JPH10312603A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable high-speed information reproduction without changing the rotation speed of a rotating drum and without complicating the configuration. SOLUTION: The reproducing head 13 is a recording head 12.
Double the number. At the time of double speed reproduction, the magnetic tape 10
Is driven at twice the speed of 1 × speed reproduction, and the rotating drum 11
Is set to be the same as that at the time of 1 × speed reproduction. The capstan control circuit 44 includes a synchronization signal REF and a control signal CT.
Based on L, the capstan drive circuit 43 is controlled so that the projection trajectory of the reproduction head 13 on the magnetic tape 10 crosses the corresponding recording track at substantially the center in the longitudinal direction, and the reproduction signal among the reproduction signals The signal at the entrance and the signal at the exit of the recording track are compared, and the capstan drive circuit 43 is controlled so that the projection trajectory of the reproducing head 13 intersects the corresponding recording track at the center in the longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus for recording and reproducing information on and from a magnetic tape by a helical scan method.

[0002]

2. Description of the Related Art For example, as a method of editing video data recorded on a magnetic tape by news gathering, a video data is temporarily copied to a recordable and randomly accessible disk-like recording medium such as a hard disk, and then the disk-shaped recording medium is used. There is a method of performing editing work. According to this method, the editing point can be accessed in a short time, so that the time required for the editing operation can be reduced. However, even with this method, if data recorded on a magnetic tape is reproduced at a normal reproduction speed and transferred to a disk-shaped recording medium, it will inevitably take a considerable amount of time.

[0003] In recent years, there has been a demand for a technique capable of reproducing and transferring data recorded on a magnetic tape at a high speed such as twice the normal reproduction speed without any loss.

Conventionally, in a helical scan type magnetic recording / reproducing apparatus, a method of reproducing and transferring data recorded on a magnetic tape at a double speed is roughly divided into the following two methods.
There were two ways.

In the first method, the same number of reproducing heads as the recording heads are mounted, and when data is transferred at a double speed, the number of rotations of the rotating drum is also increased by two times, and each reproducing head is provided with a predetermined track. In this method, the phase of the rotating drum and the capstan motor are controlled so that the data can be reproduced, and the data on the magnetic tape is reproduced and transferred at twice the normal frequency.

[0006] The second method is to use 4 to the number of recording heads.
Even if the magnetic tape is fed at twice the speed with the double number of playback heads, the rotation speed of the rotating drum remains normal,
A method in which the reproducing heads are arranged so that they can be traced all over the recording surface of the magnetic tape, and data obtained from each reproducing head is rearranged and transferred based on its ID (identification) code and the like. It is.

[0007]

However, in the first method described above, a motor with a higher torque is required to rotate the rotating drum at twice the normal speed, and
Because the state of the air film, which is the layer of air generated between the rotating drum and the magnetic tape, differs between the two counts,
There is a problem that it is difficult to optimize the contact state of the head with the magnetic tape, which hinders good recording and reproduction.

In the second method, high-precision mechanical and control systems are not required, but a large number of heads are required and a circuit for performing an operation of rearranging data is required. However, there is a problem that the configuration becomes complicated and the cost increases.

The present invention has been made in view of such a problem, and an object of the present invention is to enable high-speed information reproduction without changing the number of revolutions of a rotary drum and without complicating the configuration. To provide a magnetic recording and reproducing apparatus.

[0010]

According to the present invention, there is provided a magnetic recording / reproducing apparatus comprising: a rotating drum on which a magnetic tape is wound and rotated about an axis inclined with respect to a traveling direction of the magnetic tape; And a recording head for recording information on the magnetic tape by the helical scan method, and a recording head provided on the outer peripheral surface of the rotating drum twice as many as the number of recording heads. A reproducing head for reproducing information by a method, a control head for recording a control signal to a magnetic tape and reproducing a control signal from the magnetic tape, and a magnetic tape at a normal speed and twice the normal speed. Drivable magnetic tape drive means and each reproducing head on the magnetic tape when driving the magnetic tape at twice the normal speed Projection locus, at substantially the center in the longitudinal direction so as to intersect with the corresponding recording track, in which a magnetic tape drive control unit for controlling the magnetic tape driving means.

In the magnetic recording / reproducing apparatus of the present invention, when the magnetic tape is driven at twice the normal speed, the magnetic tape drive control means causes the projection locus of each reproducing head on the magnetic tape to move in the longitudinal direction. The magnetic tape driving means is controlled so as to intersect with the corresponding recording track substantially at the center of the recording track, whereby the recording heads recorded on each recording track by the reproducing heads provided twice as many as the recording heads. The information is reproduced.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a magnetic recording / reproducing apparatus according to one embodiment of the present invention. The magnetic recording / reproducing apparatus is provided on a rotating drum 11 around which a magnetic tape 10 is wound and rotated about an axis inclined with respect to the traveling direction of the magnetic tape 10, and provided on an outer peripheral surface of the rotating drum 11. Magnetic tape 10
The two recording heads 12 (recording heads 12 to be described later)
A and 12B are represented. ), And a reproducing head 13 (two times as many as the number of recording heads 12) provided on the outer peripheral surface of the rotating drum 11 for reproducing information from the magnetic tape 10 by the helical scan method (reproducing head 13 A described later) ₁ , 13A ₂ , 13B ₁ , and 13B ₂ ), a control head 14 for recording a control signal on the magnetic tape 10 and reproducing a control signal from the magnetic tape 10, and a magnetic tape.
It has a normal speed and a capstan motor 15 as magnetic tape driving means which can be driven at twice the normal speed.

The magnetic recording / reproducing apparatus further includes, as a recording system, a video data compression circuit 21 for compressing the input video data VIN, and data for packing the output data of the video data compression circuit 21 and the input audio data AIN. A packing unit 22, an outer code encoder 23 for adding an outer code to the output data of the data packing unit 22, and an inner code for adding an inner code to the output data of the outer code encoder 23 to create a synchronous block. It includes a code encoder 24 and a recording amplifier 25 that performs parallel-to-serial conversion of output data of the inner code encoder 24, adjusts a recording current value, and outputs the data as recording data to the recording head 12.

The magnetic recording / reproducing apparatus further includes, as a reproducing system, a reproducing amplifier 31 for adjusting the level of a reproduced signal reproduced from the magnetic tape 10 by the reproducing head 13, and an output signal of the reproducing amplifier 31 being equalized. Do the processing,
An equalizer circuit 32 that performs analog-digital conversion, further performs serial-parallel conversion, and outputs the data as synchronous block data.
An inner code correction unit 33 for performing error correction using the inner code, an outer code correction unit 34 for performing error correction on the output data of the inner code correction unit 33 using the outer code, and an outer code correction unit 34, video data, audio data, I
A data depacking unit 35 for separating the D code, a jog memory 36 connected to the data depacking unit 35 and used at the time of irregular reproduction at a reproduction speed different from the normal reproduction speed, and a data depacking unit A data thinning circuit 37 for thinning out the output data of 35 to generate video data and audio data suitable for display on a monitor.
And a video data decompression circuit 38 for decompressing video data output from the data decimation circuit 37 and outputting it as a video output signal VOUT. Data thinning circuit 37
The output audio data is audio output data AOUT
Is output to the outside. The output data of the data depacking unit 35 is output to the outside as transfer output data DOUT in which information is not lost even during irregular reproduction.

The magnetic recording / reproducing apparatus further includes a control signal recording / reproducing circuit 41 for recording a control signal on the magnetic tape 10 and reproducing the control signal from the magnetic tape 10 using the control head 14, and an output of the reproducing amplifier 31. A reproduction output detection circuit 42 for detecting a signal to detect an output level of the reproduction signal, a capstan drive circuit 43 for driving the capstan motor 15, a capstan control circuit 44 for controlling the capstan drive circuit 43, A system control unit 4 for controlling the entire magnetic recording / reproducing apparatus including the capstan control circuit 44
5 and a control panel 46 for giving various instructions to the system control unit 45.

The capstan control circuit 44 operates in response to a command COM from the system control unit 45, and controls the reference synchronization signal REF from the system control unit 45 and the control signal CTL output from the control signal recording / reproduction circuit 41. , Reproduction output detection circuit 42
And the error rate information ER output from the inner code correction section 33, and the capstan drive circuit 43 is controlled based on these. . In particular, at the time of 1 × speed reproduction which is reproduction at a normal speed, the capstan control circuit 44 outputs the synchronization signal REF and the control signal CT.
The capstan drive circuit 43 is controlled so that L is synchronized. Also, at the time of double speed reproduction which is reproduction at twice the normal speed, the capstan control circuit 4
Reference numeral 4 denotes each reproduction head 13 on the magnetic tape 10 based on at least one of the synchronization signal REF, the control signal CTL, the level signal LV, and the error rate information ER.
The capstan drive circuit 43 is controlled so that the projected locus of the target image intersects the corresponding recording track substantially at the center in the longitudinal direction. This capstan control circuit 4
4 is realized by, for example, a microcomputer.

Although FIG. 1 shows only one recording head 12, one recording amplifier 25, one reproducing head 13, and one reproducing amplifier 31, each recording head 1
2, two reproducing heads 13 and four reproducing heads 13 are provided with the recording amplifier 25 and the reproducing amplifier 31 corresponding to them.

The magnetic recording / reproducing apparatus further includes an erasing head, an audio recording / reproducing head, a motor for rotating the rotating drum 11, a control circuit therefor, and the like, but these are omitted in FIG.

FIG. 2 is an explanatory diagram showing the arrangement of heads in the magnetic recording and reproducing apparatus shown in FIG. As shown in this figure, two recording heads 12 are provided on the outer peripheral surface of the rotating drum 11 at a predetermined angle (for example, 12.8 °).
A and 12B are provided. Further, two reproduction heads 13 are provided on the outer peripheral surface of the rotating drum 11 at a predetermined angle.
A ₁ and 13B ₁ are provided, and the rotating drum 1
Two reproducing heads 13A ₂ and 13B ₂ are provided at positions symmetrical to the reproducing heads 13A ₁ and 13B ₁ with respect to _one central axis (positions separated by 180 °). The recording head 12A and the reproducing heads 13A ₁ and 13A ₂ have the same first azimuth angle, and the recording head 12B and the reproducing head 13B
_1, 13B ₂ have the same second azimuth angle of a first azimuth angle and the second azimuth angles are opposite directions. Also, on the rotating drum 11, the reproducing head 13
A ₁ and 13A ₂ are mounted at the same height, and the reproducing heads 13B ₁ and 13B ₂ are mounted at the same height. From the reproducing heads 13A ₂ and 13B ₂ , signals are obtained in series through the same rotary transformer as the reproducing heads 13A ₁ and 13B ₁ . An erasing head 19 is further provided on the outer peripheral surface of the rotating drum 11.

FIG. 3 is an explanatory diagram showing a track pattern recorded on the magnetic tape 10. As shown in FIG. As shown in the figure, on the magnetic tape 10, recording tracks 51 recorded by the recording head 12A and recording tracks 52 recorded by the recording head 12B are formed alternately. A control track 53 on which a control signal is recorded by the control head 14 is formed on one side of the magnetic tape 10, and a time code track 54 on which a time code is recorded is formed next to the control track 53. . The control signal is a synchronization signal created by using a vertical synchronization signal of video data at the time of recording.

In this embodiment, as described later in detail, the head width of the reproducing head 13 is
The width is set within a range of 1 to 2 times the width of 1, 52.

Next, an outline of the operation of the magnetic recording / reproducing apparatus according to the present embodiment will be described. First, at the time of recording,
The input video data VI
N data compression is performed, and the data packing unit 22 packs the output data of the video data compression circuit 21 and the input audio data AIN. An outer code is added to the output data of the data packing unit 22 by the outer code encoder 23, and the inner code encoder 2
4, a synchronous block is created by adding an inner code, and the output data of the inner code encoder 24 is subjected to parallel-serial conversion by the recording amplifier 25, the recording current value is adjusted, and output to the recording head 12 as recording data. And recorded on the magnetic tape 10. At the time of recording, a control signal is recorded on the magnetic tape 10 by the control signal recording / reproducing circuit 41 and the control head 14. This control signal
On the magnetic tape 10, it is recorded as a signal whose magnetic pole changes alternately.

On the other hand, at the time of reproduction, a signal is reproduced from the magnetic tape 10 by the reproduction head 13, and the level of the reproduced signal is adjusted by the reproduction amplifier 31.
The equalization circuit 32 performs an equalization process on an output signal of the reproduction amplifier 31, performs an analog-digital conversion, further performs a serial-parallel conversion, and outputs the data as synchronous block data. Then, error correction is performed on the output data of the equalization circuit 32 by using the inner code by the inner code correction unit 33, and by the outer code correction unit 34 by the
Error correction is performed using the outer code, and video data, audio data, and ID code are separated from the output data of the outer code correction unit 34 by the data depacking unit 35. The output data of the data depacking unit 35 is output to the outside as transfer output data DOUT, and is also input to the data thinning circuit 37. The data thinning circuit 37 thins out the input data and converts the audio data into the audio output data AOUT.
And outputs the video data to the video data decompression circuit 38. The video data decompression circuit 38
The video data is expanded and output to the outside as a video output signal VOUT.

At the time of reproduction, the reproduction output detection circuit 42
As a result, a level signal LV representing the output level of the reproduction signal output from the reproduction amplifier 31 is generated and input to the capstan control circuit 44. The control signal is reproduced from the magnetic tape 10 by the control head 14 and the control signal recording / reproducing circuit 41. The control signal CTL output from the control signal recording / reproducing circuit 41 is
Is input to Further, the inner code correction unit 33 generates error rate information ER indicating the magnitude of the error rate, and inputs the error rate information ER to the capstan control circuit 44. The capstan control circuit 44 operates in response to the command COM from the system control unit 45, and also controls the reference synchronization signal REF from the system control unit 45, the control signal CTL output from the control signal recording / reproduction circuit 41, and the reproduction output. The level signal LV indicating the output level of the reproduced signal output from the detection circuit 42 and the error rate information ER output from the inner code correction section 33 are input.
The capstan drive circuit 43 is controlled based on these. Specifically, at the time of 1 × speed reproduction, the capstan control circuit 44 controls the capstan drive circuit 43 so that the synchronization signal REF and the control signal CTL are synchronized.
Also, at the time of double speed reproduction, the capstan control circuit 44
Is based on at least one of the synchronization signal REF, the control signal CTL, the level signal LV, and the error rate information ER, so that the projection trajectory of each reproducing head 13 intersects the corresponding recording track at substantially the center in the longitudinal direction. Next, the capstan drive circuit 43 is controlled. In the present embodiment, the rotation speed of the rotating drum 11 is constant, for example, at 75 Hz, both at the time of 1 × speed reproduction and at the time of 2 × speed reproduction.

FIG. 4 is an explanatory diagram showing the timing of various signals during 1 × speed reproduction. FIG. 4A shows the synchronization signal R
EF is shown. FIG. 4B shows a pulse PG representing the rotational position of the rotary drum 11, that is, the rotational position of the head. The rotation of the rotating drum 11 is controlled so as to synchronize with the synchronization signal REF.
Are synchronized with the synchronizing signal REF and are output when the synchronizing signal REF rises. Also, the pulse P
One cycle of G corresponds to one rotation of the rotating drum 11. FIG. 4C shows the control signal CTL. The control signal CTL includes a positive pulse and a negative pulse output alternately at equal intervals.
The period corresponds to the period of the recording track having the same azimuth angle.

As shown in FIG. 4, during 1 × speed reproduction,
Recording track 51 formed by recording head 12A
The reproducing head 13A ₁ is traced, the recording head 12B
The recording track 52 formed by the
The capstan drive circuit 43 is controlled such that the output timing of the positive polarity pulse of the control signal CTL matches the rising timing of the synchronization signal REF and the output timing of the pulse PG so that B ₁ traces.

Next, the principle of double speed reproduction in the present embodiment will be described. In the present embodiment, the number of the reproducing heads 13 is twice the number of the recording heads 12, and the magnetic tape 10 is driven at twice the speed at the time of double speed reproduction at the time of double speed reproduction. Is set to be the same as that at the time of 1 × speed reproduction. In this case, since the projection trajectory of the reproduction head 13 on the magnetic tape 10 is not parallel to the recording track, the waveform of the reproduction signal of the reproduction head 13 (hereinafter, referred to as the reproduction track) is used.
This is called a playback waveform. ) Is, of course, not flat, and the pulse P
There are various shapes depending on the phase relationship between G and the control signal CTL.

FIG. 5 (a) ~ (c) are those in which an example of the relationship between the projected path of the reproducing head 13A ₁ on the magnetic tape 10 and the recording track at the time of double-speed playback. In these figures, reference numeral 51 and 52, as in FIG. 3 represents a recording track formed by the recording head 12A, 12B, reference numeral 61 denotes a projection locus of the reproducing head 13A _1. In FIG. 5, the head width of the reproducing head 13A is set to 1.75 times the width of the recording tracks 51 and 52. The hatched area in FIG.
A region where the azimuth angle of A _{1 and} the azimuth angle of the recording track traced by the reproducing head 13A ₁ coincide with each other. 6 (a) to 6 (c) correspond to FIG.
It illustrates a reproduction waveform of the reproducing head 13A ₁ in the case (a) ~ a (c).

FIG. 5A shows a case where the recording track 51 and the projection trajectory 61 overlap each other at the entrance of the recording track 51. In this case, as shown in FIG. The first half of the track 51 includes the reproducing head 13A
₁ can trace data on the track 51 of the same azimuth, but can reproduce data in the latter half because it traces the track 52 on the reverse azimuth. As a result, only half of the data can be picked up.

In the case of FIG. 5B, the projection trajectory 61 has a recording track 52 of reverse azimuth over substantially the entire area of the track.
In this case, no data can be picked up as shown in FIG. 6B.

In the case of FIG. 5C, the projected trajectory intersects the recording track 51 at substantially the center in the longitudinal direction. In this case, as shown in FIG. Although the output is small at the entrance and exit of the track 51, all data on the recording track 51 can be picked up.
In this case, the next recording track 52 of the recording track 51 reproducing head 13A ₁ picks up data picked reproducing head 13B ₁ all data, further for the next recording track 51 reproducing head 13A ₂ are all data Pickup, and further with respect to the next recording track 52, the reproduction head 1
3B ₂ picks up all data.

FIGS. 7A and 7B show the phase relationship between the synchronization signal REF, the pulse PG, and the control signal CTL. FIG. 7A shows the synchronization signal REF, FIG.
(C) to (e) show the control signal CTL in each case of FIGS. 5 (a) to (c). In FIG. 7, as an example, the half cycle of the synchronization signal REF is 6.6667 ms. From FIG. 5 to FIG.
The head width of the reproducing head 13A is changed to the recording tracks 51 and 52.
5 (c) and FIG.
As shown in (c) and FIG. 7 (e), the output timing of the positive polarity pulse of the control signal CTL is の (１ ／) of the period of the synchronization signal REF from the rising and falling timings of the synchronization signal REF. If the drive of the magnetic tape 10 is controlled by controlling the capstan drive circuit 43 so as to be delayed by 1.6667 ms in the example of FIG. 7, each reproducing head 13 can pick up all data of all recording tracks. I understand. Therefore, in the present embodiment, first, the capstan drive circuit 43 is set so that the projection trajectory of each reproducing head 13 on the magnetic tape 10 intersects the corresponding recording track at substantially the center in the longitudinal direction.
To control the relationship between the phase of the control signal CTL and the phase of the rotating drum 11.

Next, as described above, FIG.
As shown in FIG. 7C and FIG.
0, the head width of the reproducing head 13 and the recording track width (the head width of the recording head 12)
Consider the relationship with Figure 8 (a) ~ (c), respectively, which was an example of the relationship between the projected path of the reproducing head 13A ₁ on the magnetic tape 10 and the recording track at the time of double-speed playback, the synchronization signal REF, pulse The phase relationship between PG and control signal CTL is all shown in FIG.
(A), (b), and (e).

[0034] FIG. 8 (a), if the head width of the reproducing head 13A ₁ is equal to the recording track width, FIG. 8 (b), 1.5 of the head width is a recording track width of the reproducing head 13A ₁
For times, FIG. 8 (c), the head width of the reproducing head 13A ₁ represents the case of two times the recording track width. Also,
FIGS. 9A to 9C are FIGS. 8A to 8C, respectively.
It illustrates a reproduction waveform of the reproducing head 13A ₁ in the case of. 9A to 9C, reference numerals La,
Lb and Lc each represent the maximum value of the reproduction output.

As shown in these figures, the recording track 5
Although the angle of 1 and the projection locus 61 of the reproducing head are different,
Within the scope head width of the reproducing head 13A ₁ is 2 times 1 times the recording track width, it can be seen it is possible to pick up all the data in the recording track 51. However, the head width of the reproducing head 13A ₁ is closer to 1 times the recording track width, the data is more likely to be an error. On the other hand, if the head width of the reproducing head 13A ₁ becomes 2 times the recording track width, the reproduced waveform becomes completely flat. But,
The larger head width of the reproducing head 13A ₁ is, the regeneration efficiency of the correspondingly reproducing head 13A ₁ falls, the reproduction output decreases (La>Lb> Lc), SN ratio (signal-to-noise ratio) is worse I will. The head width of the reproducing head 13A ₁ is exceeds twice the recording track width, one of the reproducing heads 13A ₁ is, for spanning two recording tracks of the same azimuth angle, it is impossible to reproduce data correctly. Until here it has been described the case of reproducing heads 13A _1, other reproducing head 13
The same applies to A ₂ , 13B ₁ , and 13B ₂ .

FIG. 10 is a characteristic diagram showing the relationship between the error rate and the off-track amount in each of the cases shown in FIGS. 8 (a) to 8 (c). In FIG. 10, the characteristics indicated by reference numerals 71a to 71c correspond to the cases of FIGS. 8A to 8C, respectively. As can be seen from the drawing, when the head width of the reproducing head 13 is large, when the off-track amount exceeds a predetermined amount, the adjacent recording track having the same azimuth angle starts to be reproduced, so that the error rate starts to deteriorate rapidly. . The off-track amount when the error rate starts to rapidly decrease becomes smaller as the head width of the reproducing head 13 increases.

As described above, in the present embodiment, the capstan drive circuit 43 is arranged such that the projection trajectory of each reproducing head 13 on the magnetic tape 10 intersects the corresponding recording track at substantially the center in the longitudinal direction. To control the relationship between the phase of the control signal CTL and the phase of the rotary drum 11, and furthermore, the head width of the reproducing head 13 is set within a range of 1 to 2 times the recording track width. . However, as shown in FIG.
Should be appropriately determined according to the S / N ratio of the tape / head system and the tracking accuracy of the magnetic recording / reproducing apparatus, and particularly preferably within the range of 1.5 to 2 times the recording track width. In the embodiment, for example, it is 1.75 times.

Next, as described above, the four reproducing heads 1
3 is, for example, 1.75 times the recording track width, and as shown in FIGS. 7A, 7B, and 7E, the projection locus of each reproducing head 13 on the magnetic tape 10 is A case is considered in which the capstan drive circuit 43 is controlled so as to intersect the corresponding recording track at substantially the center in the longitudinal direction, and the magnetic tape 10 is driven at twice the speed during normal reproduction. Reproduction head 13 on magnetic tape 10 in this case
FIG. 11 shows the relationship between the projection trajectories of A ₁ and 13A ₂ and the recording tracks. FIG. 12A shows the reproduction timings of the reproduction heads 13A ₁ and 13A ₂ in the case of FIG. 11 by reference numerals A1 and A2, respectively, and FIG.
1 shows a reproduction waveform of the reproduction heads 13A ₁ and 13A ₂ in the case of ₁ . As shown in these figures, by controlling the capstan driving circuit 43 as described above, the reproducing heads 13A ₁ and 13A ₂ can sequentially reproduce the data of all the tracks 51 having one azimuth angle. become. At this time, the output is small at the entrance and exit of the recording track 51, and the error rate is slightly worse than that at the intermediate portion between the entrance and exit, but it can be read correctly.

However, if the phase control is performed only by the control signal CTL recorded on the magnetic tape 10, if the magnetic tape 10 expands and contracts due to temperature characteristics, humidity characteristics, changes over time, etc., the entrance or exit of the recording track will be obtained. Error rate deteriorates extremely, and data that cannot be reproduced correctly starts to appear.

Therefore, in this embodiment, as shown in FIG. 13, the capstan control circuit 44 controls the error rate and the exit of the signal at the entrance 75 of the recording track among the signals reproduced by the reproduction head 13. By comparing the error rate of the signal of the section 76, or by comparing the level of the signal of the entrance section 75 with the level of the signal of the exit section 76,
The speed of the magnetic tape 10 is finely adjusted by controlling the capstan drive circuit 43 according to the result. Specifically, the capstan control circuit 44 outputs the level signal LV output from the reproduction output detection circuit 42 or the error rate information ER output from the inner code correction section 33 to the entrance and exit of the recording track. Extract the corresponding parts, calculate the average value for several tracks each,
The speed of the magnetic tape 10 is finely adjusted by controlling the capstan driving circuit 43 so that the average value at the entrance and the average value at the exit become equal. Thus, the drive of the magnetic tape 10 is controlled such that the projection trajectory of each reproducing head 13 on the magnetic tape 10 intersects the corresponding recording track at the center in the longitudinal direction.

The above-described capstan control circuit 44 is
4 and FIG. 15 will be described more specifically. Figure 14 (a), (b) is shows the relationship between each of the projection trajectory 61 of the reproducing heads 13A ₁ on the magnetic tape 10 when the resulting off-track during double-speed playback and recording tracks 51 is there. FIGS. 15A and 15B
Respectively, FIG. 14 (a), the illustrates a reproduction waveform of the reproducing head 13A ₁ in the case of (b).

FIGS. 14 (a) and 15 (a) show the case where the reproduced output at the entrance is larger than the reproduced output at the exit. In this case, the phase of the magnetic tape 10 is delayed and the projection is performed. By finely adjusting the speed of the magnetic tape 10 so that the recording track is located at the position indicated by reference numeral 81 with respect to the trajectory 61, it is possible to return to the normal state.

FIGS. 14 (b) and 15 (b) show the case where the reproduced output at the exit is larger than the reproduced output at the entrance. In this case, the phase of the magnetic tape 10 is advanced and the projection is performed. By finely adjusting the speed of the magnetic tape 10 so that the recording track is located at the position indicated by reference numeral 81 with respect to the trajectory 61, it is possible to return to the normal state.

Next, the operation at the time of double speed reproduction in the present embodiment based on the principle of double speed reproduction in the present embodiment as described above will be described. In the present embodiment, at the time of double-speed reproduction, the magnetic tape 10 is driven at twice the speed at the time of single-speed reproduction.
The number of rotations of 1 is the same as that at the time of 1 × speed reproduction. The capstan control circuit 44 controls the synchronization signal REF and the control signal C
Each reproduction head 1 on the magnetic tape 10 is
The capstan driving circuit 43 is controlled so that the projection locus of No. 3 intersects the corresponding recording track at substantially the center in the longitudinal direction, and the phase relationship between the control signal CTL and the rotating drum 11 is controlled. Further, the capstan control circuit 44 compares the error rate of the signal at the entrance of the recording track and the error rate of the signal at the exit of the signals reproduced by the reproduction head 13, or Compare the level with the level of the signal at the exit,
According to the result, each reproduction head 1 on the magnetic tape 10
3 so that the projection trajectory 3 intersects the corresponding recording track at the center in the longitudinal direction.
3, the speed of the magnetic tape 10 is finely adjusted.

In the present embodiment, the signal reproduced at the entrance of the recording track among the signals reproduced by the reproducing head 13 is, as shown by reference numeral 75 in FIG. The signal at the exit portion is at least part of the portion having a slope on the front end side, and similarly, the signal at the exit portion is, as shown by reference numeral 76 in FIG. Refers to the signal of at least a part of the portion having a slope on the side. The capstan control circuit 44 determines the timing of the entrance and the exit based on the synchronization signal REF from the system control unit 45, and extracts the signal of the entrance and the signal of the exit. The front and rear ends of the reproduced waveform are
Since it may fluctuate due to mechanical factors, it is preferable to extract portions slightly inside the front end and the rear end as the signal at the entrance and the signal at the exit.

In the capstan control circuit 44, it is not necessary to compare the outputs of all the reproducing heads 13, but the output of one reproducing head 13 may be used. Further, for example, it may be compared by taking the average value of the output of the reproducing head 13B ₁ and the reproducing head 13A ₁ output.

As described above, according to the present embodiment, it is possible to reproduce and transfer information at double speed without changing the rotation speed of the rotating drum 11. In the present embodiment, the rotation speed of the rotary drum 11 is not changed even at 2 × speed, so that it is not necessary to improve the performance of the motor that drives the rotary drum 11, and the contact state of the reproducing head 13 with the magnetic tape 10 is optimized. It becomes easy to convert. Further, in the present embodiment, the number of the reproducing heads 13 is twice as large as the number of the recording heads 12, as compared with the conventional method in which the number of the reproducing heads is four times the number of the recording heads. Therefore, the configuration is simple and the cost can be reduced.

In the magnetic recording / reproducing apparatus according to the present embodiment, since signals are obtained in series from the reproducing heads 13A ₂ and 13B ₂ through the same rotary transformer as the reproducing heads 13A ₁ and 13B ₁ , the signals are normally output. At the time of reproduction (at the time of 1 × -speed reproduction), if the reproducing heads A ₂ and 13B ₂ are utilized, they have a non-tracking relationship with each other.
Even if only the phase control using the normal control signal CTL is performed, the reliability of the magnetic tape 10 can be improved without causing a failure due to a significant expansion and contraction of the magnetic tape 10 and the like.

The present invention is not limited to the above-described embodiment. For example, the capstan control circuit 44 controls the error rate and level of the signal at the entrance of the recording track among the signals reproduced by the reproducing head 13. And the error rate and level of the signal at the outlet. Further, the capstan control circuit 44 compares the signal at the entrance and the signal at the exit of the recording track among the signals reproduced by the reproducing head 13 and monitors the error rate and level of the signal at the center. By doing so, it may be possible to prevent the phase of the control signal CTL from being inverted with respect to the normal state to be locked.

In the above embodiment, an example of an apparatus for compressing video data and recording it on a magnetic tape has been described. However, the present invention is also applicable to an apparatus for recording video data on a magnetic tape without compression. can do.

[0051]

As described above, according to the magnetic recording / reproducing apparatus according to any one of claims 1 to 6, when the magnetic tape is driven at twice the normal speed, the magnetic tape drive control is performed. The means controls the magnetic tape driving means so that the projection trajectory of each reproducing head on the magnetic tape intersects the corresponding recording track at substantially the center in the longitudinal direction,
Since the information recorded on each recording track is reproduced by the reproducing heads provided twice as many as the number of recording heads, without changing the rotational speed of the rotating drum,
In addition, there is an effect that information can be reproduced at high speed without complicating the configuration.

According to the magnetic recording / reproducing apparatus of the present invention, the head width of the reproducing head is set to be equal to the recording track width.
Since the range is doubled to doubled, the information recorded on each recording track can be more reliably reproduced.

According to the magnetic recording / reproducing apparatus of any one of claims 3 to 6, the magnetic tape drive control means controls the phase and rotation of the control signal based on the control signal reproduced by the control head. Compare the phase control means for controlling the magnetic tape driving means with the signal at the entrance of the recording track and the signal at the exit of the signals reproduced by the reproduction head so that the phase of the drum has a predetermined relationship. Since the magnetic tape driving means is controlled in accordance with the result, and fine adjustment means for finely adjusting the speed of the magnetic tape is provided, the drive of the magnetic tape can be controlled more accurately. It has the effect of being able to.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of heads in the magnetic recording and reproducing apparatus according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a pattern of a track recorded on a magnetic tape in the magnetic recording / reproducing apparatus according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing timings of various signals at 1 × speed reproduction in the magnetic recording / reproducing apparatus according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a relationship between a projection trajectory of a reproducing head on a magnetic tape and a recording track during double speed reproduction in the magnetic recording and reproducing apparatus according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a reproduction waveform of a reproduction head in each case shown in FIG. 5;

FIG. 7 is an explanatory diagram showing timings of various signals in the magnetic recording / reproducing apparatus according to one embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of the relationship between the projection trajectory of the reproducing head on the magnetic tape and the recording track during double-speed reproduction in the magnetic recording and reproducing apparatus according to one embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a reproduction waveform of a reproduction head in each case shown in FIG. 8;

FIG. 10 is a characteristic diagram illustrating a relationship between an error rate and an off-track amount in each case illustrated in FIG. 8;

FIG. 11 is an explanatory diagram showing an example of the relationship between the projection trajectory of the reproducing head on the magnetic tape and the recording track during double speed reproduction in the magnetic recording and reproducing apparatus according to one embodiment of the present invention.

12 is an explanatory diagram showing a reproduction timing and a reproduction waveform of a reproduction head in the case of FIG. 11;

FIG. 13 is an explanatory diagram showing a signal at an entrance portion and a signal at an exit portion of a recording track among signals reproduced by a reproducing head in the magnetic recording and reproducing device according to one embodiment of the present invention.

FIG. 14 is an explanatory diagram illustrating a relationship between a recording track and a projection trajectory of a reproducing head on a magnetic tape when an off-track occurs during double-speed reproduction in the magnetic recording and reproducing apparatus according to one embodiment of the present invention.

15 is an explanatory diagram showing a reproduction waveform of a reproduction head in each case of FIG.

[Explanation of symbols]

Reference numeral 10: magnetic tape, 11: rotating drum, 12: recording head, 13: reproducing head, 14: control head, 1
5: Capstan motor, 31: Reproduction amplifier, 33: Inner code correction unit, 42: Reproduction output detection circuit, 43: Capstan drive circuit, 44: Capstan control circuit, 45: System control unit.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/18 574 G11B 20/18 574E

Claims (6)

[Claims] 1. A rotating drum on which a magnetic tape is wound and rotated about an axis inclined with respect to the traveling direction of the magnetic tape, and a helical member provided on an outer peripheral surface of the rotating drum and helical to the magnetic tape A recording head for performing information recording by a scanning method; and a reproducing head provided on the outer peripheral surface of the rotary drum by twice the number of the recording heads and reproducing information from a magnetic tape by a helical scanning method. A control head for recording a control signal to a magnetic tape and reproducing a control signal from the magnetic tape; a magnetic tape driving means capable of driving the magnetic tape at a normal speed and twice the normal speed; Is driven at twice the normal speed, the projected trajectory of each reproducing head on the magnetic tape is substantially centered in the longitudinal direction. So as to intersect with the corresponding recording track, the magnetic recording and reproducing apparatus is characterized in that a magnetic tape drive control means for controlling the magnetic tape driving means. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein a head width of the reproducing head is within a range of 1 to 2 times a recording track width. 3. The magnetic tape drive control means, based on a control signal reproduced by the control head, controls the magnetic tape drive so that the phase of the control signal and the phase of the rotary drum have a predetermined relationship. Phase control means for controlling the means, and comparing the signal at the entrance and the signal at the exit of the recording track among the signals reproduced by the reproduction head, and controlling the magnetic tape driving means according to the result. 2. The magnetic recording / reproducing apparatus according to claim 1, further comprising: fine adjustment means for finely adjusting the speed of the magnetic tape. 4. The apparatus according to claim 1, wherein the fine adjustment unit compares an error rate of a signal at an entrance portion of the recording track and an error rate of a signal at an exit portion of the signals reproduced by the reproduction head. Item 4. A magnetic recording / reproducing apparatus according to Item 3. 5. The apparatus according to claim 3, wherein the fine adjustment unit compares a signal level at an entrance portion of the recording track and a signal level at an exit portion of the signals reproduced by the reproduction head. The magnetic recording and reproducing apparatus according to claim 1. 6. The fine adjustment means extracts a signal at an entrance portion and a signal at an exit portion of a recording track among signals reproduced by the reproduction head, based on a reference synchronization signal. The magnetic recording / reproducing apparatus according to claim 3, wherein