JPH07106784A - Enclosure for electronic equipment - Google Patents

Abstract

PURPOSE:To intercept electromagnetic waves in a low-frequency domain by arranging a metallic plate in an enclosure made of a plastic containing conductive fibers. CONSTITUTION:An enclosure 10 made of a plastic containing conductive fibers is manufactured by molding a thermoplastic resin containing conductive fibers, such as metallic fibers like stainless steel fibers, carbon fibers, metal-coated carbon fibers like nickel-plated carbon fiber's, etc., into a prescribed shape by injection molding, etc. Four or more pedestals 11 are formed in the enclosure 10 and an electronic circuit board 12 is fixed onto the pedestals 11. In addition, a metallic plate 13 is arranged on the bottom of the enclosure 10. The plate 13 is connected to an electronic circuit on the circuit board 12 and grounds the circuit, but the full surface of the plate 13 is not connected to the circuit board 12. After bending part of the plate 13, the part is fixed together with the circuit board 12 on one of the pedestals 11 so that the plate 13 can be connected to the circuit 12 on the pedestal 11. Therefore, electromagnetic waves in a low-frequency domain of <=80MHz can be intercepted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a housing for electronic equipment having an excellent electromagnetic shield property.

[0002]

2. Description of the Related Art Conventionally, a housing of an electronic device is molded by a plastic resin, and the inside of the housing is sprayed with zinc or plated, or a plastic resin containing a conductive fiber is used. Imparts conductivity to the molded body,
The electromagnetic wave is given a reflection property to prevent the electromagnetic wave from leaking out and also to shield the electromagnetic wave from entering from the outside. The method using zinc spraying or plating not only complicates the manufacturing process, but also has a drawback that the sprayed layer or the plated layer is separated from the plastic layer, and the electromagnetic wave shielding property is deteriorated.

On the other hand, the case of a plastic molded product containing metal fibers, which has an advantage in the manufacturing process, has an excellent electromagnetic wave shielding property at a high frequency of 80 MHz or more, but shields an electromagnetic wave in a low frequency region smaller than that. There was a problem that the sex was insufficient.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention is to provide a case made of a conductive fiber-containing plastic and capable of blocking electromagnetic waves in a low frequency region.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a housing made of a conductive fiber-containing plastic for accommodating an electronic device, and a housing of the electronic device having a metal plate grounded inside the housing. Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a schematic partial perspective view for explaining the present invention. The conductive fiber-containing plastic casing 10 is made by mixing conductive fibers such as metal fibers such as stainless fiber, metal fibers such as carbon fiber and nickel-plated carbon fiber with thermoplastic resin, and performing injection molding or the like. It is formed into a predetermined shape by a usual method. Four or more pedestals 11 are formed inside the housing 10, and an electronic circuit board 12 is fixed thereon by a well-known means.

Examples of the thermoplastic resin include ABS resin, polystyrene resin, polypropylene oxide resin, acrylonitrile-ethylene propylene rubber-styrene copolymer resin, polycarbonate resin and polyester resin. The diameter of the metal fiber is 4 to 50 μm, and the diameter of the carbon fiber and the metal coat carbon fiber is 6 to 20 μm. These conductive fibers have a length of 500
The long fibers of μm to 1000 μm have a great effect on the electromagnetic shield effect. When stainless steel fibers are used, the content of the conductive fibers is preferably 4 to 15% by weight.

Two or more kinds of these conductive fibers can be used in combination. Among them, stainless fiber is preferable because it has high strength and high rigidity and can maintain a high length / diameter ratio even after processing. . A metal plate 13 is provided on the bottom of the housing 10.
Are arranged. The metal plate 13 is a plate made of aluminum, steel or the like and having a thickness of 50 μm to 300 μm. By providing the metal plate 13 on the housing 10 so as to be grounded, it is possible to shield electromagnetic waves in the low frequency region, which was difficult only with the conductive fiber-containing plastic housing. Therefore, the metal plate may be grounded to the housing, and the size of the metal plate 13 may be larger or smaller than that of the electronic circuit board.
The number of metal plates 13 may be one or two or more. Further, the size of the metal plate 13 may be the same as the size of the electronic circuit board 12, but it is preferable to make it larger than that in order to enhance the electromagnetic wave shielding property.

The metal plate 13 is connected to an electronic circuit on the electronic circuit board 12 and is grounded. For example, the electronic circuit board 12 and the metal plate 13 are not connected on the entire surface but are connected on the base 11 part. As described above, the metal plate 13 may be bent and formed on one of the pedestals 11 and fixed together with the circuit board 12. The pedestal 11 is provided for fixing the circuit board 12 to the housing, and is not essential.

[0009]

Example 1 A casing of a portable computer was prepared by injection molding using an ABS resin containing 8% by weight of stainless fiber having a fiber diameter of 8 mm. The housing is composed of an upper part and a lower part, and an aluminum sheet having a thickness of 100 μm is installed on the bottom surface of the lower part and the surface facing the bottom surface of the upper part, and fixed to the pedestal with screws. In addition, the aluminum sheets installed at the top and bottom are electrically connected with copper film tape.

As a result of measuring the interference wave based on the technical standard of VCCI (Voluntary Control Council for Radio Interference of Information Processing Equipment) using a portable computer having the above-mentioned housing with a lead frame, 30 MHz The standard of VCCI class 2 was satisfied in the measurement frequency region of 1000 MHz.

[0011]

The housing of the electronic device of the present invention has the effect of blocking electromagnetic waves in the low frequency region of 80 MHz or less because the metal plate is placed inside the housing made of conductive fiber-containing plastic.

[Brief description of drawings]

FIG. 1 is a partial perspective view.

[Explanation of symbols]

 10: case 11: pedestal 12: electronic circuit board 13: metal plate

Claims (1)

[Claims] 1. A housing for an electronic device, comprising a conductive fiber-containing plastic housing for housing the electronic device, and a grounded metal plate inside the housing.