JPH05250610A - Magnetic head - Google Patents

Abstract

PURPOSE:To ensure enhanced wear resistance and a reduced cost for a magnetic head obtd. by fixing a magnetic core for carrying out magnetic recording or reproduction of information by relative sliding on a magnetic recording medium in a head case. CONSTITUTION:The whole of an end of a magnetic core 3 and part of a case 1 enclosing the end of the magnetic core 3 at the magnetic recording medium sliding face 2 of a magnetic head are coated with a thin film 6 of titanium nitride, etc., having higher wear resistance than the magnetic core 3 and formed by a physical vacuum thin film forming method such as ion plating. The wear resistance of the sliding face 2 can be enhanced and the wear resistance of the end of the magnetic core 3 especially requiring wear resistance can be enhanced. A low-cost material can be used as the core material and the cost of the magnetic head can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head in which a magnetic head core which slides relative to a magnetic recording medium to magnetically record or reproduce information is fixed in a head case.

[0002]

2. Description of the Related Art In a magnetic head of the type described above, abrasion of a sliding surface of a magnetic recording medium due to sliding on the magnetic recording medium poses a problem. For example, in an induction type magnetic head that performs magnetic recording or reproduction by relatively sliding a magnetic core on a magnetic recording medium, the characteristics deteriorate with time due to wear of the magnetic core due to sliding on the magnetic recording medium. Particularly, in a magnetic head used in a magnetic card reader for reading information magnetically recorded on a magnetic card using a magnetic card as a magnetic recording medium, the sliding surface is severely worn and long-term reliability is required. Therefore, sliding wear becomes a problem.

Therefore, conventionally, as a countermeasure against such sliding wear of the magnetic head, first, in order to enhance the wear resistance of the sliding surface of the magnetic head, the magnetic core is made of a material having excellent wear resistance such as sendust. The forming structure is adopted. Further, as a structure for subjecting the sliding surface of the magnetic head to a surface hardening treatment, a structure for so-called boronizing for diffusing boron ions on the sliding surface as described in JP-A-52-90209, and JP-A-52-90209 are disclosed. As described in No. 52-49008, a structure in which the surface is subjected to an ion nitriding treatment has been proposed. As another structure, a structure has been proposed in which a thin film having excellent wear resistance is formed on the magnetic sliding surface of the magnetic head in the magnetic core, particularly in a region excluding the periphery of the magnetic gap. The reason why the film is not formed in the region of the magnetic gap is to avoid a decrease in output of the magnetic head.

On the other hand, as another measure against the sliding wear of the magnetic head, the magnetic head is replaced with a new one before the wear amount exceeds a certain level and the deterioration of the characteristics of the head exceeds an allowable limit. A structure has been proposed that can be identified by the appearance of the head.

FIG. 4 shows a conventional example of such a structure. The head illustrated here is the head for the magnetic card reader described above. Reference numeral 1 is a case for accommodating the whole, and the surface provided with the opening 1a on the front side in the figure slides on a magnetic recording medium sliding surface (hereinafter referred to as sliding) on a magnetic card of a magnetic recording medium (not shown). 2). Further, reference numeral 3 is a magnetic core, and a pair of core halves is connected to a magnetic gap 4
It is configured by butt-joining via a coil, and a coil is wound around a rear portion (not shown).

Then, the magnetic core 3 is fitted into the case 1 together with other magnetic head constituent members (not shown), and the front end surface of the magnetic core 3 provided with the magnetic gap 4 is exposed to the opening 1a of the case 1. A magnetic head is constructed by casting a fixing material (not shown) made of resin in the inside of the magnetic head 1. The sliding surface 2 is polished to a mirror surface by circular polishing so that a magnetic card (not shown) slides smoothly.

In addition to such a structure, in order to determine the wear amount and wear state of the sliding surface 2 as described above, the magnetic gap of the magnetic core 3 is formed at the upper and lower side edges of the sliding surface 2 in the figure. The concave portions 5 and 5 having a predetermined depth are provided in the vicinity of the respective portions 4 by processing, for example, by grinding.

With such a structure, it is possible to determine the amount of wear and the state of wear of the sliding surface 2 based on the height difference between the bottom surfaces of the recesses 5 and 5 and the sliding surface 2.

[0009]

However, each of the above-mentioned structures has the following problems.

According to the structure in which the magnetic core is made of a material having excellent wear resistance such as sendust, the head for a magnetic card reader or the like has a high wear rate, and the head needs to be replaced frequently for maintenance. It will be troublesome. Also, core materials such as sendust are expensive and costly.

In the method of hardening the sliding surface by boronizing or ion nitriding, the materials that can be hardened are limited, and the materials forming the sliding surface of the magnetic head are limited. In addition, these processes are 40
Since it is performed at a high temperature of 0 ° C. or higher, there is a problem that the resin of the fixing material that fixes the magnetic core is deformed.

Further, according to the structure in which the thin film having high wear resistance is formed on the magnetic core portion on the sliding surface, especially on the portion excluding the magnetic gap peripheral portion, the magnetic core portion particularly requiring the wear resistance, especially the magnetic gap peripheral portion, is formed. Since no film is formed on the part, the effect of improving wear resistance is insufficient.

[0013]

In order to solve such a problem, according to the present invention, a magnetic head core that slides relative to a magnetic recording medium to magnetically record or reproduce information is used as a head case. In a magnetic head fixed inside, on the sliding surface of the magnetic recording medium consisting of the end faces of the magnetic head core and the head case, the entire end face of the head core and a part of the head case surrounding the end face of the head core. A thin film having a higher wear resistance than the magnetic head core is formed.

[0014]

According to the magnetic head having such a structure, a thin film having good wear resistance can be reliably formed on the entire magnetic head core including the magnetic gap, and the wear resistance is dramatically improved.

[0015]

Embodiments of the present invention will be described in detail below with reference to FIGS.

FIG. 1 shows, as an embodiment of the present invention, the structure of a magnetic head for a magnetic card reader as in the above-mentioned conventional example. In the figure, parts that are the same as or correspond to those of the conventional example shown in FIG.

The basic structure of the magnetic head of this embodiment is similar to that of the above-mentioned conventional example, and the magnetic gap 4 is formed on the tip surface.
The magnetic core 3 provided with is fitted into the case 1 together with other magnetic head constituent members, and the front end surface of the magnetic core 3 is exposed to the opening 1a formed in the surface forming the sliding surface 2 of the case 1. A magnetic head is formed by casting a fixing material (not shown) made of resin in the case 1. The sliding surface 2 is mirror-polished.

In addition to the basic structure as described above, in this embodiment, in order to easily discriminate the wear amount and wear state of the sliding surface 2 from the appearance of the magnetic head, the conventional sliding method is adopted. Instead of providing a recess in the moving surface 2, the sliding surface 2
In this case, a thin film 6 made of TiN (titanium nitride) is formed on the sliding surface 2 as a non-magnetic material having a color significantly different from that of the base and having a higher wear resistance than the magnetic core 3. The thin film 6 is formed so as to cover at least the magnetic gap 4 of the magnetic core 3 on the sliding surface 2. In this case, the magnetic core 3
The film is formed so as to cover the entire front end surface and the surrounding portion. Also, the thickness of the thin film 6 should be uniform over the whole area,
For example, it is about 2 μm.

Since the thin film 6 is formed after the magnetic head is assembled and the sliding surface is polished, the magnetic core 3 is formed.
It is necessary to form a film at a temperature at which the resin of the fixing material for fixing the to the case 1 does not deform. For this reason, the thin film 6 is not suitable because the processing temperature is high in plating or CVD (chemical vapor deposition), and the physical vacuum thin film forming method is most suitable. Among them, ion plating is especially suitable for mass production, and the adhesion strength of the thin film is strong.
It is optimal because it can form a thin film of ceramics such as N.

The TiN thin film is formed by ion plating using an ion plating apparatus as shown in FIG. 2 as follows. That is, first, pure titanium is used as the evaporation source 7 of the ion plating. In the apparatus, a magnetic head 8 for forming a film is supported by a supporting electrode 9 so as to face the evaporation source 7, and a positive DC voltage of about several tens of volts is applied. Then, after evacuating the inside of the apparatus to a high vacuum by a vacuum pump (not shown), nitrogen gas is inserted into the apparatus as a reactive gas through the operation valve 10. Further, an electron beam is irradiated to the evaporation source 7 by a 270 ° EB gun (electron gun) that deflects the electron beam by 270 ° and irradiates it while applying a positive DC potential of about 100 V to the bias electrode 11. As a result, the titanium particles ejected from the evaporation source 7 are ionized by the electric field of the bias electrode 11 and react with nitrogen gas to become titanium nitride, which is attached to the sliding surface 2 of the magnetic head 8 and Ti
An N thin film is formed.

In this case, the magnetic head 8 is heated, but its temperature is not so high and is slightly higher than 100.degree. Then, the resin of the fixing material has a high glass transition point so that the resin of the fixing material of the magnetic core 3 of the magnetic head 8 is not deformed at this temperature, and changes at a temperature of about 150 ° C.,
Select one that does not deform.

Further, in this case, when the resin of the fixing material is exposed on the sliding surface 2, the thin film 6 is easily peeled off. Therefore, the size of the opening 1a of the case 1 is almost the same as the size of the tip surface of the magnetic core 3. Similarly, the resin of the fixing material is not exposed to the sliding surface 2 as much as possible.

As described above, according to this embodiment, the thin film 6 made of TiN is formed on the sliding surface 2, and the thin film 6 is used to determine the wear state of the sliding surface 2. That is, when the thin film 6 is worn and removed by the sliding wear of the medium with the magnetic card, the base of the sliding surface, that is, the magnetic core 3 is exposed at the removed portion, and the thin film 6 and the magnetic core 3 are exposed as described above. Since the colors are remarkably different, the areas of different colors of the thin film 6 and the magnetic core 3 on the sliding surface 2 change, and this change allows the wear state of the sliding surface 2 to be easily discriminated at a glance.

Particularly, the thin film of TiN has a golden color, and the magnetic core 3 is generally white or silver, but it is markedly different and suitable for the above discrimination. As other ceramics having excellent wear resistance, for example, SiC is black and Al2O3 is white, both of which are not so conspicuous and are not suitable for the above function.

3A to 3C show the sliding surface in the head of this embodiment due to the change of the different color regions of the thin film 6 and the base (magnetic core 3) on the sliding surface 2 as described above. 2 shows how the wear state is discriminated. The wear test is sequentially performed by attaching the magnetic card guides 13 and 13 and the mounting feet 14 to the magnetic head and incorporating them into the magnetic card reader. The state of running sliding path, the state of sliding running 3 million paths,
And a state in which sliding travel for 6 million passes is shown.

As shown in FIG. 3A, the abrasion of the thin film 6 is small and the removed portion of the thin film 6 is not present after 1 million passes.

However, when the number of passes is about 3 million, FIG.
As shown in (B), the thin film 6 is scraped off at both sides of the magnetic gap 4 where the magnetic card slides most strongly,
A removed portion indicated by reference numeral 15 is generated, and the tip end surface of the magnetic core 3 is exposed in the removed portion 15.

Then, after about 6 million passes, FIG.
As shown in (C), the removed portion 15 of the thin film 6 spreads along the magnetic gap 4, and the magnetic gap peripheral portion of the magnetic core 3 is exposed at the same portion. In this state, since the wear of the peripheral portion of the magnetic gap 4 has already started, it is better to replace the magnetic head. Even after the magnetic gap 4 is almost entirely exposed, the head can be used for about 1 million more passes, but it takes time to replace the head. It is better to look at the time of about 1 million pass quantiles as a margin time to wait. In this way, the magnetic head can be replaced before the malfunction of the magnetic card reader occurs, and no inconvenience occurs.

As described above, according to the magnetic head of the present embodiment, the wear state of the sliding surface can be extremely easily changed by the change of the different colored areas of the thin film 6 and the magnetic core 3 of the base on the sliding surface 2. You can tell at a glance. Moreover, since the thin film 6 can be uniformly managed with extremely high accuracy of, for example, about 0.1 micrometer by forming the thin film 6 by, for example, ion plating as described above, the wear state of the sliding surface 2 can be determined. Can be done accurately. Then, it is possible to accurately determine the proper replacement time of the magnetic head for sliding wear, and it is possible to perform good maintenance of the magnetic card reader.

Further, according to this embodiment, since the wear resistance of the thin film 6 is superior to that of the magnetic core 3, the wear resistance of the sliding surface 2 can be improved. In addition, since the thin film 6 is formed on the entire tip surface of the magnetic core 3 including the magnetic gap 4, the wear resistance of the magnetic core 3 itself, which particularly poses a problem of wear resistance on the sliding surface, can be improved.

When the thin film 6 is formed on the magnetic gap 4 of the magnetic core 3 as in this embodiment, the electromagnetic conversion output of the magnetic head is reduced, but in the case of a head for a magnetic card reader, the magnetic field of the medium is reduced. Since the output from the card is large, the recording wavelength is long, and the signal processing is digital processing, the above-mentioned decrease in output does not pose a problem.

Further, according to the present embodiment, the wear resistance of the magnetic core 3 can be effectively improved in this way, so that an inexpensive material such as permalloy can be used as the core material without using expensive sendust. Therefore, the cost of the head can be reduced accordingly.

Further, according to the present embodiment, the thin film 6 can be formed at a temperature of about 100 ° C. as described above, so that the problem due to the deformation of the resin of the fixing material can be avoided.

The material for forming the thin film 6 such as the magnetic core 3 forming the sliding surface 2 is not particularly limited, and the degree of freedom in design is increased.

As described above, when the thickness of the thin film 6 is set to about 2 μm, the adhesion strength and the quality of the TiN film are good, and the output of the magnetic head is less likely to decrease. It is not limited to. In consideration of wear resistance, the thickness of the thin film 6 is preferably in the range of about 0.5 μm to 5 μm in the case of TiN, and the above-mentioned effect is appropriately obtained.

The structure for forming the thin film is not limited to the magnetic head for the magnetic card reader, but can be applied to other magnetic heads.

[0037]

As is clear from the above description, according to the present invention, a magnetic head core for sliding information relative to a magnetic recording medium to magnetically record or reproduce information is fixed in a head case. In the head, in a magnetic recording medium sliding surface composed of the end faces of the magnetic head core and the head case, the head spans the entire end face of the head core and a part of the head case surrounding the end face of the head core, and By adopting a structure in which a thin film that is more wear resistant than the magnetic head core is formed, the wear resistance of the magnetic head is dramatically improved, cost can be reduced, and design flexibility can be obtained. Excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a magnetic head according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a film forming method by ion plating of a thin film formed on a medium sliding surface of the same head.

FIG. 3 is an explanatory diagram showing a worn state of a sliding surface due to different numbers of times of medium sliding in a wear test conducted on the head.

FIG. 4 is a perspective view showing the structure of a conventional magnetic head.

[Explanation of symbols]

 1 Case 2 Magnetic Recording Medium Sliding Surface 3 Magnetic Core 4 Magnetic Gap 6 Thin Film 8 Magnetic Head 15 Thin Film Removal Area

Claims (3)

[Claims] 1. A magnetic head in which a magnetic head core for performing magnetic recording or reproduction of information by sliding relative to a magnetic recording medium is fixed in a head case, the magnetic head core and an end surface of the head case. On the sliding surface of the magnetic recording medium, a thin film is formed which extends over the entire end surface of the head core and a partial region of the head case surrounding the end surface of the head core and which has a higher wear resistance than the magnetic head core. A magnetic head characterized in that 2. The magnetic head according to claim 1, wherein the thin film is formed by a physical vacuum thin film forming method. 3. The magnetic head according to claim 1, wherein the thin film is made of titanium nitride and is formed by ion plating.