JPH0831050A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a means capable of consecutive recording without tracking deviation of a recording head even in the case of no reproducing circuit of the recording head in a magnetic tape recording and reproducing device having the recording head and a reproducing head independently. CONSTITUTION:Relation between reproducing level information 19 of the reproducing heads P0 and P1 and reproducing timing of a control signal CTL is obtained as to a tape recorded and a tape to be consecutiveiy recorded by the same device by means of a servo controller 11. Then, the consecutive recording is performed by the control in giving an offset by this difference to the reproducing timing of the control signal CTL.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking system in an apparatus for recording / reproducing a signal on / from a magnetic tape by a rotary head provided with a recording head and a reproducing head independently.

[0002]

2. Description of the Related Art In a commercial VTR or a magnetic tape device that handles data for a computer, in order to obtain recording reliability, a signal recorded on a magnetic tape can be reproduced immediately after recording and the recording state can be confirmed. There is a function. In order to do this, it is necessary to separately provide a recording head and a reproducing head. Further, in order to achieve high performance, it is necessary to use heads having materials and structures suitable for recording and reproduction, so that the heads may be independent. A recording and reproducing head of a current digital VTR for broadcasting is described in, for example, Journal of Television Society Vol. 45, No. 12, pp. 1
527-1533 (1991).

In a device having a recording head and a reproducing head independently, in the case of performing so-called joint recording, in which recording is continuously performed on a previously recorded helical track, it is necessary to perform tracking of the recording head. In normal continuous recording, the tape is run before the recording start point, and the tape speed is raised to the normal playback speed before reaching the recording start point, and then tracking control is performed so that there is no deviation between the recording head and the track. I do. Roughly, the recording head tracking detects the reproduction signal level of the recording head, and the tape running control is performed so that the reproduction signal level becomes maximum.

[0004]

Therefore, in order to perform the tracking control of the recording head, a circuit for realizing the function of obtaining the reproduction signal level of the recording head is required. This circuit includes a recording / reproducing switching SW circuit, an amplifier circuit, an envelope detection circuit, and the like. Therefore, there is a problem that the circuit scale of the device increases and the cost becomes high. Further, the reproduction signal of the recording head is S of the signal compared to the reproduction signal of the reproduction head.
Since / N is bad, reliable tracking control becomes relatively difficult. This is because the recording head, unlike the reproducing head, is not always designed to have the optimum reproducing characteristics. It may also have a playback preamplifier in the drum for the playback head to achieve high performance. In this case, the S / N ratio of the reproduced signal is further improved.

Therefore, a recording head tracking system by a reproducing head is effective, which does not require a reproducing circuit of the recording head and can perform tracking with a signal having a high S / N and high reliability.

A problem in realizing this is the positional relationship between the recording head and the reproducing head. Normally, the recording head and the reproducing head are mounted so as to scan the same position on the tape to enable simultaneous reproduction. However, simply performing tracking control so that the reproduction signal of the reproduction head is maximized does not guarantee that the recording head is correctly tracked.

This is because, firstly, the reproducing head has a tolerance in the mounting position with respect to the recording head. Even if the reproducing head is perfectly aligned with the tracking, the tracking deviation of the recording head occurs due to the tolerance of the mounting position.

Secondly, when the recording head and the reproducing head are independent, the width of the reproducing head is often wider than the track width. Since tapes recorded by other devices have different track bends, it is advantageous in terms of performance that the width of the reproducing head can be traced in the entire track width direction to some extent. However, if the reproduction head width is wider than the track width, the tracking range where the reproduction signal becomes maximum is not one point, so that the control target including the first problem cannot be determined.

[0009]

In order to solve the above problems, it is necessary to know the positional relationship between the recording head and the reproducing head of the apparatus.

Therefore, in a device having a control track for controlling tape running on a linear track, the relationship between the reproduction timing of the periodic control signal recorded on the control signal track and the reproduction signal level of the reproduction head is obtained. A tape recorded by the same device is reproduced, and the change characteristic of the reproduction signal level when the tracking of the reproduction head of the control track is shifted is examined and stored.

In the format having no linear track, when a tape recorded by the same device is reproduced, a drum of a specific signal (hereinafter referred to as an index signal) recorded at a fixed position on the helical track. The relationship between the reproduction timing and the reproduction signal level of the reproduction head with respect to the rotation of is reproduced and stored.

When the apparatus has a plurality of heads, the characteristics of each reproducing head are stored.

Next, it is necessary to compare the tape for splicing and recording with the tape recorded by the same device to know the difference.

Similarly, for a tape on which splicing recording is performed, the relationship between the reproduction level and the reproduction timing of the control signal or index signal is examined, and the tracking deviation amount with the characteristic when the recording is performed by the same device is evaluated. Then, recording is performed in a state in which the timings of the control signal and the index signal are deviated from the normal timing by the amount of the shift.

[0015]

The positional relationship between the recording head and the reproducing head can be obtained by storing the relationship between the reproducing timing and the reproducing timing of the control signal and index signal when the tape recorded by the same device is reproduced. In addition, by performing a tape running control by giving a tracking offset by a difference between the reproduction timing of the control signal or index signal and the reproduction signal level of the tape recorded by the same device and the tape used for the joint recording, the recording in the joint recording is performed. Head tracking is possible using the reproducing head. As a result, the reproducing circuit of the recording head, which has been necessary in the past, becomes unnecessary, so that the device can be supplied at a low cost. Further, since it is possible to perform control by using a stable reproduction signal of the reproducing head having a good S / N, it is possible to perform tracking with a highly reliable recording head with less tracking deviation.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the construction of a magnetic tape running system which is an example of the present invention. R1 and R2 are recording heads P
0, P1 is a reproducing head, 1 is a drum, 2 is a magnetic tape,
3 is a tape guide, 4 is a drum motor, 5 is a capstan motor, 6 is a capstan, 7 is a pinch roller, 8 is a drum pulse generator, 9 is a capstan frequency generator, 10 is a control signal head, 11 is a servo controller, 12 is a drum control signal, 13 is a capstan control signal, 14 is a reference signal generator, 15 is a reference signal, 16 is a memory, 17 is tracking data, 18
Is an envelope detector, 19 is reproduction level information, 20a
And 20b are recording currents, 21 is a rotary transformer, 22
Is a reproduction preamplifier, 23a and 23b are reproduction signals, X is a drum rotation direction, Y is a tape running direction, CTL is a control signal, DPG is a drum pulse signal, and CFG is a capstan frequency signal.

FIG. 2 shows the tape pattern of the magnetic tape 2. T0 and T1 are tracks, and 31 is a control track. The track T0 has the same azimuth angle as the reproducing head P0 and the recording head R0, and the track T1 has the same azimuth angle as the reproducing head P1 and the recording head R1. The control track 31 is a longitudinal track in which the control signal CTL is recorded.

The components of FIG. 1 and their operation will be described below.

The magnetic tape 2 is wound around the drum 1 about 180 degrees by the tape guide 3. Recording heads R0 and R1 and reproducing heads P0 and P1 are fixed to the drum 1.
The recording heads R0 and R1 and the reproducing heads P0 and P1 are in contact with the magnetic tape 2, and the recording and reproducing of the magnetic tape 2 are performed by rotating the drum 1.

The operation of the drum 1 and the magnetic tape 2 is performed by the servo controller 11. The servo controller 11 is mainly composed of a microcomputer and its peripheral circuits.

The servo controller 11 drives the drum motor 4 to rotate the drum 1 in the rotation direction X. With the magnetic tape 2 sandwiched between the capstan 6 and the pinch roller 7, the servo controller 1
1 drives by driving the capstan motor 5. During recording or normal reproduction, the magnetic tape 2 runs in the tape running direction Y.

The servo controller 11 controls the rotation of the drum 1 and the tape operation. At this time, the servo controller 11 controls by referring to some signals.

In controlling the rotation of the drum 1, the drum pulse signal DPG generated by the drum pulse generator 8 and the reference signal 15 generated by the reference signal generator 14 are referred to.
The drum pulse generator 8 generates a drum pulse signal DPG with a constant rotation phase of the pulse signal once for each rotation of the drum 1. The reference signal 15 is a signal having a constant and stable cycle, and all servo system operations are performed based on this signal. The servo controller 11 applies a drum control signal 12 to the drum motor 4 so that the drum pulse signal DPG always has a constant phase relationship with the reference signal 15 to control the rotation of the drum 1.

In order to control the running of the magnetic tape 2, the rotational speed and rotational phase of the capstan 6 are controlled. The purpose of controlling the rotational speed of the capstan 6 is to run the magnetic tape 2 at a certain speed, and the purpose of controlling the rotational phase is to keep the positional relationship between the head and the tape constant and to enable head tracking control. This is because.

In order to control the rotation speed of the capstan 6, the servo controller 11 generates a capstan frequency signal C generated by the capstan frequency generator 9.
Refer to FG. The capstan frequency generator 9 installed in the capstan motor 5 generates a capstan frequency signal CFG which is a signal having a frequency proportional to the rotation speed of the capstan 6. Since the tape speed is proportional to the rotation speed of the capstan 6, the tape speed can be detected by detecting the frequency of the capstan frequency signal CFG. The servo controller 11 applies a capstan control signal 13 to the capstan motor 5 so that the capstan frequency signal CFG has a frequency corresponding to the target tape speed, and drives the capstan motor 5. Although not shown, it is assumed here that the servo controller 11 has a counter inside and can detect the frequency of the capstan frequency signal CFG.

In order to control the rotational phase of the capstan 6, the servo controller 11 refers to the control signal CTL reproduced from the control signal head 10 and the reference signal 14. The control signal CTL is recorded as a pulse-shaped signal on the control track 31, which is a longitudinal track of the magnetic tape 2, each time the drum 1 makes a half rotation and one track T1 or T2 is recorded. At the time of normal reproduction, the servo controller 11 gives a capstan control signal 13 to the capstan motor 5 so as to control the control signal CTL in synchronization with the reference signal 15.

At the time of recording a signal, the servo controller 11
The recording currents 20a and 20b are applied to the recording heads R0 and R1 via the rotary transformer 21 while the magnetic tape 2 is running at the normal speed. As a result, the tracks T0 and T1 are recorded on the magnetic tape 2. At the same time, the servo controller 11 sends a control signal CTL.
Is generated and recorded on the control track 31 of the magnetic tape 2 by the control head 10.

The reproduction signals 23a and 23b are reproduced by the reproduction head P.
The signals reproduced from the tracks T0 and T1 of the magnetic tape 2 by 0 and P1 are amplified by the reproduction preamplifier 22 and generated via the rotary transformer 21. The reproduction signals 23a and 23b are converted by the envelope detector 18 into reproduction level information 19 whose DC level changes according to the level of the reproduction signal, and input to the servo controller 11. Although not shown, the servo controller 11 has an A / D converter and the like inside, which enables detection of the reproduction signal level.

FIG. 3 shows the timing relationship of each signal during reproduction. The servo controller 11 outputs the reference signal 15
The drum 1 is controlled to rotate once per cycle in synchronism with. Therefore, the drum pulse signal DPG is the reference signal 15
Sync to. In the period when the state of the reference signal 15 is "Low", the reproducing head P0 scans the magnetic tape 2 to generate the reproducing signal 23a, and the state of the reference signal 15 is "High".
In this period, the reproducing head P1 scans the magnetic tape 2 to generate the reproducing signal 23b. At the same time, the servo controller 11 synchronously controls the control signal CTL with respect to the reference signal 15. By changing the phase relationship between these signals, the tracking states of the reproducing heads P0 and P1 can be changed. Here, the time from the falling point of the reference signal 15 until the pulse of the control signal CTL is generated is defined as the tracking deviation time td.

When the tracking deviation time td is changed, the tracking state changes and the reproduced signals 22a and 22b are changed.
The signal level of changes. The signal levels of the reproduction signals 22a and 22b can be detected by the servo controller 11 as reproduction level information 19. FIG. 4 shows the tracking shift time td.
2 is an example of a relationship between a reproduction signal level of a reproduction head and a reproduction signal level. The solid line shows the case where the tape recorded by the same device is reproduced. At this time, the range of the tracking deviation amount that maximizes the reproduction signal level is not one point. This is because the width of the reproducing head is wider than the track width in this example.

FIG. 2 also shows the operating state of the head during recording. The helical track recording method of this example is guard bandless recording, and the width of the recording heads R0 and R1 is larger than the width of the tracks T0 and T1. Also, the reproducing head P
It is assumed that the widths of 0 and P1 are larger than the widths of the recording heads R0 and R1.

FIG. 5 shows various tracking states of the reproducing head P0 on the magnetic tape 2 recorded by the same apparatus. The state in which the reproducing head P0 is tracking the position B during reproduction corresponds to the case where the control signal CTL is controlled to reproduce at the same timing as the control signal CTL generated for the reference signal 15 during recording. Tracking deviation time t in this case
Let d be 0.

The deviation of the tracking of the reproducing head P0 in the direction A means that the control signal C is different from the reference signal 15.
This corresponds to the delay of the TL reproduction timing, that is, the increase of the tracking deviation time td. Therefore, the tracking state of the boundary points C and D in the range where the reproduction signal level in FIG.
0 corresponds to positions C and D.

In the guard bandless recording method as in this example, when the joint recording is performed, the end of the recording head is shown in FIG.
It is necessary to perform tracking so as to meet the boundary E of the track shown in. As a result, it is possible to eliminate unnecessary cutting of adjacent tracks at the start point of the joint recording and to avoid rewriting of tracks. In a tape recorded by the same device, this state is nothing but the reproduction head P0 being in the B position.

The positional relationship between the recording head and the reproducing head of the same device has a fixed relationship. Since the track boundary E corresponds to the end of the recording head, the amount of tracking deviation when the end of the reproducing head is aligned with that corresponds to the amount of positional deviation between the end of the recording head and the end of the reproducing head. .

Therefore, for the tape recorded by the same device in FIG. 4, the tracking deviation time td0 in the tracking state C where the end of the reproducing head is the boundary E of the track represents the deviation amount between the end positions of the recording head and the reproducing head. Become. Here, td0 will be referred to as reference deviation time.

From the above, the tape recorded on the same device is reproduced, and the relationship between the reproduction timing of the control signal CTL and the reproduction signal level of the reproduction head when the tracking is shifted by the servo controller 11 is examined to obtain the reference deviation time td0. Thus, the positional relationship between the recording head and the reproducing head of this device can be obtained. The reference deviation time td0 obtained by the servo controller 11 is stored in the memory 16 as tracking data 17. When there are a plurality of reproducing heads as in this example, the reference deviation time td0 is calculated for each of them. However, when the recording head that starts recording when performing the joint recording is determined, the reference deviation time td0 may be calculated for only that recording head.

The standard deviation time td0 is the same for magnetic tapes recorded by the same device, but not necessarily for tapes recorded by other devices. Therefore, when continuous recording is performed with a tape recorded by another device, tracking deviation of the recording head may occur.

FIG. 6 shows an example of the scanning positional relationship between the track T0, the recording head R0, and the reproducing head P0 on a tape recorded by the same device and a tape recorded by another device. The tracking deviation time td of the control signal CTL at this time is set to 0. Since the left end of the recording head R0 coincides with the left end of the track T0 with respect to the recording tape recorded by the same apparatus, there is no problem even if the continuous recording is performed in this tracking state. However, with respect to a tape recorded by another device, a positional deviation may occur between the track T0 'and the recording head R0. This is because the relationship between the helical track and the control track and the track width may differ when recorded by another device. In this example, a part of the track adjacent to the left side of the track T0 'is overwritten and the track width becomes narrow.

Therefore, before performing the joint recording, the relationship between the tracking deviation time and the reproduction signal level is obtained by the method described above. The relationship in which a tape recorded by another apparatus in the state shown in FIG. 6 is obtained is shown in FIG. The deviation time td0 ′ at this time is obtained, and the difference from the reference deviation time td0 when recording is performed by the same device is the amount to be corrected for tracking.

Therefore, the reference deviation time td0 stored in the memory 16 is referred to, and the difference td from the deviation time td0 '.
A state in which the reproduction timing of the control signal CTL is delayed by 0'-td0 with respect to the normal state (in this example, | td
The tape running control is performed by the servo controller 11 by giving an offset so as to be synchronized with 0'-td0 | As a result, the left end of the recording head R0 is moved to the track T
Since it can be aligned with the left end of 0 ', tracking deviation does not occur in joint recording. When the recording heads having a plurality of heads and starting the joint recording cannot be specified, the shift amount of each head is obtained, and the optimum offset amount of the reproduction timing of the control signal CTL is obtained by processing such as averaging.

Further, in the format in which the tape runs in the direction opposite to that of this example, the way the tracks are overlapped by guard bandless recording is reversed. Therefore, in this case, the reference deviation time td0 and the deviation time td0 ′ are obtained for the boundary point D.

The above is the description of the tracking control method of the recording head in the format having the control track in the linear track. Next, an example of recording head tracking control in a format having no linear track is shown.

The difference between this and the case where the linear track has a control track is that the control target is different. Here, instead of the control signal, the reproduction timing of the specific signal recorded on the helical track is used to perform the control.

FIG. 7 shows an example of the recording pattern of the magnetic tape 2. 41 is an index signal. Here, the index signal 41 is a signal of a single frequency, and the track T0,
It is assumed that it is recorded near the beginning of T1. FIG. 8 shows the structure of the tape running system. 42 is a filter and 43 is an index timing signal. The difference from the configuration of FIG. 1 is that these components are added and the control signal CTL is eliminated. The filter 42 reproduces the frequency formed by the index signal 41 from the reproduction signal 23.
The index timing signal 43, which is a pulse signal indicating the detection of the index signal, is generated by extracting from the a and 23b. The timing of the index timing signal 43 with respect to the reference signal 15 is detected by the servo controller 11. The timing of reproducing the index signal 41 changes depending on the tracking state of the reproducing head P0. The reproducing head P in the direction A shown in FIG.
When the tracking of 0 is deviated, the timing of reproducing the index signal 41 is delayed.

FIG. 9 shows the timing relationship of each signal. Similar to FIG. 3, the drum 1 rotates in synchronization with the reference signal 15 to generate the reproduction signals 23a and 23b. The generation timing of the index timing signal 43 changes when the tracking state changes. Here, the index timing signal 4 from the falling point of the reference signal 15
The time until the 3rd pulse is generated is defined as the tracking deviation time td.

Therefore, the relationship between the reproduction signal level of the reproduction head P0 and the tracking deviation time td is obtained for the tape recorded by the same device. Then, the relationship of FIG. 4 obtained in the case of having the control track described above is similarly obtained. In this case, it is necessary to perform tracking so that the end of the recording head is aligned with the track boundary E shown in FIG. Here, the control target is only the index signal 41 from the control signal CTL, and the control method is basically the same as the method having the linear track.

That is, when the tape recorded by the same device is reproduced and the tracking is shifted by the servo controller 11, the relationship between the reproduction signal level of the reproduction head and the index timing signal 43 is checked to determine the reference deviation time td0.
Is obtained and stored as tracking data 17 in the memory 16. Similarly, for the tape on which splicing recording is performed, the relationship between the reproduction signal level of the reproduction head and the index timing signal 43 is checked to obtain the shift time td0 '.

Therefore, the reference deviation time td0 stored in the memory 16 is referred to, and the difference td from the deviation time td0 '.
The servo controller 11 is offset by 0'-td0 so as to be synchronized with the reproduction timing of the index timing signal 43 delayed from the normal state.
To control tape running. As a result, tracking deviation does not occur in continuous recording.

When the recording heads having a plurality of heads and starting the joint recording cannot be specified, the deviation amount of each head is obtained and the optimum offset amount of the reproduction timing of the index timing signal 43 is obtained by averaging. Ask.

Further, in this example, the index signal 41 is a signal having a single frequency.
A preamble signal, a postamble signal, or any other signal that can be specified and detected at a fixed position on the track may be used. In that case, it is necessary to provide a detection circuit according to the type of index signal.

[0052]

According to the present invention, in a magnetic tape recording / reproducing apparatus having a recording head and a reproducing head independent of each other, the reproducing signal level of the reproducing head when the tracking is shifted and the control signal of the linear track or the helical track. The relationship between the reproduction timing of the index signal is obtained for the tape recorded by the same device and the tape for the continuous recording, and the difference is obtained. By shifting the reproduction timing of the control signal of the linear track or the index signal of the helical track by the difference, it is possible to perform the joint recording without the tracking deviation of the recording head without the reproducing circuit of the recording head.

[Brief description of drawings]

FIG. 1 is a block diagram of a tape running system.

FIG. 2 is a tape recording pattern diagram.

FIG. 3 is a timing chart of signals.

FIG. 4 is a relationship diagram between a tracking shift time and a reproduction signal level.

FIG. 5 is an explanatory diagram of a tracking state of a reproducing head.

FIG. 6 is an explanatory diagram of a positional relationship between a reproducing head, a recording head, and a track.

FIG. 7 is a tape recording pattern diagram.

FIG. 8 is a block diagram of a tape running system.

FIG. 9 is a timing chart of signals.

[Explanation of symbols]

 1 ... Drum, 2 ... Magnetic tape, 6 ... Capstan, 7 ... Pinch roller, 17 ... Tracking data, 19 ... Reproduction level information, 43 ... Index timing signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Aizawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd.Inside the Media Research Laboratory, Hitachi, Ltd. (72) Minor Kosuge 2880, Kozu, Odawara-shi, Kanagawa Hitachi, Ltd. Storage System Division

Claims (4)

[Claims] 1. A drum, a recording head and a reproducing head provided on the drum, means for rotating the drum, means for winding a magnetic tape around the drum, means for running the magnetic tape, and the magnetic A means for recording and reproducing a control signal in the longitudinal direction of the tape, a means for controlling the running of the magnetic tape by referring to the control signal, a means for supplying a recording current to the recording head, and a reproduction signal from the reproducing head. And a means for detecting the level of the reproduction signal, the means for obtaining and storing the relationship between the reproduction signal level and the reproduction timing of the control signal for the magnetic tape recorded by the same apparatus. , Playback of the above playback signal level and the above control signal on a magnetic tape recorded by any device A means for obtaining a timing relationship, a means for obtaining a difference in the reproduction timing relationship of the control signal between the magnetic tape recorded by the same apparatus and a magnetic tape recorded by an arbitrary apparatus, and a relationship between the reproduction timing of the control signal The magnetic recording / reproducing apparatus is provided with means for shifting the reproduction timing of the control signal by an amount corresponding to the difference, and causing the magnetic tape recorded by an arbitrary device to run. 2. A means for recording after moving a magnetic tape recorded by an arbitrary device by shifting the reproduction timing of the control signal by an amount corresponding to the difference in the reproduction timing of the control signal. The magnetic recording / reproducing apparatus according to claim 1, wherein 3. A drum, a recording head and a reproducing head provided on the drum, means for rotating the drum, means for winding a magnetic tape around the drum, means for running the magnetic tape, and the magnetic It is provided with means for recording and reproducing a specific signal on the helical track of the tape, means for giving a recording current to the recording head, means for obtaining a reproduction signal from the reproduction head, and means for detecting the level of the reproduction signal. In the apparatus, means for controlling the running of the magnetic tape by referring to the specific signal, and means for obtaining and storing the relationship between the reproduction signal level and the reproduction timing of the specific signal for the magnetic tape recorded by the same apparatus. , Find the relationship between the reproduction signal level and the reproduction timing of the specific signal for a magnetic tape recorded by an arbitrary device And means for obtaining the difference in the relationship of the reproduction timing of the specific signal between the magnetic tape recorded by the same device and the magnetic tape recorded by an arbitrary device, and the difference in the relationship of the reproduction timing of the specific signal. A magnetic recording / reproducing apparatus comprising means for moving a magnetic tape recorded by an arbitrary device by shifting the reproduction timing of the above-mentioned specific signal by an amount. 4. A means for recording after moving the magnetic tape recorded by an arbitrary device by shifting the reproduction timing of the specific signal by an amount corresponding to the difference in the reproduction timing relationship of the specific signal. The magnetic recording / reproducing apparatus according to claim 3, wherein