JP2806418B2 - Helical scan type magnetic tape unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type magnetic tape apparatus for forming a track diagonally from a digitized video signal or other information signal using a rotary head.
It relates to.

[0002]

2. Description of the Related Art Conventionally, a so-called video tape recorder (VTR) has been used as a magnetic recording / reproducing apparatus for recording and reproducing signals on a magnetic recording medium such as a magnetic tape using a rotary head.
And a digital tape recorder (DAT). These devices have a feature that they can perform high-density recording and reproduction of a video / audio signal or an audio signal converted into a digital signal, respectively.

[0003] However, in such a conventional apparatus, since the recording rate is constant, when a recording / reproducing operation at a data rate A is performed at a lower recording rate using an apparatus capable of recording / reproducing the data, a surplus data is required. Recording and reproduction were performed by filling the area with zero data and setting the entire data rate to A. For this reason, the recording time could not be lengthened despite recording a signal with a low data rate.

In order to solve such a problem, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 1-139906 discloses an apparatus having a pair of heads attached to a rotating cylinder and having different azimuth angles, and a tape running means for winding the tape around the rotating cylinder and causing the tape to run normally. A second taper which is 1/3 of the first tape running speed and the first tape running speed by the tape running means.
It is disclosed that the recording / reproducing is performed once every three times in the number of times the head traces on the tape at the time of the second tape traveling speed. As a result, a data rate of 1/3 of the basic data rate A could be handled.

[0005]

However, today's digital data recording / reproducing apparatuses include MPEG1 and MPE.
It is required to efficiently record and reproduce signals of various data rates, such as G2, DVB, ATV, and the like. There was a problem that it could not be improved.

Further, the recording / reproducing technique disclosed in Japanese Patent Application Laid-Open No. 61-139906 is simply extended to 1 / (2
When applying to a data rate of N) (N is a natural number), there is a problem that adjacent tracks on the magnetic tape have the same azimuth, and guard bandless azimuth recording cannot be performed.

On the other hand, if the rotational speed of the rotary cylinder is changed during reproduction, when signals at the same magnetic reversal interval are reproduced on the magnetic tape, the reversal cycle of the reproduced signal changes according to the rotational speed. However, there is a problem that it is necessary to change the conversion circuit according to the number of rotations, and the configuration becomes complicated.

Accordingly, an object of the present invention is to realize recording / reproducing at a tape running speed of 1 / integer without using an additional head, while keeping the cylinder rotational speed during reproduction constant.

[0009]

SUMMARY OF THE INVENTION The present invention provides the following structure to solve the above problems.

According to the present invention, there is provided a magnetic tape wound around a rotary cylinder using at least one pair of magnetic heads having different azimuth angles disposed at a distance of 180 ° on the rotary cylinder. In a helical scan type magnetic tape device for recording / reproducing information having a first or second information amount on a track in an oblique direction, a traveling speed of the magnetic tape is set to a first tape traveling speed or the first tape. A tape running speed control means for selectively controlling a second tape running speed to be 1 / n (n is an integer of 2 or more) times the running speed, and a rotation speed of the rotary cylinder being set to the first rotation speed or the first rotation speed.
Rotating cylinder control means for selectively controlling the rotation speed to a second rotation speed that is 1 / n times the rotation speed of the tape,
Information along with the information having the first or second information amount
Recorded on the track in the direction of
Tape running speed recording that reproduces information about the running speed
Reproducing means and the tape running speed recording / reproducing means.
According to the information on the tape running speed during recording.
Tracking phase control means for controlling the locking phase;
The provided, when recording information with an information amount of said first, the tape running speed control means magnetic tape selected controlled to be the first tape traveling speed and the rotational cylinder control means the rotating select control so that the rotational speed of the cylinder is a first rotational speed, on the other hand, when recording information with an information amount of said second, the tape running speed control means the
The magnetic tape is selected and controlled to have a second tape running speed, and the rotating cylinder control means controls the rotation of the rotating cylinder.
When the information having the first information amount is reproduced, the tape running speed control means selects the magnetic tape so as to have the first tape running speed. controlled and the rotational cylinder control means the rotary Siri
When the information having the second information amount is reproduced , the rotation speed of the slider is selectively controlled to be the first rotation speed.
The tape traveling speed control means magnetic tape selection control such that the second tape traveling speed and the rotational cylinder control means selects a control so that the first rotational speed a rotational speed of the rotary cylinder, the Reproduce information having second information amount
And the second tape running speed is an even number of the first tape running speed.
When it is a fraction, the tracking phase control means
At the time of the recording reproduced by the tape traveling speed recording / reproducing means
Track during playback based on the
The king phase is set to 180 × (1/1) at the recording start position of the track.
2n) degrees, and the second tape running speed becomes the first tape.
If the speed is an odd fraction of the loop speed, the tracking
The phase control means is replayed by the tape running speed recording / reproducing means.
On the basis of the generated information on the tape traveling speed at the time of the recording.
The present invention provides a helical scan type magnetic tape device characterized by not controlling a tracking phase during reproduction .

[0011]

1 is a block diagram for explaining a magnetic recording / reproducing apparatus according to one embodiment of the present invention, FIG. 2 is a plan view of a rotary cylinder, and FIG. 3 is a tape formed at a first tape running speed. FIG. 4 is a view for explaining a pattern, FIG. 4 is a diagram for explaining a tape pattern formed at a second tape running speed, and FIG. Embodiments will be described below with reference to the drawings.

The outline of the present embodiment focuses on the fact that it is not necessary to change the recording circuit even if the number of rotations of the rotary cylinder is changed at the time of recording, and when recording at a low tape speed (1 / n times speed), Similarly, by setting the rotation speed to 1 / n, the inclination angle (running angle) of the recording track is the same as that at 1 × speed, and the track recorded at 1 / n speed is reproduced at 1 / n speed. In some cases, a reproduction signal is obtained by completely tracing one track by at least n scans while traversing a plurality of tracks recorded with the rotation speed of the cylinder at 1 × speed.

Referring to FIG. 1, an input digital information signal aa is supplied to an input interface circuit 1, where it is converted into a signal form to be stored in a memory 2 at the next stage. The data is supplied to the memory 2. The memory 2 accumulates data for at least one track period, exchanges data with the outer code generation circuit 3, and generates an output signal. The outer code generation circuit 3 generates and adds an outer code for error correction corresponding to data of one track unit. The output signal of the memory 2 is supplied to an inner code generation circuit 4 for generating and adding an inner code in units of a plurality of data blocks constituting one track.

The output signal of the inner code generation circuit 4 is supplied to a recording processing circuit 5. The recording processing circuit 5 includes a not-shown formatter circuit, recording modulation circuit, and the like. The formatter circuit adds a synchronization signal and an ID signal to each of the plurality of data blocks, and converts data arranged in a predetermined recording order. Generate. The generated data is subjected to recording modulation such as EFM by a recording modulation circuit to generate an output signal of the recording processing circuit 5. The output signal of the recording processing circuit 5 is amplified to a predetermined recording level by the recording amplifier 6, and then recorded on the magnetic tape T via the magnetic heads H1 and H2. To explain the magnetic heads H1 and H2, as shown in FIG. 2, both magnetic heads are mounted on a rotating cylinder at a distance of 180 °, and the azimuth angles thereof are different from each other. I have. Note that the azimuth angle directions may be the same, but the reverse azimuth direction is desirable in consideration of crosstalk interference between adjacent tracks.

Returning to FIG. 1, at the time of reproduction, a signal reproduced from the magnetic tape T via the magnetic heads H1 and H2 is supplied to a reproduction amplifier 7, amplified to a predetermined reproduction level, and then supplied to a reproduction processing circuit 8. The reproduction processing circuit 8 includes a waveform equalization circuit, a clock reproduction circuit, a reproduction demodulation circuit, a synchronization detection circuit, a deformatter circuit, and the like (not shown).
Since the waveform equalization circuit has a constant rotation speed of the rotating cylinder during reproduction regardless of the data rate as described later,
The characteristics are not changed according to the data rate. Further, the clock recovery circuit generates a reference clock in units of bits (bytes) based on the output signal of the waveform equalization circuit. The reproduction / demodulation circuit has a complementary relationship with the recording / modulation circuit and performs predetermined demodulation. The synchronization detection circuit detects the start of data by detecting a synchronization signal added at the time of recording. Further, the deformatter circuit has a complementary relationship with the formatter circuit, and restores the data to the original arrangement to generate the output signal of the reproduction processing circuit 8.

The inner code correction circuit outputs an output signal obtained by correcting each of the plurality of data blocks to the memory 10.
The memory 10 accumulates the output signal for at least one track period, transmits and receives a signal to and from the outer code correction circuit 11, and supplies the corrected output signal to the output interface circuit 12. Then, the output interface circuit 12 generates an output digital information signal bb in accordance with the reproduced signal and outputs it to a transmission line (not shown).

Now, let us assume a first data rate and a second data rate having a 1 / n rate with respect to the first data rate. At the time of recording, the first and second data rates are determined by the data rate determination circuit 13, and information representing the data rate in the input digital information signal aa is identified here to generate the control signal 13a. I have. The data rate determination circuit 13 may of course be based on any signal from the input to the output of the recording processing circuit 5.

The tape running speed control means 14 determines the running speed of the magnetic tape T based on the control signal 13a. That is, when the control signal 13a indicates the first data rate, the output signal is generated so as to be the first running speed, while when the control signal 13a indicates the second data rate, the output signal is generated. The output signal is generated such that the second traveling speed is 1 / n times the speed. Then, the output signal of the tape running speed control means 14 is supplied to one input of an addition circuit 17, and is added to the output signal of the fixed tracking control means 15 during recording which is supplied to the other input. Is driving.

The control signal 13a is also supplied to the rotary cylinder control means 16, and when the control signal 13a indicates a first data rate, an output signal is generated so as to have a first rotation speed. When the signal 13a indicates the second data rate, an output signal is generated so that the rotation speed becomes 1 / n times the first rotation speed, and the output signal controls the cylinder motor 19. .

Further, a control signal 13a indicating the running speed of the magnetic tape or the number of rotations of the rotary cylinder at the time of recording is supplied to the memory 2, where an outer code and an inner code are added together with normal data, and a predetermined signal on the magnetic tape T It is recorded in the recording area.

In this manner, the magnetic head H having the first and second azimuth angles at both the first and second data rates.
1, H2 can be the azimuth recording using alternating, track inclination angle (during running) is the same across the first, second data rate. Also, the second data rate is 1 / n times the first data rate, but the rotation speed of the rotary cylinder is also 1 / n times, so the minimum reversal interval of the magnetization recorded on the magnetic tape is Are the same. And the first,
The tape pattern corresponding to the second data rate is shown in FIG.
4 respectively.

At the time of reproduction, the first and second data rates are identified by a reproduction control signal 9a output from the inner code correction circuit 9 obtained by reproducing the control signal 13a inserted in the data at the time of recording. .

The reproduction control signal 9a is supplied to the memory 10 and the outer code correction circuit 11, and is also supplied to the inner code correction circuit 9.
I use it myself. That is, the control of the write address of the memory 10 and the correction timing of the inner code / outer code is performed based on the reproduction control signal 9a.

Further, it determines the running speed of the magnetic tape T on the basis of a tape running speed control means 14 in the reproduction control signal 9a. That is, when the reproduction control signal 9a indicates the first data rate, the output signal is generated so as to have the first running speed, while when the reproduction control signal 9a indicates the second data rate, the output signal is generated. The output signal is generated such that the second traveling speed is 1 / n times the traveling speed of the second traveling speed.

The tracking control means 15 determines the tracking amount based on the reproduction control signal 9a. That is, when the reproduction control signal 9a indicates a data rate that is 1 / even times the data rate ( 1 / n times the data rate,
When the time n is an even number of 2 or more ), an output signal is generated such that the tracking phase is shifted by 180 / (2n) ゜ at the track start position.

The reproduction control signal 9a is not supplied to the rotary cylinder control means 16, and the reproduction of the signal corresponding to the second data rate is performed in the same manner as in the case of the first data rate. An output signal is generated so as to be the number of revolutions.

Now, a case of reproducing a signal recorded at the second data rate will be described in detail with reference to FIG. FIG. 3 shows a case where the second data rate has a data rate which is 1/2 times the first data rate.

The signal recorded at the second data rate is reproduced at the second tape running speed and the rotation speed of the rotary cylinder at the first rotation speed. When reproduction is performed in this state, the rotating head traces across the track on the magnetic tape as shown in FIG. Therefore, when the second tape running speed is selected to be 1 / n times the speed, the data for almost one track is completed while the magnetic head having the same azimuth angle as the azimuth angle of the track to be reproduced scans n times. , In this case twice.

At this time, the trace of the track at the time of reproduction is shifted by 45 degrees from the position where the track becomes the just track. In particular, the tracking phase is set to 180 × (1/2)
By shifting by n) degrees, the data of the first azimuth track and the data of the second azimuth track can be obtained uniformly. When the tape running speed is set to an odd number, it is not necessary to shift the tracking phase of reproduction.

Further, when the tape running speed is set to an even number, the head width is set to Tp where Tp is the track pitch.
The track can be completely traced by increasing the width by p × (1 + ／ n). In the above-described embodiment, it is needless to say that the winding angle and the head touch can be normally set within a range in which the track length for recording and reproduction can be changed.

[0031]

As described above, according to the configuration of the present invention,
By changing the number of rotations of the rotating cylinder according to the tape speed during recording, the same track pitch as at 1x speed can be achieved, and azimuth recording can be achieved regardless of the value of n at 1 / nx speed. There is an effect that crosstalk interference between adjacent tracks can be prevented , and high-quality reproduction information can be obtained. Further, since the rotation speed of the rotary cylinder is fixed at the first rotation speed regardless of the magnetic tape traveling speed, when signals at the same magnetic reversal interval are reproduced on the magnetic tape, the reversal period of the reproduced signal does not change. There is an effect that a single waveform equalization circuit is sufficient.

According to the configuration of the present invention, the tracking phase is set to 180 × (1/1) at the recording start position of the track only when the second tape traveling speed is set to an even fraction of the first tape traveling speed. Since the tracking phase control means is shifted by 2n) degrees, it is possible to uniformly obtain reproduction information obtained from tracks recorded at different azimuth angles.

Further, as described above, according to the configuration of the present invention, information on the tape running speed during recording is recorded on the magnetic tape.
Recorded on, because it has a means for reproducing this information at the time of reproduction, there is an effect that can automatically detect the tape running speed to be reproduced during playback.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a magnetic recording / reproducing apparatus according to one embodiment of the present invention.

FIG. 2 is a plan view of a rotary cylinder.

FIG. 3 is a tape pattern formed at a first tape running speed.

FIG. 4 is a tape pattern formed at a second tape running speed.

FIG. 5 is a diagram for explaining a head trajectory when reproducing a tape pattern formed at a second tape running speed.

[Explanation of symbols]

 14 Tape running control means 15 Tracking control means 16 Rotary cylinder control means T Magnetic tape H1, H2 Magnetic head

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 15/467

Claims (1)

(57) [Claims] 1. A longitudinal direction of a magnetic tape wound around a rotary cylinder using at least one pair of magnetic head pairs having different azimuth angles arranged at 180 ° apart on the rotary cylinder. in helicopter Cal scan type magnetic tape device in which information for the record playback with the first or second information amount in the oblique direction of the track, the running speed of the magnetic tape first tape traveling speed or the first tape A tape running speed control means for selectively controlling a second tape running speed to be 1 / n (n is an integer of 2 or more) times the running speed, and a rotation speed of the rotary cylinder being set to the first rotation speed or the first rotation speed. A rotation cylinder control means for selectively controlling the rotation speed to a second rotation speed of 1 / n times the rotation speed, and information relating to the tape traveling speed during recording to the first or second rotation speed.
Recorded on diagonal tracks with information having the amount of information
At the time of playback, information about the tape running speed is read from the track.
And a tape running speed recording and reproducing means for reproducing the broadcast, the time of recording to be reproduced at the tape running speed recording and reproduction means
Tracking phase according to information on tape running speed
When information having the first information amount is recorded, the tape running speed control unit controls the magnetic tape to select the magnetic tape at the first tape running speed. And the rotating cylinder control means selectively controls the rotating speed of the rotating cylinder to be a first rotating speed, while the tape running speed controlling means is used when recording information having the second information amount. Is the magnetic tape
And the rotating cylinder control means selectively controls the rotating speed of the rotating cylinder to be a second rotating speed, and reproduces the information having the first information amount. In this case, the tape running speed control means selects and controls the magnetic tape so as to have the first tape running speed, and the rotary cylinder control means selects the rotation speed of the rotary cylinder so as to be the first rotation speed. controlled, whereas, when reproducing information with the information amount of said second, the tape running speed control means magnetic tape
And the rotating cylinder control means selectively controls the rotating speed of the rotating cylinder to be the first rotating speed to reproduce the information having the second information amount. Then the second tape run
When the line speed is an even fraction of the first tape running speed
Is the tracking phase control means, the tape running speed is
Tape running speed at the time of the recording reproduced by the recording / reproducing means
Tracking phase during playback based on
180 ° (1 / 2n) degrees at the recording start position
And the second tape running speed is odd with the first tape running speed.
When it is a fraction, the tracking phase control means
At the time of the recording reproduced by the tape traveling speed recording / reproducing means
Track during playback based on the
A helicopter scan type magnetic tape device characterized by not controlling the king phase .