JPS63142511A - Magneto-resistance type magnetic head - Google Patents

Abstract

PURPOSE:To detect even a minute shift against a track of a magnetic storage medium, and to improve the detection accuracy by making the width of a magneto-resistance element which consists of a magnetic anisotropic material, and whose axis-of-easy magnetization direction is used as lengthwise direction, different in the center part and the side part. CONSTITUTION:As for a slender magneto-resistance element 12 which consists of a magnetic anisotropic material such as 'Permalloy(R)', etc., and whose axis-of-easy magnetization, the center part in the lengthwise direction is a narrow width magnetism detecting part 12a, and both outsides are wide width magnetism detecting parts 12b, 12c. In the magneto-resistance element 12, an equipotential thin wire 13 consisting of a good conductive material is formed at an angle of 30-60 deg. with its axis-of-easy magnetization. When a prescribed current is allowed to flow to a magnetism detecting element 11 constituted in such a way, and an external magnetic field is brought close, an output characteristic of the element 11 is related to width w1 of the center narrow width part, its length l and wide width w2. When the length l of the center part 12a is made almost equal to width of a track of a magnetic storage medium, a shift of the external magnetic field can be detected clearly from its output.

Description

[Detailed Description of the Invention] [Summary] In a magnetic head equipped with a magnetoresistive element made of a magnetically anisotropic material on which equipotential and highly conductive stripes are formed, the longitudinal center portion of the resistance element is connected to its side portions. By making the width narrower or wider, the accuracy of detecting the position of the external magnetic field is improved.

[Industrial application field]

The present invention provides a magnetoresistive magnetic head equipped with a magnetoresistive element formed with highly conductive stripes, particularly a WZR magnetic head for writing and reading desired information on a magnetic storage medium.
The present invention relates to an improvement in a magnetic head used for servo for accurately tracing tracks on the medium.

A servo magnetic head is used because a W/R magnetic head for writing and reading desired information on a storage medium needs to be correctly opposed to the tracks of the storage medium.

As the density of stored information increases, the track width becomes narrower, and for example, the storage density of one track is 16,000 to 25,000 BP.
I (focus/inch), track density 1200-15
On a 00T P I (tracks per inch) magnetic disk, the width of the written information track is 13 to 1
8 μm, and the W/ is shifted laterally by 50% of the track width.
The output from the R magnetic head is reduced to about 50%.

Therefore, it is necessary for the W/R magnetic head to accurately face the track of the storage medium, but generally there is a guard band on each side of the track with a width of about 2 μm and no information is written, so that 100% output cannot be achieved. The margin obtained is 2 μm on the left and right sides.

On the other hand, a normal servo magnetic head has a track width of about 2
The structure is such that the track position can be detected within a range twice as large (for example, 26 μm).

[Conventional technology]

A servo magnetic head that uses magnetic resistance to detect an external magnetic field is a magnetic resistance element made of a magnetically anisotropic material whose length is in the direction of its easy magnetization axis, and a pattern of highly conductive equipotential strips is provided on the magnetic resistance element. Barber pole type magnetic sensing elements are widely used.

FIG. 4 is a perspective view showing the main parts of a conventional barber pole type magnetic sensing element. The magnetic sensing element 1 consists of an elongated magnetoresistive element 2 whose length direction is the axis of easy magnetization of a magnetically anisotropic material. It is formed by patterning well-conducting equipotential strips 3 and electrodes 4. Magnetoresistive element 2 that generally uses permalloy
consists of a detection section 2a and a pair of connection sections 2b, and the strips 3 and electrodes 4 are made of gold.

In such a magnetic detection element 1, the length of the magnetic detection part 2a is, for example, 26 μm, and the inclination angle of the highly conductive strips 3, which are inclined in opposite directions on the left and right sides from the center of the detection part 2a, is
The angle is 30 to 60 degrees (for example, 45 degrees) with respect to the length direction of a, and corresponds to the position of the external magnetic field narrower than the length of the magnetic detection section 2a. Positional deviation can be detected.

[Problem that the invention seeks to solve]

FIG. 5 is an output characteristic diagram of the conventional magnetic detection element 1. When the vertical axis is the output voltage V, and the horizontal axis is the strength H of the magnetic field input from the external magnetic field, the output characteristic A is the external magnetic field (magnetic field). When the magnetic field (from the track of the storage medium) is located at the center of the detection unit 1a, it is zero, and when the input magnetic field shifts to the right or left from the center, it outputs 10 voltages or 1 voltage corresponding to the shift.

That is, the conventional magnetic detection element 1 has a problem in that when the deviation between the center of the detection part 1a and the track of the magnetic storage medium is minute, the output swings around ±Ov, resulting in a decrease in detection accuracy. With the increasing density of magnetic storage media, there has been a strong demand for improvements.

[Means for solving problems]

The present invention, which aims to eliminate the above-mentioned problems, was realized by focusing on the fact that the output changes depending on the width of the magnetic detection element.According to FIG. The magnetoresistive element 12 is provided with an elongated magnetoresistive element 12 in which the central part 12a in the longitudinal direction with the length in the axial direction is narrower or wider than the side parts 12b and 12c, and the resistance element 12 has a 30 to 60 mm width in the direction of the easy magnetization axis. This is a magnetoresistive magnetic head characterized in that equipotential strips 13 made of a highly conductive material are formed at an angle of 10°.

(Function) According to the above means, the output from the magnetoresistive element changes depending on when the external magnetic field faces the central part of the element and when the external magnetic field faces the side parts of the element. When the magnetic head, whose central part of the magnetoresistive element faces the magnetic field, shifts slightly to the side, the shift can be changed sharply as a positive or negative output from the side of the magnetoresistive element. With this magnetoresistive element, it is possible to detect with high precision a deviation where the output is close to ±0.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Magnetoresistive magnetic heads according to embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view (a) showing a main part of a magnetic detection element according to an embodiment of the present invention, and a diagram of its output characteristics (b).

In FIG. 1(A), the magnetic detection element II is formed by forming a pattern of highly conductive equipotential strips 13 and electrodes 14 on a magnetoresistive element 12 whose axis of easy magnetization is in the longitudinal direction.

The elongated magnetoresistive element 12, which is made of a magnetically anisotropic material such as permalloy and whose axis of easy magnetization is in the longitudinal direction, has a narrow magnetic detecting section 12a located at the center in the longitudinal direction, and a detecting section 1.
A wide magnetic detection section 12b outside of 2a.

12c, and a detection section 12b, 1 for connection to an external circuit.
It consists of connecting parts 12d and 12e provided on the outside of the connecting parts 12d and 12e, respectively.
An electrode 14 connected to 3 is deposited.

As an example, in a magnetoresistive element 12 made of permalloy about 500 mm thick, each strip 13 of about 5000 mm thick gold at an angle of 45 degrees with its axis of easy magnetization is placed 10 mm thicker than the magnetoresistive element 12. It is equipotential because it is twice as thick and the conductivity of gold is about 10-15 times higher than that of permalloy.

When a predetermined current is passed through the magnetic detection element 1) and an external magnetic field is brought close to it, the output characteristics of the element 1) are determined by the width W1 of the narrow magnetic detection section 12a, its length l, and the wide magnetic detection section 12.
b, relates to the width W2 of 12c.

Therefore, when the width W1 is set to 8 mm, the length l is set to be the same as the track width of the storage medium, and the width W2 is set to 16n+m, the output of the magnetic sensing element 1) becomes as shown in FIG. 1 (I+).

In FIG. 1 (rl), the vertical axis represents the output voltage ±Δ■.

The horizontal axis is an axis corresponding to the length of the magnetic storage track 5 in the figure. Characteristic B with a small amplitude is the output when the track 5 faces the narrow magnetic detection section 12a, and characteristic C with a large amplitude is the output when the track 5 faces the narrow magnetic detection section 12a. is the output when facing the wide magnetic detection section 12b or 12c, and the outputs B and C have a sine wave shape corresponding to the polarity given by subdividing the track 5.

Therefore, if the slice level L is set between characteristics B and C as shown by the dotted line in the figure, a pulse will be generated when the magnetic detection element 1) deviates from the 7-axis 5. Move the W/R magnetic head to a position where it is not used.

Note that FIG. 2 is a diagram showing the relationship between the width and output of the magnetic detection section according to the present invention, where the vertical axis represents the output voltage ± and the horizontal axis represents the strength of the input magnetic field. The output obtained by inputting a magnetic field increases as the width of the magnetic detection section increases. In other words, the characteristics when the width of the magnetic detection part is 8 mm are 16
The characteristic E with mn+ has different rise angles as shown by the dashed line and the solid line in the figure, and the characteristic E with the same movement of the external magnetic field has a larger output than the characteristic E.

Note that in the magnetic detection element 1), the narrow magnetic detection section 12
When the length β of a is smaller than the width of the external magnetic field, only the same output as the conventional one can be obtained for a movement in which the external magnetic field does not exceed the length l. On the other hand, when the length l is larger than the width of the external magnetic field, the output of the narrow magnetic detecting section 12a is connected to the wide magnetic detecting section 12.
Since the outputs from part of b or 12c are superimposed, the output change becomes smaller accordingly. Therefore, the deviation of the external magnetic field can be detected most clearly when the length l is made equal to the width of the external magnetic field.

FIG. 3 is a perspective view showing the main parts of a magnetic detection element according to another embodiment of the present invention.

In FIG. 3, a magnetic detection element 21 is formed by forming a pattern of highly conductive equipotential strips 23 and electrodes 24 on a magnetoresistive element 22 whose axis of easy magnetization is in the longitudinal direction.

The elongated magnetoresistive element 22, which is made of a magnetically anisotropic material such as permalloy and whose axis of easy magnetization is in the longitudinal direction, has a wide magnetic detecting section 22a located at the center in the longitudinal direction, and a detecting section 2.
A narrow magnetic detection section 22b outside of 2a.

22c, and a detection section 22b, 2 for connection to an external circuit.
Connection parts 22d and 22e provided on the outside of 2c, respectively.
An electrode 24 connected to the strip 23 at the extreme end is attached on top of the connecting portions 22d and 22e.

This magnetic detection element 21 has a configuration in which the narrow magnetic detection part 12a and the wide magnetic detection part 12b of the magnetic detection element 1) are replaced, and the length of the wide magnetic detection part 22a is set such that the external magnetic field<vA of the magnetic storage medium. When the width is the same as that of the magnetic field from the track, the deviation from the external magnetic field can be detected with the highest accuracy.

〔Effect of the invention〕

As explained above, according to the present invention, by configuring a magnetic detection element by combining magnetic detection parts with different widths,
Even minute deviations in the external magnetic field can be detected, and when applied to a servo magnetic head of a W/R magnetic head used in a high-density magnetic disk, the effect of increasing the accuracy of writing and reading stored information is remarkable.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a magnetic detection element according to an embodiment of the present invention and its output characteristic diagram. FIG. 2 is a diagram showing the relationship between the width and output of a magnetic detection section according to the present invention. FIG. FIG. 4 is a perspective view of a conventional barber-pole type magnetic detecting element; FIG. 5 is an output characteristic diagram of the conventional magnetic detecting element. In the figure, IL21 is a magnetic detection element, 12.22 is a magnetoresistive element, 12a, 22a are the central part of the magnetic detection part, 12b, 12
c, 22b, 22c are both sides of the magnetic detection section, 13.
23 indicates an equipotential strip. (b) δ (Town broom 2 diagram

Claims (2)

[Claims] (1) The central part (12a) is made of a magnetically anisotropic material and its length is in the direction of its easy magnetization axis, and the side part (12a) is
b, 12c) comprises an elongated magnetoresistive element (12) formed narrower or wider than the above, and an equipotential made of a highly conductive material is attached to the resistance element (12) at an angle of 30 to 60 degrees with the axis of easy magnetization. A magnetoresistive magnetic head characterized by forming strips (13). (2) The magnetoresistive magnetic head according to claim 1, wherein the length (L_1) of the central portion (12a) is approximately equal to the track width of the magnetic storage medium.