JPH0922516A - Digital recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce bit error rate in the reproduction with respect to a digital recording/reproducing device provided with a rotary head for reading out a signal on the recording track which is formed by inclining against the longitudinal direction of a magnetic tape. SOLUTION: The positions of reproducing heads 24a, 24b against recording heads 23a, 23b mounted on a rotary drum 22 are arranged with the level difference ΔH2 of the position offset by a specified space within the range of difference between the width of the reproducing heads 24a, 24b and a track pitch, taking the level difference for making the scanning center position coincides with the center position of the recording track as a reference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital recording / reproducing apparatus provided with a rotary head for forming a recording track by inclining it with respect to a longitudinal direction of a magnetic tape and reading a signal on the recording track.

[0002]

2. Description of the Related Art Conventionally, a DAT (Digital Audio Tape Recorder) is used as a rotary head for recording and reproducing a digital audio signal or a digital signal such as digital data on a track inclined with respect to the longitudinal direction of a magnetic tape. There is a digital recording / reproducing device such as an 8 mm VTR (video tape recorder). In such an apparatus, a magnetic tape is inclined and wound around a rotary head to record and reproduce a digital signal on an inclined track.

Therefore, FIG. 3 shows an explanatory view of the relationship between a conventional rotary head and a magnetic tape. 3A to 3C, in the rotary head 11, the heads W ₁ , R ₁ , W ₂ , and R ₂ are arranged and fixed at 90 ° intervals on the lower peripheral edge of the rotary drum 12, and are counterclockwise. Rotate in the direction. In this case, the write recording heads W ₁ , W ₂ are 180
Read heads R ₁ and R ₂ facing each other at a position of 1 degree
Face each other at a position of 180 degrees.

As shown in FIG. 3B, a fixed drum 13 is arranged below the rotary drum 12, and a stepped lead 13a for tape guide is formed on the fixed drum 13 in an inclined manner. . Then, the magnetic tape 14 is guided by the guide posts 15a and 15b and the inclined posts 16a and 16b and wound around the rotary head 11 over a predetermined angle (for example, 100 °), and the magnetic tape 14 is rotated by the capstan motor. The driven capstan 17 and the pinch roller 18 are driven to pinch and run, and the rotary drum 12 is rotated to record digital signals by the recording heads W ₁ and W ₂ , and are reproduced by the reproduction heads R ₁ and R _2. The digital signal is reproduced.

Here, the rotary drum 12 shown in FIG. 3 (B).
3 when the lower end surface of the head is at the head reference height position.
As shown in (C), the recording heads W ₁ and W ₂ are positioned at the head reference height position, and the reproducing heads R ₁ and R ₂ are below the head reference height position by a height ΔH ₁ (fixed drum 1
3 side). In this case, ΔH ₁ is T _W (n + 1/2) + α (n is the number of delayed tracks, and α is the track width of the reproducing head or 90 when the track pitch is T _W.
It is a correction value when it is shifted.)
μm, the reproducing heads R ₁ and R ₂ and the recording heads W ₁ and W
₂ The scanning center locus is aligned with the (recording track 14a).

FIG. 4 is an explanatory view of the positional relationship of the reproducing head on the track of the conventional magnetic tape.
As shown in FIG. 4A, the recording tape 14a (14a) is tilted on the magnetic tape 14 by the recording heads W ₁ and W _{2.
1 to} 14a ₃ ) are formed, and the reproducing heads R ₁ and R
_When reading is performed by ₂ , the center positions of the reproducing heads R ₁ and R ₂ and the recording track 14a ₂ are substantially aligned as shown in FIG. 4 (B). That is, the reproducing heads R ₁ , R
_In order to make the tracking offset amount zero by making the center positions of ₂ and the recording track 14a substantially coincide with each other, the reproducing head R
Height position ΔH of ₁ and R ₂ with respect to recording heads W ₁ and W _2
1 is set.

For example, the width of the recording heads W ₁ and W ₂ is about 2
0 μm, the width of the reproducing heads R ₁ and R ₂ is about 13 μm,
If the track pitch of the recording tracks 14a formed on the magnetic tape 14 by the recording heads W ₁ and W ₂ is about 9 μm, the width of the crosstalk amount is about a ₁ = a ₂ = 2 μm on both adjacent recording tracks. . And RAW
When the written data is read out after writing (Read After Write),
Assuming that the reproducing heads R ₁ and R ₂ read out 6 tracks before, the recording heads W ₁ and W ₂ and the reproducing heads R ₁ and R ₂
The step ΔH _{1 of} R ₂ is set to about 60 μm.

[0008]

FIG. 5 shows a BER characteristic graph during reproduction when a conventional rotary head is used. In FIG. 5, the reproducing heads R ₁ and R ₂ are generally used.
The BER (bit error rate) of the reproduction signal is minimum when the tracking offset amount for the track No. is zero, and gradually increases when the offset amount exceeds a predetermined amount in the upper and lower directions of the magnetic tape 14. And its BER characteristic should ideally be as shown by the solid line in FIG.

[0009] However, and when the reproduction head R _1, R ₂ are attached shifted particularly to the tape lower within a tolerance to the rotary drum 12, the by variations in the characteristics of the reproducing head R _1, R ₂ Even if the offset amount is theoretically zero, there is a problem that the BER characteristic shown by the broken line in FIG.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a digital recording / reproducing apparatus having a rotary head for reducing the bit error rate in reproduction.

[0011]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, a predetermined number of recordings for forming recording tracks by recording digital data by inclining in a longitudinal direction with respect to a magnetic tape to be wound. In a digital recording / reproducing apparatus having a rotary head in which a head and a predetermined number of reproducing heads for reading digital data on the recording track are provided on a rotating drum at a predetermined step in the height direction, the step is used as a reference, A digital recording / reproducing apparatus is provided in which the reproducing head is provided on the rotary head by offsetting the center scanning position with respect to the recording track by a predetermined amount within the range of the difference between the track pitches of the recording tracks in the width of the reproducing head. .

That is, the position at which the reproducing head is provided with respect to the recording head is provided by offsetting the center scanning position by a predetermined amount within the range of the difference between the reproducing head width and the track pitch with reference to the initial step. As a result, the reproducing head is offset in the direction in which the bit error rate is minimized, the actual deterioration of the bit error rate when the offset amount is zero is avoided, and the bit error rate can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration diagram of an embodiment of the present invention. FIG. 1A is a plan view of a head arrangement of a rotary drum, FIG. 1B is a side view of the whole, and FIG. 1C is an explanatory view of a head step.

As shown in FIGS. 1A and 1C, the rotary head 21 is used in a digital recording / reproducing apparatus such as a DAT, and two recording heads 23a are provided on the outer periphery of the lower end surface of the rotary drum 22. (W ₁ ) and 23b (W ₂ ) are arranged opposite to each other at a position of 180 degrees in the rotation direction of the rotary drum 22. On the other hand, the two reproducing heads 24a (R ₁ ) and 24b
(R ₂ ) are arranged opposite to each other at a position of 180 ° in the rotation direction of the rotary drum 22. In this case, the reproducing head 24a
The gap between (R ₁ ) and the recording head 23a (W ₁ ) is arranged so as to be displaced by about 90 degrees in the rotation direction of the rotary drum 22. Playback head 24b (R ₂ ) and recording head 23b
The positional relationship of (W ₁ ) is also about 90 degrees. The step ΔH ₂ between the mounting positions of the recording heads 23a and 23b and the reproducing heads 24a and 24b will be described later.

Here, the recording heads 23a and 23b have ferrite cores 25a and 25a, as shown in FIG. 1C, for example.
Metals 26a and 26b such as sendust are formed on the opposing surfaces forming a gap 25b, and glass 27 is filled in the gap and its vicinity. The reproducing heads 24a and 24b are, for example, ferrite cores 28a and 28b.
The predetermined end faces of b are opposed to each other to form a gap, and the glass and the vicinity thereof are filled with glass 27.

Further, as shown in FIG. 1B, the rotary drum 22 is rotatably provided on a fixed drum 29, and a tape guide lead 29a is provided on the fixed drum 29.
Are formed in an inclined shape. The magnetic tape which is a recording medium guided by the leads 29a has, for example, approximately 100
It is wound in a spiral shape many times. That is, as shown in FIG. 2, which will be described later, the inclination of the lead 29a is the magnetic tape 30.
It is the inclination (θ) of each track above.

Further, the rotary drum 22 shown in FIG.
When the lower end surface is at the head reference height position in the rotation axis direction
As shown in FIG. 1C, the recording head 23a
(W₁), 23b (W_Two) Is at the head reference height position
The playback head 24a (R ₁), 24b (R
_Two) Is a step (mounting height) ΔH from the head standard height position
_TwoOnly the lower side (fixed drum 29 side) is positioned.

For example, the recording heads 23a,
The width of 23b is about 20 μm, the width of the reproducing heads 24a and 24b is about 13 μm, and the track pitch is about 9 μm.
In the case of reading 6 tracks before, the reference step between the recording heads 23a and 23b and the reproducing heads 24a and 24b is about 60 μm, and the step ΔH ₂ is 6
It is set at a position offset by a predetermined amount from 0 μm (described later).

Then, as in the case of FIG. 3 described above, the magnetic tape is loaded by a guide post or the like, and is fixed on the fixed drum 29.
The lead 29a is wound as a guide and is driven to travel by a capstan. Therefore, FIG. 2 shows an explanatory view of the positional relationship of the reproducing head of FIG. 1 with respect to the recording track. 2 corresponds to FIG. 4, and in FIG. 2A, a recording track 26a on which a digital signal is recorded is formed on the magnetic tape 26 by recording heads 23a and 23b inclining in the longitudinal direction. The scanning center lines of the reproducing heads 24a and 24b are positioned offset by a predetermined amount in the tape upper direction from the center line of 26a, and reading is performed in this state.

That is, as shown in FIG. 2B, recording
Truck 26a_TwoThe upper reproducing heads 24a and 24b are
The scanning center line is located above the tape (recording track 26a_ThreeSide)
The recording track 26 is positioned offset from the recording track 26.
a_ThreeOff-track amount b_Two(Recording track 26a₁~ side
Off-track amount of b₁And when b_Two> B₁)
You. Specifically, the recording track 26a_TwoPlay play
The track width of the head 24a (width of the reproducing head 24a)
T_W, Track pitch is T_PAnd when (T _W−
T_P) / 4, for example, 1 μm under the above conditions
Bit offset by offsetting to the upper side of the tape
That can set the error rate to a minimum
You.

That is, when the bit error rate characteristic shown by the broken line in FIG. 5 described above tends to deteriorate on the lower side of the tape, the reproducing head 24a reaches the minimum value of the bit error rate on the upper side of the tape. , 2
4b for offsetting the reproduction head 24
The a and 24b are attached to the rotary drum 22 by mounting the step difference ΔH in FIG. 3 on the reference recording heads 23a and 23b.
_The step difference ΔH ₂ is about 1 μm shorter than ₁ above.

The rotary heads of the reproducing heads 24a and 24b are rotated.
Mounting on the ram 22 has a step ΔH₁(Fig. 3)
And the playback head 24
The variation in the characteristics of a and 24b affects the bit of FIG.
The error rate characteristics tend to be worse on the upper side of the tape (that is,
5), the broken line in FIG.
Offset the raw heads 24a and 24b to the lower side of the tape
Therefore, the reference step ΔH ₁(Fig. 3) To make it longer
Step ΔH_Two(B₁> B_Two) Should be set.

As described above, a good bit error rate can be obtained when the digitally recorded recording track 26a is reproduced in the RAW mode.

[0024]

As described above, according to the invention of claim 1,
The position where the reproducing head is provided with respect to the recording head is set such that the center scanning position is offset by a predetermined amount within the range of the difference between the reproducing head width and the track pitch based on the initial step, so that the reproducing head can reduce the bit error rate. It is possible to reduce the bit error rate by avoiding the actual deterioration of the bit error rate when the offset amount is zero, because the offset is offset in the minimum direction.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a positional relationship between the reproducing head of FIG. 1 and a recording track.

FIG. 3 is a configuration diagram of a conventional rotary head.

FIG. 4 is an explanatory diagram of a positional relationship between the reproducing head of FIG. 3 and a recording track.

FIG. 5: B during reproduction using a conventional rotary head
It is a graph of ER characteristics.

[Explanation of symbols]

21 rotary head 22 rotating drum 23a, 23b recording head 24a, 24b reproduction head 25 fixed drum 25a leads 26 a magnetic tape 26a (26a ₁ ~26a ₃₎ recording tracks

Claims (1)

[Claims] 1. A predetermined number of recording heads for recording digital data by forming a recording track by inclining in a longitudinal direction with respect to a wound magnetic tape, and a predetermined number of reproducing heads for reading digital data on the recording tracks. And
In a digital recording / reproducing apparatus provided with a rotary head provided on a rotary drum at a predetermined step in the height direction, the reproduction is performed within a range of a difference between track pitches of the recording tracks in the width of the reproducing head with reference to the step. A digital recording / reproducing apparatus, wherein a head is provided on the rotary head with a center scanning position offset from the recording track by a predetermined amount.