JP2002183916A - Magnetoresistive magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain satisfactory reproducing characteristics and to narrow a gap by reducing the electrical short-circuit between a magnetic shield layer and a magnetoresistive element and between a pair of electrode layers. SOLUTION: In the MR head 20 provided with the MR element 28, a pair of electrode layers 32 disposed at both end parts of it, and the lower shield layer 24 and upper shield layer 25 holding the MR element 28 and a pair of electrode layers 32 between them through gap layers 26, 27, a pair of electrode layers 32 has the shape to be narrowed toward the medium sliding surface 20a, and the sum of widths at the side exposed from the medium sliding surface 20a of a pair of electrode layers 32 is regulated to be equal to or larger than unmagnified width and not exceeding 5 times with respect to the width at the side exposed from the medium sliding surface 20a of the MR element 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-resistance effect type magnetic head which reproduces a signal recorded on a magnetic recording medium while sliding on the magnetic tape by a helical scan method.

[0002]

2. Description of the Related Art In recent years, the density of magnetic recording has been further increased, and in consideration of, for example, narrower tracks, lower inductance, and higher transfer speed, the range of use of thin-film magnetic heads, which are more advantageous than bulk heads, has expanded. I have.

The thin-film magnetic head is manufactured by using a film forming technique such as vapor deposition and sputtering, similar to a semiconductor integrated circuit, and a photolithography technique such as photolithography and etching. It has the advantage that heads of high precision can be produced on a wafer at once.
Thin-film magnetic heads have become the mainstream of magnetic heads used in high-density recording / reproducing systems such as current hard disk drives and magnetic tape devices.

[0004] In a hard disk drive, it is common to mount a magnetoresistive head (hereinafter, referred to as an MR head) as a reproducing head. In the future, a magnetic tape device and a floppy (registered) device will be used. It is considered that the system will spread to recording / reproducing systems such as (trademark) disks.

The MR head can obtain a higher output than a magnetic induction type magnetic head in which a coil is wound around a general magnetic core (hereinafter referred to as an inductive head). Since it is not affected by inductance, it can transfer signals at high frequencies, and is an essential device in a high-density recording / reproducing system.

Here, the hard disk drive is shown in FIG.
As shown in FIG. 1, a flying slider 101 is provided at the tip end of a suspension 100 for flying at a small interval on a signal recording surface of a magnetic disk. A composite magnetic head 102 in which a head and an inductive head which is a recording-only head are combined is mounted.

As shown in FIG. 12, the composite magnetic head 102 has a structure in which a lower shield layer 105 and an upper shield layer 106 are provided on a nonmagnetic layer 104 formed on one main surface of a substrate 103. An MR head having a magnetoresistive effect element (hereinafter, referred to as an MR element) 109 sandwiched between a lower gap layer 107 and an upper gap layer 108, and a lower core layer 106 and an upper core Layer 11
0 and an inductive head, which is disposed to face each other with a magnetic gap layer 111 interposed therebetween, and has a structure in which a protective layer 112 is formed thereon.

Note that the upper shield layer 106 and the lower core layer 106 are the same member, and in the MR head,
A pair of magnetic shields is formed together with the lower shield layer 105, and in the inductive head, a pair of magnetic cores is formed together with the upper core layer 110.

At both ends of the MR element 109, a pair of permanent magnet films 113 for applying a bias magnetic field to the MR element 109, and a sense current is applied to the MR element 109 on the pair of permanent magnet films 113. A pair of conductive films 114 to be supplied is provided as a pair of electrode layers 115, and the width between the pair of electrode layers 115 is a reproduction track width.

On the other hand, the inductive head is provided with a thin film coil (not shown) for generating a magnetic field between the lower core layer 106 and the upper core layer 110, and the upper core layer 110 is connected to the lower core layer 106. A magnetic gap is formed by being arranged to face the upper core layer 11.
The width of 0 is the recording track width.

In this hard disk drive, as shown in FIG. 13, the flying slider 101 moves over the signal recording surface 116a of the magnetic disk 116 with a small gap F.
While flying at H (flying height), the composite magnetic head 102 mounted on the flying slider 101 records and reproduces signals.

On the other hand, as shown in FIG. 14, a magnetic tape device for recording and reproducing signals from a magnetic tape 200 by a helical scan method includes a rotating drum 201 which rotates in the direction of arrow P in the figure. Drum 201
MR head 202 which is a read-only head
And an inductive head 203 which is a recording-only head
And are installed.

As shown in FIGS. 15 and 16, the MR head 202 has a lower shield layer 206 on a non-magnetic layer 205 formed on one main surface side of a first substrate 204.
Between the lower gap layer 20 and the upper shield layer 207.
8 and the upper gap layer 209, the MR element 210 is sandwiched therebetween.
Substrate 212 is bonded.

At both ends of the MR element 210, a pair of permanent magnet films 213 for applying a bias magnetic field to the MR element 210, and a sense current is supplied to the MR element 210 on the pair of permanent magnet films 213. A pair of conductive films 214 for supply are provided as a pair of electrode layers 215, and the width between the pair of electrode layers 215 is a reproduction track width.

Further, a pair of lead conductors 216 are connected to the pair of electrode layers 215, and external connection terminals 217 connected to an external circuit are provided at the ends of the pair of lead conductors. ing.

As shown in FIG. 17, the MR head 202 has a substantially rectangular medium sliding surface 202a that slides on the magnetic tape 200, and the medium sliding surface 202a has a substantially rectangular shape. Magnetic tape 20 indicated by arrow Q in the figure
In addition to being ground into a cylindrical shape along the sliding direction of 0, the ground is also ground into a cylindrical shape along a direction orthogonal to the sliding direction of the magnetic tape 200 shown by the arrow R in the figure.

In this magnetic tape device, the MR head 202 is arranged on the outer peripheral surface of the rotating drum 201 so as to be oblique to the direction substantially perpendicular to the sliding direction of the magnetic tape 200 in accordance with the azimuth angle. Then, the signal is reproduced while the MR head 202 slides on the magnetic tape 200.

[0018]

In the hard disk drive described above, while the flying slider 101 flies above the magnetic disk 116 at a small interval FH, the composite magnetic head 1 mounted on the flying slider 101
02 performs recording and reproduction of signals on and from the magnetic disk 116, so that the composite magnetic head 102 and the magnetic disk 1
16 does not come into contact.

On the other hand, in the above-described magnetic tape device, the signals recorded on the magnetic tape 200 are reproduced while the MR head 202 mounted on the rotating drum 201 slides on the magnetic tape 200.

Further, in the magnetic tape device, since the rotating drum 201 shown in FIG. 14 is rotationally driven at several thousand revolutions per minute in the direction of arrow P in the figure, the relative speed between the MR head 202 and the magnetic tape 200 is , About 10m / sec,
At very high speed, the MR head 202 and the magnetic tape 20
0 slides.

For this reason, as shown in FIG. 18, when the MR head 202 slides at a high speed with the magnetic tape 200, a scratch 218 is formed on the medium sliding surface 202a due to, for example, a scratch or dust on the magnetic tape 200. Sometimes occurred. The scratch 218 is a mechanical deformation that causes the lower shield layer 206 and the upper shield layer 207 to be stretched. Cause a short circuit.

In this case, in the MR head 202, for example, deterioration of the reproduction output, asymmetry change of the reproduction output (vertical symmetry of the reproduction waveform), Barkhausen noise, and the like occur, resulting in a fatal defect.

The medium sliding surface 20 of the MR head 202
The frequency of occurrence of an electrical short circuit due to the scratch 218 generated in 2a is closely related to the thicknesses of the lower gap layer 208 and the upper gap layer 209, and the shorter the thickness, the more likely it is to occur. However, the lower gap layer 208
In addition, the thickness of the upper gap layer 209 needs to be reduced in order to improve the reproduction resolution. For this reason, MR
An electrical short circuit on the medium sliding surface 202a of the head 202 is expected to become a major problem in achieving higher recording density in the future.

In the above-described MR head 202, when the medium sliding surface 202a is cylindrically ground, mechanical deformation occurs such that the lower shield layer 206 and the upper shield layer 207 are stretched without being ground. That is, the lower shield layer 206, the upper shield layer 207, and the MR element 2
There is a problem that an electrical short circuit occurs between the electrode 10 and the electrode layer 215.

In this case, in the MR head 202, the resistance of the MR element 210 varies. Since the height of the MR element 210 in the depth direction is determined by measuring the resistance value of the MR element 210, if the resistance value of the MR head element 210 varies, the MR element 210 Will vary greatly in the height in the depth direction.

The height of the MR element 210 in the depth direction has a great influence on the reproduction output of the MR head 202 and the asymmetry of the reproduction waveform.

FIG. 19 shows the results of measuring the asymmetry of the reproduced waveform when the height of the MR element 210 in the depth direction is changed. FIG. 19 shows the MR element 21
FIG. 8 is a characteristic diagram showing a relationship between a height of 0 in a depth direction and asymmetry of a reproduced waveform.

From the measurement results shown in FIG.
It can be seen that when the height in the depth direction of 0 changes, the asymmetry of the reproduced waveform also changes greatly. For this reason, the height of the MR element 210 in the depth direction is ± 0.
It is necessary to process to an accuracy of about 1 μm.
Variation in the resistance value of 0 is a serious problem.

In the MR head 202, as a countermeasure against an electric short-circuit caused by the cylindrical grinding of the medium sliding surface 202a, the short-circuit is performed by increasing the thicknesses of the lower gap layer 208 and the upper gap layer 209. Can be reduced.

However, as described above, there is a close relationship between the thickness of the lower gap 208 and the upper gap 209 and the reproduction resolution characteristics. It is very disadvantageous in narrowing the gap between the upper shield layer 207 and the upper shield layer 207.

Therefore, the present invention has been proposed in view of such conventional circumstances. The present invention is mounted on a rotating drum, and a signal recorded on a magnetic tape while sliding on the magnetic tape by a helical scan method. In a magneto-resistance effect type magnetic head for reproducing information, good reproduction characteristics can be obtained by preventing an electrical short circuit between a pair of magnetic shield layers and a pair of electrode layers disposed at both ends of the magneto-resistance effect element. It is another object of the present invention to provide a magnetoresistive magnetic head capable of obtaining a narrow gap.

[0032]

A magnetoresistive head according to the present invention, which achieves this object, is mounted on a rotating drum and recorded on a magnetic tape while sliding on the magnetic tape by a helical scan method. A magneto-resistance effect type magnetic head for reproducing signals; a magneto-resistance effect element for detecting a signal from a magnetic tape; a pair of electrode layers disposed at both ends of the magneto-resistance effect element; A pair of magnetic shield layers sandwiching the pair of electrode layers via a gap layer. And a pair of electrode layers,
It has a shape constricted toward the medium sliding surface that slides on the magnetic tape, and the sum of the widths of the pair of electrode layers on the side exposed from the medium sliding surface is equal to the medium sliding surface of the magnetoresistive element. It is characterized in that it is not less than 1 and not more than 5 times the width of the side exposed from.

As described above, in the magneto-resistance effect type magnetic head according to the present invention, since the pair of electrode layers has a shape narrowed toward the medium sliding surface that slides on the magnetic tape, the pair of electrode layers is narrowed. The width of the electrode layer on the side exposed from the medium sliding surface can be made smaller than before. This allows
During the sliding with the magnetic tape or the cylindrical grinding of the medium sliding surface, an electrical short circuit between the pair of magnetic shield layers generated on the sliding surface of the medium, the magnetoresistive element and the pair of electrode layers is prevented. Can be reduced.

In this magnetoresistive head, the sum of the widths of the pair of electrode layers exposed from the medium sliding surface is equal to the total width of the pair of electrode layers exposed from the medium sliding surface of the magnetoresistive element. By making the width 1 to 5 times the width, the occurrence of Barkhausen noise is suppressed while reducing the electrical short circuit between the pair of magnetic shield layers and the magnetoresistive element and the pair of electrode layers. be able to. Therefore, with this magnetoresistive head, good reproduction characteristics can be obtained even when the gap is narrowed.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

In the drawings used in the following description, in order to make the characteristics easy to understand, the characteristic portions may be shown in an enlarged manner, and the dimensional ratio of each component may not be the same as the actual one. Not exclusively.

As an embodiment of the present invention, a magnetic tape device 1 shown in FIG. 1 includes a magnetic head device 3 for recording and reproducing signals on and from a magnetic tape 2 by a so-called helical scan method. While running with the take-up reel 5 in the direction of arrow A in FIG.
The rotary drum 6 of the magnetic head device 3 is driven to rotate in the direction of arrow B in FIG. 1, and a pair of read-only magnetoresistive magnetic heads (hereinafter, referred to as MR heads) 7 mounted on the rotary drum 6. And a magnetic induction type thin-film magnetic head (hereinafter, referred to as an inductive head) 8 dedicated to recording performs reproduction and recording of signals while sliding on the magnetic tape 2.

Further, the magnetic tape device 1 is provided between the supply reel 4 and the take-up reel 5 with rolls 9a to 9g for drawing the magnetic tape 2, and among these, a roll 9c and a roll 9d are provided. Magnetic head device 3 between
Is arranged, and the magnetic tape 2 is slid with the rotating drum 6,
The magnetic tape 2 hung on the roll f is fed out by a capstan motor 10a that rotates the capstan 10 while being sandwiched by the capstan 10.

The magnetic head device 3, as shown in FIG.
The rotating drum 6 includes a driving motor 11 for driving the rotating drum 6 to rotate in the direction of arrow B in FIG. Also, this rotating drum 6
The above-described MR head 7 and the inductive head 8 are attached to the outer peripheral surface 6a of the. And MR
The head 7 and the inductive head 8 are 180
They are arranged facing each other with a similar phase difference of °. The MR head 7 and the inductive head 8 are arranged such that the magnetic gap is oblique to the direction substantially perpendicular to the running direction of the magnetic tape 2 according to the azimuth angle.

The magnetic head device 3 includes a rotating drum 6
The magnetic tape 2 travels obliquely in the direction of arrow A in FIG. 2 along the lead guide portion 12b of the fixed drum 12. The outer peripheral surface 12a of the fixed drum 12 and the outer peripheral surface 6a of
It is designed to slide over a degree.

In the magnetic tape device 1 configured as described above,
At the time of recording, an inductive head 8 slides on the magnetic tape 2 to record a signal on the magnetic tape 2, while at the time of reproduction, the MR head 7 slides on the magnetic tape 2 while recording the signal on the magnetic tape 2. Will be reproduced.

Incidentally, in the magnetic head device 3, the MR head 7 is an MR head to which the present invention shown in FIG.
Each component of the MR head 20 is laminated on a first substrate 21 by, for example, a thin film forming technique such as a plating method or a sputtering method, and a second substrate 2
2 are bonded together. Note that this MR
In the head 20, the second substrate 22 is the first substrate 2
1 and a pair of lead conductors 33 and external connection terminals 3 (described later) formed on the first substrate 21.
4 is exposed.

The MR head 20 has a medium sliding surface 20a which slides on the magnetic tape 2 in a substantially rectangular planar shape, and the medium sliding surface 20a has a magnetic tape indicated by an arrow C in FIG. 2 and along the direction perpendicular to the sliding direction of the magnetic tape 2 indicated by arrow D in the figure.

More specifically, as shown in FIGS. 4 and 5, the MR head 20 includes a lower shield layer 24 and an upper shield layer on a non-magnetic layer 23 formed on the main surface of the first substrate 21. This is a so-called shield type MR head in which an MR element 28 is sandwiched between a layer 25 and a lower gap layer 26 and an upper gap layer 27. The second substrate 22 described above is bonded on the upper shield layer 25 with a protective layer 29 interposed therebetween.

The first substrate 21 and the second substrate 22 are made of, for example, Al ₂ O ₃ —TiC (altic), α-Fe ₂ O
₃ (α-hematite), Ni-Zn ferrite or other ceramic substrate.

The nonmagnetic layer 23 and the protective layer 29 are formed by depositing, for example, an alumina film (Al ₂ O ₃ ) having a thickness of several μm. Preferably, the surface of the alumina film is flattened by mechanical wrap during film formation.

Lower Shield Layer 24 and Upper Shield Layer 2
5 has a width sufficient to magnetically shield the MR element 28, and the lower shield layer 24 and the upper shield layer 25 form the MR element 28 through the lower gap layer 26 and the upper gap layer 27. By sandwiching, it functions so that the magnetic field outside the reproduction target among the signal magnetic fields from the magnetic tape 2 is not drawn into the MR element 28. That is, MR
In the head 20, a signal magnetic field that is not to be reproduced with respect to the MR element 28 is guided to the lower shield layer 24 and the upper shield layer 25, and only the signal magnetic field that is to be reproduced is applied to the MR element 2.
8 will be led. Therefore, MR head 2
At 0, the frequency characteristics and reading resolution of the MR element 28 are improved.

Lower Shield Layer 24 and Upper Shield Layer 2
5 is formed by forming a soft magnetic thin film such as FeAlSi (sendust) by sputtering or the like. The lower shield layer 24 and the upper shield layer 25
The material is not particularly limited as long as the material exhibits good soft magnetism and is excellent in wear and corrosion.

Lower gap layer 26 and upper gap layer 2
Numeral 7 magnetically isolates the lower shield layer 24, the upper shield layer 25, and the MR element 28 from each other, and the gap between the lower shield layer 24, the upper shield layer 25, and the MR element 28 is a so-called gap. It is long.

Lower gap layer 26 and upper gap layer 2
7 is formed by forming a film by sputtering or the like, for example, _Al 2 _{O 3} or the like of the alumina _(Al 2 _{O 3)} film or the like. The lower gap layer 26 and the upper gap layer 27
The material is not particularly limited as long as it is a material having excellent insulating properties and wear resistance.

The MR element 28 utilizes a so-called magnetoresistive effect in which the electric resistance changes according to a change in an external magnetic field. By detecting the change, the signal recorded on the magnetic tape 2 is reproduced.

More specifically, for example, the SAL
(Soft Adjacent Layer) This is a so-called SAL bias type MR element in which a bias layer, an intermediate layer, an MR layer, and the like are sequentially laminated by sputtering or the like.

The MR element 28 has the above-mentioned S element.
The invention is not limited to the AL bias type MR element 28. For example, a giant magnetoresistive effect (GMR: Gaiant Mgnetro-Resistivi) of a spin valve film or the like that can obtain a larger output.
ty) may be used.

The M element is provided at both ends of the MR element 28.
A pair of permanent magnet films 30 for applying a bias magnetic field to the R element 28, and a pair of conductive films 31 for supplying a sense current to the MR element 28 on the pair of permanent magnet films 30
Are provided as a pair of electrode layers 32. Note that the width between the pair of electrode layers 32 is the reproduction track width.

The pair of permanent magnet films 30 are made of, for example, CoNi.
It is formed by forming a ferromagnetic film such as Pt or CoCrPt by sputtering or the like.

The pair of conductive films 31 is formed by depositing, for example, Cr, Ta or the like by sputtering or the like.

Further, a pair of lead conductors 33 are electrically connected to the pair of electrode layers 32, and an end of the pair of lead conductors 33 has an external connection terminal connected to an external circuit. 34 are provided respectively.

The pair of lead conductors 33 is formed by, for example, forming a film of Ti, Cu, or the like by sputtering or the like.
An m-thick Cu film or the like is formed by, for example, plating or the like.

The pair of electrode layers 32 has a shape obliquely narrowed toward the medium sliding surface 20 a of the MR head 20. That is, the pair of electrode layers 32
Is smaller on the side exposed from the medium sliding surface 20a than on the side connected to the pair of lead conductors 33.

The sum of the widths of the pair of electrode layers 32 on the side exposed from the medium sliding surface 20a is
It is preferable that the width be 1 to 5 times the width of the MR element 28 exposed on the side. This will be described later in detail.

The MR head 20 configured as described above
Are arranged on the outer peripheral surface 6a of the rotary drum 6 such that the magnetic gap is oblique to the direction substantially perpendicular to the running direction of the magnetic tape 2 according to the azimuth angle. And this M
The R head 20 reproduces a signal recorded on the magnetic tape 2 while sliding obliquely with respect to the magnetic tape 2.

Specifically, when a signal is reproduced from the magnetic tape 2 using the MR head 20, a predetermined voltage is applied to the MR element 28. At this time, MR
The conductance of the sense current flowing through the element 28 changes the signal recorded on the recording track of the magnetic tape 2 according to the magnetic field. Therefore, in the MR head 20, the voltage value of the sense current flowing through the MR element changes, and the signal recorded on the recording track is reproduced by detecting the change in the voltage value of the MR element. It will be.

By the way, the MR head 2 to which the present invention is applied
0, the pair of electrode layers 32 disposed at both ends of the MR element 28 have a shape obliquely narrowed toward the medium sliding surface 20a that slides on the magnetic tape 2 as described above. I have. That is, specifically, in this MR head 20,
The width of the side exposed from the medium sliding surface 20a is smaller than the width of the side of the pair of electrode layers 32 connected to the pair of lead conductors 33. The pair of electrode layers 32 are formed on the medium sliding surface 20 from the pair of lead conductors 33.
The angle formed between the medium sliding surface 20a and the straight line toward the side a is θ
In this case, the angle θ is, for example, 45 ° and the shape is obliquely narrowed.

In this case, in the MR head 20, the width of the pair of electrode layers 32 exposed from the medium sliding surface 20a can be smaller than in the related art.

For example, if the width of the MR element exposed from the medium sliding surface in the conventional MR head is 7 μm and the sum of the widths of the pair of electrode layers is 80 μm, the MR element and the pair of electrodes exposed from these medium sliding surfaces are assumed to be 80 μm. 87 μm total with electrode layer
Becomes On the other hand, as shown in the present embodiment, the sum of the widths of the pair of electrode layers 32 exposed from the medium sliding surface 20a is MR
If the width of the element 28 is one time, the medium sliding surface 20a
The total width of the MR element 28 and the pair of electrode layers 32 exposed to the outside is 14 μm.

Therefore, in the MR head 20 according to the present embodiment, as compared with the conventional MR head, the total width of the MR element 28 and the pair of electrode layers 32 can be reduced to about 1/6, and the medium slides. Lower shield layer 2 generated on surface 20a
4 and upper shield layer 25, MR element 28 and electrode layer 3
2 can reduce the probability of an electrical short circuit to 1/6.

Thus, in the MR head 20, even when the magnetic tape 2 is slid at a high speed, the lower shield layer 24 and the upper shield layer 24 generated on the medium sliding surface 20a due to, for example, scratches or dust of the magnetic tape 2. Layer 25 and MR element 2
8 and the pair of electrode layers 32 can be electrically short-circuited.

Therefore, even when the distance between the pair of shield layers is reduced, the MR head 20 can obtain good reproduction characteristics.

Further, in this MR head 20, even when the above-described medium sliding surface 20a is cylindrically ground, the lower shield layer 24 and the upper shield layer 25 generated on the medium sliding surface 20a, the MR element 28, and the Electrical short-circuit with the electrode layer 32 can be reduced.

In this case, in the MR head 20, since the variation in the resistance value of the MR element 28 is reduced, the M
M determined by measuring the resistance value of R element 28
Variations in the height of the R element 28 in the depth direction can be reduced.

Therefore, it is possible to process the MR element 28 with high precision without variation in the height dimension in the depth direction.
A high-quality MR head 20 that can obtain good reproduction output and asymmetry of the reproduction waveform can be obtained.

In the MR head 20, the sum of the widths of the pair of electrode layers 32 exposed from the medium sliding surface 20a is the sum of the widths of the pair of electrode layers 32 exposed from the medium sliding surface 20a. It is preferable that the width be 1 to 5 times the width.

Here, as shown in FIG. 4, the widths of the pair of electrode layers 32 exposed from the medium sliding surface 20a are E and E ', respectively.
The width of the side exposed from a is F. The ratio of the sum E + E ′ of the widths E and E ′ of the pair of electrode layers 32 on the side exposed from the medium sliding surface 20 a to the width F on the side exposed from the medium sliding surface 20 a of the MR element 28. Was changed, the occurrence rate of a short-circuit occurring during cylindrical grinding of the medium sliding surface of the MR head 20 and the occurrence rate of Barkhausen noise of the MR head 20 were measured. Here, the width of the MR element 28 was 7 μm, and the height of the MR element 28 in the depth direction was 3 μm.

FIG. 6 shows the above measurement results. FIG.
In the figure, M shown in the figure represents widths E and E of the pair of electrode layers 32 on the side exposed from the medium sliding surface 20a of the MR element 28 with respect to the width F on the side exposed from the medium sliding surface 20a. A graph X showing the ratio of the sum E + E ′ of FIG.
Shows the relationship between this ratio M and the short circuit, and the graph Y shown in the figure shows the relationship between this ratio M and the occurrence rate of Barkhausen noise.

Table 1 below shows the measurement results at each point of the graphs X and Y shown in FIG.

[0076]

[Table 1]

From the graph X shown in FIG. 6, it can be seen that the occurrence rate of short-circuit increases as the ratio M increases. In particular, it can be seen that when the ratio M is 5 or more, the occurrence rate of short-circuits is greatly increased.

Further, it can be seen from the graph Y that the occurrence rate of Barkhausen noise sharply decreases between 0 and 1 as the ratio M increases, and the occurrence rate of Barkhausen noise becomes substantially constant. .

In this case, as shown in FIG.
When the sense current flows in the direction indicated by the arrow Is in FIG.
Magnetic fields that are not parallel to the MR element 28, that is, unstable regions G and G ′ in which the sense current does not take a fixed direction are generated at both ends of the MR element 28.

In this case, since the reproduction characteristics of the MR head 20 become unstable, it is desirable to set the ratio M to 1 or more as shown in the above-mentioned figure.

Accordingly, in the MR head 20, in order to suppress the electrical short circuit between the lower shield layer 24 and the upper shield layer 25 and the MR element 28 and the electrode layer 32 and to reduce the Barkhausen noise at the same time, MR head 2
It is preferable to set the range Z of the ratio M of 0 to 1 or more and 5 or less. That is, in the MR head 20, the sum of the widths of the pair of electrode layers 32 exposed from the medium sliding surface 20a is larger than the width of the MR element 28 on the side exposed from the medium sliding surface 20a. It is preferably at least 1 and at most 5 times.

As described above, according to the MR head 20, good reproduction characteristics and narrowing of the gap corresponding to high-density recording can be realized.

The MR head 20 to which the present invention is applied
Are a pair of electrode layers 3 disposed at both ends of the MR element 28.
2 is not necessarily limited to a shape narrowed obliquely toward the medium sliding surface 20 a sliding on the magnetic tape 2, and the pair of electrode layers 32 are provided on the medium sliding surface 20 a of the MR head 20. What is necessary is just to have the shape narrowed toward.

For example, the MR head 40 shown in FIGS. 8 and 9 may be used. In the MR head 40, the description of the same configuration and parts as those of the MR head 20 described below is omitted, and
The same reference numerals are given in the drawings.

In this MR head 40, only a portion where the pair of electrode layers 41 disposed at both ends of the MR element 28 are connected to the MR element 28 toward the medium sliding surface 40 a on which the magnetic tape 2 slides. Have a constricted shape that protrudes.

Also in this case, in the MR head 40, the width of the electrode layer 41 exposed from the medium sliding surface 40a can be smaller than in the related art.

Thus, in the MR head 40, even when the magnetic tape 2 is slid at high speed, the lower shield layer 24 and the upper shield layer 24 generated on the medium sliding surface 40a due to, for example, scratches or dust of the magnetic tape 2 Layer 25 and MR element 2
8 and the pair of electrode layers 41 can be electrically short-circuited. Therefore, even when the distance between the pair of shield layers is reduced, the MR head 40 can obtain good reproduction characteristics.

In the MR head 40, even when the above-described medium sliding surface 40a is cylindrically ground, the lower shield layer 24 and the upper shield layer 25 generated on the medium sliding surface 40a, the MR element 28, and the Electrical short-circuit with the electrode layer 41 can be reduced.

In this case, in the MR head 40, since the variation in the resistance value of the MR element 28 is reduced, this M
M determined by measuring the resistance value of R element 28
Variations in the height of the R element 28 in the depth direction can be reduced.

Therefore, it is possible to machine the MR element 28 with high accuracy without variation in the height dimension in the depth direction.
A high-quality MR head 40 that can obtain good reproduction output and asymmetry of the reproduction waveform can be obtained.

As shown in FIG. 10, in the MR head 40, the pair of electrode layers 41 are formed on the medium sliding surface 40a.
The sum H + H ′ of the widths H and H ′ on the side exposed from
It is preferable that the width be 1 to 5 times the width I of the MR element 28 on the side exposed from the medium sliding surface 40a.
FIG. 10 is an enlarged plan view showing a state where only a portion where the electrode layer 41 of the MR head 40 is connected to the MR element 28 projects toward the medium sliding surface 40a.

Also in this case, similarly to the above-described MR head 20, the lower shield layer 24 and the upper shield
The occurrence of an electrical short circuit between the R element 28 and the electrode layer 41 can be reduced, and the occurrence of Barkhausen noise can be suppressed.

In the MR head 40, the electrode layer 4
Since 1 has a constricted shape in which only a portion connected to the MR element 28 protrudes, it is possible to suppress a large decrease in the area of the pair of permanent magnet films 30.

In this case, in the MR head 40, a stable bias magnetic field can be applied to the MR element 28 by the pair of permanent magnet films 30.

Therefore, in the MR head 40, good reproduction characteristics can be obtained, and high-density recording can be performed by narrowing the gap.

[0096]

In the magnetoresistive head according to the present invention, the pair of electrode layers has a shape narrowing toward the medium sliding surface that slides on the magnetic tape. The width of the side exposed from the surface can be made smaller than before, and when sliding with a magnetic tape or cylindrical grinding of the medium sliding surface, a pair of magnetic shield layers generated on this medium sliding surface In addition, an electric short circuit between the magnetoresistive element and the pair of electrode layers can be reduced.

In this magnetic head, the sum of the widths of the pair of electrode layers on the side exposed from the medium sliding surface is made to be equal to the width of the magnetoresistive element on the side exposed from the medium sliding surface. By setting the ratio to 1 to 5 times, the occurrence of Barkhausen noise can be suppressed while reducing the electrical short circuit between the pair of magnetic shield layers and the magnetoresistive element and the pair of electrode layers. Therefore, according to the magnetoresistive head, good reproduction characteristics can be obtained, and the gap can be narrowed.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a configuration example of a magnetic tape device.

FIG. 2 is a schematic perspective view showing the configuration of a magnetic head device.

FIG. 3 is a perspective view showing a configuration example of an MR head to which the present invention is applied, showing a state where an electrode layer is obliquely narrowed toward a medium sliding surface.

FIG. 4 is an end view of a main part of the MR head as viewed from a medium sliding surface.

FIG. 5 is a diagram for explaining a configuration of the MR head, and is a schematic plan view showing a state where an electrode layer is obliquely narrowed toward a medium sliding surface.

FIG. 6 is a characteristic diagram showing the relationship between the ratio M of the MR head and the occurrence ratio of short circuits, and the relationship between the ratio M and the occurrence ratio of Barkhausen noise.

FIG. 7 is a schematic plan view showing the vicinity of an MR element of an MR head to which the present invention is applied in an enlarged manner.

FIG. 8 is a diagram showing another configuration example of the MR head to which the present invention is applied, in a narrowed state in which only a portion where the electrode layer is connected to the magnetoresistive element toward the medium sliding surface projects. FIG.

FIG. 9 is a diagram for explaining the configuration of the MR head, and is a schematic plan view showing a narrowed state in which only a portion where the electrode layer is connected to the magnetoresistive element protrudes toward the medium sliding surface. It is.

FIG. 10 is a schematic plan view showing an enlarged main part of a narrowed state in which only a portion where an electrode layer of the MR head is connected to the magnetoresistive element toward a medium sliding surface projects.

FIG. 11 is a schematic perspective view showing a flying slider provided in the hard disk drive.

FIG. 12 is a schematic end view of a conventional composite magnetic head viewed from a medium sliding surface.

FIG. 13 is a diagram showing a state in which a flying slider flies over a magnetic disk.

FIG. 14 is a schematic perspective view showing a configuration of a magnetic head device provided in the magnetic tape device.

FIG. 15 is a schematic end view of a conventional MR head viewed from a medium sliding surface.

FIG. 16 is a schematic plan view for explaining the configuration of the conventional MR head.

FIG. 17 is a perspective view for explaining the configuration of the conventional MR head.

FIG. 18 is a schematic end view showing a state in which a scratch has occurred on a medium sliding surface of the conventional MR head.

FIG. 19 is a characteristic diagram showing the relationship between the height of the MR element in the depth direction and the asymmetry of the reproduced waveform.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 magnetic tape device, 2 magnetic tape, 3 magnetic head device, 6 rotating drum, 7 MR head, 7a medium sliding surface, 20 MR head, 20a medium sliding surface, 24
Lower shield layer, 25 upper shield layer, 26 lower gap layer, 27 upper gap layer, 28 MR element, 30
Permanent magnet film, 31 conductive film, 32 electrode layer, 40 MR head, 40a medium sliding surface, 41 electrode layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D034 BA03 BA08 BA12 BA19 BB08 BB12 CA00 CA04 DA07 5D111 AA11 AA12 AA19 AA23 DD06 DD24

Claims (5)

[Claims] A magnetoresistive head mounted on a rotating drum and reproducing a signal recorded on a magnetic tape while sliding on the magnetic tape by a helical scan method, wherein a signal from the magnetic tape is read. A magnetoresistive element to be detected; a pair of electrode layers provided at both ends of the magnetoresistive element; A shield layer, wherein the pair of electrode layers has a shape narrowed toward a medium sliding surface that slides on the magnetic tape, and a side of the pair of electrode layers exposed from the medium sliding surface. Wherein the sum of the widths of the magnetoresistive elements is 1 to 5 times the width of the magnetoresistive element exposed from the medium sliding surface. 2. The magnetoresistive head according to claim 1, wherein said pair of electrode layers have a shape narrowed obliquely toward said medium sliding surface. 3. The magnetic device according to claim 1, wherein the pair of electrode layers have a constricted shape in which only a portion connected to the magnetoresistive element protrudes toward the medium sliding surface. Resistance effect type magnetic head. 4. The pair of electrode layers includes a pair of permanent magnet films for applying a bias magnetic field to the magnetoresistive element, and the magnetoresistive device formed on the pair of permanent magnet films. 2. The magnetoresistive head according to claim 1, further comprising a pair of conductive films for supplying a sense current to the magnetic head. 5. A magnetoresistive head according to claim 1, wherein said medium sliding surface is curved by cylindrical grinding.