JPH0697642B2 - Magnetic head core for prepaid card - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic head core used for recording and / or reproducing a so-called prepaid card such as a telephone card, a pachinko card, or a stored card.

[Conventional technology]

Conventionally, a magnetic head core has been used for recording and / or reproducing on a magnetic surface of a magnetic tape or a prepaid card. As a material for the magnetic head core, an Fe-Si-Al-based alloy (generally referred to as Sendust (registered trademark)) is widely used because it has excellent magnetic properties, wear resistance, and corrosion resistance. The manufacturing method of the magnetic head core using this Fe-Si-Al alloy is to manufacture an ingot of the Fe-Si-Al alloy, process the ingot into a flat plate by hot working, etc., and then cut and grind it. While processing into a predetermined shape by mechanical processing such as, removing the strain at the time of processing, and for the purpose of expressing appropriate magnetic characteristics, a method of manufacturing by annealing, a method of manufacturing a magnetic head core using a so-called bulk material and Alternatively, a molten Fe-Si-Al alloy is rapidly quenched into a thin strip using the roll method, annealed if necessary, and then a number of cores cored from this thin strip are bonded and laminated with an adhesive. And then polishing and manufacturing [[Latest magnetic head] Publisher: Mimatsu Data System, 1984 10
Issued on the 15th of the month]

On the other hand, in the prepaid cards used in recent years, the coercive force (Hc) of the magnetic medium on the magnetic surface is about 800 Oe
What has been, has improved to over 2750 Oe.

[Problems to be Solved by the Invention]

By the way, when recording and / or reproducing is performed on a prepaid card having a high coercive force of a magnetic medium having a magnetic surface as described above with a magnetic head core or a laminated magnetic head core using the bulk material described above, the magnetic field is reduced before the card is saturated. The head core is more saturated with the input current, and the previous signal may remain when overwriting (overwriting a different signal on the signal once written on the magnetic medium).
As a result, writing and reading mistakes occur. On the other hand, various types of printing have been performed on the surface of recent prepaid cards, and the thickness of the printing layer has been increased. Therefore, the gap between the magnetic medium on the magnetic surface and the magnetic head core is inevitably widened, and a magnetic head core that generates a stronger magnetic flux and has a high magnetic permeability is required.

Furthermore, from now on, there may be a demand for prepaid cards that can be used for multipurpose products, and in order to respond to this, it is necessary to improve the security of the information recorded on the cards. Is required to be further increased, or the input / output signal needs to have a complicated waveform. Further, it is required to improve the recording density of the card and the reproduction / recording speed.

In order for the magnetic head to meet these demands, a magnetic head core having a large magnetic flux density and a high magnetic permeability and having stable reproducing / recording characteristics from low frequencies to high frequencies is required.

Therefore, the present inventors have used a Fe-Si-Al-based alloy excellent in wear resistance and corrosion resistance for the purpose of developing a magnetic head core having high magnetic flux density and high magnetic permeability in order to meet the above demands. However, the research has been repeated focusing on the behavior of the magnetic characteristics. As a result, it was confirmed that the magnetic head core in which the thin ribbons are laminated has superior magnetic characteristics as compared with the magnetic head core made of a bulk material, and it is also found that even in the laminated magnetic head core, the magnetic characteristics vary considerably. did.
Then, the cause was investigated and the present invention was completed.

[Means for Solving the Problems]

The magnetic head core for a prepaid card according to the present invention, which has been developed by the above-described process, has a cross-sectional structure in the thickness direction of which the central part is a granular structure and the upper and lower parts are columnar structures.
-Si-Al-based alloy ribbons are formed by laminating a predetermined number of layers in the thickness direction.

〔Example〕

A thin strip according to the present invention having a thickness of 60 μm was produced from a molten Fe-Si-Al alloy composed of Si: 8.5 wt%, Al: 5.5 wt% and the balance Fe by a twin roll method at a linear velocity of 200 m / min. did. The cross-sectional structure in the thickness direction of the obtained ribbon is shown in Fig. 1 (a). As is clear from this figure, the thin ribbon according to the present invention has a cross-sectional texture form in the thickness direction in which the central part is a granular structure and the upper and lower parts are columnar structures. On the other hand, for comparison, the cross-sectional structure in the thickness direction of the ribbon obtained under the normal condition of a linear velocity of 500 m / min is shown in FIG. 1 (b). The usual condition is that the ribbon can be manufactured generally, and the cross-sectional structure of the ribbon is formed only by the columnar structure grown from the upper and lower surfaces.

When manufacturing an amorphous ribbon by the liquid quenching method as described above, it is possible to obtain a stable supercooled state by increasing the cooling rate as fast as possible (increasing the linear velocity), so the normal linear velocity is at least 300 m / min or more. I am taking it.

However, in the case of the ribbon of the crystal chamber such as Fe-Si-Al alloy, in the case of the twin roll method, when the linear velocity is 300 m / min or more, the ribbon having the cross-sectional structure as shown in Fig. 1 (b) is obtained. On the other hand, it was found that at a cooling rate slower than this, that is, at a linear velocity between 160 and 300 m / min, a ribbon having a cross-sectional structure as shown in FIG. Furthermore, it was found that a linear velocity between 190 and 230 m / min is preferable in order that each structure of the cross section shows a stable thickness. Further, the cross-sectional structure as shown in FIG. 1 (a) is obtained by cooling from one side of the ribbon as in the single roll method.
It was found that no cooling rate was obtained, and cooling from both sides of the ribbon as in the twin roll method was necessary.

Fig. 2 shows the increase in the thickness of the core material and μ1kHz and μ100kHz.
FIG. 3 is a diagram showing the relationship with the AC magnetic permeability in Example 2 by comparing a core material obtained by laminating the thin strips according to the present invention obtained above and a core material obtained from a bulk material. As is clear from this figure, in the core material in which the thin strips according to the present invention are laminated,
In the case of 60 μm, 1 mm, and 2 mm, the decrease in AC magnetic permeability due to the increase in the number of laminated layers was not recognized as shown by the measured values. On the other hand, in the core material obtained from the bulk material performed for comparison, the thickness of 0.2 mm, 1 mm, and 4 mm shows that the measured values show that the permeability increases as the thickness increases. It is clearly reduced by the effect. This means that when the thin strips according to the present invention are stacked, no matter how the number of stacked layers is increased, the magnetic flux sufficiently penetrates into all the thin strips in the stacking direction. A magnetic head core having a flat AC magnetic permeability can be obtained regardless of.

The thickness of the quenched ribbon of Sendust (registered trademark) alloy in the present invention is preferably 100 μm or less. Thickness 1
If it exceeds 00 μm, the rapid cooling effect cannot be obtained during the production of the ribbon, and the material becomes brittle.

On the other hand, the thickness of the core is preferably 0.1 mm or more. Thickness is 0.1mm
This is because, as shown in FIG. 2, the difference in AC magnetic permeability is less than that of the bulk material and the meaning of forming the core by laminating the thin strips is lost as shown in FIG.

Next, the thin strip according to the present invention was laminated to a thickness of 2.4 mm and was molded to manufacture a magnetic head core. The characteristics of the magnetic head core of the present invention were investigated using a prepaid card in which the magnetic medium of the magnetic surface has a high coercive force (Hc: 2750Oe). For comparison, the same investigation was performed using a magnetic head core molded in the same shape using a bulk material.
The results are shown in FIG. 3 (a) and FIG. 3 (b).
Shown in.

In FIG. 3 (a), the horizontal axis represents the current value during recording and the vertical axis represents the card output during reproduction. This figure shows that the smaller the current value during recording and the larger the card output during reproduction, the better the characteristics as a magnetic head core. As is clear from the figure, the magnetic head core of the present invention is made of a bulk material. It has a smaller current value and a larger output than the magnetic head core. That is, the magnetic head core of the present invention can record with a small current value and reproduce with a large output,
It has excellent properties.

The characteristic shown in FIG. 3 (b) is obtained by measuring the magnetic flux generated from the gap of the magnetic head core when a current is caused to flow in the magnetic head core. In the figure, the horizontal axis represents the current value flowing in the magnetic head core, and the vertical axis. Indicates the magnetic flux generated from the gap of the magnetic head core (ratio to the standard magnetic head core). In this figure, the larger the value on the vertical axis, the larger the magnetic flux generated from the magnetic head core and the better the recording characteristics. Therefore, as is clear from the figure, the magnetic head core of the present invention is superior to the magnetic head core of the bulk material also in this characteristic.

Further, FIG. 4 shows the effect of the change in the Fe content of the Fe-Si-Al alloy on the AC permeability, magnetic flux density and rust when the thin strip (thickness 60 μm) according to the present invention has a thickness of 0.2 mm. It is a figure which compares and shows the laminated core material and the core material which consists of a bulk material of the same thickness. According to this figure, there is a clear tendency for both materials to show a common tendency. That is, although the decrease in the AC magnetic permeability due to the improvement in the magnetic flux density (increase in the Fe content) has the same tendency, the absolute value of the core material according to the present invention is much larger than that of the bulk material. is there. This means that the core material according to the present invention can have a high magnetic flux density and a magnetic permeability equal to or higher than the magnetic permeability of the bulk material at a low magnetic flux density. By increasing the amount of Fe in the -Al alloy, it is possible to manufacture a magnetic head core having a high magnetic flux density and a high magnetic permeability. Further, the core material according to the present invention has the same amount of Fe.
As far as the amount is concerned, the number of rust points is far smaller than that of the core material made of bulk material, and the corrosion resistance is excellent. The reason why the core material according to the present invention is excellent in corrosion resistance is considered to be that the crystal grains are much smaller than the core material of the bulk material, and that casting defects and processing defects are small.

In the above description, the Fe-Si-Al alloy was described as a representative example of the Sendust (registered trademark) -based alloy according to the present invention, but other Fe-Si-Co, Fe-Si-Ge, Fe-Al-Ga alloys are also described. Of course, Sendust (registered trademark) alloys such as the above are also applicable.

〔The invention's effect〕

As described above, according to the magnetic head core for a prepaid card according to the present invention, magnetic characteristics of high magnetic flux density and high magnetic permeability can be obtained. For prepaid cards that have been printed with or for multipurpose prepaid cards with a high information density to be recorded, it is possible to process without overwriting the previous signal when overwriting, and therefore writing and reading errors on the prepaid card Can be reduced.

[Brief description of drawings]

FIG. 1 (a) is a sectional structural view in the thickness direction of the Fe—Si—Al alloy ribbon of the present invention, and FIG. 1 (b) is a thickness of the Fe—Si—Al alloy ribbon of a comparative example. Fig. 2 is a diagram showing the relationship between the increase in the thickness of the core material and the AC permeability at µ1kHz and µ100kHz. Fig. 3 (a) is the current value during recording and during reproduction. FIG. 3 (b) is a diagram showing the relationship between the current value applied to the magnetic head core and the magnetic flux generated from the gap of the magnetic head core, and FIG. 4 is a graph showing Fe-Si- Al
It is a figure which shows the relationship between the amount of Fe of an alloy, alternating magnetic permeability, magnetic flux density, and rusting.

Claims (1)

[Claims] 1. A quenching ribbon of a Fe—Si—Al alloy having a cross-sectional morphology in the thickness direction in the center of which is a grain structure and upper and lower columns of which are columnar structures is formed by laminating a predetermined number of layers in the thickness direction. A magnetic head core for a prepaid card, which is characterized by: