JPH08102109A - Tracking controller - Google Patents

Abstract

PURPOSE: To facilitate the tracking control at the time of variable speed reproduction in a magnetic recording/reproducing device for recording video data for variable speed reproduction by independently distributing the data on the scanning locus of a reproducing head corresponded to the tape speed. CONSTITUTION: The recording is made while adding a specified mark to a control signal by a mark adding means 113 depending on the start timing of the recording of the data for variable speed reproduction. At the time of variable speed reproduction, the mark in the control signal is detected by a mark detecting means 117, and the phase of a capstan is controlled by the phases comparison between the mark detection timing and a reference signal. The variable speed reproduction tracking is easily realized by this mark detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital V for recording / reproducing a digital video signal 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 With the rapid progress of digital technology in recent years, various information has been digitized and stored, transmitted,
It is becoming possible to reuse.

In particular, digitization of audio signals has been promoted from an early stage, and digital audio products represented by compact discs (CDs) have become a well-known technique.

On the other hand, in the fields of broadcasting and communication, digitization of video signals is progressing, and along with the progress of image compression technology, digital broadcasting is about to be put to practical use in the United States and the like.

Under such a background, the digital VT
Development of R is also in progress. For example, it has been considered to perform digital recording using a so-called VHS system VTR which is widely used as a home VTR. V
When recording a digital video signal in a home VTR such as the HS system, it is necessary to rely on an image compression technique in view of the recording image quality, recording time, tape consumption, and the like.

As an image compression technique, for example, there is an MPEG (Moving Picture Experts Group) system standardized by ISO. Many image compression techniques such as the MPEG system utilize correlation between frames in order to realize a high compression rate without degrading image quality. This utilizes the characteristic that the image hardly changes in consecutive frames, and only the difference between the two frames is encoded to significantly reduce the data amount. However, on the contrary, there is a disadvantage that only images of consecutive frames can be reproduced.

When the variable speed reproduction is performed on the image data recorded on the VTR, the rotary magnetic head reproduces the data across the tracks. Therefore, the image data reproduced by the variable speed reproduction is continuous frame data. Don't
Therefore, when the image-compressed video is recorded in the VTR, variable speed reproduction cannot be performed.

[0008] As a recording / reproducing method which uses image compression by the MPEG system and also supports variable speed reproduction, for example, "FIRST SCAN TECHNOLOGY FOR DIGITAL VIDEO TAPE
RECORDERS (IEEE Transactions on Consumer Electroni
cs Vol.39, No.3, AUGUST 1993) "has been proposed.

According to this method, the image for variable speed reproduction is set at a specific position on the magnetic tape that matches the scanning locus of the reproducing head according to the tape speed so that the image can be restored even during variable speed reproduction. The data is separately distributed and recorded. If the intra-frame compression is performed on the data for variable speed reproduction, the image can be restored from the reproduced one frame of data for variable speed reproduction.

FIG. 9 shows an example of data arrangement on the magnetic tape when recording is performed by this method.

In FIG. 9, 104 is a magnetic tape, 402 is a scanning locus of the rotary magnetic head during normal reproduction, 403 is a scanning locus of the rotary magnetic head during 3 × speed reproduction, and 404 is a rotary magnetic head during 9 × speed reproduction. A scanning locus, 405 is a video data recording area for normal reproduction, 406 is a video data recording area for 3 × speed reproduction, 407 is a video data recording area for 9 × speed reproduction, and 408 is a control track.

During 3 × speed reproduction, the rotary magnetic head is 40
Since playback is performed across 3 tracks like 3
Video data for triple speed reproduction is arranged at a position such as 406. Further, since the scanning locus of the rotary magnetic head during 9 × speed reproduction is 404, if the 9 × speed reproduction video data is arranged at the position 407, the 9 × speed reproduction data can be reproduced. .

[0013]

However, when variable speed reproduction is performed by the conventional method as described above, there are the following problems.

That is, in the above-mentioned conventional example, since the video data for variable speed reproduction is recorded on a specific track, it is not necessary to perform control so that the rotary magnetic head accurately scans this track during variable speed reproduction. But not
No control means for this is considered.

In the conventional so-called VHS type VTR,
A control signal is recorded on a control track for tracking control, and the position of the reproduction track is detected based on this control signal during reproduction. But,
Since the control of scanning a specific track during variable speed reproduction is not considered, it is difficult to detect the position of the variable speed reproduction track when the above-mentioned data arrangement is performed.
The image data for variable speed playback cannot be played back correctly.

[0016]

In order to solve the above-mentioned problems, according to the present invention, a recording signal processing means for distributing the data reproduced at the time of variable speed reproduction to a predetermined track and performing a recording signal processing, and the above-mentioned variable speed. Mark adding means for adding a mark corresponding to the recording position of the reproduction data to the control signal, a control head for recording / reproducing the control signal, and mark detecting means for detecting the mark from the control signal reproduced from the magnetic tape, Phase comparison means for performing a phase comparison between the detection result of the mark detection means and the reference signal; and a capstan servo for controlling the rotation phase of the capstan according to the comparison result of the phase comparison means,
A diagonal track is formed on the magnetic tape to record information for normal reproduction, and information for variable speed reproduction at an arbitrary speed faster than normal reproduction is located at a position corresponding to the scanning locus of the rotary magnetic head during variable speed reproduction. In addition to recording in a dispersed manner, a mark corresponding to the recording start timing of the information for the variable speed reproduction is added to the control signal and recorded, and the mark is detected from the control signal reproduced at the time of the variable speed reproduction. The mark and the reference signal are compared in phase, and the capstan phase is controlled based on the comparison result.

[0017]

Since the information about the recording start position of the variable speed reproduction data is added as a mark to the control signal and recorded, the recording start position of the variable speed reproduction data can be known. During variable speed reproduction, the rotary magnetic head scans a predetermined track on which the variable speed reproduction data is recorded by comparing the phase of the mark detection timing with the reference signal and controlling the phase of the capstan.

[0018]

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 FIG. 1, 101 is a supply reel for supplying a magnetic tape, 102 is a rotary magnetic head for recording and reproducing signals, 103 is a drum in which the rotary magnetic head is arranged, 104
Is a magnetic tape for recording signals, 105 is a control head for recording and reproducing control signals, 106 is a capstan for running the magnetic tape, 107 is a pinch roller, 108 is a take-up reel for winding the magnetic tape, 1
Reference numeral 09 is a switching means, 110 is a reproduction signal processing means for performing reproduction signal processing, 111 is a recording signal processing means for performing recording signal processing, 112 is a reference signal generating means for generating a reference signal, and 113 is a mark added to a control signal. Mark adding means, 114 switching means, 115 a capstan servo for controlling the rotation of the capstan, 116 phase comparing means for comparing the phases of the reference signal and the reproduction control signal, 117 a predetermined value from the reproduced control signal. Is a mark detecting means for detecting the mark, 118 is a system controlling means for instructing a reproduction speed, 119 is a signal output terminal, and 120 is a signal input terminal.

First, the operation of the digital VTR during recording will be described.

A digital video signal recorded by the digital VTR is input to the signal input terminal 120. 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 into blocks having a predetermined length by the recording signal processing circuit 111.
A block address indicating an address on the tape of the block and an error correction code for correcting an error during reproduction are added to the data of each block. This is because even if the rotary magnetic head 102 partially reproduces data across a track, the data can be reproduced in block units.

Similarly, for variable speed reproduction data, a block address and an error correction code are added in block units,
As shown in FIG. 9, it is inserted at a predetermined position on the track. The variable speed data may be obtained by storing compressed data in a memory unit in a memory and dividing the data into a plurality of predetermined tracks for output. Then, the data of each track is modulated and converted into a signal suitable for recording on the magnetic tape 104.

By these controls, the signal for each track which has been subjected to the predetermined processing in the recording signal processing circuit 111 is
It is supplied to the rotary magnetic head 102 synchronized with the reference signal and recorded on the magnetic tape 104.

The rotating magnetic head 103 has its rotation speed controlled to 1800 rpm by a drum servo (not shown), and its rotation phase also has a reference signal 112 (30).
Hz) and a drum tack pulse or the like to perform a phase comparison control so that the reference signal 112 has a predetermined phase relationship. Further, the tape speed is controlled to a predetermined speed by the capstan servo, and the traveling phase is controlled by phase comparison control (not shown) between the signal obtained by appropriately dividing the capstan FG signal and the reference signal 112. Is also done. These controls are conventional analog VH
There is no difference from the S / VTR.

On the other hand, on the magnetic tape, in addition to the video signal track for recording the video signal, a control track 408 for recording the control signal is provided in the longitudinal direction of the magnetic tape. The control signal is recorded by the control head 105, which is a fixed head, and is used for head tracking control during reproduction.

In the conventional analog VHS / VTR, the 30 Hz reference signal 112 used for phase control of the capstan is directly recorded as a control signal, and at the time of reproduction, the reproduction timing of the control signal and the phase of the reference signal 112. The tracking control is performed so that the head properly scans the recording track by the comparison control.

In the digital VTR according to the present invention, the variable speed reproduction track to be scanned by the rotary magnetic head at the time of variable speed reproduction is determined in advance, so a signal for tracking control for this variable speed reproduction track is also required. Therefore, in FIG. 1, a mark for identification information is added to the control signal synchronized with the recording start head track of the variable speed reproduction data by the mark adding means 113 and used as a control signal for tracking during variable speed reproduction. .

The recording signal processing circuit 111 supplies a mark addition signal to the mark addition circuit 113 at a position corresponding to the track for variable speed reproduction. The mark adding circuit 113
A mark is added to the reference signal according to the mark addition signal, and a recording signal is output to the control head 105.

The operation of the mark adding circuit 113 will be described below with reference to a specific embodiment shown in FIG.

In FIG. 2, 201 is a reference signal input, 202 is a mark addition signal input, 203 is a first pulse generating means,
Reference numeral 204 is a second pulse generating means, 205 is a switching means, 206 is a control signal output, 207 is an output of the first pulse generating means, and 208 is an output of the second pulse generating means.

The output signal of the reference signal generating means 112 is 3
0 Hz (cycle t = 33.3 ms), duty ratio 50
%, And this reference signal is input to the input terminal 201. The first pulse generation circuit 203 generates a pulse of 10 ms at the rising edge of the reference signal (207). Similarly, the second pulse generation circuit 204 is configured to generate a pulse of 5 ms from the rising edge of the reference signal (208). The switching means 205 responds to the mark addition control signal 202 by the reference signal 201, the output 207 of the first pulse generating circuit, and the output 20 of the second pulse generating circuit.
Switch 8 The output 207 of the first pulse generation circuit is a duty ratio of 30%, and the output 2 of the second pulse generation circuit is 2.
08 corresponds to a duty ratio of 15%. As a result, as shown in the timing chart of FIG.
A control signal 206 whose duty ratio is modulated can be obtained in accordance with 02, and the reference signal with a mark is transmitted to the control head through the switching means 114 and recorded on the magnetic tape as a control signal.

By the above processing, a control signal with a mark is recorded on the magnetic tape in synchronism with the recording start head track of the variable speed reproduction data as shown in FIG. In the example of the track pattern shown in FIG. 4, the first pulse output is the mark b for triple speed, and the output of the second pulse generation circuit is the mark c for triple speed and 9 × speed.
Is used as.

Next, the operation at the time of variable speed reproduction will be described by taking the triple speed as an example.

When the variable speed reproduction is instructed, the system control means 118 causes the capstan 106 to operate at a speed three times as high as that at the time of recording.
The capstan servo 115 is instructed to rotate. As a result, the magnetic tape 104 runs at triple speed. At this time, the recorded control signal is reproduced from the control head 105 at a triple speed. The control signal is supplied to the mark detecting means 117 through the switching means 114.

The mark detection means 117 detects a mark corresponding to the reproduction speed from the marks added to the control signal during recording. In 3 × speed reproduction, a mark corresponding to a 3 × speed track is detected.

The operation of the mark detecting means 117 will be described below.

FIG. 5 shows a concrete example of the mark detection circuit. In FIG. 5, 501 is a control signal input, and 502 is a control signal input.
Is a speed designation signal input, 503 is a pulse generating means, 504
Is a latch circuit, 505 is a mark detection signal output, and 506 is an output of the pulse generating means.

A control signal reproduced from the control head is input to the control signal input terminal 501. A speed designation signal from the speed control means 118 is input to the speed designation signal input terminal 502.

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 becomes 90 Hz. Here, when the duty ratio of the control signal in which the mark b for 3 × speed reproduction is recorded is 30%, and the duty ratio of the control signal in which the mark c for 3 × speed and 9 × speed reproduction is recorded is 15%, In the mark part, the control signal H
The level periods are about 3.3 ms and 1.6 ms, respectively. The control signal with no mark recorded has a duty ratio of 50%, so the H level period is about 5.5 m.
s. Therefore, the marks b and c can be detected by investigating a portion where the H level period of the control signal is shorter than 4 ms, for example.

FIG. 6 shows the operation waveform, but the pulse generation circuit 503 generates a pulse of 4 ms from the rise of the control signal 501 input to the control signal input terminal (506). The latch 504 outputs the pulse 506.
The control signal 501 is latched at the falling edge of. In a normal control signal in which no mark is recorded, the H level period is longer than 4 ms, so the latched result (505) is always at the H level.
On the other hand, in the mark parts b and c, the control signal 50
Since the H level period of 1 is short and the control signal falls before the pulse 506, the latch result 505 becomes L level, so that the positions of the marks b and c can be detected from the control signal 501.

The phase comparator 116 is the mark detecting means 117.
Mark detection signal and reference signal 1 of 30Hz cycle generated in
Phase comparison with 12 is performed, and the rotation phase of the capstan motor (not shown) is controlled so that the comparison error becomes a predetermined value.

As a result, the tracking phase of the rotary magnetic head 102 scans a predetermined track 403 on which data for triple speed reproduction is recorded.

The data for triple speed reproduction on the magnetic tape is reproduced by the rotary magnetic head 102. The data reproduced by the rotary magnetic head 102 is input to the reproduction signal processing circuit 110 through the switching unit 109 and is output to the signal output terminal 119 as video data by a predetermined process.

In the above embodiment, since the start positions of the variable speed reproduction tracks of 3 × speed and 9 × speed overlap,
The mark c indicates two types of variable speed reproduction tracks. For example, by arranging the respective variable speed reproduction tracks in a staggered manner as shown in FIG. 7, one mark corresponds to one reproduction speed. You can also In this case, in order to be able to detect each mark independently, the mark detecting means may be provided with two pulse generating means so as to detect only the mark having a predetermined width.

In the recording as shown in FIG. 4, if the position of the 9 × speed mark c is known, the position of the 3 × speed mark b can be obtained from the relationship of the tracks, so that the mark to be recorded may be only the mark c. . FIG. 8 shows this embodiment. It is possible to easily identify the start position of the triple speed track by measuring the number of control signals after detecting the mark c. Further, even if the arrangement of the tracks for variable speed reproduction is changed, if this is already known, if there is one or more marks, the start position of each track can be obtained by calculation.

Further, in the above-mentioned example, the description has been made by taking the variable speed reproduction of 3 × speed and 9 × speed as an example, but the present invention is not limited to these, and the data for the variable speed reproduction track of an arbitrary reproduction speed. It is needless to say that the present invention can be used for tracking control of a magnetic tape on which is recorded, and further, it can be used for tracking control of variable speed reproduction not only in the forward direction but also in the reverse direction.

Further, in the above example, the method of recording the mark is such that the duty ratio modulation of one control signal is performed, but the present invention is not limited to this, and for example, a plurality of consecutive control signals are subjected to the same duty ratio modulation. It is also possible to identify the marks by the number thereof and to record the marks using a pattern in which control signals having different duty ratios are combined.

There is also a method of changing the recording current of the control signal of the mark portion or adding a specific signal to the control signal instead of performing the duty ratio modulation, which can be variously modified without changing the gist of the present invention. Is easy.

[0051]

As described above, according to the present invention, the magnetic tape in which the information for the variable speed reproduction of the arbitrary speed higher than the normal reproduction speed is dispersed and recorded in the track position corresponding to the scanning locus of the rotary head is recorded. It is possible to provide a tracking control device capable of accurately tracking a variable speed reproduction track on which variable speed reproduction data is recorded when performing variable speed reproduction.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a configuration of a mark adding means of the embodiment of FIG.

FIG. 3 is a timing chart showing the operation of the mark adding means of the embodiment shown in FIG.

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

5 is a diagram showing a configuration of a mark detecting means of the embodiment of FIG.

FIG. 6 is a timing chart showing the operation of the mark detection means of FIG. 1 embodiment.

FIG. 7 is a diagram showing a recording pattern on another magnetic tape according to the embodiment in FIG.

FIG. 8 is a diagram showing a recording pattern on another magnetic tape according to the embodiment in FIG. 1;

FIG. 9 is a diagram showing a recording pattern on a magnetic tape in a conventional digital VTR.

[Explanation of symbols]

102 ... Rotating magnetic head 105 ... Control head 106 ... Capstan 111 ... Recording signal processing means 112 ... Reference signal generating means 113 ... Mark adding means 115 ... Capstan servo 116 ... Phase comparing means 117 ... Mark detecting means 118 ... System controlling means 203 ... First pulse generating means 204 ... Second pulse generating means 205 ... Switching means 402 ... Scan locus of rotary magnetic head during normal reproduction 403 ... Scan locus of rotary magnetic head during 3x speed reproduction 404 ... 9x speed reproduction Scanning locus of the rotary magnetic head 405 ... Recording area for normal reproduction data 406 ... Recording area for 3x speed reproduction data 407 ... Recording area for 9x speed reproduction data 409 ... Mark indicating recording start position of 3x speed reproduction data 410 ... Indicates the recording start position of 3 × speed and 9 × speed reproduction data Over click 503 ... pulse generating means 504 ... latch circuit

Claims (4)

[Claims] 1. A magnetic recording / reproducing apparatus for recording and reproducing a digital signal on a magnetic tape by means of a rotary head, wherein the recording signal processing means disperses data for variable speed reproduction on a predetermined track and performs recording signal processing. Mark adding means for adding a mark corresponding to the recording position of the variable speed reproduction data to a control signal, a control head for recording / reproducing the control signal, and detecting the mark position from the control signal reproduced from the magnetic tape. Mark detection means, phase comparison means for performing phase comparison between the detection result of the mark detection means and a reference signal, and rotation phase of the capstan for controlling the running speed of the magnetic tape according to the comparison result of the phase comparison means And a capstan servo means for controlling the Information, and information for variable speed reproduction at an arbitrary speed faster than normal reproduction is dispersed and recorded at positions according to the scanning locus of the rotary magnetic head during variable speed reproduction, and the information for variable speed reproduction is also recorded. The mark corresponding to the recording timing of is recorded by adding it to the control signal, the mark position is detected from the control signal reproduced at the time of variable speed reproduction, and the phase comparison between the mark position and the reference signal is performed. The tracking control device is characterized in that the phase of the capstan is controlled by. 2. The tracking control device according to claim 1, wherein the mark adding means adds the mark by changing the duty ratio of one or a plurality of continuous control signals. 3. The tracking control device according to claim 1, wherein the mark adding means adds a mark by changing a recording current of one or a plurality of continuous control signals. 4. The tracking control device according to claim 1, wherein the phase comparison means includes a phase adjustment means for variably shifting the detection result of the mark detection means or the phase of the reference signal.