed that one turn is made after the track jump until the head data of the track can be read while the servo is in a stable state.

In this example, three rotations are required to obtain one field of data. To perform reverse n-times speed reproduction, two tracks are accessed during three rotations, and (n
* 3-2) Tracks may be skipped.

[0035]

However, in the above conventional example, the first problem is that a plurality of heads are required when performing non-linear reproduction in the MCAV system. The reason is that after the track jump, extra rotation is required until the tracking servo becomes stable and the data at the head of the track can be reproduced, and one field of data extends over a plurality of tracks. It depends. Therefore, if only one head is used, the data rate read from the disk is sufficient.

The second problem in the above-mentioned prior art is that the CLV method cannot perform non-linear reproduction. The reason is that in the case of the CLV system, the rotation speed differs depending on the access position, but the rotation speed of the disk is large, so that the rotation speed does not immediately reach the desired rotation speed. Therefore, even if a plurality of heads are used, the data rate read from the disk becomes insufficient.

Further, a third problem in the prior art is that
This means that the amount of data obtained from the disc during the quick reproduction or reverse reproduction is smaller than the data to be output. The reason is that one field of data spans multiple tracks, and after a track jump,
This is because extra rotation is required until the tracking servo (and the spindle servo in the case of the CLV method) becomes stable and the data at the head of the track can be reproduced. As a result, the data rate read from the disk is lower than in the case of normal reproduction.

[0038]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art. In the MCAV system, when performing non-linear reproduction, a plurality of heads are not required. To provide a video disc playback device capable of performing non-linear playback, and in the case of performing quick-view playback or reverse playback, ensuring that data obtained from the disc is not less than output data. Is its purpose.

[0039]

According to the present invention, in the case of non-linear reproduction, quick-view (thinning-out) reproduction and reverse reproduction, the disk rotation speed is made faster than that in normal reproduction, thereby solving the various problems described above. I did it.

Hereinafter, specific means for solving the problems of the present invention will be described.

According to the first aspect of the present invention, there is provided a synchronizing signal generator for generating a reference track synchronizing signal for controlling a disk rotation speed and a field synchronizing signal or a frame synchronizing signal for determining a timing of outputting reproduced output data. A drive control unit that operates in synchronization with the reference track synchronization signal and controls the movement of a head that reads data on a disk medium. In addition, the data read by the head is stored in a buffer memory, read out and output in synchronization with a field synchronization signal or a frame synchronization signal, and written when the amount of data stored in the buffer memory exceeds a predetermined amount. And a read data processing unit for causing the drive control unit to perform control to trace the read head again to the same track on the disk medium.

Further, in a video disk reproducing apparatus provided with a system controller for controlling the operation of each of the above-mentioned units and a function for reproducing digital image data from a disk medium having a recording length per bit which is almost constant,
The above-described system controller has an arbitrary read control function of performing control of reading data on the disk medium in an arbitrary order by one read head, and
When data is read from the disk medium in an arbitrary order by one read head, the rotation speed of the disk medium is set to be faster than that in the normal reproduction.

Therefore, according to the first aspect of the present invention,
First, the drive control unit drives and controls the disk drive unit and the head drive unit in synchronization with the reference track synchronization signal Sr from the synchronization signal generation unit according to an instruction from the system controller. The data recorded on the disk is read from the head and input to the reproduction data processing unit.

In this reproduction data processing section, the data read from the head is stored in a buffer memory, and the data is read out from the buffer memory in synchronization with a field synchronization signal or a frame synchronization signal from a synchronization signal generation section. , And output as reproduction output data Do. When the amount of data stored in the buffer memory exceeds a predetermined amount, the writing to the buffer memory is interrupted, and the drive control unit performs control to return the head by one track.

The system controller 10 generates a playback mode signal for switching between playback modes such as normal playback (variable playback or reverse playback) and non-linear playback, and generates a synchronization signal generator, a drive controller, and a playback data processor. To set the reproduction mode and drive-control each section.

As described above, according to the first aspect of the present invention, in consideration of the time during which data cannot be acquired during a track jump, the disk rotation speed is set to the normal reproduction time during non-linear reproduction in which data is read out in an arbitrary order. The speed of the data acquisition was increased to make the data acquisition faster, so that there was no interruption in the reproduced video, and non-linear reproduction was sufficiently possible with a single head.

According to a second aspect of the present invention, in the video disk reproducing apparatus of the first aspect, Ns (N
s is a natural number) After data is read continuously for at least tracks, a track jump is performed, and after the track jump, the number of rotations until the data can be read again is N.
t (Nt is an integer of 0 or more), when reading data on the disk medium in an arbitrary order with one read head, the rotation speed of the disk medium after the track jump is changed to (Nt + Ns) / Ns times or more.

Therefore, according to the second aspect of the present invention,
In addition to functioning in the same manner as the first aspect of the present invention, the error occurrence rate is reliably reduced.

According to a third aspect of the present invention, in the video disk reproducing apparatus according to the first aspect, Ns (N
(s is a natural number) The data is read out continuously for at least tracks and a track jump is performed. After the track jump, the maximum value of the number of revolutions until data can be read out again is Nmax (Nmax is an integer of 0 or more). Once, 1
When the data on the disk medium is read in an arbitrary order by one read head, the rotation speed of the disk medium is set to (Nmax + Ns) / Ns times or more of the normal reproduction.

Therefore, according to the third aspect of the present invention,
In addition to functioning equivalently to the above-described first aspect of the present invention, data can be obtained from a disk medium at a data rate equal to the output data rate, so that non-linear reproduction can be reliably performed with one head.

According to the fourth aspect of the present invention, there is provided a synchronization signal generator for generating a reference track synchronization signal for controlling a disk rotation speed and a field synchronization signal or a frame synchronization signal for determining a timing of outputting reproduced output data. A drive control unit that operates in synchronization with the reference track synchronization signal and controls the movement of a head that reads data on a disk medium.

The data read by the above-described head is stored in a buffer memory, read out and output in synchronization with a field synchronization signal or a frame synchronization signal, and the amount of data stored in the buffer memory is reduced to a predetermined amount. A reproduction data processing unit is provided which suspends writing when the data exceeds the limit and causes the drive control unit to perform control to trace the read head again to the same track on the disk medium.

Further, in a video disk reproducing apparatus provided with a system controller for controlling the operation of each of the above-described units and having a function of reproducing digital image data from a disk medium having a substantially constant recording length per bit, the system controller In addition to having a thinning-out reading control function for reading out data on the disk medium while thinning out the data at an arbitrary interval, when reproducing the data on the disk medium while thinning out the data at an arbitrary interval, the rotation speed of the disk medium is set to be lower than that in the normal reproduction Speed up.

Therefore, in the invention according to claim 4,
At the same time, the disc rotation speed was set faster than during normal playback when thinning-out reading at any interval data, so data acquisition was faster, and therefore, the frequency of dropped frames could be reduced, thereby reducing the playback video. Can be effectively prevented from being interrupted.

According to the fifth aspect of the present invention, there is provided a synchronizing signal generating section for generating a reference track synchronizing signal for controlling a disk rotation speed and a field synchronizing signal or a frame synchronizing signal for determining a timing of outputting reproduced output data. A drive control unit that operates in synchronization with the reference track synchronization signal and controls the movement of a head that reads data on a disk medium.

The data read by the head is stored in a buffer memory, read out and output in synchronization with a field synchronization signal or a frame synchronization signal, and
A reproduction data processing unit is provided which suspends writing when the amount of data stored in the buffer memory exceeds a predetermined amount, and causes the drive control unit to perform control to trace the read head again to the same track on the disk medium. .

Further, in a video disk reproducing apparatus provided with a system controller for controlling the operation of each of the above-mentioned units and having a function of reproducing digital image data from a disk medium having a recording length per bit which is almost constant,
The system controller has a reverse reading control function of reading data from the disk medium so that output images are in reverse order, and when reproducing data on the disk medium so that output images are in reverse order, The rotation speed is made faster than in the case of normal reproduction.

Therefore, according to the fifth aspect of the present invention,
As described above, when the output image is reproduced in reverse order, the disk rotation speed during variable speed reproduction is set faster than during normal reproduction in anticipation of the time during which data cannot be acquired during a track jump, so that data acquisition becomes faster. For this reason, the frequency of dropped frames can be reduced, and the interruption of the reproduced video can be effectively prevented.

According to a sixth aspect of the present invention, in the video disk reproducing apparatus according to any one of the first to fifth aspects, an equalizing means for equalizing data read from the disk medium is provided. The configuration is such that the characteristics of the equalizing means are changed according to the rotation speed of the disk medium.

Therefore, according to the invention of claim 6,
In addition to functioning equivalently to the above-described inventions, the characteristics of the equalizer for compensating the waveform of data read from the disk medium are changed in accordance with the disk rotation speed. Optimal waveform compensation can be performed, and therefore, the error rate (loss ratio) can be reduced.

[0061]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a video disc reproducing apparatus according to an embodiment of the present invention.

In the video disk reproducing apparatus shown in FIG. 1, reference numeral 1 denotes a disk medium, and reference numeral 2 denotes a disk drive for driving the disk medium 1. Reference numeral 3 denotes a reproducing head, and reference numeral 4 denotes a head drive unit that holds the head 3 and reciprocates along the radial direction of the disk medium 1. Reference numeral 5 denotes a rotation sensor speed for constantly detecting the rotation speed of the disk medium 1. And
The disk drive unit 2 and the head drive unit 4 are driven by a drive control unit 6 and driven at a predetermined speed.

Reference numeral 7 denotes a synchronization signal generator. The synchronizing signal generator 7 has a function of generating a reference track synchronizing signal for controlling the disk rotation speed and a field synchronizing signal or a frame synchronizing signal for determining the timing of outputting the reproduction output data. The drive control unit 6 has a function of controlling the movement of the head 3 in synchronization with the reference track synchronization signal.

Reference numeral 8 denotes a reproduction data processing unit. The reproduction data processing unit 8 stores the data read by the head 3 in the buffer memory 9 and reads and outputs the data in synchronization with the field synchronization signal or the frame synchronization signal. When the accumulated data amount exceeds a predetermined amount, the writing is interrupted, and the drive control unit 6 is provided with a function to control the read head 3 to trace the same track on the disk medium 1 again. I have.

Reference numeral 10 denotes a system controller for controlling the operation of each of the above components. By the overall operation of the system controller 10, the above-described video disk reproducing apparatus has a function of reproducing digital image data from a disk medium having a substantially constant recording length per bit.

Further, the system controller 10 includes:
An arbitrary read control function is provided for controlling the reading of the data on the disk medium 1 in an arbitrary order by one read head 3. The system controller 10 has a thinning-out reading control function of reading out data on the disk medium 1 while thinning the data at arbitrary intervals, and a reverse-order reading control function of reading data from the disk medium 1 so that output images are in reverse order. Is also provided at the same time. Then, when executing each of these functions, in the present embodiment, the rotation speed of the disk medium 1 is controlled so as to be faster than in the case of normal reproduction.

More specifically, in FIG. 1, the drive control unit 6 receives information indicating the disk rotation speed from the rotation speed sensor 5 and receives a tracking error signal and a track number from the head 3 described above.
In accordance with an instruction from the system controller 10, the disk drive 2 and the head drive 4 are controlled in synchronization with the reference track synchronization signal Sr from the synchronization signal generator 7. Data recorded on the disk 1 is read from the head 3 and input to the reproduction data processing unit 8.

In the reproduction data processing section 8, the data read from the head 3 is subjected to reproduction processing such as equalization processing by the equalizer 11, and then temporarily stored in the buffer memory 9. The data is read from the buffer memory 9 in synchronization with the field synchronization signal or the frame synchronization signal from the synchronization signal generator 7 and is output as reproduction output data Do. When the amount of data stored in the buffer memory 9 exceeds a predetermined amount, the writing to the buffer memory 9 is interrupted, and the drive control unit 6 controls the head 3 to return one track.

The synchronizing signal generator 7 generates a reference track synchronizing signal Sr for controlling the disk rotation speed, and a field synchronizing signal or a frame synchronizing signal for determining the timing of outputting the reproduction output data.

The system controller 10 performs normal reproduction,
A playback mode signal Sm for switching between playback modes such as variable speed playback, reverse playback, and non-linear playback is generated and passed to the synchronization signal generator 7, drive controller 6, and playback data processor 8.

FIG. 2 shows a specific example of the synchronization signal generator 7 described above.

The synchronization signal generator 7 shown in FIG.
To generate a reference track synchronization signal Sr, which is passed to the drive control unit 6. Decoder 14
Switches the decode value according to the reproduction mode signal Sm received from the system controller 10 to change the cycle of the reference track synchronization signal Sr.

Next, the operation of the entire embodiment described above centering on the synchronizing signal generator 7 shown in FIG. 2 will be described.

At the time of normal reproduction, only a jump to an adjacent track occurs, but at the time of special reproduction (at the time of non-linear reproduction, at the time of variable-speed reproduction, at the time of reverse reproduction), there is a possibility that a jump between any tracks may occur. is there. When jumping over a number of tracks, the time required for the tracking to be stable becomes longer than that during normal reproduction. Further, in the case of the CLV method, it takes time until the rotation of the disk is stabilized. In any case, data cannot be acquired during the period when the servo is unstable. From this point of view, the following description is based on non-linear reproduction (reading in an arbitrary order).
And the case of variable-speed reproduction (decimation, reverse order).

First, the case where data on the disk is reproduced in an arbitrary order, that is, the case of non-linear reproduction will be described.

It is assumed that the maximum value of the number of rotations until the track jumps and data can be obtained again is Nmax, and the rotation speed during normal reproduction is W. As a rule in the non-linear reproduction, the continuous track reproduction is set to N
Let's say we do more than s rotations. In this case, the rotation speed at the time of the special reproduction need only be “W * (Nmax + Ns) / Ns” or more.

The decoder 14 outputs a reference track synchronization signal Sr having a cycle such that the rotation speed becomes W when the decoder 14 recognizes the normal reproduction by the reproduction mode signal. Is "W * (Nma
x + Ns) / Ns ". As a result, "Nmax + Ns" rotation can be performed in the time corresponding to Ns rotation in the normal reproduction, and data for Ns tracks can be obtained.

That is, since data can be obtained from the disk at a data rate equal to the output data rate, non-linear reproduction can be performed with one head 3. The non-linear reproduction by this method can be performed by either the MCAV method or the CLV method.

As a specific example, a description will be given of a case of an MCAV video disk reproducing apparatus in a system handling NTSC color television signals.

When the data amount in the innermost track is equal to the data amount for one field, the rotation speed W during normal reproduction is W = 1.001 / 60 [Hz].

Assuming that a track jump of 160 tracks per rotation is possible and the total number of tracks is 54720 tracks, Nmax = 342 (for servo stability when a track jump from the outermost track to the innermost track is performed). = 5
4720/160).

Lower limit Ns of number of revolutions for performing continuous track reproduction
= 684, the disk rotation speed when performing non-linear reproduction with one head is W * (Nmax + Ns) / Ns = (1.001 / 60) * (342 + 684) / 684 = (1.0001 / 60) ) * 1.5. In this case, the rotation speed during non-linear reproduction is 1.5 times that during normal reproduction.

As another example, assuming that the lower limit Ns = 342 of the number of revolutions for performing continuous track reproduction, the disk rotation speed when performing non-linear reproduction with one head is W * (Nmax + Ns) / Ns = (1 0.0001 / 60) * (342 + 342) / 342 = (1.001 / 60) * 2. In this case, the rotation speed at the time of the non-linear reproduction is twice that at the time of the normal reproduction.

As described above, by increasing the number of revolutions, the lower limit Ns of the number of revolutions for performing continuous track reproduction can be reduced.

Assuming that the time of the servo instability period associated with the track numbers before and after the track jump is Nt rotations after the track jump, the rotation speed at the time of special reproduction is (W * (Nt + Ns)). / Ns)
For example, it may be changed for each track jump.
In this case, since the reproduction can be performed at the rotation speed according to the track jump, that is, at the rotation speed according to the servo instability time, it is unnecessary to increase the rotation speed and increase the error occurrence rate.

In the system described in the above specific example,
When jumping 1000 tracks, "1000/1
60 = 6.25 ”, so the fraction is rounded up and Nt = 7
And The rotation speed after jumping 1000 tracks is W * (Nt + Ns) / Ns = W * (7 + 684) /684=W*1.01. This rotation speed is smaller than the rotation speed magnification of 1.5 when Nt = Nmax, and the error occurrence rate is reduced.

Next, in the case of variable speed reproduction, in particular, M
The case of quick-view reproduction (decimation, forward and reverse directions) in the CAV method will be described.

When normal reproduction is performed in the format as shown in FIGS. 4 and 5 by the MCAV method, the time for one rotation may be equal to the time for one field.

In the case of n-times-speed quick reproduction (n> 1), the head moves within the range of "n * i" fields on the disc in the time of i fields, or the head moves while rotating j times. Move by “n * J” tracks.

After the track jump, it is assumed that reproduction cannot be performed during Nt rotations for servo stability.
It is assumed that a maximum of two tracks are accessed to read one field of data. Therefore, each time a jump is made, the rotation is made (2 + Nt).

In order to perform the n-times fast playback, two tracks are accessed, "(2 + Nt) * n-2" tracks are skipped, and the head is moved to "(2 + Nt)" during (2 + Nt) rotations.
+ Nt) * n "tracks. At this time, (2
(+ Nt) During the rotation, data for one field is obtained.

The rotation speed at the time of quick reproduction is set to W * K (K ≧ 1) with respect to the rotation speed W at the time of normal reproduction. Where K
If = 1, in the output image, data of (2 + Nt) -1 fields out of (2 + Nt) fields will be insufficient (dropped frames). On the other hand, if K ≧ (2 + Nt), an output image without dropped frames (no thinning) can be obtained.

When the number of rotations of the disk increases, the frequency of dropped frames decreases, but the number of reproduction errors increases. Unlike the non-linear reproduction, the variable-speed reproduction is often aimed at retrieving the contents rather than viewing the image, so that some dropped frames are often tolerated. Therefore, the disc rotation speed (W * K) may be determined where the frame drop frequency and the reproduction error rate practically match.

For example, in the case of triple-speed playback,
This will be specifically described with reference to FIGS.

Now, it is assumed that the number of rotations that cannot be reproduced after the track jump because of servo stability is Nt = 1. In this case, two tracks are accessed and 7 (= (2 + 1) * 3-
2) Track skipping to obtain data for one field during three rotations.

When tracks 12 and 13 are accessed and tracks 14 to 20 are skipped, tracks 21 and 22 are accessed and tracks 23 to 29 are skipped, fields 13 and 24 are reproduced during six rotations, Moves 18 tracks.

If the rotation speed at this time is the same as that during normal reproduction, data for two fields can be obtained in a time corresponding to six fields, and the frame drop frequency becomes 2/3. Also,
If the rotation speed is twice that of normal playback, data for two fields can be acquired in three fields, and the frequency of dropped frames (thinning) is reduced to one third. Furthermore, if the rotation speed is three times that of normal playback, it takes two fields
Data for two fields can be acquired, and no frames are dropped.

While the above description has been given of the case of the quick reproduction in the MCAV system among the variable speed reproductions, the same applies to the case of the CLV system, and data from the disk is restored until the servo disturbed by the track jump is stabilized again. can not get. Therefore, when the image is reproduced at the same rotation speed as in the normal reproduction, the frame drop occurs. Therefore, by performing reproduction at a higher rotation speed than during normal reproduction, the frequency of dropped frames can be reduced.

Next, a description will be given of the case of reverse 1x speed reproduction in variable speed reproduction. For example, description will be made assuming that reproduction is performed in the reverse direction from the field 33.

First, the track 28 is accessed to acquire data from the beginning of the field 33, and then the track 29 is accessed to acquire data up to the end of the field 33. Next, jump to the track 27 to obtain the data of the field 32 from the tracks 27 and 28. Here, to jump from track 29 to 27,
Requires two track jumps.

For track jump during normal reproduction,
That is, in order to jump to an adjacent track, a gap where no data is recorded is provided on the track. In the case of jumping several tracks, it takes longer time to stabilize the servo than during normal reproduction, and before the servo is stabilized, the head may pass through the gap and reach the data portion to be reproduced. In this case, the same track must be reproduced again. That is, one extra rotation is required.

In the case of the above example, three rotations (time for three fields in the case of the MCAV system) are required to obtain data for one field. In other words, it takes three times as long to continuously reproduce in the reverse direction.

The same applies to the case of the CLV method. Since it takes time for the servo disturbed by the track jump to stabilize again, in the case of the rotation speed at the time of normal reproduction, the image data is continuously reproduced in the reverse order and the real-time Cannot be output to

Therefore, the rotation speed at the time of reverse reproduction is set to W * K (K> 1) with respect to the rotation speed W at the time of normal reproduction. Here, if K ≧ 3 during reverse 1 × speed reproduction,
An output image without dropped frames can be obtained. In addition, 1 /
At the time of 2 × speed reproduction (slow reproduction), if K ≧ 3/2,
An output image without dropped frames can be obtained.

As described above, by skipping tracks appropriately and increasing the number of rotations appropriately, the frequency of dropped frames (decimation) is reduced in the reverse-direction quick-view reproduction as in the case of the above-mentioned quick-view reproduction. be able to.

When the decoder 14 shown in FIG. 2 recognizes the normal reproduction based on the reproduction mode signal Sm, it outputs the reference track synchronization signal Sr having a cycle such that the rotation speed becomes W, and recognizes the variable speed reproduction. If the rotation speed is (W *
K), a reference track synchronization signal Sr having a period such as that shown in FIG.

Here, the value of K is a reproduction mode signal Sm having information on the speed magnification of variable speed reproduction and forward / reverse polarity.
According to By doing so, the frequency of dropped frames during variable speed reproduction can be reduced.

FIG. 3 is a block diagram showing another example (synchronous signal generating section 7A) of the synchronous signal generating section 7 described above.

In FIG. 3, the periodic signal generated by the counter 13 and the decoder 14 is frequency-divided by the frequency divider 15 to generate a reference track synchronization signal Sr, which is passed to the drive control unit 6. The frequency divider 15 is connected to the system controller 10
The period of the reference track synchronization signal Sr is changed by switching the frequency division ratio in accordance with the reproduction mode signal Sm received from the controller.

The equalizer (circuit for compensating for amplitude distortion and phase distortion) 1 shown in the reproduction data processing section 8 in FIG.
The characteristic 1 may be changed according to the reproduction mode. In this case, if the rotation speed during the special reproduction is higher than that during the normal reproduction, the clock frequency of the reproduction data increases. Therefore, if the equalization characteristic is changed accordingly, the error rate can be further reduced.

[0112]

Since the present invention is constructed and functions as described above, according to each of the first to third aspects of the present invention, a time during which data cannot be acquired during a track jump is anticipated. During non-linear playback, in which data is read out in an arbitrary order, the disk rotation speed is made faster than during normal playback to speed up data acquisition, so non-linear playback is possible with a single head, thus reducing the overall size of the device. It is possible to provide an unprecedented and excellent video disk reproducing apparatus capable of reducing the cost and cost.

Further, in the present invention, as described above, in consideration of the time required for stabilization of the tracking servo and the spindle servo due to the track jump, the disk rotation speed during non-linear reproduction is made faster than that during normal reproduction to obtain data. , The nonlinear reproduction can be performed even in the CLV system, the reproduction clock frequency becomes constant, and the configuration of the reproduction processing circuit can be simplified.

According to the fourth aspect of the present invention, the disc rotation speed is set faster than that during normal reproduction at the time of thinning-out reading at any interval data.
Data acquisition is faster, so that the frequency of dropped frames can be reduced, thereby making it possible to effectively prevent interruption of reproduced video.

Further, according to the fifth aspect of the present invention, when reproducing the output image in reverse order, the disc rotation speed during the variable speed reproduction is set faster than that during the normal reproduction in consideration of the time during which data cannot be acquired during the track jump. As a result, data acquisition becomes faster, and thus the frequency of dropped frames can be reduced, and interruption of reproduced video can be effectively prevented.

In the sixth aspect of the present invention, the characteristics of the equalizer for compensating the waveform of the data read from the disk medium are changed in accordance with the disk rotation speed. Optimal waveform compensation can be performed, and therefore, the error rate (loss ratio) can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a video disc reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of a synchronization signal generator disclosed in FIG.

FIG. 3 is a block diagram showing still another specific example of the synchronization signal generator disclosed in FIG. 1;

FIG. 4 is an explanatory diagram showing a relationship (an example of a format) between a track on a disk and field data.

FIG. 5 is an additional explanatory diagram showing a relationship (an example of a format) between a track on a disk and field data.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 disk medium 2 disk drive unit 3 head 4 head drive unit 6 drive control unit 7 synchronization signal generation unit 8 playback data processing unit 9 buffer memory 10 system controller 11 equalizer 12 video disk playback device 13 counter 14 decoder 15 frequency divider

Claims (6)

[Claims] A synchronizing signal generator for generating a reference track synchronizing signal for controlling a disk rotation speed and a field synchronizing signal or a frame synchronizing signal for determining a timing of outputting reproduced output data; A drive control unit that operates in synchronization with the head and controls the movement of a head that reads data on a disk medium. The data read by the head is stored in a buffer memory, and the data is stored in the field synchronization signal or frame synchronization signal. Control to read and output synchronously, to interrupt writing when the amount of data stored in the buffer memory exceeds a predetermined amount, and to cause the drive control unit to trace the read head again to the same track on the disk medium. A playback data processing unit for controlling the operation of each unit A video disk reproducing apparatus comprising a controller and having a function of reproducing digital image data from a disk medium having a recording length per bit that is substantially constant, wherein the system controller reads data on the disk medium with one read head. In addition to having an arbitrary reading control function of performing reading control in an arbitrary order,
A video disk reproducing apparatus characterized in that when reading data on the disk medium in an arbitrary order with one read head, the rotation speed of the disk medium is made faster than in the case of normal reproduction. 2. The video disc reproducing apparatus according to claim 1, wherein data is continuously read out for Ns (Ns is a natural number) or more tracks, and then a track jump is performed.
When the number of rotations until the data can be read again after the track jump is Nt (Nt is an integer of 0 or more), when one read head reads data on the disk medium in an arbitrary order, The rotation speed of the disk medium after the track jump is set to (N
t + Ns) / Ns times or more. 3. The video disk reproducing apparatus according to claim 1, wherein data is continuously read out for Ns (Ns is a natural number) or more tracks, and then a track jump is performed.
After the track jump, when the maximum value of the number of revolutions until data can be read again is Nmax (Nmax is an integer of 0 or more), data on the disk medium is read in an arbitrary order by one read head. At this time, the rotation speed of the disk medium is set to (Nmax + Ns) for normal reproduction.
) / Ns times or more. 4. A synchronizing signal generating section for generating a reference track synchronizing signal for controlling a disk rotation speed, a field synchronizing signal or a frame synchronizing signal for determining a timing of outputting reproduction output data, and the reference track synchronizing signal. A drive control unit that operates in synchronization with the head and controls the movement of a head that reads data on a disk medium. The data read by the head is stored in a buffer memory, and the data is stored in the field synchronization signal or frame synchronization signal. Control to read and output synchronously, to interrupt writing when the amount of data stored in the buffer memory exceeds a predetermined amount, and to cause the drive control unit to trace the read head again to the same track on the disk medium. A playback data processing unit for controlling the operation of each unit A video disk playback device comprising a controller and having a function of playing back digital image data from a disk medium having a recording length per bit substantially constant, wherein the system controller thins out data on the disk medium at arbitrary intervals. A video disk having a thinning-out reading control function and, when reproducing data on the disk medium while thinning the data at an arbitrary interval, making the rotation speed of the disk medium faster than in the case of normal reproduction. Playback device. 5. A synchronizing signal generator for generating a reference track synchronizing signal for controlling a disk rotation speed and a field synchronizing signal or a frame synchronizing signal for determining a timing at which reproduced output data is output; A drive control unit that operates in synchronization with the head and controls the movement of a head that reads data on a disk medium. The data read by the head is stored in a buffer memory, and the data is stored in the field synchronization signal or frame synchronization signal. Control to read and output synchronously, to interrupt writing when the amount of data stored in the buffer memory exceeds a predetermined amount, and to cause the drive control unit to trace the read head again to the same track on the disk medium. A playback data processing unit for controlling the operation of each unit A video disk playback device comprising a controller and having a function of playing back digital image data from a disk medium having a recording length per bit that is substantially constant, wherein the system controller operates on the disk medium such that output images are arranged in reverse order. And a reverse reading control function for reading data from the disk medium, and when reproducing data on the disk medium so that output images are in reverse order, the rotation speed of the disk medium is made faster than in the case of normal reproduction. Video disc playback device. 6. The video disk reproducing apparatus according to claim 1, further comprising: an equalizing unit configured to equalize data read from the disk medium, wherein the equalizing unit is provided in accordance with a rotation speed of the disk medium. A video disc reproducing apparatus characterized by changing characteristics of the equalizing means.