JPH06195817A - Tracking control system for magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the effective area of use of magnetic tape and enable high-density recording. [Structure] During recording, segment information indicating a segment number of a recording track is encoded by a modulation circuit 5 together with an input video signal and recorded on a recording track of a magnetic recording tape by a rotary head. At the time of reproduction, the recording signal in which the segment number and the video signal are encoded is reproduced from the recorded magnetic recording tape by the rotary head. The reproduced recording signal is demodulated by the demodulation circuit 13, and the demodulated segment number information is input to the counter circuit 21. The counter circuit 21 determines the required movement value of the segment (the required movement track number) from the input segment number, moves the track on the magnetic recording tape, and synchronizes with the correct synchronization position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control system for a magnetic recording / reproducing apparatus, and more specifically, in a magnetic recording / reproducing apparatus such as a VTR (Video Tape Recorder) for performing multi-segment recording, external synchronization during reproduction. The present invention relates to a tracking control system for a magnetic recording / reproducing apparatus that can effectively achieve frame synchronization even when the above is required.

[0002]

2. Description of the Related Art In a multi-segment recording type VTR, 1
A video signal for a frame is divided into a plurality of tracks and recorded on a magnetic tape. In the case of the VTR of such a recording method, when the segment written first after the frame is switched at the time of recording is No. 1 segment,
Even during reproduction, if the No. 1 segment is not read out after the frame is switched, there is a problem that one frame of the reproduced image is mixed with one frame of data or one frame of data, and normal reproduction cannot be performed. Therefore,
In the multi-segment recording method, frame synchronization is required to always reproduce from the No. 1 segment track with respect to frame switching.

Conventionally, as a general frame synchronization system,
There is a CTL method in UNIHI-VTR. This C
In the TL system, a control track is provided in a portion other than recording of a video signal or the like on a tape pattern, and the C written on the control track at the time of reproduction.
This is a method of detecting the TL signal and performing frame synchronization. In Japanese Patent Laid-Open No. 3-238648, n types of pilot signals are superposed and recorded on a video signal, and ATF (Automati
A method has been proposed in which frame synchronization is performed while performing tracking control of the c Track Fainding method.

[0004]

As described above, in the conventional CTL signal system, the frame synchronization signal (CTL signal) is written by providing another track in addition to the track for recording the video signal and the like. A dedicated fixed head is required, which complicates the mechanism. Further, since the magnetic recording tape has a dedicated track, there is a problem that it is disadvantageous when performing high density recording. Further, in the frame synchronization method disclosed in Japanese Patent Laid-Open No. 3-238648, for example, when recording one frame with 6 segments, pilot signals of six different frequencies are required, and one frame is required. When recording with 8 segments, the number of types of pilot signal frequency increases as the number of segments per frame increases, such as the need for 8 types of pilot signals, so the circuit scale of the servo circuit may increase. To be

The present invention has been made in view of the above circumstances, and increases the effective area of use of a magnetic tape by performing frame synchronization in multi-segment recording without requiring a dedicated control track. It is an object of the present invention to provide a tracking control method for a magnetic recording / reproducing apparatus that enables high-density recording.

[0006]

According to the present invention, in order to achieve the above object, the video signal of one field is recorded in a plurality of segments, the rotary head output level is detected during reproduction, and automatic tracking is best. In a magnetic recording / reproducing apparatus that controls so that the information indicating the segment phase at the time of recording is written to each recording track, the segment phase is detected from the information recorded at the time of reproduction, and the number of certain values determined from the detection signal is obtained. The feature is that the phase is matched with the frame synchronization signal by shifting the recording track.

[0007]

The magnetic recording / reproducing apparatus of the present invention is a so-called multi-segment recording system in which a video signal for one frame is divided into a plurality of segments at the time of recording and recorded on a magnetic recording tape. The segment information indicating the number is encoded together with the input video signal by the modulation circuit and recorded on the recording track of the magnetic recording tape by the rotary head. At the time of reproduction, the rotary head reproduces a recording signal in which the segment number and the video signal are encoded from the magnetic recording tape recorded by the above method. The reproduced recording signal is demodulated by the demodulation circuit. The demodulated segment number information is input to the counter circuit, and in the counter circuit,
By determining the required movement value of the segment (the required number of movement tracks) from the input segment number and adding the DC voltage to the capstan error voltage finally output from the capstan servo as a segment error,
Move the track on the magnetic recording tape to synchronize to the correct synchronization position (The frame synchronization signal for phase synchronization during playback is a frame synchronization signal generated from the system synchronization signal generation circuit because there is no external input. ). Therefore, it is possible to achieve frame synchronization in multi-segment recording without the need for a dedicated control track of the conventional CTL system.

[0008]

Embodiments will be described below with reference to the drawings. FIG. 1 is a configuration diagram for explaining an embodiment of a tracking control system of a magnetic recording / reproducing apparatus according to the present invention.
It is a block diagram of a digital VTR. In the figure, 1 is an input terminal, 2 is an A / D (analog / digital) converter, 3
Is a compression encoder, 4 is an ECC (Error Correcting Cod)
es; error correction code) encoder, 5 modulation unit, 6 recording equalizer, 7 amplifier, 8 magnetic head, 9 magnetic tape, 10 magnetic head, 11 amplifier, 12 reproduction equalizer, 13 demodulation unit , 14 is an ECC decoder, 15
Is a compression decoder, 16 is a D / A converter, and 17 is an output terminal.

Digital VTR as a magnetic recording / reproducing apparatus
In particular, the frame synchronization will be described in detail. In addition to the video signal, the VTR also records an audio signal and other additional information. For example, in one block of the video signal divided into blocks, in addition to the video data,
An ID (Identifica- tion) having a sync code for determining a block start point, recording track information, and segment information described later.
code) and error correction parity are added. Further, other sync code, ID code and error parity of the voice data or the additional information data are added to each block of the voice signal and the additional information divided into blocks. In order to simplify the description, the configuration for processing only the video signal will be described as an example in FIG. 1.

In the embodiment of the present invention, two different azimuths are used.
In this example, one head is arranged to face a rotating drum, the number of rotations of the drum is set to 5400 rpm, and one frame of data is composed of 10 segments and divided recording is performed on 10 tracks. Note that S0 to S9 described in FIG. 2 indicate the track segment numbers, and f1 and f2
Is a pilot signal recorded with the video signal, A, B
Indicates a head for tracing the magnetic recording tape.

As shown in FIG. 1, the VTR constitutes a recording system (recording means) for recording a video signal as an input signal on a magnetic tape. That is, the A / D converter 2, the compression encoder 3, the ECC code 4, the modulator 5, the recording equalizer 6, the recording amplifier 7, the recording head 8, the system synchronizing circuit 18 as the frame pulse generating means, and the servo circuit 1
Have nine.

The recording operation of the VTR will be described below. As shown in FIG. 1, the video signal input to the input terminal 1 of the VTR is converted into a digital signal by the A / D converter 2 and then compressed by the compression encoder 3. After this, the video signal is the ECC encoder 4
The error correction parity is added by, the ID code is added by the modulator 5, and then the ID code is modulated by the modulator 5 and the synchronization code is added to the head of the block. Then, the data is recorded on the magnetic tape 9 via the recording amplifier 7 and the recording head 8.

The audio code and the additional information are also recorded in the same manner as the video signal. Further, it is also input to the system synchronization circuit 18 at the same time as the input video signal. The system synchronization circuit 18 detects a frame pulse a synchronized with the video signal from the input video signal. The frame pulse a serves as a reference for the recording system, and the system synchronizing circuit 18
Applies the frame pulse a to the compression encoders 3 and E
It outputs to the CC encoder 4, the modulator 5, and the servo circuit 19.

2A to 2E are diagrams showing track patterns written on the magnetic recording tape, and are timing diagrams at the time of recording. The servo circuit 19 receives the frame pulse shown in FIG. 9A by the system synchronizing circuit 18 and generates the recording head switching pulse shown in FIG. The phase relationship between the head switching pulse and the frame pulse is such that the rising edge of the frame pulse coincides with the rising edge of the head switching pulse. Then, when the head switching pulse is "H" (High), the A head of the recording head 8 traces the magnetic tape 9 and writes the A head recording signal shown in FIG.
The B head of the L "recording head 8 traces the magnetic tape 9 and writes the B head recording signal shown in FIG.

Since the video signal is alternately supplied to the A head and the B head of the recording head 8 in the order of the segments No. S0, S1 ... S9 from the rising edge of the frame pulse, the recording signal shown in FIG. At the rising edge of the frame pulse, the A head of the recording head 8 always records in order from the S0 track. Therefore, the track pattern on the magnetic tape 9 is repeatedly recorded in order from S0 to S9. As described above, the track format in one track is the segment N in the ID code added to each block of the block-divided video signal, audio signal, and additional information.
o. Segment information indicating S0 to S9 is written. The above is the description of the operation of the video signal recording system.

Next, the reproducing operation of the VTR will be described.
The output from the reproducing head 10 tracing the magnetic recording tape 9 is input to the demodulating unit 13 via the reproducing amplifier 11 and the reproducing equalizer 12, and the demodulating unit 13 detects the sync code. The demodulated signal is error-corrected in the ECC decoder 14 based on the error-correction parity, and then compressed data is restored in the compression decoder 15, and thereafter, is converted into an analog signal by the D / A converter 16. The converted video signal is converted into a reproduced video signal, which is output from the output terminal 17 to a television monitor or the like.

FIGS. 3A to 3E show timing charts during reproduction. At the time of reproduction, when there is no input signal serving as a reference for the frame pulse, the system synchronization circuit 18 as the frame pulse generating means generates the temporary frame pulse shown in FIG. It is output to the circuit 19, the compression decoder 15, the ECC decoder 14, and the demodulation unit 13. In the present invention, it is also possible to input a frame synchronization signal from the outside to establish synchronization. The purpose of external synchronization at the time of reproduction is necessary, for example, in the case of a digital VTR, when it is connected to a computer with an extended function and an image is taken in as data, or when data is transferred using a digital line. . Further, in the case of analog recording, if a TBC (time axis correction device) is mounted on the VTR as a reproduction jitter correction circuit, synchronization will be taken during reproduction from the TBC.

The servo circuit 1 which receives the frame pulse
9 generates a reproducing head switching pulse shown in FIG. 9 (b), which rises at the same position as the rise of the temporary frame pulse similarly to the time of recording, and further the reproducing head 10 ensures the recording track on the magnetic tape 9. Match the tracking so that it traces. As a method of matching the tracking, there are a method of matching so as to maximize the reproduction envelope, a method of superimposing and recording a pilot signal, and the like.

However, the servo circuit 19 may trace S0 first with respect to the rising edge of the temporary frame pulse, but since it is multi-segment recording, S0 is surely reproduced by the above-mentioned tracking method. Not necessarily. Incidentally, as shown in FIG. 3, as the reproduced phases, three kinds of reproduction signal phases are generated as shown in FIGS. That is, since azimuth recording is performed, the reproduction signal becomes either S0, S4, or S8 from the relationship of the pilot signal with respect to the rise of the temporary frame pulse (the probability that the correct reproduction phase is 1 / 3).

Therefore, the demodulation unit 13 that has received the temporary frame pulse detects which track is first reproduced at the rising edge of the temporary frame pulse from the segment information in the ID code. The segment information is
Since the number of blocks of the video signal, the audio signal and the additional information is written in one track, even if some errors occur in the segment information, the segment number of the track can be accurately determined by the majority logic or the like. Can be detected. When the first reproduced segment number is detected at the rising edge of the provisional frame pulse, the number of tracks up to the correct reproduction phase (S0 in this case) can be naturally determined. For example, if S4 is traced at the rising edge of the tentative frame pulse, then 9-4 = 5, and by skipping 5 tracks, S0 becomes in phase synchronization with the rising edge of the tentative frame pulse.

A method of skipping a predetermined number of tracks will be described below. The number of skipped lines is determined by the above calculation, and the counter circuit 21 is loaded with data. Counter circuit 2
The number 1 counts the number of tracks from the demodulation unit 13 and adjusts the reproduction phase to a target point. As a practical means of jumping over the phase, a certain value of DC voltage generated by the DC voltage bias circuit is added to the motor control voltage of the capstan motor drive circuit (tape drive circuit) of the servo circuit and recorded on the recording tape. You can jump over different track patterns. What is important in the operation of this reproduction phase synchronization is to count the number of skipped tracks.

When the number of tracks of a certain value calculated based on the segment information detected by the segment information detection method (performed by the demodulation unit 13) is moved, the movement can be detected by recording a video signal and an audio signal at the time of recording. As information to be recorded together with the signal and other additional information, ATF (Automati
There is a method in which pilot signals used in the c Track Finding method are superposed on a tape or coded and recorded, and the number of the pilot signals is counted at the time of reproduction to obtain movement information.

The recorded pilot signal is shown in FIG.
There are two types, f1 and f2, as shown in FIG. The two types of pilot signals are recorded with independent frequencies, and are used for the tape tracking operation. When the track is shifted, as shown in FIGS. 4A to 4D, the reproduction pilot detection signal shown in FIG. 4A appears from the demodulator 13 as the frequency component of the pilot signal from the track. The detected reproduction pilot signal is sent to the counter circuit 21 as the edge signal of FIG. 4 (d) in which rising edges and falling edges are formed from the waveform-shaped reproduction pilot signal shown in FIG. 4 (c). The sent edge signal (FIG. 4 (d)) is used as the counter pulse of the counter circuit.
Therefore, by counting the edge signal (FIG. 4 (d)), the movement information of the track is obtained.

The above is the description of the embodiments of the present invention. Although the present invention shows an example in which one frame of data is composed of 10 segments and dividedly recorded on 10 tracks,
However, the present invention is not limited to this. For example, one frame of data may be recorded by dividing eight tracks. As described above, according to the present invention, by writing the information indicating the segment phase in each segment at the time of recording, detecting the segment phase from the information recorded at the time of reproduction, and shifting the segment by the number of a certain value determined from the detection signal. , Is characterized by matching the phase.

[0025]

As is apparent from the above description, the present invention has the following effects. That is, it has a frame pulse generating means for generating a frame switching pulse synchronized with an input signal at the time of recording and a temporary frame pulse at the time of reproducing, and the recording means has the segment information indicating the segment number of the recording track as the input signal. Along with recording on the recording track, the reproducing means detects the segment information detecting means for detecting the segment information contained in the reproduction signal, the first track synchronized with the temporary frame pulse, and obtains the number of jumping tracks. By applying the DC voltage of the value to the tape drive circuit,
By skipping a predetermined number of tracks and always reproducing the segment S0 of the track at the rising edge of the frame pulse, frame synchronization with the track becomes possible.
Therefore, it is possible to establish frame synchronization when external synchronization is not necessary at the time of reproduction and also in multi-segment division recording. Therefore, the above-described synchronous operation can be performed without the need for a dedicated control track, and it is very advantageous when high density recording is performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a tracking control system of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram showing a timing chart during recording according to the present invention.

FIG. 3 is a diagram showing a timing chart during reproduction according to the present invention.

FIG. 4 is a diagram showing a track number count timing chart of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input terminal, 2 ... A / D conversion part, 3 ... Compression encoder, 4 ... ECC (Error Correcting Codes) encoder, 5 ... Modulation part, 6 ... Recording equalizer, 7
... amplifier, 8 ... magnetic head, 9 ... magnetic tape, 10 ... magnetic head, 11 ... amplifier, 12 ... reproduction equalizer, 13
... demodulation section, 14 ... ECC decoder, 15 ... compression decoder, 16 ... D / A conversion section, 17 ... output terminal.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus for recording a video signal of one field in a plurality of segments, detecting a rotary head output level at the time of reproduction and automatically controlling the tracking so as to optimize the segment phase at the time of recording. The information shown is written to each recording track, the segment phase is detected from the information recorded at the time of reproduction, and the recording track is shifted by a certain value calculated from the detection signal to match the phase with the frame synchronization signal. The tracking control method for the magnetic recording / reproducing apparatus.