JPH06150272A - Rotary head type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reproduce a magnetic record recorded on a tape in the LP mode without deteriorating the quality of reproduced signals by using a VTR which makes recording or reproduction by simultaneously operating a pair of heads having a level difference equal to the track pitch of the SP mode between them. CONSTITUTION:Heads A1 and B1 are closely arranged on a rotary drum so that they can have a level difference equal to the track pitch (=S) of the SP mode. At the time of reproducing a magnetic record recorded on a tape in the LP mode, tracking is performed so that the center between the upper edge of the head A1 and the lower edge of the head B1 can coincide with the boundary of tracks on a recording pattern (alpha=alpha' in the figure). When the tracking is performed in such a way, the reproducing outputs of the heads do not decrease and the cross-talk between adjacent tracks does not increase and no cross-talk occurs between a track and the track next but one. Therefore, the quality of reproduced signals is not deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording / reproducing a digital video signal or the like onto / from a magnetic tape wound on a rotary drum, and more particularly to a tracking control system for the apparatus.

[0002]

2. Description of the Related Art Conventionally, a rotary head type digital signal recording / reproducing apparatus having a head as shown in FIG. 5 has been considered. In FIG. 5, a pair of recording / reproducing heads A having different azimuth angles (angles in the extension direction of the gap).
1, B1 are arranged at positions close to the rotary drum D with a predetermined step Ds. A pair of recording / reproducing heads A2, B2 having different azimuth angles are arranged at a position 180 ° away from the pair of recording / reproducing heads A1, B1 with a predetermined step Ds. Has been done. The recording / reproducing heads A1 and A2 have the same azimuth angle, and the recording / reproducing heads B1 and B2 have the same azimuth angle.

A magnetic tape (not shown) is wound around the rotary drum D on which the head is arranged as described above over an angle smaller than 180 °, for example 170 °, and rotates in the direction of arrow P. As a result, an oblique track is formed with respect to the magnetic tape running in a direction slightly inclined from the rotation direction.

FIG. 6 is a diagram showing a connection relationship from a recording / reproducing amplifier to a recording / reproducing head of the rotary head type digital signal recording / reproducing apparatus shown in FIG. Recording / playback head A
1, A2, B1 and B2 are connected to recording / reproducing amplifiers 6 to 9 via coils 1 to 4 of channels 1 to 4 of a rotary transformer, respectively. A pair of recording / reproducing heads A1 and B1 and A are provided between the coils 2 and 3.
A short ring 5 is provided to prevent interchannel crosstalk between the pair of B2 and B2.

FIG. 7 is an operation timing chart at the time of recording of the rotary head type digital signal recording / reproducing apparatus shown in FIG. 5, and FIG. 8 is a diagram showing the relationship between the track pattern and the rotary head. Hereinafter, the recording operation of the conventional rotary head type digital signal recording / reproducing apparatus will be described with reference to FIGS.

As shown in FIG. 7, the rotating drum D
Every half rotation of the pair of recording / reproducing heads A1 and B1 and A
For example, the pair of B2 and B2 are alternately turned on by 160 °.
As a result, as shown in FIG. 8, the pair of recording / reproducing heads A1 and B1 form tracks T _A1 and T _B1 at the first half rotation of the rotary drum D, and the recording / reproducing head A2 at the next half rotation. , B2 form tracks T _A2 , T _B2 . At this time, the track pitch Tp = Ds. Thereafter, in the same manner, T _A1 ,
T _B1 , T _A2 , T _B2 , ... _Are formed.

Here, the recording / reproducing heads A1, B1 and A
The digital signals supplied to the pairs B2 and B2 are input to the recording / reproducing amplifiers 6 to 9 after the signals of one system are doubled in the time axis and converted into the signals of two systems. The outputs of the recording / reproducing amplifiers 6 to 9 are the coils 1 to 4 of the rotary transformer, respectively.
It is supplied to the recording / reproducing heads A1, A2, B1 and B2 through the line 4.

At this time, the crosstalk between channels 1 and 3 and the crosstalk between channels 2 and 4 through the rotary transformer are reduced by the short ring 5. Also, the winding angle of the magnetic tape is 1
Since it is smaller than 80 °, the recording / reproducing heads A1 and A2 and B1 and B2 do not operate at the same time, respectively, so that the problem of crosstalk does not occur between channels 1 and 2 and between channels 3 and 4.

The operation at the time of reproduction is the same as that at the time of recording except that the flow of signals is opposite to that at the time of recording, and therefore the description thereof will be omitted.

[0010]

In the rotary head type digital signal recording / reproducing apparatus in which the recording / reproducing heads are arranged as shown in FIG. 5, the recording / reproducing heads A arranged close to each other are used.
Since the track pitch is determined by the step difference Ds between 1, B1 and A2, B2, recording / reproduction is performed by one device at the first track pitch (= S) and the second track pitch (= L) smaller than that. In order to carry out (hereinafter, the mode for recording / reproducing at the first track pitch is referred to as SP mode, and the mode for recording / reproducing at the second track pitch is referred to as LP mode), four for each track pitch value, a total of 8
Recording / playback heads are required. Therefore, the cost becomes high, and it becomes difficult to construct a multi-channel rotary transformer within a limited outer diameter.

Therefore, only the recording / reproducing head having a step equal to the track pitch of the SP mode is provided, and the recording is performed by the S
It is conceivable that only the P mode is enabled, and the recording and reproducing head reproduces the magnetic tape recorded in the SP mode and the magnetic tape recorded in the LP mode.

However, when reproducing a magnetic tape recorded in the LP mode with a pair of recording / reproducing heads having a step equal to the track pitch in the SP mode, the quality of the reproduction output of one of the pair of recording / reproducing heads is high. There was a problem of deterioration. For example, as shown in FIG. 9, when L = 2/3 × S, one recording / reproducing head A1
When the center of the recording track T _A1 travels over the center of the recording track T _A1 , the other recording / reproducing head B1 travels at a position deviated from the recording track T _B1 to be originally traced. For this reason, the reproduction output of the head B1 is reduced by the amount deviated from the recording track T _B1 , and the portion for reproducing the adjacent track is increased, so that the crosstalk is increased. Furthermore, if the track width of the recording / reproducing head B1 is large, the adjacent tracks may be reproduced next to each other.

As described above, the off-track of one recording / reproducing head causes a decrease in reproduction output and an increase in crosstalk from adjacent and adjacent tracks, which deteriorates the quality of the reproduced signal. The present invention has been made to solve such a problem, and by limiting the track width of the head and the tracking method, it is possible to reduce the reproduction output and increase the crosstalk from adjacent and adjacent tracks. It is an object of the present invention to provide a rotary head type magnetic recording / reproducing device which can be prevented.

[0014]

In order to solve the above problems, the present invention provides a pair of recording / reproducing heads having different azimuth angles, which are arranged close to each other on a rotary drum with a predetermined step. Of the tracks recorded at the first track pitch and the second track pitch smaller than the first track pitch. In a rotary head type magnetic recording / reproducing apparatus adapted to perform reproduction, a first track pitch S, a second track pitch L, and a track width W of a pair of recording / reproducing heads satisfy the condition of S ≦ W <4L−S When the track recorded on the second track pitch is reproduced while setting so as to satisfy the formula, the center of the overlapping portion of the pair of recording / reproducing heads is the boundary of the track. And configured to perform a tracking control so as to travel on.

[0015]

According to the present invention, a pair of recording / reproducing heads having a step equal to the track pitch of the SP mode is used for LP.
When reproducing the magnetic tape recorded in the mode, since the reproduction output of the pair of recording / reproducing heads and the crosstalk from the adjacent track are equal, the quality of the reproducing signal of one recording / reproducing head is deteriorated as in the conventional example. There is nothing to do.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a tracking method of a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention. Here, the recording / reproducing heads A1 and B1 are the same as those shown in FIG.
Like the one shown in FIG. 2, the tracks are arranged close to each other on the rotating drum so as to have a step equal to the track pitch (= S) of the SP mode.

When reproducing the magnetic tape recorded in the LP mode, the center between the upper edge of the recording / reproducing head A1 and the lower edge of the recording / reproducing B1 should be aligned with the track boundary line of the recording pattern. Tracking. That is, α (the interval between the boundary between the tracks T _A1 and T _B1 and the upper edge of the recording / reproducing head A1) = α ′ (the boundary between the tracks T _A1 and T _B1 and the lower edge of the recording / reproducing head B1) Tracking is performed so that the distance becomes).

When tracking is performed in this way, the width of the recording / reproducing head _A1 scanning the track T _A1 = the width of the recording / reproducing head B1 scanning the track T _B1 = L, and the recording / reproducing head A1 is adjacent to the track T A1. Width for scanning _B1 , T _B2 = α + β = W−L = width for scanning the recording / reproducing head B1 on the adjacent tracks T _A1 , T _A2 = α ′ + β ′. Therefore, according to the present invention, since the reproduction output of the pair of recording / reproducing heads and the crosstalk from the adjacent tracks are equal, the quality of the reproduction signal of one head does not deteriorate unlike the conventional example.

Next, the conditions that the track width W of the recording / reproducing heads A1 and B1 should satisfy will be described. In FIG.
Assuming that the interval between the upper edge of the recording / reproducing head A1 and the lower edge of B1 is a, the condition that both the upper and lower edges of both the recording and reproducing heads A1 and B1 do not reproduce adjacent tracks next to each other when reproducing in the LP mode a / 2 <L ... (1) S + a / 2 <2L ... (2) must be satisfied. Since W = S + a (3), the track width W that simultaneously satisfies the expressions (1) and (2) is W <4L-S (4).

On the other hand, W ≧ S (5) must be satisfied in order to prevent generation of a guard band during recording in the SP mode. Therefore, the recording / reproducing head A
The track widths of 1 and B1 are S ≦ W <4L−S (6) from the equations (4) and (5).

For example, the track pitch in SP mode is L
In the format in which the track pitch in the P mode is 1.5 times, the track width W of the head is set to S ≦ W <2.5L (= S + L) (7), and the tracking method described above is used. L
It is possible to reproduce the P-mode recording tape without causing crosstalk from the adjacent tracks next to each other and with the reproduction outputs of the recording / reproducing A1 and B1 being equal. Recording / playback head A
The same is true for A2 and B2 arranged 180 ° apart on the rotating drum with respect to the pair of 1 and B1.

Next, a control method for performing tracking as described above will be described. The amount of overlap α, β, α ′ of the recording / reproducing heads A1 and B1 on the adjacent tracks,
β ′ has a relationship of α + β + L = W (8) α ′ + β ′ + L = W (9). From this, α + β = α ′ + β ′ (10)

Here, assuming that the head recording / reproducing A1 and B1 are configured to obtain the tracking error output by the ratio of the crosstalk voltage proportional to the crosstalk from the adjacent tracks, the recording / reproducing heads A1 and B1 are Tracking error outputs E _A and E _B that try to move them upward in FIG. 6 are respectively E _A ∝ β / α (11) E _B ∝-β '/ α' (12) Becomes

Letting the sum of the tracking control voltages of the recording / reproducing heads A1 and B1 be the tracking error output E, E = E _A + E _B ∝β / α−β ′ / α ′ (13) When E = 0, β / α = β ′ / α ′ = k (k is a constant) (14) β = k × α (15) β ′ = k × α ′ ... (16) By substituting the equations (15) and (16) into the equation (8), α = α ′, and when the tracking error output E = 0, the center of the overlapping portion of the recording / reproducing heads A1 and B1 is on the boundary line of the recording track. You can see that you are driving.

FIG. 2 is an explanatory diagram of a tracking control method of the rotary head type magnetic recording / reproducing apparatus according to the embodiment of the present invention. The operation of this embodiment is performed by the recording / reproducing heads A1 and B1.
Is common to the pair A and B2, so in the following explanation, A
The pair of 1, B1 and the pair of A2, B2 are described as recording / reproducing heads A, B without particularly distinguishing them.

In FIG. 2, tracks T1 (A), T3
(A), T5 (A) and T7 (A) are recording / reproducing heads A
Are recorded in the LP mode by a head having the same azimuth angle as the tracks T2 (B), T4.
(B), T6 (B) and T8 (B) are recording / reproducing heads B
Is recorded in the LP mode by a head having the same azimuth angle.

A second identification signal (frequency f2 = 984 kHz) for crosstalk detection is provided at the head entrance portion of the tracks T2 (B) and T6 (B) over a length four times the offset amount Dx between the tracks. The first part for determining the timing of reproducing the second identification signal is recorded at the entrances of the tracks T1 (A), T3 (A) and T5 (A), T7 (A) at both ends of these tracks. Identification signal (frequency f1 = 656 kHz) is recorded over the length of 2Dx and 4Dx. In addition, track T4
No identification signal is recorded at the entrance portions of (B) and T8 (B).

On the other hand, at the exit portion of each track, the first and second identification signals are recorded in a state in which the signs of the entrance portion and tracks A and B are exchanged. In this figure, for example, the recording / reproducing head A discriminates the first identification signal from the signal reproduced from the entrance portion of the track T3 (A), and at the time point 2Dx after the trailing edge of this signal, the track T2 ( The level of the second identification signal recorded in B) is detected. Next, the first identification signal is discriminated from the signal reproduced from the entrance portion of the track T5 (A), and when the signal moves 2Dx from the trailing edge of the signal, the second disc recorded on the track T6 (B) is discriminated. The level of the identification signal of is detected. The level of the second identification signal recorded in the track T2 (B) corresponds to β in FIG. 1, and the level of the second identification signal recorded in the track T6 (B) is in FIG. Since it corresponds to α, the recording / reproducing head A can be calculated by calculating these ratios.
The tracking error output E _A can be obtained.
As described above, the recording / reproducing head A detects the crosstalk from the level of the second identification signal recorded at the entrance portion of the track, and obtains the tracking error output E _A.

Similarly, the recording / reproducing head B is used for the track T.
The first identification signal is discriminated from the signal reproduced from the exit portion of 4 (B), and the second identification signal recorded on the track T5 (A) is detected at the time point 2Dx after the trailing edge of this signal. Detect the level. Next, track T6 (B)
The first identification signal is discriminated from the signal reproduced from the exit portion of the signal, and the level of the second identification signal recorded in the track T5 (A) is detected at the time point 2Dx after the trailing edge of this signal. . Since the level of the second identification signal detected first corresponds to β ′ in FIG. 1, and the level of the second identification signal detected next corresponds to α ′ in FIG. The tracking error output E _B of the recording / reproducing head B is obtained by calculating the ratio of In this way, the recording / reproducing head B detects crosstalk from the level of the second identification signal recorded at the exit portion of the track, and obtains the tracking error output E _B.

Then, as described above, tracking control is performed so that E _A + E _B = 0. In this case, the second identification signal is provided for every four recording tracks, so that the two identification signals are not detected simultaneously. Therefore, the length is not limited to 4Dx and can be set to any length. Further, although the number of times crosstalk is detected is every four tracks, if one frame of a digital signal recorded on a magnetic tape, for example, a digital video signal is divided into about 10 tracks and recorded, it is recorded per one frame. The number of times of control does not decrease.

FIG. 3 is a block diagram showing the configuration of the tracking control unit in the embodiment of the present invention, and FIG. 4 is its operation timing chart. The operation of the tracking controller will be described below with reference to FIGS. In FIG. 3, the reproduction signal of the recording / reproducing head A is the reproduction amplifier 11
It is taken out to the output terminal 12A through A, and is supplied from there to a digital video signal processing circuit or the like (not shown).

Further, the output signal of the reproduction amplifier 11A is supplied to the bandpass filter 13A for extracting the signal of the frequency f2, and the output signal b of this bandpass filter 13A is supplied to the envelope detection circuit 14A. Further, the output signal of the envelope detection circuit 14A is passed through the low-pass filter 15A to the sample hold circuits 16A, 1A.
Supplied to 7A.

The output signal of the reproduction amplifier 11A has a frequency f1.
Is supplied to the bandpass filter 18A for extracting the signal of, and the output signal a of this bandpass filter 18A is supplied to the envelope detection circuit 19A. Further, the output signal of the envelope detection circuit 19A is supplied to the level comparison circuit 21A through the low pass filter 20A, and the period when the signal level is equal to or higher than a predetermined value is taken out.

The output signal of the level comparison circuit 21A is supplied to the timing generation circuit 22A. The timing generation circuit 22A is composed of a mono-multi, a gate circuit, etc.,
The sampling pulses c and d for the sample hold circuits 16A and 17A are output. Sample and hold circuit 1
The output signals of 6A and 17A are supplied to the differential circuit 23A,
Here, the difference in logarithmic value is taken out and supplied to the adder 25 through the amplifier 24A.

Therefore, when the recording / reproducing head A scans the track T3 (A) in the first half rotation of the rotary drum and scans the track T5 (A) in the next half rotation, the bandpass filter 18A outputs the data shown in FIG. A signal as shown in (a) is output. In addition, the bandpass filter 13
A signal as shown in FIG. 4B is output from A. Here, for simplification of illustration, all signal levels are the same.

The output a of the bandpass filter 18A is the envelope detection circuit 19A, the lowpass filter 20A,
Timing generation circuit 22 through level comparison circuit 21A
Pulse c supplied to A and sampling the output of the low pass filter 15A in the first half revolution of the rotating drum, as shown in FIG. 4 (c), and as shown in FIG. 4 (d). A pulse d for sampling the output of the low-pass filter 15A is generated by the next half rotation of the rotary drum, and is supplied to the sample hold circuits 16A and 17A, respectively.

Then, these sampling pulses c,
The difference between the outputs sampled and held by d is supplied to the adder 25 as a tracking error output E _A. A tracking error output E _B is similarly created for the reproduction signal of the recording / reproducing head B and is supplied to the adder 25. The output of the adder 25 is supplied to the capstan control system from the terminal 26, and the running of the magnetic tape is controlled so that the output of the adder 25 becomes zero.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made within the scope of the present invention, and these modifications are not excluded from the scope of the present invention. For example, the present invention has a wrap angle of 1 for a magnetic tape.
It can also be applied to a rotary head type magnetic recording / reproducing apparatus having an angle of 80 ° or more.

The tracking control method may be any control method as long as it is a method of detecting crosstalk from adjacent tracks, and for example, a 4-frequency pilot signal adopted in 8 mm video can be used. is there. Further, in FIG. 5, a pair of recording / reproducing heads A1, B1 and A2, B2 arranged close to each other are provided at 180 ° intervals, but a recording / reproducing apparatus provided with only one pair of recording / reproducing heads. The present invention can also be applied to a recording / reproducing device having four pairs of recording / reproducing heads at 90 ° intervals.

[0040]

As described above in detail, according to the present invention, a pair of heads having a step equal to the track pitch of the SP mode reduces the reproduction output and increases the crosstalk from the adjacent tracks. Also, the recorded tape in the LP mode can be reproduced without causing crosstalk from the adjacent tracks.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a tracking method of a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a tracking control method for a rotary head type magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a tracking control unit in the embodiment of the present invention.

FIG. 4 is an operation timing chart of the tracking control unit in the embodiment of the present invention.

FIG. 5 is a diagram showing an arrangement and a schematic structure of heads in a conventional rotary head type magnetic recording / reproducing apparatus.

FIG. 6 is a diagram showing a connection relationship from a recording / reproducing amplifier to a recording / reproducing head of a conventional rotary head type digital signal recording / reproducing apparatus.

FIG. 7 is an operation timing chart at the time of recording of the conventional rotary head type digital signal recording / reproducing apparatus.

FIG. 8 is a diagram showing a relationship between a track pattern and a rotary head of a conventional rotary head type digital signal recording / reproducing apparatus.

FIG. 9 is an explanatory diagram of a tracking method of a conventional rotary head type digital signal recording / reproducing apparatus.

[Explanation of symbols]

A1, B1 ... Recording / reproducing head, D ... Rotating drum, T _A1 ,
T _B1 , T _A2 , T _B2 ... Recording track

Claims (1)

[Claims] 1. A pair of recording / reproducing heads having different azimuth angles, which are arranged close to each other on a rotary drum and have a predetermined step, are simultaneously operated to record at a first track pitch equal to the step. In the rotary head type magnetic recording / reproducing apparatus, the track recorded at the first track pitch and the track recorded at the second track pitch smaller than the first track pitch are reproduced. The first track pitch S, the second track pitch L, and the track width W of the pair of recording / reproducing heads are set to satisfy the following conditional expression: S ≦ W <4L−S, and the second track pitch When reproducing a track recorded at a track pitch, tracking is performed so that the center of the overlapping portion of the pair of recording / reproducing heads runs on the boundary line of the track. Rotary head type magnetic recording reproducing apparatus, which comprises carrying out.