JPS6017997A - Radio wave shielding material - 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 the Invention The present invention relates to radio wave shielding that follows radio waves generated from electronic devices, electronic circuit units, etc. in a dynamic manner.・Background technology and its problems Receiving device or transmitting device equipped with an oscillator or high frequency amplification section,
Alternatively, in digital devices equipped with high-speed arithmetic circuits and digital processing circuits, high frequency ('f4)
L magnetic waves) may leak and interfere with surrounding video and audio equipment. For this reason, in some countries and regions, all electronic devices, including computer equipment, have a
Standards have been established to limit leakage radio waves of z or higher to below a certain level.

In order to meet these standards, it is sufficient to carefully scrub the radio wave shield of the device housing or the case of the circuit unit that is the source of radio waves, but since thick sheet metal with good processing accuracy is carefully used, This is contrary to the direction of reducing the weight and size of devices.

Materials made of polypropylene plastic structural materials filled with surface-treated mica (nickel-plated mica flakes, etc.), materials filled with aluminum flakes, materials filled with aluminum fibers, or plastics mixed with conductive substances such as metal or carbon. Structural materials are being researched. Attempts have also been made to mix ferrite-based radio wave absorbers into plastic structural materials or coating materials such as paint and rubber sheets.

Providing a radio wave shielding function to the molded structural material or covering material of the device housing in this way is useful in terms of making the device lighter and smaller. However, the housing, components, and circuit unit cases of electronic devices always have an opening, and radio waves leak through the gap between the lid and the housing that cover this opening. This problem cannot be solved by improving molded structural materials or covering materials. Generally, an opening in a housing or case is provided for the convenience of adjusting or repairing the internal circuit, and the lid is part of the side plate, top plate, or bottom plate of the housing or case, and these are usually screwed. It is removably fixed to the opening with a stopper or the like. These housings, cases, and removable side plates and top plates are usually made of as thin a sheet metal as possible in consideration of the weight and workability of electronic devices, so they can warp when fastened with screws, making it impossible to create a highly enclosed space. You can't expect to get anything. For this reason, measures have been taken to tighten and secure the side plates and bottom plates that close the openings of the housing and case with a large number of screws, but this is completely disadvantageous in terms of manufacturing man-hours and ease of maintenance and repair. .

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and the present invention has been made in view of the above-mentioned problems. It is an object of the present invention to provide a radio wave shielding material that can be inserted into a gap that occurs when the radio wave shielding material is blocked, and can obtain a sufficient radio wave shielding effect.

Summary of the Invention The radio wave shielding material of the present invention is a felt-like mixture of highly conductive metal fibers and flexible non-metallic fibers, and is made of a felt-like mixture of highly conductive metal fibers and flexible non-metallic fibers. When inserted into the gap that occurs in 17JJ, the gap is effectively sealed against radiated radio waves due to its flexibility (cushioning properties), and a sufficient radio wave shielding effect can be obtained.

Example The present invention will be explained below based on examples and with reference to the drawings.

FIG. 1 is a perspective view of the main body of an electronic device (sheet metal housing excluding the decorative frame) in which the radio wave shielding material according to the present invention is used, in which the top side of the box-shaped base frame (1) is removable ( 2)
This top plate (2) is made up of overhanging pieces (6a) to (3d) that protrude inward from the four upper edges of the base frame (1). The base frame (1) and the top plate (2) are made of thin sheet metal, and the overhanging pieces (
A gap is formed between 6a) to 6d and the four sides of the top plate (2), and radio waves leak to the outside through this gap.

Therefore, the plan view of the base frame (1) with the top plate (2) removed in Fig. 2, and the 6
As shown in Figures A to 6C, the four side overhang pieces (3a) to
(6d) along radio wave shielding sheet material (5a) to (
5e) is interpolated. These sheet materials (5a) ~
(5e) connects the top plate (2) and the overhanging pieces (3a) to (3
d) the gap between the two is almost sealed against radiated radio waves,
Leakage radio waves are significantly reduced. Sheet material (5aX5b)
- For example, it is a felt-like mixture of metal fibers (95 to 5 volumes) and organic fibers (5 to 95 volumes), and has extremely high flexibility (cushioning properties), so the gap between gaps is extraordinary. Even if there is a wide change along the mounting surface of the plate (2), it will adapt to this change and perform a sufficient sealing function.
Also, the mixed metal fibers, which have good conductivity, provide a sufficient radio wave shielding function. Other sheet materials (5C) ~
(5e) is a sheet material with a thickness of 0.8 mm ± 0.3 made by woven carbon fiber with a thickness of 7 μm, the weight is 90 g/m2, and the conductivity is 200 Ω with a length of 100 mm. It has a sexual nature. Therefore, this sheet material (5C) ~ (5
e) also has flexibility and exhibits similar properties as a sealed radio wave shielding material.

By using these sheets 4'A' (5a) to (5e), it is possible to sufficiently conduct the base frame (1) and the top plate (2) without using any special conductive means, and the casing It is possible to reduce induced interference to the outside by keeping the entire body at the same potential.

Felt-like sheet material (5aX5b) As the metal fiber used in the IC, stainless steel fiber, copper fiber, aluminum fiber, iron fiber, etc. with a fiber thickness of 8 μm to 60 μm can be used. Also, as an organic fiber, Fiber Tai! 1.
5De~15I)e wool, polyester, acrylic,
Fibers such as nylon can be used.

As an example, a stainless steel fiber with a thickness of 12 μm and a thickness of 3]
)e and polyester fibers having a length of 64 μm are mixed into a felt shape at a ratio of 50% by volume (dol punch) to produce a sheet material for radio wave shielding (5a) shown in Fig. 2.
~ (No. 5) was used, and a sufficient shielding effect could be obtained. This sheet material has a thickness of 2.7 mm±0.6,
It weighed 600 g/m 2 and exhibited conductivity of 50 Ω at a length of 100 mm. In addition, stainless steel fiber 3 is the same material as above.
The felt material, which is a mixture of 8t% of polyester fibers and 70% of polyester fibers, exhibits conductivity of 2Ω at a length of 100mm, and although its performance as a radio wave shielding material decreases somewhat, its sealing function is sufficient and it is the required material. radio wave shielding effect was obtained.

In addition, 50 body ff% stainless steel fiber (12 μm),
60 volume polyester fiber (3De x 64mm
), needle punch felt (weight 400 g/m2, thickness 2.5 mm) made of a mixture of 20 i% wool noil,
Needle punch felt (heavy fti: 250.ji'/m, thickness 1.6 mm) made of 50 volume thick stainless steel fiber (8 μm) and 70 volume thick acrylic fiber (5I) eX78 mm) can also be used as a radio wave shielding material with cushioning properties. It showed good properties.

Note that vegetable fibers can be used as the organic fibers, and other inorganic fibers such as glass fibers can also be used.

In the above-described embodiment, a flexible sheet-shaped radio wave shielding material is inserted into the gap between the main body and the lid plate attached to the opening of the device housing, but other structural parts, For example, the radio wave shielding material of the present invention can also be used in a partition plate mounting portion where the internal space of a housing is divided by a partition plate.

Effects of the Invention As mentioned above, the radio wave shielding material of the present invention is a felt-like mixture of highly conductive metal fibers and flexible non-metallic fibers, and exhibits sufficient flexibility and conductivity. It is. Therefore, when inserted into the gap between the edge 110 of the sheet metal case of an electronic device and its lid plate, the gap is effectively sealed due to its flexibility (cushioning properties).
Further, due to the conductivity, a sufficient shielding effect can be obtained in the secret area.

For this reason, even if thin sheet metal materials with low strength are used as mechanical structural materials for the device casing (main body) and lid plate, it is necessary to use a large number of screws to fix the lid plate in consideration of warpage caused by screw fixing. By combining it with this radio wave shielding material, it is possible to use electronic equipment that is lightweight, requires few screws, makes it easy to open and close the cover plate during service, and has a very low level of radio wave leakage. .

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main body of an electronic device in which the radio wave shielding material according to the present invention is used, FIG. 2 is a plan view of FIG. 1 with the top plate removed, and FIGS. 3A to 3C are respectively FIG. 2. FIG. In addition, in the drawing numbers, (1)・・・・・・・・・・・・Base frame (2)・・・・・・・・・・・・・・・・・・Top plate (6a) to (5d)... Overhanging pieces (4a) to (4d)... Screws (5a) to (5e)... Sheet material. Agent Katsu Ueya Yoshi Tsuneka Male Sugiura Sugiura Negative (Voluntary) Procedural Amendment 1. Indication of Matter A'1 1982 i:fn'f Kfi No. 125894'
U2゛54''゛''] 11711.3 F+; Relationship with radio wave shielding material all'l 'U2゛54''゛''] 17? l'rI! No. 5 (21
8) Soni - ('T-type company (2 others) 6, number of inventions increased by sleeve ■ 7 sleeve it (D subject) Detailed explanation of the invention in the specification, among the amendments in column 8?l Specification letter 3 In line 13 of the page, "Warping occurs," is corrected to "Warping occurs, and gaps may be created due to variations in the dimensions of individual parts during assembly of the device casing." 1 or more 443 −

Claims (1)

[Claims] A radio wave shielding material characterized by a felt-like mixture of highly conductive metal fibers and flexible non-metallic fibers.