JPH08298641A - Tracking controller - Google Patents

Abstract

PURPOSE: To stably and accurately attain tracking control for variable speed reproduction by detecting a mark in a control signal, pulling in the signal into a required scanning track and then controlling tracking based upon a sub- information signal to be reproduced. CONSTITUTION: A mark is added to a control signal corresponding to a recording start position for variable speed reproducing picture data by a mark adding means 113, and at the time of variable speed reproduction, the mark is detected by a mark detecting means 114. The phase of mark detection timing is compared with that of a reference signal by a phase comparing means 115 to pull in the phase into a required scanning track. After leading the scanning phase of rotary magnetic heads 102a, 102b into the prescribed range of a required phase, the contact of a switching means 120 is switched by a control means 121 and a tracking error is detected based upon a sub-information signal for the track number and block number of a reproducing signal to control tracking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a control signal as a tracking control signal, and a digital V signal for recording and reproducing a digital video signal by using a rotary magnetic head.
The present invention relates to TR, and more particularly to a tracking control method during variable speed reproduction in which reproduction is performed at an arbitrary speed higher than the normal reproduction speed.

[0002]

2. Description of the Related Art Recent advances in digital technology are remarkable,
In the fields of broadcasting and communication, digitization of video signals is progressing,
Digital broadcasting is being put to practical use in the United States and elsewhere.

Under such circumstances, digital VTRs are being developed in various places. For example, there has been attempted a method of recording and reproducing digital moving image data using a so-called analog VHS system VTR which is widely used as a home VTR.

When digitizing moving image data, an image compression technique is used because the amount of information is huge.

A well-known MPEG (Moving picture Experts Group) system is a typical image compression technique. However, many image compression techniques such as the MPEG system provide a high compression rate without degrading the image quality. To achieve
A method of coding and compressing only the difference between frames (motion compensation predictive compression) using frame correlation is used.
The amount of data is being reduced.

However, even with the digital image data compressed as described above, the data can be compared with the conventional analog recording.
The amount of data is very large, and when recording on a tape by helical scanning, even one frame of image data spans several tracks. For this reason, in high-speed reproduction (variable speed reproduction), reproduction data does not become a continuous frame, and a frame in which motion compensation predictive compression is performed from preceding and succeeding images cannot be reproduced (restored). Therefore, there is a drawback that variable speed reproduction cannot be performed simply by increasing the tape speed as in the conventional analog recording.

In view of the above-mentioned drawbacks, as a method of utilizing the image compression by the MPEG method and enabling variable speed reproduction, for example, "FIRST SCAN TECHNOLOGY FOR DIGITAL VI
DEOTAPE RECORDERS (IEEE Transaction on Consumer El
ectronics Vol.39, No.3, AU-GUST 1993) ”has been proposed. This method allows variable speed reproduction to be performed in advance so that image data can be restored even in variable speed reproduction. The dedicated image data processed for variable speed reproduction is dispersedly recorded at a specific position on the tape corresponding to the scanning locus of the reproducing head according to the recording pattern. FIG. 11 shows an example of an example (corresponding to 3 × speed and 9 × speed variable speed reproduction in the forward direction).

In FIG. 11, 103 is a magnetic tape, 401
Reference numerals 402 and 402 are scanning loci of a magnetic head having a positive azimuth angle and a negative azimuth angle during normal reproduction, 403 and 404 are scanning trajectories of a positive azimuth angle and a negative azimuth angle head during triple speed reproduction, respectively, and 405 and 406 are respectively. The scanning loci of the positive and negative azimuth angle heads during 9 × speed reproduction, the blank area 407 is the area in which image data for normal reproduction is recorded, and the shaded area 408 is 3
The double-speed reproduction and the shaded area 409 are the areas in which the image data for the 9-speed reproduction are recorded.
The data No. 9 shows an example in which recording is performed independently for both the positive azimuth angle head and the negative azimuth angle head.
Further, reference numeral 410 is a control track in which a control signal is recorded as a signal for tracking control, like the conventional analog VHS / VTR.

As is clear from FIG. 11, according to the present recording method, the positive and negative azimuth angle heads are made to scan the loci of 403 and 404, or 405 and 406, respectively, so that the positive and negative azimuth tracks are scanned. The group of image data 408 and the group of 409 can be reproduced, and high-speed reproduction of 3 × speed and 9 × speed can be performed, respectively.

[0010]

However, in order to realize the variable speed reproduction operation by the recording method as described above,
There are the following issues.

First, since the image data for variable speed reproduction is recorded only on a specific track that matches the head scanning locus, when the normal reproduction state is changed to the variable speed reproduction, or the variable speed reproduction is performed. When the speed is changed in the reproducing state, the phase control (tracking control) is naturally performed so that the rotary magnetic head accurately scans a predetermined track on which image data corresponding to the reproducing speed is recorded. That's what you have to do.

As is well known, in the conventional tracking control in the variable speed reproduction of the analog VHS / VTR, the reproduction control signal is simply divided according to the speed ratio of the variable speed reproduction, and the divided signal and the phase reference are used. It suffices to perform control by performing a phase comparison with a reference signal, which is used as the control signal.However, since the recording track of the image data is specified in this recording method, the control signal is simply divided and the phase comparison signal is It is not possible to apply a conventional technique such as In other words, it is indispensable to identify the control signal corresponding to the variable speed reproduction track, and to apply the accurate tracking method in consideration of the compatible reproduction of the tape.

The second problem is high-speed access in consideration of operability. Considering access to a variable speed reproduction track as shown in FIG. 11, it is the track phase pull-in control that affects the access time. Assuming that the variable speed reproduction speed is n, the phase pull-in of maximum ± n tracks is required, and naturally, the larger the variable speed reproduction speed n is set, the longer the time required for the phase pull-in. Image data for variable speed reproduction is not reproduced until the scanning phase of the rotary magnetic head scans a desired track, and during this period, the reproduced image is interrupted,
Considering the operability and the quality of the reproduced image, it is desired that this time be shortened as much as possible.

However, any solution to these problems has not been considered and disclosed in the prior art.

An object of the present invention is to solve the above problems and to accurately bring the scanning phase of a rotary magnetic head to a desired variable speed reproduction track during variable speed reproduction, and also for special reproduction in a compatible reproduction. It is an object of the present invention to provide a tracking control device capable of accurately tracking the center of a track without needing to perform, and capable of speeding up pulling into a variable speed reproduction track.

[0016]

In order to achieve the above object, according to the present invention, a high speed running control means for running a magnetic tape at a speed faster than a normal playing speed, and a predetermined speed of variable speed playing data on a magnetic tape. Recording signal processing means for performing recording signal processing so as to form a track for variable speed reproduction by being dispersed at the positions, and reproduction signal processing for recovering image information and sub information signal from the signal reproduced by the rotary magnetic head. Means, mark adding means for adding a mark indicating the recording start position of the variable speed reproduction track to the control signal, mark detecting means for detecting the mark position from the reproduced control signal, the mark position and the reference signal Phase comparison means for performing the phase comparison of the above, and at the time of variable speed reproduction by the high speed traveling control means, the above-mentioned sub information signal reproduced by the reproduction signal processing means Based on the tracking error detecting means for detecting the deviation of the scanning phase of the rotary magnetic head from the desired scanning track center, the switching means for switching the output of the phase comparing means and the output of the tracking error detecting means, and the output of the switching means. A phase control means for controlling the rotational phase of the capstan for controlling the running speed of the magnetic tape, the high speed running control means, the switching means,
The phase control means and the control means for controlling the mark detection means are provided.

Further, according to the present invention, in order to speed up the access, there is provided a damping coefficient control means which is controlled by the control means and controls a damping coefficient when the tape traveling speed is controlled by the high speed traveling control means. did.

[0018]

When the signal is recorded, the mark adding means adds a mark corresponding to the recording start track position of the image data for variable speed reproduction to the control signal for recording.

The mark detecting means detects the mark from the control signal in the variable speed reproduction operation and outputs the detection timing to the phase comparing means.

The phase comparison means compares the mark detection timing with the reference signal for phase comparison, and has a polarity corresponding to the phase error direction and a level for track pull-in corresponding to the error amount. Works to output control signals.

Further, the tracking error detecting means detects the sub-information signal of the track number and the block number of the head scanning track which is reproduced and outputted by the reproduction signal processing means, and uses the reference track number and the block number for the desired scanning phase. And a tracking control error signal is generated according to the comparison error.

With this structure, in the variable speed reproduction operation, when the tape speed reaches a predetermined speed under the control of the high speed traveling control means, the desired scanning track of the rotary magnetic head is generated based on the control signal of the phase comparison means. After the phase pull-in control is performed and the head scanning phase is pulled within a predetermined range of the desired phase, the control by the switching unit performs the tracking control based on the control signal of the tracking error detection unit. . That is, after the track scanning error is introduced by using the mark detection in the control signal, tracking control is performed based on the sub information signal which is the reproduction signal of the head itself.

Further, the damping coefficient control means sets the damping coefficient to the first predetermined value and the desired phase until the scanning phase of the rotary magnetic head reaches a predetermined range of the desired phase by the control of the phase comparison means. After reaching the predetermined range, it works to switch to the second predetermined value larger than the first. As a result, the damping effect of the speed control can be weakened during the phase pull-in process to the variable speed reproduction track, and the maximum speed of the capstan motor is increased to accelerate the phase pull-in, that is, the pull-in response to the variable speed reproduction track. Access can be speeded up.

[0024]

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

FIG. 1 is a block diagram showing an embodiment of a tracking control device according to the present invention. In the figure, 10
Reference numeral 1 is a rotary drum, and 102a and 102b are a pair of rotary magnetic heads mounted on the rotary drum and having mutually opposite azimuth angles.
Let 2b have a negative azimuth angle. 103 is a magnetic tape, 104 is a control head for recording and reproducing control signals, 105 is a capstan for driving the tape, 106 is a pinch roller, and 107 is a capstan 1.
A capstan motor for controlling the rotation of 05, 108 is an FG (tachogenerator) that generates a frequency signal synchronized with the rotation speed of the capstan motor 107, 109 is for rotating the capstan motor 107 at high speed, and the tape is run at high speed. High-speed traveling control means, 110 is an adder, 111 is a motor drive circuit, 112a and 112b are changeover switches, 113 is mark addition means for adding a mark to a control signal, and 114 is a predetermined mark detected from a reproduced control signal. Mark detection means, 115 is phase comparison means for comparing the phase difference between the reproduced control signal and the reference signal, 116 is phase control means for controlling the rotational phase of the capstan 105, 117 is recording signal processing for performing recording signal processing. Reference numeral 118 denotes a reproduction signal processing means for performing reproduction signal processing, Tracking error detecting means for detecting a tracking error for variable speed reproduction track of the magnetic head 19, 120 switching unit, the control unit 121, 122 is a signal input terminal, 123 is a signal output terminal.

First, the outline of the recording operation in the embodiment of FIG. 1 will be described.

A digital video signal to be recorded by this digital VTR is input to the signal input terminal 122. The digital video signal has been subjected to image compression by, for example, the MPEG system, and is received through satellite broadcasting, cable television or the like.

The digital video signal is divided by the recording signal processing means 117 into blocks of a predetermined length.
To each block of data, a track number indicating the track position of the block, a block number indicating an address on the track of the block, an error correction code for correcting an error during reproduction, and the like are added to the data of each block. This is because even if the rotary magnetic heads 102a and 102b partially reproduce the data across the tracks, the data can be reproduced in block units.

The track number is given, for example, in correspondence with the number of scanning tracks per one rotation of the drum in variable speed reproduction. In the example of FIG. 11, it corresponds to the maximum speed of 9 times speed. Then, the scan start track (based on the scan start of the head 102a) is numbered 0, and the repetition numbers 0 to 17 are given. Also, since the tape speed in the 3 × speed reproduction is 1/3 of that in the 9 × speed reproduction, the scan start track is not only 0 but also 6 and 12
Would be equivalent to this.

Similarly, variable speed reproduction data is added with a block number, an error correction code, etc., in block units, as shown in FIG.
Insert it in place on the track as shown in. The variable-speed reproduction data is made by storing data compressed in frame units in a memory, dividing the data into a plurality of predetermined tracks, and outputting the divided tracks.

By these controls, the signal for each track which has been subjected to the predetermined processing by the recording signal processing means 117 is
The rotary magnetic head 102a synchronized with the reference signal after being converted into a signal suitable for recording on the magnetic tape 103.
And 102b and recorded on the magnetic tape 103.

The recording pattern of the digital VTR tape which is the object of the present invention recorded in this manner is also shown in FIG.
It is similar to that shown in FIG. Details of recording are omitted because they are not directly related to the gist of the present invention, but a compressed image signal for normal reproduction and a dedicated image signal compatible with variable speed reproduction are recorded on a track according to a predetermined format.

The recording track is azimuth recording by two heads 102a and 102b facing each other by 180 degrees,
A head 102a having a positive azimuth angle sequentially records + azimuth tracks in FIG. 11, and a head 102b having a negative azimuth angle sequentially records −azimuth tracks.

Taking variable speed reproduction (forward direction) of 9 × speed and 3 × speed as an example, the 9 × speed reproduction data is stored in the + azimuth track on the scanning locus 405 of the head 102a and the head 102b as shown in FIG. The azimuth track on the scanning locus 406 is recorded as a group 409, and the triple speed reproduction data group 408 is similarly recorded on the scanning locus 403 of the head 102a and the scanning locus 404 of the head 102b.

The basic principles of the drum rotation control and the tracking control during normal reproduction in the embodiment of FIG. 1 are no different from those of the conventional analog VHS / VTR.
That is, the rotation of the drum is controlled to 1800 rpm (30 Hz) by the speed and phase control using the FG signal and the tack pulse (neither is shown), and the rotation phase is also relative to the reference signal (30 Hz). It is controlled so as to have a predetermined phase. This control is the same when recording and reproducing a signal.

At the time of recording, the control head 104 controls the control track 4 on the magnetic tape.
The reference signal used for controlling the drum rotation phase is recorded as a control signal on the recording medium 10 as it is. During normal reproduction, the head is recorded on the recording track by controlling the phase comparison between the reproduction timing of this control signal and the reference signal. The tracking operation is performed so as to properly scan. In addition, since the absolute position of mounting the control head varies from device to device, tracking adjustment means or the like is also provided to absorb this and make compatible reproduction possible.・ VTR is well known.

On the other hand, in the conventional analog VHS / VTR, since there is no specific track for variable speed reproduction, the phase comparison control of the signal obtained by appropriately dividing the control signal and the reference signal is used to perform variable speed reproduction. Tracking control was possible.

However, the digital V according to the present invention
Since there is a specific track for variable speed reproduction in the HS / VTR, a tracking control signal for pulling the rotary magnetic head into the variable speed reproduction track is required. That is, an identification signal indicating the recording position of the variable speed reproduction track is required. Furthermore, once the desired variable speed reproduction track is pulled in, it is stable and accurate without the need for complicated control such as tracking correction in compatible reproduction due to the variation in the mounting position of the control head. A good tracking control method is required.

Therefore, the digital VHS.V according to the present invention is used.
In TR, a mark indicating the recording position of a variable speed reproduction track is added to a control signal for recording, and this mark is detected and used as a control signal for pulling in the track during variable speed reproduction. The tracking error is detected based on the block address data which is the reproduction signal of itself, and tracking is performed.

The configuration and operation of each part of the embodiment shown in FIG. 1 will be described below.

FIG. 2 is a block diagram showing a specific example of the structure of the mark adding means 113. In the figure, 201 is a reference signal input terminal, 202 is a mark control signal input terminal, 203 is a first pulse generating circuit, 204 is a second pulse generating circuit, 205 is a changeover switch, and 206 is a control signal output terminal. is there. The reference signal is a signal having a frequency of 30 Hz (cycle T = 33.3 msec) and a duty ratio of 50%, and this reference signal is input to the input terminal 201. The pulse generation circuit 203 generates a pulse of 10 msec at the rising edge of the reference signal, and the pulse generation circuit 204
Is configured to generate a pulse of 5 msec according to the rising edge of the reference signal, and each pulse corresponds to a signal having a duty ratio of 30% and a duty ratio of 15%.

The change-over switch 205 is responsive to the mark control signal 202 output from the recording signal processing means 117, the reference signal 201 and the output 20 of the first pulse generating circuit.
7. Switching control is performed so that a predetermined signal is output from three outputs 208 of the second pulse generation circuit.

As a result, as shown in the timing chart of FIG. 3, the control signal 206 whose duty ratio is modulated according to the mark control signal 202 can be obtained, and the reference signal with the mark added is the changeover switch 112a.
It is transmitted to the control head 104 through and is recorded on the magnetic tape 103 as a control signal.

As a result of the above processing, a control signal with a mark added to the control track 410 is recorded on the magnetic tape in synchronization with the recording start head track of the variable speed reproduction data as shown in FIG. It FIG.
In the example of the track pattern shown in FIG. 3, the output 207 of the first pulse generating circuit is used as the mark b for the triple speed, and the output 208 of the second pulse generating circuit is used as the mark c for the triple speed and the 9 × speed reproduction. .

The mark detecting means 114 detects the mark corresponding to the reproduction speed from the marks added to the control signal during recording. For example, in the 3 × speed reproduction, the marks b and c corresponding to the 3 × speed track are detected.

FIG. 5 is a block diagram of a specific example of the structure of the mark detecting means 114. In FIG. 5, 501 is a control signal input terminal, 502 is a speed command signal input, 503 is a pulse generating circuit, 504 is a latch circuit, Reference numeral 505 is a mark detection signal output terminal, and 506 is an output of the pulse generation circuit.

A control signal reproduced from the control head 104 is input to the control signal input terminal 501. Further, the speed command signal input terminal 502 is supplied with 3 corresponding to the triple speed from the control means 121 as the speed information signal.

At 3 × speed, the control signal is also reproduced at 3 × speed as compared with normal reproduction. At this time, the frequency of the control signal 501 is 90 Hz (cycle T = 11.1 mse.
c). Since the duty ratio of the control signal recorded with the mark b is 30% and the duty ratio of the control signal recorded with the mark c is 15%, the high level period of the control signal is about 3.3 msec. And 1.6 msec. The control signal with no mark recorded has a duty ratio of 5
Since it is 0%, the High level period is about 5.5 msec. Therefore, if the High level period of the control signal is compared with, for example, 4 msec, the marks b and c are compared.
Can be detected.

FIG. 6 shows the operation waveform. The pulse generation circuit 503 generates a pulse 506 of 4 msec from the rising edge of the control signal 501 input to the control signal input terminal. Latch circuit 504 is pulse 50
At the falling edge of 6, the control signal 501 is latched. With a normal control signal with no mark recorded, the High level period is 4 mse
Since it is longer than c, the latched result 505 is always High.
It is the h level. On the other hand, in the mark b and the mark c, the high level period of the control signal 501 is short, and the control signal falls before the pulse 506, so that the latch result 505 becomes low level. As a result, the mark b and the mark c are detected from the control signal 501.

The phase comparison means 115 is the mark detection means 1
The mark detection signal generated in 14 is compared with the reference signal in phase, and an error signal corresponding to the phase difference is output to the phase control means 116 for controlling the rotation phase of the capstan motor 107. That is, when the phase of the mark detection timing is delayed with respect to the reference signal, an error signal having a positive polarity and a level corresponding to the phase delay amount is used, and conversely, the error signal of the mark detection timing is compared with the reference signal. When the phase is advanced, a negative polarity and an error signal of a level corresponding to the amount of phase advance are generated,
Works to output.

The tracking error detecting means 119 detects the deviation of the rotary magnetic head from the center of the desired scanning track based on the sub information signals of the track number and block number reproduced by the reproduction signal processing circuit 118, and detects the deviation direction. A tracking error signal having a corresponding polarity and a level corresponding to the shift amount is generated.

FIG. 7 shows a block diagram of a specific structural example of the tracking error detecting means 119. In the figure, 701
Is a reproduction signal input terminal, 702 is a block number detection circuit,
Reference numeral 703 is a specific track number detection circuit, 704 is a block error calculation circuit, 705 is an error signal generation circuit, 706 is a speed command input terminal, and 707 is a tracking error signal.

The sub information signal reproduced from the reproduction signal processing means 118 is inputted to the block number detecting circuit 702 and the specific track number detecting circuit 703. The block number detection circuit 702 detects the block number added to each block from the sub information signal, and the block error calculation circuit 70
Supply to 4. Further, the specific track number detection circuit 703 detects a specific track number from the track number added to each block from the sub information signal, and supplies it to the block error calculation circuit 704. Block error calculation circuit 704
Detects the amount of deviation from the center of the desired scanning track from the reproduction block number at a specific track number scanned by the rotary magnetic head, based on the track number and block number of the reproduced sub information signal and the speed command signal 706. .

This operation will be described below by taking variable speed reproduction at 9 × speed as an example.

For 9 × speed reproduction, the rotary magnetic head 102a
Reproduces data across 9 tracks in one scan. Therefore, for example, one track is numbered from 0 to 95
If it is composed of 6 blocks, about 12 blocks are recorded per track for the 9 × speed reproduction data.

FIG. 8 shows the specific track number 2 shown in FIG.
9 shows the relationship between the desired scan of the head 102a and the block address (enlarged view), and the variable speed reproduction data of 9 × speed is recorded in the block positions of block numbers 18 to 29 in the track of track number 2. . In order to reproduce this, the scanning phase of the head 102a is as shown in FIG.
801 indicated by a thick solid line (here, it is assumed that data can be reproduced if the head 102a scans ½ of the track width).

On the other hand, when the tracking of the head 102a shifts in the direction A or the direction B in the figure, the reproduced block number shifts vertically. That is, the block number is shifted in the direction A, for example, in the tracking state as shown by the thin solid line in the figure, the block number to be reproduced is 20 to 31, which is higher than the desired block. Conversely, in the tracking state as shown by the broken line in the figure, the reproduction block number shifts from 16 to 27, which is below the desired block.

For example, when the track number is specified as 2 by the specific track number detection circuit 703, the block error calculation circuit 704 is based on the maximum value and the minimum value of the block number reproduced in this track, with respect to the reference value. The deviation of the average block number is detected. That is, the average block number 23.5 (the average value of the minimum value 18 and the maximum value 29) serving as the reference is calculated as 25.5 (the minimum value 20 and the maximum value 31) as the average block number in the scan of A, +2 is output as an error with respect to the value 23.5. On the contrary, in the scan of B, 21.5 (the average value of the minimum value 16 and the maximum value 27) is calculated as the average block number, and the reference value 23.
As an error with respect to 5, -2 is output.

The error signal generation circuit 705 also generates a tracking error signal 707 having the characteristic shown in FIG. 9 according to the block error calculation result from the block error calculation circuit 704. That is, when the deviation is in the A direction (the scanning phase of the head is advanced), the error signal of the positive polarity and the level corresponding to the block deviation is deviated in the B direction (the scanning phase of the head is delayed). If so, an error signal having a negative polarity and a level corresponding to the block shift amount is output as a control signal for tracking. This control signal is a very fine signal in block units. That is, in 9 × speed reproduction, since signals for 96 blocks are reproduced over 8 tracks, detection in units of 1 block corresponds to a resolution of about 0.1 (8/96) in terms of track width. In other words,
This is equivalent to detecting a tracking error with an accuracy of 1/10 or less of the track width.

The phase control means 116 is controlled by the control means 121 and controls the scanning phase of the rotary magnetic head on the basis of the error signal of the phase comparison means 115 or the tracking error detection means 119 input through the switching means 120, that is, , The tape traveling speed is controlled. Control means 12
If the command from 1 is an "open" command, a fixed reference voltage is output to the adder 110, and if it is a "close" command, the phase control loop is based on the control signal of the switching means 120. Work to close. As a result, when the error signal of the phase comparison means 115 or the tracking error detection means 119 has a positive polarity, the tape speed is accelerated to relatively delay the scanning phase of the rotary magnetic head, and conversely, when the error signal has a negative polarity. The tape speed is reduced to relatively advance the scanning phase of the rotary magnetic head so that the phase comparing means 115 controls the tracking error pull-in and the tracking error detecting means 1.
Tracking control of the rotary magnetic head with respect to the desired scan track center is performed by 19.

The configuration and operation of each part of the embodiment shown in FIG. 1 have been described above.

The overall operation of this structure will be described below.

The configuration and operation of each part of the embodiment shown in FIG. 1 have been described above.

The overall operation of this configuration will be described below.

A user operates a command key (not shown) for variable speed reproduction, for example, 9 times speed reproduction (forward).
Is selected, the control means 121 first recognizes this, the contact of the switching means 120 is closed to the side b in the figure, the phase control means 116 is opened, and the high speed traveling control means 109 is further selected.
At the same time as issuing a control signal for starting the control of n, n = 9 is supplied to the mark detecting means 114 as a speed command value.

As a result, the rotational speed control of the capstan motor 107 by the high speed traveling control means 109 is started in the state where the tracking phase control system is not operated,
The speed of the tape 103 is raised to the designated 9 × speed reproduction speed.

Next, when the tape speed reaches the predetermined 9 times speed, the control means 121 causes the high speed traveling control means 109.
This is detected from the state of convergence of the control error voltage of the speed control system included in the above, and the control signal is issued again so that the operation of the phase control means 116 is closed. As a result, when the tape speed reaches 9 times speed, the phase control system based on the control signal of the phase comparison means 115 is closed, and the phase control is brought into the operating state.

At the moment when the phase control system is closed, the head 10
The scanning trace of 2a (as is the case with head 102b) is 9
The recording track of the double-speed reproduction data is not always scanned, and a deviation occurs from the desired scanning loci of 405 and 406 shown in FIG.

After the phase control system is closed, the head 102
When the scanning of a is in the trajectory 405 of FIG. 4, that is, when the phase advances with respect to the desired variable speed reproduction track (when scanning the left side in the drawing), the phase comparison means 115 causes the positive polarity by the above operation. Since an error signal for pulling in the track is output, the phase control means 116 accelerates the capstan motor 107, that is, the tape speed so that the error signal becomes zero, and the head scanning track number error Retract.

On the contrary, when the scanning of the head 102a is delayed in phase with respect to the locus 405 after the phase control system is closed (when scanning the right side in the figure), the phase comparison means 115 outputs A negative error signal is output. As a result, the tape speed is controlled to be decelerated, and the head scanning phase is similarly controlled to be drawn into the variable speed reproduction track.

Next, when the scanning phase of the head 102a reaches within a predetermined range of the desired scanning phase, for example, within one track by the track pull-in control by the phase comparison means 115, the control means 121 converges the error signal of the phase comparison means 115. This is detected from the situation, and the control signal for switching the contact of the switching means 120 from b to a in the drawing is output again. As a result, the control by the phase control means 116 thereafter is switched to the tracking control using the control signal of the tracking error detection means 119.

As described above, the control signal of the tracking error detection means 119 is an extremely fine error signal for block unit detection, and the head 1 is controlled by this control signal.
The scanning of 02a accurately tracks the center of the track on which the variable speed reproduction data is recorded.

The embodiment of FIG. 1 has been described above.

In the above embodiment, the 9 × speed reproduction in the forward direction is taken as an example, but the present invention is not particularly limited, and variable speed reproduction in the reverse direction can be similarly developed, and the speed can be changed as necessary. And can operate at any speed.

Further, in FIG. 1, the tracking error detecting means 1
Although an example of performing the error detection operation by 19 on one specific track has been shown, this is not a limitation and the tracking error detection may be similarly performed on a plurality of tracks as necessary.

Further, FIG. 1 shows the structure in which the phase control means 116 is provided independently, but the structure is not limited to this, and for example, the phase comparison means 115 and the tracking error detection means 119 are provided with this function. This is easily possible and can be omitted.

Further, in the mark adding means in the embodiment of FIG. 1, the mark ratio is changed by changing the duty ratio of one control signal, but this is also particularly limited. But a plurality of continuous controllers
The duty ratio of the control signal may be changed, or the duty ratio of the "H" level section or the "L" level section of one or a plurality of continuous control signals may be changed. Further, it is also possible to mark the combination of the control signals having different duty ratios, and it is easy to make various modifications without departing from the scope of the present invention.

FIG. 10 is a block diagram showing an embodiment of another tracking control device according to the present invention. In the figure, reference numeral 124 designates a damping coefficient control means, the other parts having the same reference numerals as those in FIG. 1 indicate the same parts, and their operations are also the same.

In the embodiment of FIG. 10, the damping coefficient control means 124 is controlled to weaken the damping coefficient of the speed control to increase the maximum speed of the capstan motor only in the track pull-in control process by the phase comparison means 115, and the phase is increased. To speed up the access to the variable speed reproduction track.

In the control system which uses both speed control and phase control, the response of the phase pull-in becomes slower as the damping coefficient of the speed control, that is, the sensitivity ratio of the speed control system to the phase control system becomes larger, and conversely the sensitivity ratio becomes smaller, That is, the smaller the damping coefficient, the faster the response. Therefore, in order to accelerate the phase pull-in, it is sufficient to set the damping coefficient small. However, considering the stability of the control system during normal phase control (tracking control), the damping coefficient cannot be uniquely reduced. .

In consideration of the stability of the control system, the damping coefficient is generally set to a value of about 1 to 2, so that the response of the phase pull-in is naturally restricted. However, the stability of the control system is not particularly required in the phase pull-in process to the predetermined track for variable speed reproduction, and the damping coefficient can be reduced only in this process.

In view of this point, the embodiment of FIG. 10 does not require the stability of the control system in the phase pull-in process of the track, and therefore damping is weakened to speed up the access.

Although not described in detail, the damping coefficient control means 124 sets the damping coefficient of the speed control system to a second predetermined value during normal reproduction (including variable speed reproduction) and a second predetermined value.
In order to switch to a first predetermined value smaller than the predetermined value of, for example, a gain switching circuit is configured, and the control means 1
The control signal from 21 switches the gain.

With this structure, as described in the embodiment of FIG. 1, when the tape speed reaches the predetermined variable speed reproduction speed under the control of the high speed running control means 109, the control means 121 outputs a control signal.

When the damping coefficient control means 124 receives the control signal from the control means 121, it functions to switch the gain to the first value smaller than the second value during normal reproduction. As a result, the control sensitivity of the speed control system is weakened during the phase pull-in control operation by the phase comparison means 115 to the desired scanning track. That is, the control sensitivity of the phase control system becomes relatively strong, which increases the maximum speed of the capstan motor and speeds up the phase control response.

Then, by the phase pull-in control by the phase comparison means 115, the scanning phase of the head 102a is within a predetermined range of the desired scanning phase, that is, 1 described in the embodiment of FIG.
When it reaches within the track, a control signal is output again from the control means 121 to the damping coefficient control means 124. When the damping coefficient control means 124 receives this, the control signal is again output.
It functions to switch the gain from the first small value to the second value during normal reproduction. As a result, during tracking control using the tracking error detection means 119, the damping coefficient of the speed control system is held at the second regular value corresponding to normal reproduction, and thereafter, the stability of the control system is ensured. The tracking operation is performed.

The embodiment of FIG. 10 has been described above.

In FIG. 10, the damping coefficient control means 12
4 has been shown to be arranged in the speed control path, this is not particularly limited. For example, it may be arranged in the phase control system path and the phase control system of the phase control system is relatively moved during the phase pull-in process to the desired track phase. The control sensitivity may be increased. Further, since the switching of the damping coefficient may be performed before the transition to the tracking control, it is not particularly limited to the time when the phase error converges within one track as described above, and the switching is performed once. The present invention is not limited to this, and may be performed a plurality of times or stepwise in accordance with the convergence of the phase pull-in to a predetermined track, and various modifications can be easily made without changing the gist of the present invention. is there.

[0089]

As described above, according to the present invention,
The control signal is used for the tracking control signal,
Variable speed reproduction of variable speed reproduction at an arbitrary speed faster than normal reproduction Variable speed reproduction of magnetic tape in which dedicated digital image data is recorded independently at each track position according to the scanning trajectory of the rotating magnetic head. For data
A mark is added to the control signal according to the recording start position of the data, and during variable speed reproduction, this mark is detected and the phase is compared with the reference signal to pull in the phase to the desired scanning track. After the scanning phase of the rotary magnetic head has been pulled within a predetermined range of the desired phase, tracking control is performed by detecting a tracking error based on the sub information signal of the track number and block number which are reproduction signals of the head itself. To do. As a result, in the variable speed reproducing operation, the scanning phase of the head can be accurately drawn to a desired variable speed reproducing track, and at the same time, it is possible to use a control method known in the related art.
It is possible to realize a stable and highly accurate tracking control device that can perform compatible reproduction without the need for tracking correction means that is essential due to variations in the mounting position of the head.

Further, according to the present invention, the damping coefficient of the speed control is controlled to be switched to a small value in the process of pulling in the phase to the variable speed reproduction track.
It is possible to realize a tracking control device capable of speeding up access and improving operability and quality of reproduced images.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a tracking control device according to the present invention.

FIG. 2 is a block diagram showing a specific configuration example of mark adding means in the embodiment of FIG.

FIG. 3 is a timing chart for explaining the operation of the mark adding means in FIG.

FIG. 4 is a diagram showing a recording pattern on a magnetic tape according to the embodiment in FIG.

FIG. 5 is a block diagram showing a specific configuration example of a mark detecting means in the embodiment of FIG.

FIG. 6 is a timing chart for explaining the operation of the mark detecting means in FIG.

FIG. 7 is a block diagram showing a specific configuration of tracking error detection means in the embodiment of FIG.

FIG. 8 is a diagram for explaining the operation of the tracking error detection means in FIG.

9 is a diagram showing characteristics of an output signal of the tracking error detecting means of FIG.

FIG. 10 is a block diagram showing an embodiment of another tracking control device according to the present invention.

FIG. 11 is a diagram showing a recording pattern of a magnetic tape according to the present invention.

[Explanation of symbols]

101 ... rotary drum, 102a, 102b ... rotary magnetic head, 103 ... magnetic tape, 105 ... capstan, 1
07 ... Capstan motor, 109 ... High-speed traveling control means, 113 ... Mark adding means, 114 ... Mark detecting means, 115 ... Phase comparing means, 116 ... Phase controlling means, 1
17 ... Recording signal processing means, 118 ... Reproduction signal processing means,
119 ... Tracking error detecting means, 121 ... Control means, 124 ... Damping coefficient control means

Claims (4)

[Claims] 1. A helical scan system having a rotary magnetic head, wherein a control signal is used for tracking control, each track on a tape is divided into a plurality of data blocks, and each block is divided into a plurality of blocks. A digitized image information signal for normal reproduction and a sub-signal for identification information such as a track number and a block number are recorded, and a digital image data for variable speed reproduction at an arbitrary speed faster than normal reproduction is recorded.
Is a tracking control device for reproducing magnetic tape recorded in a distributed manner at each track position according to the scanning locus of the rotating magnetic head, wherein the magnetic tape is reproduced at a speed higher than the normal reproduction speed. High-speed traveling control means for traveling, recording signal processing means for processing the recording signal so as to disperse the variable-speed reproduction data on a predetermined track, and the image information signal and sub-signal from the signal reproduced by the rotary magnetic head. Reproduction signal processing means for restoring the information signal, control head for recording and reproducing the control signal, mark adding means for adding a mark according to the recording position of the variable speed reproduction data to the control signal, and the magnetic Mark detection means for detecting the mark from the control signal reproduced from the tape, and the detection result of the mark detection means And a reference signal, and a phase comparison means for comparing the phase with a reference signal, and a tape by the high-speed traveling control means, at the time of high-speed traveling, desired scanning of the rotary magnetic head based on the sub-information signal reproduced by the reproduction signal processing means. A tracking error detecting means for detecting a tracking error with respect to the track center, a switching means for switching the output of the phase comparing means and the output of the tracking error detecting means, and a running speed of the magnetic tape based on the output of the switching means. It comprises a phase control means for controlling the rotational phase of the capstan to be controlled, a control means for controlling the high speed traveling control means, the mark detecting means, the phase control means and the switching means, and the magnetic field during recording. A diagonal track is formed on the tape to record digital image information for normal playback, and it is faster than normal playback. The variable speed playback data and records are divided into tracks on the scanning locus of the rotary magnetic head according to the speed of the magnetic tape, the mark corresponding to the recording position of the data for the variable speed reproduction,
The mark is added to the control signal for recording, and during variable speed reproduction at an arbitrary speed higher than the normal reproduction speed, after the magnetic tape speed is raised to a predetermined value by the high speed running control means. , The phase control means pulls the scanning phase of the rotary magnetic head to a desired phase, and after the scanning phase of the head reaches within a predetermined range of the desired phase,
A tracking control device characterized in that the switching means is controlled to perform tracking control of the rotary magnetic head based on a control signal of the tracking error detection means. 2. The mark adding means has a duty ratio of one or a plurality of consecutive control signals, or "H" of one or a plurality of consecutive control signals.
2. The tracking control device according to claim 1, wherein the mark is added by changing the duty ratio of the level section or the "L" level section. 3. The mark adding means uses a combination of a plurality of control signals having different duty ratios.
The tracking control device according to claim 1, wherein the tracking control device is configured to add a clock. 4. The variable speed reproduction operation according to claim 1, further comprising damping coefficient control means which is controlled by the control means and controls a speed damping coefficient at the time of tape traveling speed control by the high speed traveling control means. By the phase pull-in control by the phase comparison means, the damping coefficient reaches the first predetermined value and reaches the predetermined range of the desired phase until the scanning phase of the rotary magnetic head reaches the predetermined range of the desired phase. After that, the damping coefficient is set to the second value larger than the first value.
The tracking control device is characterized in that it is controlled to be switched to a predetermined value.