JPH025033B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic shielding device for preventing electromagnetic interference and magnetic interference.

Traditionally, this type of interference has been treated as noise, electrical noise, static noise, radio frequency interference, etc. from the standpoint of preventing unnecessary electromagnetic wave pollution, but in recent years electromagnetic interference from electronic devices has become a major problem, and The frequency components and characteristics of sources have been classified and discussed, and their magnitudes have come to be measured and described in terms of electric fields, magnetic fields, the strength of electromagnetic fields, or the amplitudes of specific frequencies or frequency bands.

Generally, there are three types of shields: electrostatic shields, electromagnetic shields, and magnetic shields. Electrostatic shields prevent interference due to electrostatic coupling, and can be effective by passing current through and grounding even with a relatively high resistance. In addition, the frequency that electromagnetic shielding is symmetrical is mainly high frequency from 10kHz to 1000MHz, and it prevents magnetic flux interference by using low-resistance metal and using current flowing through it, and is subject to radio wave regulations. It's summery. Furthermore, magnetic shielding is mainly used for low frequencies and uses materials with high magnetic permeability to prevent the induction of magnetic flux, but this is not subject to radio wave regulations.

Furthermore, the transmission of electromagnetic interference between electronic devices is generally referred to as ``radiated electromagnetic interference,'' which is transmitted in the form of electromagnetic waves radiated into space, and shielding methods using metal materials have been established for a long time. In recent years, there has been a significant shift from metal materials to plastics due to design, weight reduction, economic efficiency, etc., and it has become impossible to meet electrical technical standards unless a plastic housing is shielded.

90% of the current shielding methods are spraying zinc on plastic surfaces or spraying or brushing conductive paint, and other techniques are still at the development and research stage. For example, applying ultrafine metal powder to a plate or box-like body to partially absorb electromagnetic waves, or amorphous metal produced by processing iron-cobalt-nickel alloy using ultra-quenching technology in the United States. Since the development of a ribbon-like material, it has become known to fabricate a flexible cylindrical body by weaving it singly or in a mesh to absorb electromagnetic waves. In any of these cases, the electromagnetic shielding effect is expressed in decibels (dB), and is generally put into practical use with an effect of about 30 to 40 dB. The level classification of the shielding effect is as follows: 0 to 10 dB: Almost no effect;
10-30dB: minimal effect is observed, and
30 to 60 dB is average, 60 to 90 dB above average, and 90 dB or more is represented by shielding with the best technology.

In general, amorphous metals have various material properties depending on the composition range of their components, but alloys with a magnetostriction of about 10×10 ^-6 are mainly used as magnetic shielding materials, and alloys with zero magnetostriction are mainly used as magnetic shielding materials. Used as a magnetic head material. This is a current crystalline metal, i.e., a metallic high magnetic permeability material that has a wide range of applications.It is an excellent material with effective magnetic permeability, saturation magnetic flux density, and low coercive force that is comparable to, or even higher than, permalloy alloys. However, in either case, it was limited to use as a single metal or as a material woven into a mesh.

The present invention has investigated and solved these problems, and has developed an amorphous amorphous metal that absorbs all electromagnetic waves from low frequencies to high frequencies, their directions and angles, with an extremely high shielding effect of 90 dB or more, eliminating any negative effects. The present invention provides a plate-like body that utilizes.

To explain the present invention based on the drawings, an amorphous alloy ribbon having a certain shape and having soft magnetic properties mainly composed of iron-cobalt-nickel manufactured by a continuous melt quenching method, that is, an appropriate ribbon as shown in FIG. A rectangular ribbon piece 2 whose tip is set at α and cut into an arbitrary length from a coiled ribbon 1 wound to a size.
If the rear end in the longitudinal direction is β, then this ribbon piece 2
As shown in FIG. 2, a plurality of ribbon pieces 2 are arranged in parallel with their leading ends α and rear ends β aligned in the same direction, and the side ends of adjacent ribbon pieces 2 are partially overlapped with each other, and are integrated into one piece. A sheet of plate-like body 11 is formed. In this case, there are various methods for forming the plurality of ribbon pieces 2 into a single plate-like body 11, such as covering the entire ribbon with plastic, integrating them with plastic tape, and bonding them together with adhesive. method can be taken.

However, the high-frequency current generator generates electromagnetic waves based on a high-frequency current of a constant output along the longitudinal direction A-A' of the ribbon piece 2 formed with this plate-like body 11 and the B-B' that intersects at right angles with this direction. When the electromagnetic wave is moved while generating, the direction of movement of this electromagnetic wave is A.
It has been found that in the -A' direction, no absorption effect, ie, electromagnetic wave attenuation effect occurs, but in the BB' direction, an absorption effect, ie, electromagnetic wave attenuation effect, occurs.

Also, magnetic powder such as iron powder is placed under the N to S magnetic field of the magnet, and the magnet is brought close to the magnetic powder at a distance where the magnetic powder is attracted, and the magnetic powder has an arbitrary size in the middle, as shown in FIG. 3A. For example, the plate-shaped body 11 consisting of a plurality of ribbon pieces 2 facing the same direction shown in FIG. ,
A comparison of two plate-like bodies 11 stacked with the directions α and β at right angles revealed that magnetic powder is not adsorbed better when the plate-like bodies 11 are stacked at right angles even if the number of stages is small. It worked. From this result, as shown in FIG. 3A, the plate-like bodies 11 facing the same direction
We confirmed the basic phenomenon that even if layers are layered, little damping effect can be obtained, and also clarified that simply increasing the thickness is not the answer, as is generally said. As a result, for electromagnetic wave shielding, simply forming a planar mesh shape as in the past has little shielding effect, and for electromagnetic waves, that is, radioactive electromagnetic interference, etc., the α to β direction of this ribbon piece 2 is It has been found that the combination of directions is extremely important, and the combination shown in FIG. 3B exhibits a particularly remarkable electromagnetic shielding effect.

As described above, the high-frequency electromagnetic wave shielding plate 10 of the present invention has a rectangular ribbon piece 2 created by cutting an amorphous metal ribbon 1.
A plurality of ribbon pieces 2 are arranged in parallel with their rear ends β aligned in the same direction, and the side ends of adjacent ribbon pieces 2 are partially overlapped and integrated to form a single plate-shaped body 11. The two plate-shaped bodies 11 are overlapped and integrated so that the longitudinal directions of the strip-shaped ribbon pieces 2 forming each plate-shaped body are substantially orthogonal to each other.

Next, a shielding device 12 using the electromagnetic wave shielding plate 10 of the present invention will be explained.

As shown in the top view of FIG. 4 and the cross-sectional view of FIG. The units connected by the frame 8 are used as a base, and each unit has one wall surface 4 and an adjacent wall surface 5,
The shield plate 10 of the present invention is adhered to each wall surface 4, 5 so that the directions of the ribbon pieces 2 are perpendicular to each other, or the plate-like body 11 is adhered to form a continuous plate-like assembly of hexagonal columnar units 3. Furthermore, as shown in FIG. etc.) The polygonal bodies 7 are alternately inserted obliquely at different angles and directions as shown, and fixed with double-sided adhesive tape or the like as shown in FIG. 6. The arrows in FIGS. 4 and 6 indicate an example of the α to β directions of the ribbon pieces 2 constituting the polygonal plate-shaped body 7 and the like.

Such a shield device has a remarkable effect against radiated electromagnetic waves from all angles and directions. A familiar example is a hair dryer,
When a rotating object such as a rotating toothbrush or a rotating eraser is brought close to the television, the screen changes; however, by placing each of these objects in a box-like body made of the above-mentioned device and sealing the source, the television screen becomes stationary.

In other words, it is extremely effective as an electromagnetic wave shielding device that can completely prevent the adverse effects of noise. For example, when soft PVC is used as the synthetic resin material in this device, it becomes a flexible electromagnetic shielding device, and when it is hardened with glass fiber reinforced plastic, it has features such as robustness, rust prevention, and weather resistance. It becomes an electromagnetic shielding device.

To briefly explain the function of this electromagnetic wave shielding device 12 with reference to the diagram, shielding absorbs or reflects the energy of electromagnetic waves and prevents the energy from being transmitted from the surface to the inside. The shielding effect is the degree to which the energy of electromagnetic waves can be attenuated.

FIG. 7 shows a hexagonal columnar unit 3 of the shielding device 12 using the electromagnetic wave shielding plate 10 of the present invention.
FIG. 2 is a diagram illustrating the effect of electromagnetic wave attenuation in an amorphous metal ribbon whose cross-sectional structure is shown in FIG. When the electromagnetic energy 9 collides with the shield plate 10 on the upper surface 6, part of it is reflected while the other part is incident, attenuated, and emitted into the hexagonal columnar unit 3 as a radiation component. Here, most of the energy is reflected by the polygonal plate-shaped body 7 installed diagonally to increase the reflection efficiency.
A significant damping condition then occurs due to walls 4, 5, etc. in which the ribbon pieces 2 are directed in different directions, for example, within the unit. Furthermore, even if a part of the reflected energy enters the adjacent unit, it is almost attenuated by the wall surface in a different direction and the polygonal plate-shaped body 7 in a different direction. Here, the energy that passes through the polygonal plate-shaped body 7 and weakens is attenuated by different wall surfaces in the same direction,
The remainder passes through the plastic frame 8 and reaches the shield plate 10 on the lower surface 6'. As with the shield plate 10 on the top surface 6, almost no energy is emitted to the opposite side due to the attenuation effect explained with reference to FIG. However, we were able to absorb it with a shielding effect of over 90dB and eliminate any negative effects. This shield device 12 is an example of using the shield plate 10 of the present invention, and by using the shield plate 10, depending on the planar or three-dimensional configuration, the same excellent effects can be obtained although there are differences in degree. It is something that plays.

In this way, the high-frequency electromagnetic wave shielding plate of the present invention has a plurality of strip-shaped ribbon pieces 2 created by cutting an amorphous metal ribbon, arranged in parallel with the leading and trailing ends at the time of cutting aligned in the same direction, and adjacent to each other. A strip-shaped ribbon piece in which the side ends of the ribbon pieces are partially overlapped and integrated to form one plate-shaped body, and the two plate-shaped bodies are further formed to form each plate-shaped body. Since the ribbons are overlapped and integrated so that their longitudinal directions are almost perpendicular to each other, electromagnetic waves do not leak from the gaps between the ribbon pieces, and the ribbon-like The front and rear ends of each ribbon piece that forms the body are in the same direction, and the ribbon pieces of the two overlapping plate-like bodies are almost perpendicular to each other. It can provide a shielding effect.

Therefore, by making effective use of the electromagnetic shielding plate of the present invention, it will not only be highly effective in the future industry, but also contribute to our lives in terms of regulations for preventing radio interference. There is something immeasurable about this.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an amorphous metal ribbon, Fig. 2 is an explanatory diagram of a plate-like body made up of ribbon pieces oriented in the same direction, and Fig. 3A is an illustration of a plurality of plate-like bodies having ribbon pieces oriented in the same direction stacked together. Fig. 4B is an explanatory diagram of an embodiment of the present invention, Fig. 4 is a top view of an electromagnetic shielding device using the present invention, Fig. 5 is a cross-sectional view thereof, and Fig. 6 is an explanatory diagram of an embodiment of the present invention.
The figure is a configuration diagram of one unit in the device, and FIG. 7 is an explanatory diagram of the electromagnetic wave attenuation state in the device. DESCRIPTION OF SYMBOLS 1... Amorphous metal ribbon, 2... Ribbon piece, 10... Electromagnetic shielding plate, 11... Plate-shaped body, α... Tip, β... Back end.

Claims (1)

[Claims] 1. A plurality of strip-shaped ribbon pieces 2 made by cutting an amorphous metal ribbon 1 are arranged in parallel with the cutting ends α and rear ends β aligned in the same direction, and the lateral ends of the adjacent ribbon pieces 2 are aligned. Partially overlapped with each other and integrated to form a single plate-shaped body 11,
Further, the two plate-like bodies 11 are overlapped and integrated so that the longitudinal directions of the strip-shaped ribbon pieces 2 forming each plate-like body are substantially perpendicular to each other. Electromagnetic shield plate for use.