JPS62149199A - Static magnetic field shielding structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a static magnetic single field shield structure for preventing magnetic leakage failure in the field of electronic and electrical equipment, where mass and miniaturization are progressing. This relates to a static magnetic field shield structure that can be easily and inexpensively constructed to achieve static magnetic field shielding, has little weight increase due to construction, and can effectively achieve shielding under high magnetic flux density. be.

Various electronic and electrical devices have become extremely popular in recent years, but problems caused by magnetic leakage from permanent magnets incorporated in these devices have been raised as a major problem, and a solution to this problem is strongly required. Therefore, various studies are being conducted to prevent such magnetic disturbances, and one widely used method is to encapsulate the magnetic source with a static magnetic field shielding material such as permalloy or silicon steel plate. However, among the static magnetic field shielding materials used in the above-mentioned shielding method, permalloy has an insufficient 1i11 air shielding effect if it is a thin material, and a considerably thick material must be used in order to achieve the desired shielding effect. The problem is that it has to be done. In other words, the above method increases the weight and size of the equipment, but since the electronic and electrical equipment fields are becoming lighter and more compact, the crushed stone n-field shield structure also needs to be improved! It is required that the permalloy material be small in size and large in quantity, and the permalloy thick inner material as described above cannot be said to be able to satisfy these demands. Also permalloy white/
-) 1. + uirukyu/4. ) Δ This is a major cause of public failure and increases the construction cost of the static magnetic field shield structure. Furthermore, the above alloys themselves have poor formability and cannot be formed into complex shapes, and their magnetic shielding properties rapidly deteriorate as a result of the forming process. It also has the disadvantage of requiring annealing. - Almost the same situation exists for steel plates, and in order to exhibit a sufficient static magnetic field shielding effect, high grade steel plates must be used, so the price also rises. Moreover, in the case of a silicon steel plate, its formability is even worse, and it is not only difficult to form it into a complicated shape, but also requires an annealing treatment after forming.

As mentioned above, the method of magnetic shielding using static magnetic field shielding materials such as permalloy or silicon steel plate has various drawbacks and is not satisfactory, but poor formability is the most important problem to be solved. ing. Conventionally, therefore, magnetic shielding has been attempted by surrounding the magnetic source with a plate-like material or wrapping belt-like materials in layers without performing any molding process.

[Problems to be solved by the invention] However, it is difficult to completely seal the magnetic source by enclosing plate-like materials or overlapping belt-like materials, and magnetic leakage from gaps cannot be prevented, making it impossible to eliminate magnetic shielding defects. I can't do it.

Furthermore, the above method cannot handle complex shapes. In addition, when thin permalloy is used, there seems to be a tendency for magnetic leakage to increase rapidly as the strength of magnetization of the magnetic source increases.

The present invention was made by focusing on such magnetic fields, and the present inventors had previously filed a patent application (Japanese Patent Application No. 12687-1987).
4) An attempt is made to solve the above-mentioned problems at once by using a static magnetic field shielding material with L/3. In other words, the static magnetic field shielding material related to the above-mentioned prior application has excellent formability, is inexpensive, and has excellent magnetic shielding properties, but the conditions for effectively demonstrating its characteristics have not yet been established, and it is difficult to use it. Depending on the embodiment, magnetic shielding may not be effectively achieved. In particular, when the magnetic force of the magnetic source itself is small, the magnitude of the leaked magnetism is weak and the degree of damage is minor, but if it becomes large, the problem becomes serious, so it is necessary to prevent magnetic leakage in such cases. It is necessary to suppress the

[Means for solving the problems] The present invention that solves the above problems is based on a thickness of 0.01 to 1.0
The gist is that the static magnetic field shielding material, which is formed by laminating magnetic shielding metal plates via a non-conductive resin of 1.5 mm, is placed in a region where the magnetic flux density on the center line of the magnetic pole is 200 Gauss or more.

[Operation] The static magnetic field shielding material used in the present invention is made by laminating magnetic shielding metal plates through non-conductive resin, and is made of a non-magnetic material, non-conductive resin, and a metal material with high saturation magnetic flux density. The combination produces a static 6n field shielding effect. That is, although the non-conductive resin is a non-magnetic material like A1 etc., it exhibits a static magnetic field shielding effect superior to that of AI. On the other hand, the 6n air shielding metal plate exhibits a static magnetic field shielding effect by being magnetized itself, and is made of a metal material with a high saturation magnetic flux density. When such magnetic shielding metal plates are laminated with a non-conductive resin in between, it is possible to obtain a static magnetic field shielding effect that is greater than the simple sum of the static magnetic field shielding effects of both metal plates. Although the reasons for this effect have not been clearly determined, (1) a discontinuous magnetic field is formed within the static magnetic field shield by interposing a non-conductive material between the magnetic shielding metal plates; (2) The point where the distance between the magnetic shielding metal plate on the side far from the magnetic source and the magnetic source is secured by the non-conductive resin (
Distance maintenance function: magnetic flux density decreases in inverse proportion to the square or cube of the distance) and (3) the reason for this is that at least two magnetic shielding metal plates, the inner and outer ones, act to shield the superimposed static magnetic field. It can be mentioned as follows.

As described above, in the present invention, since a material having an excellent static magnetic field shielding effect is used, it is possible to reduce the weight of the static magnetic field shielding material necessary to ensure the same shielding effect.

Further, as will be described later, the material used is far cheaper than permalloy or silicon steel plate, and the static magnetic field shielding structure can be formed at low cost.

The non-conductive resin, which is one of the materials constituting the static magnetic field shield material, may be a film or sheet made of polyester resin, polyurethane resin, polypropylene resin, polyethylene resin, polycarbonate resin, or a modified resin. Examples include polyethylene heat-sealable films, modified polypropylene-based heat-sealable films, and the like. The thickness of the non-conductive resin needs to be 0.01 to 1.0 mm, and if the thickness is less than 0.01 mm, the mutual static magnetic field shielding effect due to lamination with the magnetic shielding steel plate will not be sufficiently exhibited. On the other hand, materials exceeding 1.0 m111 are excluded in order to meet the demands of the field of thin, lightweight, and excellent moldability.

On the other hand, the magnetic shielding metal plate, which is another material constituting the static magnetic field shielding material, is not particularly limited as long as it is a material with excellent formability and high saturation magnetic flux density, but specifically steel containing pure iron is used. Foil, steel plate, silicon steel plate with low Si content, etc. are recommended. Further, there is no need to set any special restrictions on the thickness of the magnetically shielding metal plate, but it is desirable to set the thickness to 0.04 to 1.0 +n+u in order to perform the disconnection function and meet market demands. That is, if the thickness is less than Q, 04 mm, the shielding effect of itself is insufficient, so the mutually stimulating shielding effect of lamination becomes weak, and since it is a thin film, manual labor is difficult and moldability is also reduced. On the other hand, if it exceeds 1.0 mm, it becomes difficult to meet the demands of the field of thinness, lightness, and excellent moldability as described above.

Next, regarding the number of laminated layers of the magnetic shielding metal plate, the number of laminated layers is 3 to 3.
Up to 5 layers, the static magnetic field shielding effect increases, but even after 6 layers, no further improvement is observed, and simply increasing the number of layers results in wasted material or reduced weight and thickness. It just makes it unnecessarily large. Therefore, it is desirable to limit the number of layers to five or less.

By the way, although the static magnetic field shielding material having the above structure generally has poor static magnetic field shielding performance, its shielding characteristics have not been sufficiently clarified.

Therefore, the inventors of the present invention developed the conventional permalloy, ■0.02m
Static magnetic field shielding material with steel foil laminated through m-thick modified polyethylene resin.

About the four types: ■ Quiet n-field shielding material laminated with steel foil through 0.1 mm thick modified polyethylene resin, ■ Static magnetic field shielding material laminated with steel foil through 1.0 mm thick polycarbonate resin. When the shielding characteristics of each were investigated under the same conditions, the results shown in FIG. 1 were obtained. The shielding characteristics are shown by plotting the magnetic flux densities of each shielding material on the magnetic generation source side and on the side opposite to the magnetic generation source in a case where the magnetic flux density is different at the shielding material placement position.

As shown in Figure 1, the shielding characteristics of Examples (■ to ■) and ■
Comparing the shielding characteristics of the conventional example, it is found that the conventional example exhibits better shielding characteristics when the 6n flux density at the shield placement position is low. However, in a high magnetic flux density region, the relationship between the two is reversed, and the example exhibits much better shielding characteristics. In addition, the laminated static magnetic field Thiefred O used in the present invention is
The thickness of the non-conductive resin is specified to be 0.01 to 1.0 mm because it is necessary to have sufficient static magnetic field shielding performance. Under these constraints, looking at the experimental results shown in Figure 1, we find that
It can be seen that the laminated static magnetic field shielding material exhibits better shielding characteristics than the conventional example in a region where the magnetic flux density is 200 Gauss or more. In practice, magnetic interference becomes a particular problem when the magnetic strength of the magnetic source is large, that is, when the magnetic flux density in the vicinity is high, and it is precisely at this time that static magnetic field shielding material is placed and the shielding structure is constructed. need to be formed. That is, in the present invention, the laminated static magnetic field shield material is arranged in a relatively high magnetic flux density region of 200 Gauss or more, and the shield structure of the present invention provides an excellent 611-magnetic shield at the required location. It can be effective.

[Embodiment Fig. 2.3 shows a static magnetic field shielding structure showing an embodiment of the present invention. A laminated magnetic field shielding material formed into a cup shape was placed so as to cover it. However, on the magnetic pole center line of the 611 magnetic fluid axis, the laminated magnetic field shield material wall was designed to be placed at a position where the magnetic flux density was 200 Gauss. Further, in FIG. 3, the micromotor section is covered with a sealed layered static magnetic field shielding material wall. In this case as well, the laminated static magnetic field shield material was designed to be placed at a position where the magnetic flux density was 200 Gauss on the magnetic pole center line of the micromotor section.

In all of the above examples, the static magnetic field shielding material was placed at a position on the magnetic pole centerline where the magnetic flux density was 200 Gauss or more, so that magnetic leakage could be efficiently prevented.

[Effects of the Invention] The present invention is configured as described above, and can obtain the effects summarized below.

(1) By using a static magnetic field shielding material made by laminating magnetically shielding metal plates with a non-conductive resin in between, it is possible to economically form a static magnetic field shielding structure that is lightweight and has excellent shielding properties. And so.

(2) By arranging the laminated static ffJ field shielding material with excellent formability in a region on the magnetic pole centerline where the magnetic flux density is 200 Gauss or more, the function of the static magnetic field shielding material can be effectively exhibited; It was possible to prevent harmful magnetic leakage.

[Brief explanation of drawings]

FIG. 1 is a graph showing the shielding characteristics of the static magnetic field shielding material according to the present invention and the conventional static magnetic field shielding material, and FIG. 2.3 is a schematic diagram showing an example of the present invention. 1...Magnetic source

Claims (1)

[Claims] A static magnetic field shielding material made by laminating magnetic shielding metal plates via a non-conductive resin with a thickness of 0.01 to 1.0 mm is placed in an area where the magnetic flux density on the center line of the magnetic pole is 200 Gauss or more. Characteristic static magnetic field shield structure.