JPH08335304A - Magneto-resistive head - Google Patents

Abstract

PURPOSE: To read plural magnetic information tracks without using plural magneto-resistive heads by executing the adhesion of a supporting substrate and a protective substrate without the occurrence of thermal deterioration and thermal stresses of a magneto sensitive part and setting the spacing from a sliding surface to the magnetosensitive part at a desired size. CONSTITUTION: This magneto-resistive head is provided with an MR sensor 16 which is the magnetosensitive part have a magneto-resistance effect, the supporting substrate 18 metal evaporated with this sensor and the protective substrate 20 for protecting the MR sensor 16 by adhering the sensor to the supporting substrate 18 by a resin adhesive. The length of the MR sensor 16 is set smaller than the width of the magnetic information track of the magnetic recording medium, such as magnetic card. The spacing adjusted to a prescribed value by the cylindrical polishing of the sliding surface is formed between the sliding surfaces of the supporting substrate 18 and the protective substrate 20 facing the magnetic recording medium and the MR sensor 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head. More specifically, the present invention relates to a magnetoresistive head suitable for a card reader that reads a magnetic tape of a magnetic card.

[0002]

2. Description of the Related Art Conventionally, magnetoresistive heads have been used in hard disk devices in most cases, and have a support substrate to which a magnetic sensing portion for reading magnetic signals is fixed, and a protective substrate for protecting the magnetic sensing portion. Is bonded by an inorganic substance such as sodium silicate. Adhesion with an inorganic substance is performed by pouring a molten inorganic substance at 400 to 600 ° C. between a supporting substrate and a protective substrate and curing the inorganic substance.

Then, the tip of the assembled magnetoresistive head is cylindrically polished to form a sliding surface. The magnetoresistive head is held by a support block and mounted on a device such as a hard disk device. Here, since the magnetic signal from the disk surface of the hard disk device is relatively weak, it is easily affected by ambient noise when reading by the magnetoresistive head. Therefore, the support substrate and the protective substrate of the magnetoresistive head are
It is made of an opaque and magnetically shieldable material such as ferrite or sendust. Here, although materials such as ferrite and sendust have a hardness that is not so high, they do not wear because they do not come into contact with the disk surface of the hard disk device.

On the other hand, when the magnetoresistive head is used in a card reader, the magnetoresistive head comes into contact with the magnetic tape of the magnetic card to read a magnetic signal. Here, since the magnetoresistive head is provided with only one magnetic sensitive section, as shown in FIG. 5, the magnetic signal of the magnetic tape 12 having, for example, three magnetic information tracks 10, 10, 10 is transmitted. For reading, three magnetoresistive heads will be used. Then, each magnetoresistive head is arranged corresponding to one magnetic information track 10, and a magnetic signal is read for each magnetic information track 10.

[0005]

However, in the above-described magnetoresistive head, the permalloy used in the magnetic sensing part is oxidized because it is heated to 350 ° C. or higher when the supporting substrate and the protective substrate are bonded. As a result, the resistance value may increase and the reading accuracy may decrease. Also, after the bonding, when the temperature returns to room temperature, thermal stress is generated, which may distort the magnetically sensitive portion and reduce the accuracy of reading the magnetic signal.

Further, for example, when the magnetoresistive head is used in a card reader, the magnetoresistive head comes into contact with the magnetic card, so that the sliding surface is worn. For this reason, it is necessary to increase the distance from the sliding surface of the magnetoresistive head to the magnetically sensitive portion as much as possible in the range where a magnetic signal can be sufficiently read during cylindrical polishing.
That is, if this interval is too large, the magnetic signal from the magnetic card may not reach sufficiently and the accuracy of reading may be reduced.If the interval is too small, the magnetic sensitive part may be exposed when the sliding surface is worn. Therefore, the life of the magnetoresistive head may be shortened. Therefore, it is desirable to set the interval as large as possible while ensuring the minimum reading accuracy.

However, in the above-described magnetoresistive head, since the supporting substrate and the protective substrate are made of an opaque material, the gap between the sliding surface and the magnetically sensitive portion during cylindrical polishing of the sliding surface. Can not be confirmed accurately. For this reason,
This interval may be too large or too small.

Further, when used in a card reader,
Since multiple magnetoresistive heads are usually used,
This obstructs the reduction in size and weight of the card reader device and requires complicated azimuth adjustment for each magnetoresistive head.

Therefore, the present invention provides a magnetoresistive head in which, when the supporting substrate and the protective substrate are bonded together, the magnetic sensing portion is not deteriorated by heat and thermal stress is not generated after bonding. That is the first purpose.

A second object of the present invention is to provide a magnetoresistive head capable of setting a desired distance from the sliding surface of the magnetoresistive head to the magnetic sensitive portion during cylindrical polishing. I am trying.

A third object of the present invention is to provide a magnetoresistive head which does not require a plurality of magnetoresistive heads even when reading magnetic signals from a magnetic tape having a plurality of magnetic information tracks. .

[0012]

In order to achieve such an object, a magnetoresistive head according to the invention of claim 1 has a magnetosensitive portion having a magnetoresistive effect, a support substrate to which the magnetic sensitive portion is fixed, In a magnetoresistive head including a protective substrate which is adhered to the support substrate to protect the magnetic sensitive portion, the length of the magnetic sensitive portion is made smaller than the width of the magnetic information track of the magnetic recording medium, while supporting The substrate and the protective substrate are bonded with a resin adhesive, and the sliding surface between the supporting substrate and the protective substrate facing the magnetic recording medium and the magnetic sensitive portion are adjusted to a predetermined value by cylindrical polishing of the sliding surface. Defined intervals are formed.

Further, in the invention of claim 2, the resin adhesive is an epoxy resin adhesive or a phenol resin adhesive.

Further, in the invention of claim 3, at least one of the supporting substrate and the protective substrate is made of a transparent or semitransparent material.

Further, according to the invention of claim 4, a plurality of magnetic sensitive portions are provided on the support substrate.

[0016]

Therefore, in the magnetoresistive head of the first aspect of the present invention, the resin adhesive is poured between the support substrate to which the magnetic sensing portion is fixed and the protective substrate which is overlaid on the magnetic sensing portion. Are joined together. At this time, since the resin-based adhesive cures at a relatively low temperature, the magnetically sensitive portion does not oxidize due to heat. Further, the distance between the sliding surface and the magnetic sensitive portion is adjusted to a predetermined value by cylindrical polishing of the supporting substrate and the protective substrate.

When the magnetic recording medium is read, the length of the magnetically sensitive portion is made smaller than the width of the magnetic information track to be read, so that a plurality of magnetic information tracks are arranged in parallel. When reading the magnetic information track, the magnetic signal of the adjacent magnetic information track is not affected.

According to the second aspect of the present invention, since the resin adhesive is an epoxy resin adhesive or a phenol resin adhesive, curing is performed by heating at a relatively low temperature where oxidation of the magnetic sensitive portion cannot occur. It can be performed and sufficient strength can be obtained.

Further, according to the third aspect of the invention, the position of the magnetic sensing portion can be recognized from the transparent or semitransparent substrate of the support substrate and the protective substrate. Therefore, when the cylindrical surface of the sliding surface of the magnetoresistive head is polished, it can be carried out while confirming the distance between the end of the magnetically sensitive portion and the sliding surface.

Further, according to the invention of claim 4, since a plurality of magnetic sensitive portions are provided on the support substrate, for example, only when reading a magnetic signal of a magnetic tape provided with a plurality of substantially parallel magnetic information tracks. The magnetoresistive head can read each magnetic information track at the same time.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment in which the magnetoresistive head of the present invention is applied to a card reader. The magnetoresistive head 14 includes a magnetoresistive element (hereinafter referred to as “MR sensor”) 16 as a magnetic sensing unit for reading a magnetic signal, a support substrate 18 to which the MR sensor 16 is fixed, and an MR sensor 16. And a protective substrate 20 adhered to the support substrate 18 so as to be superposed on.

The support substrate 18 and the protective substrate 20 are both made of a transparent glass substrate. Of these, the support substrate 18 has reinforcing electrodes 22, 22, an MR sensor 16 and electrodes 24 extending from both ends thereof. , 24 and protective film 26
And are overlapped and a pattern is formed by metal deposition. The MR sensor 16 is preferably made of Permalloy, and the protective film 26 is preferably made of semitransparent SiO ₂ .

The length L of the MR sensor 16 is set to be smaller than the width of the magnetic information track 10 from which the magnetic signal is read, and specifically, 2/3 to 1/4 of the width of the magnetic information track 10. It is desirable that the length is up to. As a result, there is no influence of the magnetic signal of the magnetic information track 10 adjacent to the magnetic information track 10 to be read, or the other magnetic information track 10 is not erroneously read, and reading can be performed with extremely high accuracy. Be seen.

Here, when assembling the magnetoresistive head 14, the protective substrate 20 is superposed on the pattern of the supporting substrate 18 and the supporting substrate 18 and the protective substrate 20 are lightly tightened. Then, as shown by the arrow in FIG. 2, the resin-based adhesive is applied between the support substrate 18 and the protective substrate 20 to form the electrode 2
Pour in by capillary action from here with the 4, 24 side facing up. The resin adhesive is preferably an epoxy resin adhesive or a phenol resin adhesive. In this case, it can be hardened at a temperature of about 160 ° C. for strong bonding.

After the resin adhesive is poured between the supporting substrate 18 and the protective substrate 20 substantially uniformly, the resin adhesive is heated and cured at about 160.degree. As a result, the magnetoresistive head 14 is assembled.

The surface close to the MR sensor 16 serves as the sliding surface 14a, and cylindrical polishing is performed. At this time, the gap G between the tip of the sliding surface 14a and the end of the MR sensor 16 can be observed with a microscope or the like from the outside through the transparent support substrate 18 or the protective substrate 20. Therefore, by performing cylindrical polishing while observing the gap G between the tip of the sliding surface 14a and the end of the MR sensor 16 with a microscope, the gap G can be set to a desired size with high precision. .
For example, even if the gap G is set to 25 μm,
The polishing can be performed almost accurately.

Therefore, it is possible to reliably prevent exposure of the MR sensor 16 from being deteriorated in accuracy of reading a magnetic signal due to the gap G being too large, and from being exposed to wear of the sliding surface 14a due to the gap G being too small. it can. As a result, the life of the magnetoresistive head 14 is not shortened while maintaining high accuracy reading.

The chip-shaped magnetoresistive head 14 obtained as described above is housed in a resin support block to form a completed magnetoresistive head. For example, as shown in FIG. 3, lead wires 26, 26 are soldered to the electrodes 24, 24, and the magnetoresistive head 14 is supported by a support block 28 so that the sliding surface 14a is exposed. The support block 28 is preferably made of polyamide resin such as nylon. Then, the support block 28 supporting the magnetoresistive head 14 is attached to the card reader device to read the magnetic card.

According to this embodiment, since the supporting substrate 18 and the protective substrate 20 are formed of glass substrates, the hardness is higher than that of the conventional case of forming ferrite or sendust. Therefore, even when the present magnetoresistive head 14 is applied to a card reader, it is possible to prevent wear of the sliding surface 14a due to contact with the magnetic card as much as possible. Since the magnetic signal from the magnetic information track of the magnetic card is relatively strong, it is hardly affected by ambient noise, and there is no need to perform magnetic shielding with ferrite or the like.

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG.
8 patterns of three MR sensors 16 are formed in a line,
A structure in which the protective substrate 20 is bonded may be used. According to this structure, even if the magnetic tape 12 of the magnetic card 30 is provided with, for example, three magnetic information tracks 10, 10, 10, the magnetic signal can be read by only one magnetoresistive head 14. it can. Therefore, the magnetoresistive head 14 corresponding to each magnetic information track 10 is provided.
It is possible to reduce the size and weight of the card reader without the need to provide the card reader.

Further, since it can be easily replaced with a conventionally used electromagnetic head of the electromagnetic induction type, other parts of the card reader can be used as they are and new parts can be developed. No need.

Further, in the above-mentioned embodiment, the supporting substrate 18
Although both the protective substrate 20 and the protective substrate 20 are made of transparent glass substrates, only one of the substrates may be made of glass substrate. For example, when only the protective substrate 20 is made of an opaque material, the gap G between the MR sensor 16 and the sliding surface 14a may be observed through the transparent support substrate 18 during cylindrical polishing. Further, when only the support substrate 18 is made of an opaque material, the transparent protective substrate 2 is used for cylindrical polishing.
It is sufficient to observe the gap G between the MR sensor 16 and the sliding surface 14a through 0.

In the embodiment described above, the support substrate 18
At least one of the protective substrate 20 and the protective substrate 20 is formed of a transparent glass substrate. However, it is sufficient if the gap G between the MR sensor 16 and the sliding surface 14a can be observed. It may be configured. Therefore, the range of selection of the material is increased in consideration of the durability and the magnetic shield property of the magnetoresistive head 14.

Further, in the above-described embodiment, the case where the magnetoresistive head 14 is used for the card reader has been described, but it may be used for other devices. For example, it may be applied to a floppy disk drive.

[0036]

As is apparent from the above description, in the magnetoresistive head according to the first aspect of the present invention, the supporting substrate and the protective substrate are adhered to each other by the resin-based adhesive, and therefore, when the head is cured. In addition, it is possible to avoid a decrease in the accuracy of reading the magnetic signal due to an increase in the resistance value and a decrease in the accuracy of reading due to the distortion of the magnetic part due to thermal stress, without requiring a temperature high enough to oxidize the part. . Therefore, claim 1
According to the magnetoresistive head described above, it is possible to read a magnetic signal with high accuracy. Further, since the length of the magnetic sensitive portion is set smaller than the width of the magnetic information track to be read, crosstalk can be eliminated. Therefore, the accuracy of reading the magnetic signal of the magnetic tape in which a plurality of magnetic information tracks are arranged in parallel is further improved.

According to the second aspect of the invention, since the resin adhesive is an epoxy resin adhesive or a phenol resin adhesive, the heating for curing at the time of adhesion is about 160 ° C. It's enough. Therefore, it is possible to reliably prevent oxidation and distortion of the magnetic sensing part. Moreover, since a sufficient strength of adhesion can be obtained, even if the magnetoresistive head is slid while contacting the magnetic card, the supporting substrate and the protective substrate are not easily peeled off.

Further, in the third aspect of the present invention, since at least one of the supporting substrate and the protective substrate is made of a transparent or semi-transparent substrate, cylindrical polishing of the sliding surface of the magnetoresistive head is performed. When performing, it is possible to set the size to a predetermined size while confirming the distance between the end of the magnetic sensing part and the sliding surface. For this reason, it is possible to reliably prevent the magnetically sensitive portion from being exposed even if this interval is too large and the accuracy of reading the magnetic signal is reduced, or if the interval is too small and the sliding surface is slightly worn. . Therefore, it is possible to extend the life of the magnetoresistive head without lowering the reading accuracy.

Further, in the invention according to the fourth aspect, since the plurality of magnetic sensitive sections are provided on the supporting substrate so that crosstalk does not occur, a single magnetoresistive head is used to generate a plurality of magnetic information tracks. Magnetic signals can be read simultaneously. Therefore, it is not necessary to provide a magnetoresistive head for each magnetic information track, and it is possible to reduce the number of parts and reduce the size and weight of a device such as a card reader.

Further, since it is not necessary to perform the azimuth adjustment for each track, the complicated adjustment work can be simplified and the manufacturing cost can be reduced. That is, since the azimuths of the respective magnetic information tracks are almost the same, if the azimuth adjustment is performed only once for the magnetoresistive head, it means that the azimuth adjustments have been performed for all the magnetic information tracks.

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention.

FIG. 3 is a perspective view showing a state in which an embodiment of the present invention is mounted on a support block.

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is a schematic plan view showing a magnetic information track of a magnetic card.

[Explanation of symbols]

 10 Magnetic Information Track 14 Magnetoresistive Head 14a Sliding Surface 16 MR Sensor (Magnetically Sensitive Section) 18 Support Substrate 20 Holding Substrate

Claims (4)

[Claims] 1. A magnetoresistive effect type device comprising: a magnetic sensing part having a magnetoresistive effect; a supporting substrate to which the magnetic sensing part is fixed; and a protective substrate which is adhered to the supporting substrate to protect the magnetic sensing part. In the head, while the length of the magnetic sensing portion is made smaller than the width of the magnetic information track of the magnetic recording medium, the supporting substrate and the protective substrate are bonded with a resin adhesive, and the supporting substrate and the protective substrate are combined. A magnetoresistive head, wherein a gap adjusted to a predetermined value by a cylindrical polishing of the sliding surface is formed between the sliding surface facing the magnetic recording medium and the magnetic sensing portion. 2. The magnetoresistive head according to claim 1, wherein the resin adhesive is an epoxy resin adhesive or a phenol resin adhesive. 3. The magnetoresistive head according to claim 1, wherein at least one of the support substrate and the protective substrate is made of a transparent or semitransparent material. 4. The magnetoresistive head according to claim 1, wherein a plurality of the magnetic sensing parts are provided on the support substrate.