KR920001147B1 - Multi-channel magnetic ressistance aqqect type magnetic head - Google Patents

Abstract

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Description

Multichannel Magnetoresistive Magnetic Head

1 is an enlarged plan view of the main portion of a magnetoresistive effect magnetic head.

2 is a cross-sectional view taken along line A-A.

3 is a magnetoresistance characteristic curve of the magnetoresistive element.

4 is a magnetoresistive characteristic curve for explaining the comparison.

5 is a block diagram of a differential magnetoresistance effect type magnetic head by constant current driving.

6 is an output waveform diagram.

7 is a basic configuration of a magnetic head according to the present invention.

8 is an electrical connection diagram of an example of the present invention.

9 is a schematic arrangement diagram of an example of a magnetoresistive element of a magnetic head according to the present invention.

10 is a layout diagram of an example of a bias conductor of the bias generating means.

11 is an enlarged plan view of a main portion of an example of a magnetic head according to the present invention.

12 and 13 are enlarged sectional views taken along line A-A and line B-B of FIG.

14 is a pattern diagram of an example of a bias magnetic field generating means for a magnetoresistive element.

15 is a pattern diagram of a magnetic head including a bias correction conductor for canceling the self bias of the magnetoresistive element.

16 is an enlarged cross-sectional view of the main portion.

* Explanation of symbols for the main parts of the drawings

MRn ₁ and MRn ₂ (MR ₁₁ and MR ₁₂ , MR ₂₁ and MR ₂₂ ,…): magnetoresistive element

21: thin film having a magnetoresistive effect 22: bias conductor

23: magnetic gas 24, 37: insulating layer

41 ₁ , 41 ₂ , 42 ₁ ), 42 ₂ : Magnetic layer 45: Upper protective substrate

The present invention relates to a multichannel magnetoresistive effect magnetic head.

An example of a conventional magnetoresistive effect (hereinafter referred to as MR) type regenerated magnetic head, in particular, a so-called rear type magnetic head in which the MR element is disposed at a position receding from a contact surface with a magnetic medium, is for example. As shown in FIG. 1, an enlarged plan view of the main part of the recess is shown, and an enlarged weak cross-sectional view of the AA line is shown in FIG. 2, for example, an insulating magnetic gas composed of Ni-Zn-based ferrite (1). ), A target conductive film 2 serving as a current path as a bias magnetic field generating means for imparting a bias magnetic field to the MR element by electromagnetic induction or the like is deposited thereon, For example, an MR effect element 4 made of a Ni-Fe-based alloy or a Ni-Co-based alloy thin film is deposited, and a pair of magnetic layers made of a Ni-fE-based alloy or the like is formed thereon through the insulating layer 5. 6) and (7) in the direction across the element 4 The furnace 4 is also maintained on the element 4 so as to face the required gap, and the outer end of one magnetic layer 6 faces the base 1 through at least one of the insulating layers 3 and 5. The magnetic gap g is formed, and the outer end of the other magnetic layer 7 is connected to the base 1 through a window formed through the insulating layers 3 and 5. Then, the nonmagnetic protective layer 8 is covered by covering the conductive layers 2, the MR elements 4, the magnetic layers 6 and 7, and the protective gas 10 is covered by the adhesive layer 9 thereon. The contact surface 11 with the magnetic recording medium is formed over both the bases 1 and 10, and the magnetic gap g faces the contact surface 11, and the magnetic The magnetic path including the gap g and the MR element 4, i.e., the magnetic gas 1-the magnetic gap g-the magnetic layer 6-the MR element 4-the magnetic layer 7-the magnetic body 1 A porcelain is formed.

In such a configuration, when the biasing magnetic field required for the MR element 4 is applied to the conductive layer 2 through the current Is required for generating the bias magnetic field, and the current I flows through the MR element 4, the magnetic An electrical signal, i.e., an output signal due to a change in resistance due to the magnetic field of the recording element recorded on it from the magnetic recording medium facing or facing the gap g, is given to the MR element 4, that is, the output signal is the MR element 4. It is obtained at both ends of.

However, such an MR effect type magnetic head, particularly a magnetic head in which magnetic bodies are arranged in close proximity, such as a rear type, has a problem of nonlinearity. That is, in this type of magnetic head, since the magnetic H-resistance R characteristic of the MR element shows a secondary curve as shown in FIG. 3, as shown in this figure, the MR element 4 is biased. Given that the signal magnetic field indicated by the sign 12 is given in the state where the magnetic field H _B is given, the output time due to the change in resistance in the MR element 4 is asymmetrical as indicated by the sign 13 in this figure. Becomes a distorted signal. Furthermore, the magnetoresistance characteristics when the magnetic element is not close to the MR element show the characteristics of widening of the bottom portion as shown in Fig. 4, and since the portion having the excellent linearity exists, the required bias magnetic field H At ' _B ', an output signal 13 'having excellent symmetrical undistortion with respect to the signal magnetic field 12' can be obtained. This is due to the influence of the anti-magnetic field occurring on both end faces of the MR element, but as in the rear configuration shown in Figs. 1 and 2, the magnetic layer 6 is close to both end faces of the MR element 4. ) And (7) are considered to be because the influence on the characteristic by such a diamagnetic field becomes small.

In order to eliminate such a nonlinear component in such an MR element, it is proposed to set it as a differential type | mold structure. As shown in FIG. 5, this differential MR magnetic head is composed of two MR elements MR ₁ and MR ₂ having _one end in common, and terminals t ₁ and each derived from the other end of each MR element MR ₁ and MR ₂ . t ₂ is connected to independent constant current sources S ₁ and S ₂ , respectively, and is connected to the input side of the differential amplifier Amp. The common potential terminal t ₃ derived from the midpoint of connection between the _two MR elements MR ₁ and MR ₂ is given a predetermined potential, for example, a ground potential, and a constant current i is given to each MR element MR ₁ and MR ₂ in the reverse direction. It is, in a direction perpendicular to this is given by the bias-based H _B reverse to each MR element MR ₁ and ₂ MR. According to the differential magnetic head having such a configuration, when the input signal magnetic field common to each of the MR elements MR ₁ and MR ₂ is given from the magnetic recording medium, the output signals 14 ₁ having different configurations from those shown in FIG. 14 ₂ ), from the output terminal t _out of the amplifier Amp, a signal 14 is obtained in which they have a positive symmetry, i.e., a nonlinear component canceled _out by the synthesis of the signals.

According to such a constant current automatic MR magnetic head, the nonlinear component of the MR element can be canceled and a reproduction signal without distortion excellent in symmetry can be obtained. However, this type of magnetic head requires the derivation of three terminals t _{1 to} t ₃ , and requires two independent signal lines connected to the differential amplifier Amp and two independent constant current sources. Therefore, when applied to a multichannel magnetic head, assuming that the number of channels is n, at least 2n + 1 terminals need to be derived from the multichannel magnetic head, and at least 2n constant current sources are required again. In addition, since it is a constant current driver, its power consumption is large and its circuit size is large, for example, n is unsuitable for application to a multi-channel magnetic head of 10 to 50.

As a solution to such a drawback, it has been proposed to connect a pair of MR elements in series, apply constant voltage to both ends thereof, and take out the output differentially from the midpoint of connection of both elements.

According to the differential magnetic head by the constant voltage driving, the second harmonic component can be canceled as in the case of the constant current driving described above. SN ratio and signal power at power become the same as in the case of constant current drive. Compared to the constant current differential MR magnetic head, it is necessary to provide two constant current sources for each channel independently, and a large number of terminal outflows and a large number of wirings are unnecessary, thereby simplifying the configuration. It brings great benefits in the channel type magnetic head.

It has already been proposed to take a so-called self-biased configuration as the MR head by such constant voltage driving. Examples of this self-biased configuration include those disclosed in Japanese Patent Laid-Open No. 52-23920, or so-called barb balls. These are made so that the direction of the current through each MR element has an easy magnetization direction and the required angle, and a bias magnetic field having this and the required angle is generated by the current through the element.

For example, in a bobbin ball-type MR head, a plurality of biconductors of both conductive lines made of, for example, Au are inclined with respect to the easy magnetization direction along the longitudinal direction of the thin-film MR element, i. In order to minimize the MR element in order to reduce the channel pitch in the multi-channel magnetic head, in this case, it is necessary to narrow the interval between the conductive wires. This causes various problems such as the fact that the MR element becomes substantially smaller in resistance, making the output signal difficult to handle.

In addition, bias conductor terminals for imparting a bias magnetic field are required at the midpoints and both sides of two MR elements, and three for each magnetic head element. Therefore, multiple terminal drawing is required in a multichannel magnetic head.

The present invention provides a multi-channel magnetoresistive effect type magnetic head which eliminates such drawbacks, and in particular, the current supply power supply terminal in the bias magnetic field generating means for each channel is common to all channels, for example. It is possible to simplify the configuration by providing the required bias magnetic field to each MR element of each channel only by excavation.

In the present invention, as shown in FIG. 7, the basic configuration is provided with a pair of magnetoresistive element MR elements MRn ₁ and MRn ₂ connected in series for each channel. Then, the constant voltages V ₁ and V ₂ are supplied to both ends of each of the pair of MR elements MRn ₁ and MRn ₂ , and each current i through the MR elements ₁ and MRn ₂ and a predetermined angle, for example, 90 degrees. In degrees, the same bias magnetic fields H _B and -H _B are applied to each other along the MR element film. The output terminal t _sn is derived from the serial connection midpoints of the MR elements MRn ₁ and MRn ₂ , and the output is taken from the amplifier A through this.

EMBODIMENT OF THE INVENTION Next, the Example of this invention is described in detail according to drawing.

8 shows an example of an electrical connection of a multi-channel magnetoresistive magnetic head according to the present invention, wherein each channel CH ₁ , CH ₂ , CH ₃ . Each pair of MR elements MRn ₁ and MRn ₂ (MR ₁₁ and MR ₁₂ , MR ₂₁ , and MR ₂₂ MR ₃₁ and MR ₃₂ ... MRm ₁ and MRm ₂ ) described in FIG. 7 with respect to CHm are excreted. Terminals t _sn (t _s1 , t _s2 , t _s3 , ... t _sm ) are derived from the connection points, respectively. In addition, each other end of each pair of MR elements MRn ₁ and MRn ₂ in each channel CHn is connected in parallel to a common feed line l ₁ and l ₂ in which predetermined voltages V ₁ and V ₂ are popular, respectively. .

Each of these MR elements MRn ₁ (MRn ₁₁ , M ₂₁ ,... MRm ₁ ) and MRn ₂ (MR ₁₂ , MR ₂₂ ,... MRm ₂ ) are each E-shaped with magnetoresistance effect as shown in FIG. Metal thin film of a pattern, for example, Ni-Fe-based alloy or Ni-Co-based alloy thin film 21 is formed, the outer edges (21 ₁ ) and (21 ₂ ) of each of the voltage V ₁ , V ₂ is connected to the given lines l ₁ and l ₂ , and signal output terminals t _sn (t s ₁ , t s ₂ ,... T _sm ) are derived from the central corner portions 21s, respectively. Then, MR elements MRn ₁ and MRn ₂ are formed between the respective portions 21 ₁ and 21s of the thin film 21 and between 21s and 21 ₂ , respectively. In this manner, each MR element MRn ₁ and MRn ₂ of each channel CHn are connected in series to allow them to pass through the current i in the same direction. The thin film 21 of the E-shaped pattern is formed symmetrically with respect to the center line passing through the center of the center angle portion 21s, so that both MR elements MRn ₁ and MRn ₂ have the same characteristics.

Then, for each of these MR elements MRn ₁ and MRn ₂ , the required angles that do not coincide with this in the current direction, for example, orthogonal to this, and the bias magnetic fields H _B and -H _B reverse from each other Grant. As a means for imparting a reverse bias magnetic field to the paired MR elements MRn ₁ and MRn ₂ in this manner, in particular, in the present invention, it is due to electron induction. As an example, as shown in FIG. 10, for example, the above-described example has the magnetoresistive effect of the E-shaped panel, and is composed of the MR thin film 21 and the insulating layer constituting each pair of MR elements MRn ₁ and MRn ₂ . Thus, for example, a bias conductor 22 made of a conductive layer having an electrostatic resistance having an E-shaped pattern is formed by laminating through it. The bias conductor 22 has a shape having a connecting portion 22c for connecting both side portions 22 ₁ and 22 ₂ of the E-shaped pattern to each other, and each adjacent channel is formed in the center angle portion of the E-shaped pattern ( 22s), i.e., the portion corresponding to the connection center point of the paired MR elements MRn ₁ and MRn ₂ is connected to the connecting portions 22c of both sides of the conductor pattern 22 of the channel of the next step, and is located at the outermost position. A current source for bias field generation is connected between the connecting portions 22c of each of the E-shaped patterns of one channel CH ₁ and the central portions 22s of the channel CHm, which are also located on the other side. In this manner, the bias conductors 22 are arranged in series between adjacent channels in parallel to the paired MR elements MRn ₁ and MRn ₂ , and the current source terminals for generating the bias magnetic field t _b from both ends thereof. And t ′ _b .

Then, the positive terminal t _b t for each of the bias magnetic field occurs in the conductive parts corresponding to the respective elements MRn ₁ and MRn ₂ of "supplying ib ₁ + ib ₂ in the current source for the bias magnetic field is generated between _b and the thin film 21 as a conductor By passing the current ib ₁ + ib ₂ , the bias magnetic fields H _B -H _B in the opposite directions can be applied to each pair of MR elements MR n ₁ and MR n ₂ .

As described above, in the present invention, the bias conductor 22 is provided, and in this case, the energization mode is set to be parallel with respect to the paired MR elements MRn ₁ and MRn ₂ in the respective channels. because such that in series, the power terminals for the bias magnetic field occurs, so it is only being a two terminal t _b, t _'b that are connected to a common power source disposed with respect to all the channels, as shown, the configuration is simple.

Next, the specific structure of the multichannel MR type magnetic head according to the present invention described above will be described based on FIG. 11 to FIG. FIG. 11 is a schematic enlarged plan view of a main portion of an example of a multi-channel MR type magnetic head according to the present invention, FIG. 12 shows an enlarged plan view on line AA, and FIG. 13 also shows an enlarged sectional view on line 11, BB line. Reference numeral 23 denotes a magnetic gas 23 serving as a lower core, for example, a magnetic gas 23 made of a Ni-Zn-based ferrite, on which a bias conductor 22 and feed lines l ₁ of constant voltages V ₁ and V ₂ are placed. And conductors 31 and 32 forming l ₂ are deposited, on which MRn ₁ and of each pair of MR elements of each channel CHn (CH ₁ , CH ₂ ... CHm) are formed through the insulating layer 24. MR thin films 21 forming MRn ₂ (MRn ₁₁ and MRn ₁₂ , MRn ₂₁ and MRn ₂₂ ..., MRm ₁ and MRm ₂ ) are each deposited in a desired pattern. These bias conductors 22, the insulating layer 24, and the MR thin film 21 are deposited on the magnetic gas 23 sequentially by deposition, sputtering, and the like, respectively, on the magnetic gas 23, and then patterned.

In this case, in order to raise the adhesion strength to the base body 23 of this conductor layer, as needed, for example, a Cr layer as a base layer is deposited by vapor deposition, sputtering, etc. in whole thickness, for example, 3000 micrometers. Then, as described above, a conductive layer, for example, an Au metal layer, which forms the bias conductors 22, the feed conductors 31, and 32, is also deposited by vapor deposition, sputtering, and the like, and then over the entire surface. Si ₃ N ₄ or Al ₂ O ₃ , which forms the insulating layer 24, and the like, for example, a Ni-Fe-based alloy, a Ni-Fe-based alloy, which forms the MR thin film 21 thereon, Alternatively, a Ni—Co-based alloy thin film is entirely deposited by vapor deposition or sputtering. Then, over the portion forming these MR thin films 21, the insulating layer underneath, the conductive layer underneath, and the base layer underneath, for example, the angle in each channel CHn selectively. A portion for forming the MR thin film 21 of the aforementioned E-shaped pattern for forming the pair of MR elements MRn ₁ and MRn ₂ , also a portion for forming a bias conductor, and a feed conductor of constant voltages V ₁ and V ₂ are formed. Etching removal is successively performed by leaving the other parts or parts forming the terminal part and the other parts with the same mask for each layer, or by using the upper pattern as a mask. In this case, it is preferable to set it as the etching of a cross-sectional mold shape which becomes narrow toward an upper layer.

Next, selective etching is performed only on the MR thin film layer again to form the thin film 21 of the above-mentioned E-shaped pattern. These etchings can be performed by a wet etching method or a dry etching method, for example, chemical etching or ion etching.

In this way, the MR thin film 21 of the E-shaped pattern constituting each pair of MR elements MRn ₁ and MRn ₂ is formed, and the bias of the E-shaped pattern insulated by the insulating layer 24 overlapping thereunder is formed. The conductors 22 and the feed conductors 31 and 32 are formed. Here, as described in FIG. 10, the bias conductor 22 is a channel CH _n− of the front side of the channel adjacent to the connecting portion 22c connecting the two outer corner portions 22 ₁ and 22 ₂ . ₁ , the extension part 22'c which extends to the opposing position is provided in the center angle part 22s of these conductors 22 with the connection part 22c in between. In addition, the feed conductors 31 and 32 can be formed as a target pattern extending along the arrangement direction of each channel CHn.

Next, an insulating layer on an end portion of the center angle portion 22s of the bias conductor 22, on the extension portion 22'c, and on a portion corresponding to each channel CHn of the feed conductors 31 and 32, respectively. (24) Each of the contact windows 33 to 36 for connecting the wiring conductor layers to be described later is formed.

Subsequently, a nonmagnetic insulating layer 37 which covers these patterns and is made entirely of, for example, SiO ₂ and has a different etching property from the insulating layer 24 is deposited by a known technique. The thickness of the insulating layer 37 is formed entirely in a thickness that defines the magnetic gap length on the surface of the magnetic recording medium to be described later, for example, 0.3 mu m. Then, the insulating layer 37 is selectively etched by dry etching using, for example, wet etching or plasma etching, and each pair of the pairs of the respective E-shaped MR thin films 21 of each channel is formed. The windows 38 ₁ and 38 ₂ are formed in positions adjacent to the MR elements MRn ₁ and MRn ₂ , respectively, to remove part of the surface of the magnetic gas 23 and at the same time, each part of each MR thin film 21. (21 ₁ ), (21 ₂ ) and (21s) on each end of the window (39 ₁ ), (39 ₂ ), (39s) formed by drilling each of these parts (21 ₁ ), (21 ₂ ), A part of each surface of (21s) is faced outside. In addition, while forming each of these windows, the insulating layers 37 on the windows 33 to 36 previously formed are etched away so that the windows 33 to 36 face the outside for two days.

Next, Ni-Fe is included in the windows 38 ₁ and 38 ₂ , and also includes a position across each pair of MR elements MRn ₁ and MRn ₂ . A magnetic layer made of a system alloy layer or the like is formed, and is selectively etched by a wet method or a dry method as described above to form a magnetic layer 4 _{1 1} and 41 ₂ respectively corresponding to each of the MR elements MRn ₁ and MRn ₂ . (42 ₁ ) and (42 ₂ ) are formed on both sides of each MR element through the insulating layer 37 on the ground, and are formed so as to face each other by maintaining the required interval G therebetween. The width across the ground of the MR elements of the magnetic layers 4 _{1 1} and 4 _{1 2} , 4 _{2 1} , and 42 ₂ is selected to be about 1 μm, for example, when the width of the MR element is 5 μm. do. Then, the magnetic layer is made of one here (42 _1), and (42 ₂₎ is partially through the window ₍₃₈₎ and (38 ₂₎ of the insulating layer 37 so that the connecting and the magnetic substrate (23).

On the other hand, at least in each of the windows 33 to 36, 39 ₁ except for the portion where the magnetic layers 4 _{1 1} and 4 _{1 2} , 42 ₁ , and 42 ₂ on the base 23 are arranged. ), (39 ₂ ), (39s) over the entire surface, for example, conductive layer 40 is deposited, and selectively etched between the window (39 ₁ ) and (36), between the window (39 ₂ ) and The etching is removed while leaving the wiring conduction portion that extends between (35) and between the windows (33) and (34), and also the wiring portion for deriving the external output terminal t _sn from the window (39s). Then, one via power supply terminal t _b is derived from the extension portion 22'c of the bias conductor 21 of _one channel CH ₁ , and the wiring portion 40 connected to the center angle portion 22s of the other channel. The terminal t _b ′ on the other side is derived.

In addition, a protective film 43 made of, for example, SiO ₂ or the like is deposited on the entire surface including each of these patterns, and the upper protective substrate 45, for example, a glass plate, is made of an inorganic or organic adhesive layer 44 such as glass. To join. Then, the protective substrate 45 is cut and polished on the outer end side of one of the magnetic layers 4 _{1 1} and 4 _{1 2} for each MR element paired with each channel CHn over the magnetic gas 23. A mating surface 51 with the medium is formed.

In this way, the magnetic gaps g ₁ , g ₂ having a gap length defined according to the thickness of the nonmagnetic insulating layer 37 are formed on the magnetic substrate 23 and the magnetic layers 4 _{1 1} , ( 41 ₂ ). According to this configuration, each pair of waste paths including the magnetic gaps g ₁ and g ₂ and the MR elements MRn ₁ and MRn ₂ are respectively formed of the magnetic layers 41 ₁ and (41 ₂ ) -magnetic gas 23 and magnetic layer. A multichannel magnetic head formed of (41 ₁ ) and (41 ₂ ) -magnetic gas 23 is constructed.

The method of manufacturing the multi-channel MR type magnetic head according to the present invention is not limited to the above examples, but as described above, the conductive layer constituting the bias conductor 22 and the MR thin film layer constituting the MR thin film 21 are described. Is laminated over the entire surface through an insulating layer, and when patterning them, for example, the MR thin film 21 and the bias conductor 22 of the E-shaped pattern do not displace each other, and the insulating layer is formed. Since it is reliably electrically insulated by (24), it is possible to reliably and efficiently impart a bias magnetic field to each of the MR elements MRn ₁ and MRn ₂ . So also, the insulating layer 24 has a gap g _1, is removed in the g _2, the gap length of the gap g _1, g ₂ is only to be defined by the thickness of the insulating layer 37 as the upper layer, of the gap length Setting can be made easy. In addition, when the insulating layers 24 and 37 are made of Al ₂ O ₃ or Si ₃ N ₄ and SiO ₂ which differ in their etching properties from each other, the insulating layer 37 by the upper layer SiO ₂ is formed. On the other hand, even if it is selectively etched by, for example, plasma etching, there is an advantage that almost no etching effect occurs for Al ₂ O ₃ or Si ₃ N ₄ in the lower layer.

In the above example, a pair of MR elements may be disposed in each channel, or a plurality of pairs of MR elements may be disposed.

Further, in the above-described example, even when the magnetic element is interposed between the magnetic element and the magnetic element is disposed close to each other, even when applied to the rear MR magnetic head or when the end face of the MR element is disposed so as to face the magnetic medium. Since the magnetoresistance characteristics of these MR elements exhibit secondary curves, they can be applied to such a so-called shielded MR magnetic head.

As described above, in the present invention, each of the MR elements MRn ₁ and MRn ₂ is provided with a bias magnetic field generated by energization of the bias conductor 22 outside the MR element, or the current i through the MR element body. Due to the influence of the self biasing effect, the strength of the bias magnetic field for both the MR elements MRn ₁ and MRn ₂ that substantially pairs each channel becomes nonuniform, resulting in insufficient cancellation of the nonlinear component.

In this case, therefore, it is desired to make the bias magnetic field from the outside different for each MR element MRn ₁ and MRn ₂ in consideration of the effect of this self bias. As an example, the currents ib ₁ and ib ₂ themselves passing through each of the MR elements MRn ₁ and MRn ₂ of the above-described bias conductor 22 for imparting an external bias magnetic field are influenced by the influence of its own bias of each of the MR elements MRn ₁ and MRn ₂ . Set the value accordingly. That is, as can be seen in FIG. 10, between the direction of the current i through one MR element MRn ₁ and between the respective portions 22s and 22 ₁ of the conductor 22 for imparting an external bias magnetic field thereto. While the currents ib ₁ through the same direction coincide with each other, the directions of the current i through the other MR element MRn ₂ and the respective portions 22s and 22 of the conductor 22 for imparting an external bias magnetic field to it ( The currents ib ₂ passing through 22 ₁ ) are reversed in direction. That is, with respect to one element MRn ₁ , the direction of the self-bias magnetic field and the bias magnetic field applied from the outside act in the same direction in which the bias magnetic field is strengthened by the self-bias, and with respect to the other element MRn ₂ itself. The direction of the vias magnetic field and the bias magnetic field applied externally act in the direction in which the bias magnetic field is weakened by the self bias. That is, now both elements MRn MRn ₁ and ₂ substantially in the magnetic field H ₁ and H ₂ are given to the

It becomes Here, H H _B1 and _B2 are the respective elements MRn MRn ₁ and ₂ to the outside of the bias magnetic field, H H _MR1 and _MR2 is a self-bias magnetic field of each element MRn MRn ₁ and _2.

By the way, the contribution rate A which actually acts as a bias magnetic field to the MR element by the current ib through the conductor 22 differs from the contribution rate B which acts as a bias magnetic field of the magnetic field by the current i flowing through the MR element itself. This is, for example, the lower magnetic gas 23-magnetic layer 41 ((41 ₁ ) (41 ₂ ))-MR element-magnetic layer 42 ((42 ₁ ) (42 ₂ ) as in the above-described magnetic head. When a conduit is formed by the method, and the conductor 22 is under the MR element, and the lamination part of the conductor 22 with the MR element is surrounded by this conduit, the contribution rate A can be regarded as approximately 1. However, since the MR element itself faces the waste path through the gap G between the magnetic layers 41 and 42, the contribution rate B is B <1 due to leakage of the magnetic flux therefrom. / A 'was 1/2 to 4/5.

On the other hand, in order to achieve a differential configuration, the magnetic fields H ₁ and H ₂ to be substantially applied to both MR elements MRn ₁ and MRn ₂ need to satisfy the condition of H ₁ and -H ₂ for H ₁ = H ₂ . _The currents iH ₁ and IH ₂ to obtain ₁ and H ₂

therefore

Each of the currents ib ₁ and ib ₂ may be described as follows.

In this manner, the currents ib ₁ through the respective sides st ₁ and st _{2 corresponding} to the respective MR elements MRn ₁ and MRn ₂ between the respective portions 22s and 22 ₁ and 22 ₂ of the conductor 22, respectively. As a method of obtaining a current value based on Eq. (3) different from each other in ib ₂ , the resistances R ₁ and R ₂ between the center portion 22s and the feeding position P to the connecting portion 22c through each side st ₁ and st ₂ are obtained. Is obtained by setting to the required value. For example, it can be set as to sandwich the R ₁ and R ₂ each consisting of a leg ₍₂₂₎ and (22 _2), each one layer set to a resistance value of the resistor required such as in, as shown in Figure 14. The setting of the resistors R ₁ and R ₂ is, for example, the setting of the specific resistance of the resistor layer, the film thickness, the film width, and the like, as well as the feed line P and the respective parts 22 ₁ and 22 to the connecting portion 22c. _It can obtain by changing each space | interval with _two .

In the above-described example, the currents ib ₁ and ib ₂ through these sides st ₁ and st ₂ are set by setting the resistance values R ₁ and R ₂ associated with each side st ₁ and st ₂ of the conductor 22. The value is set to the required value so as to exclude substantially the nonuniformity of the magnetic field caused by the self bias of each of the MR elements MRn ₁ and MRn ₂ , but in some cases, the bias of the self bias in these MR elements MRn ₁ and MRn ₂ is biased. It can also be made to cancel by the magnetic field which generate | occur | produced by the energization to the bias correction conductor arrange | positioned separately from the conductor 22. FIG. As an example in this case, for example, as shown in FIG. 15, the extension direction of each MR element MRn ₁ and MRn ₂ is common with respect to each channel CHn, so that the bias conductor 22 is an extension direction of each side st ₁ and st ₂ . In accordance with this, one bias correction conductor 50 is disposed, and the required current ic in the reverse direction to the current i through the MR element is placed therein.

This bias correction conductor 50 can be formed, for example, by placing a thin film conductor through the insulating layer 51 under the bias conductor 22, as shown in FIG. In this way, the magnetic field generated by the energization of the bias correction conductor can cancel its own bias magnetic field in each MR element.

And, not to mention the means by which the effect of self-bias of these MR elements is eliminated, all of them are an MR element which takes an aspect for generating a bias field according to the present invention, that is, a two-terminal, tb, tb 'configuration, and forms a pair. The MRn ₁ and MRn ₂ are not limited to the case of taking a so-called chain configuration in parallel and in series between adjacent channels.

As described above, according to the present invention, the reverse bias magnetic field is applied to a magnetic head of a differential configuration by applying constant voltage driving, for example, by applying a reverse bias magnetic field to the MR elements and taking out the output differentially. In the bias generating means, the conduction pattern of the bias conductor 22 is formed in parallel with respect to the paired MR elements MRn ₁ and MRn ₂ , and in the form of a chain pattern in series between adjacent channels. Since only a common current source, i.e., two terminals tb and tb 'can be derived, the configuration can be simplified, thus facilitating manufacture and further reducing the track pitch. .

Claims (1)

Consists of first and second magnetoresistive elements connected in series and arranged in a line shape, receives a signal magnetic field derived from a common signal track on a magnetic recording medium, and also has a central part near the center of the line shape. The first magnetoresistive element has a first end at one end of the line shape, and the second magnetoresistive effect element is a magnetoresistive effect element having a second end at the other end of the line shape, A first end of the first magnetoresistive element is connected to a first voltage, and a second end of the second magnetoresistive element is connected to a second voltage, the first and second The sensing current flows through the magnetoresistive elements of the first and second centers of the first and second magnetoresistive elements, and the magnetoresistive elements connected to the output circuit in common, and the first and second magnetisms. Resistance effect element Each of the first and second bias conductor portions disposed adjacent to each other and contiguous with each other, the first and second bias conductor portions having a central portion substantially coincident with the center portion of the line shape, and the first bias conductor portion The second bias conductor portion has a second end portion substantially coincident with the one end of the line shape, and the second bias conductor portion has a second end portion substantially coincident with the other end portion of the line shape, and the first and second biases A bias magnetic field in the first direction is applied to the first magnetoresistive element by applying a bias current between the central portion of the conductor portion and each of the first and second ends of the first and second bias conductor portions. And applying the bias magnetic field in the second direction to the second magnetoresistive element, and when the first and second magnetoresistive element receive the common signal magnetic field, Increases of resistance effect element, and a multi-channel magnetoresistive magnetic head which comprises a bias conductor means adapted to the resistance of the first magneto-resistance effect element of the second reduction.

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