JPH0750836B2 - Electromagnetic wave shield - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electromagnetic shield used for a cable penetrating opening of a metal housing of an electric or electronic device.

[Conventional technology]

Various electromagnetic wave shielding materials have been developed so far, but most of them are mixed with a plastic material 6 and conductive flakes or powders 7 in order to minimize transmission of electromagnetic waves as shown in FIG. A gasket material was used to reduce leakage at the contact surface of the molded product or the casing of the electronic device (for example, Industrial Materials Vol. 32).
No. 2).

However, when a device is connected to form a system, it may be necessary to provide an opening in the housing of the device for penetrating a coaxial cable, a bus cable, or the like. Since this kind of opening has different numbers and types of cables depending on the system configuration, it is possible to flexibly adapt to any system, at least larger than the connectors connected to both ends of the cable. Since the size is required, the diameter is relatively large.

[Problems to be Solved by the Invention]

However, this is not preferable for the purpose of shielding electromagnetic waves. Moreover, since such an opening cannot be covered with a shielding material, the electromagnetic wave shielding measures have not been taken. The use of equipment for which no measures are taken tends to cause electromagnetic interference with other equipment, and becomes a factor that prevents normal operation. Therefore, some measure for electromagnetic wave shielding against the indispensable housing opening has been demanded.

An object of the present invention is to provide an electromagnetic wave shield used for an opening for passing cables such as signal cables and bus cables.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, in the electromagnetic wave shield of the present invention, two or more sets of sheets arranged in parallel so that each side of the strip-shaped conductive rubber containing metal powder, conductive filler, etc. is in contact with each other. Of the conductive rubbers of the respective sets are stacked so that the arrangement directions of the conductive rubbers of the respective sets are different from each other, and the cable can be inserted between the conductive rubbers of the sets of the respective sheets that intersect each other.

[Action]

In a sheet in which strip-shaped conductive rubbers are arranged so that their sides contact each other without gaps, the individual conductive rubbers are in contact with the conductive rubbers that are adjacent to each other, and the equipotential is maintained as a whole. It has a function as a shielding material. When the cable is penetrated through this contact portion, a gap is created along the contact side. However, by using a structure in which the conductive rubbers of the sets of multiple sets are stacked so that the arrangement directions of the conductive rubbers are different from each other, the gap created by the penetration of the cable is limited to a very small part around the cable, and the electromagnetic shielding effect is improved. The drop is minimized.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electromagnetic wave shield according to the present invention. In the embodiment, a first sheet set A and a second sheet set B in which a plurality of strip-shaped conductive rubbers 1 are arranged so that their side edges 2 are in contact with each other without a gap are arranged. They are stacked so that the directions are perpendicular to each other. Since the cable passes through the intersection of the conductive rubbers 1,1 of the two sets A and B of the superposed sheets, the number of conductive rubbers used for both sets A and B is the opening where the electromagnetic shield is mounted. Adjust according to the maximum number of cables that can be passed through the section. As shown in FIG. 2, the peripheral portions of the sets A and B of both sheets are fixed to a conductive frame 3 made of metal or the like. These have a function as an electromagnetic wave shield because they are sandwiched and fixed by means of a conductive adhesive or the like so as to always maintain an equipotential.

FIG. 3 shows an example in which the electromagnetic wave shield according to the present invention is attached to a cable penetrating opening of a metal housing 4 of an electronic device. The metal housing 4 and the conductive frame 3 are fixed by screws, pressure bonding or the like while maintaining conductivity, and suppress electromagnetic waves leaking through the opening. The cable 5 for connecting to an external device is provided through the portions where the conductive rubbers 1, 1 of the two sets of sheets A and B intersect.

When inserting the cable 5, because of the viscoelasticity of the rubber,
It is possible to easily penetrate a cable having a relatively large connector or a bus cable having an elongated connector.

A gap is created between the adjacent conductive rubbers 1, 1 due to the penetration of the cable 5, but since the conductive rubbers of the two sets of sheets are stacked so that the arranging directions of the conductive rubbers are perpendicular to each other, the time is small in the vicinity of the cable. It stays in the part, and the reduction of the shielding effect can be suppressed to a small level. By using a set of three or more sheets and stacking the conductive rubbers of each set so that the arrangement directions of the conductive rubbers are different from each other, the gap is further reduced and the electromagnetic wave shielding effect is enhanced.

However, in order to simplify the structure, as shown in FIG. 4, it is possible to remove the conductive frame 3 and fix the conductive rubbers 1 of each set directly around the opening of the metal housing 4. At this time, as in the case of FIG. 2, it is necessary that the conductive rubber 1 and the metal casing 4 are always at the same potential by using a means such as screwing or a conductive adhesive.

〔The invention's effect〕

As described above, according to the present invention, there is an effect that effective electromagnetic wave shielding can be realized for the opening for passing the cable.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the electromagnetic wave shield according to the present invention, FIG. 2 is a view showing an example in which a conductive frame is used for fixing the electromagnetic wave shield, and FIG. The figure which shows the state installed in the cable penetration opening of a housing | casing, 4th
FIG. 5 is a view showing an electromagnetic wave shield having a simplified structure, and FIG. 5 is a perspective view of an electromagnetic wave shield according to the prior art. DESCRIPTION OF SYMBOLS 1 ... Belt-shaped conductive rubber, 2 ... Contact side of conductive rubber 3 ... Conductive frame, 4 ... Metal housing of equipment 5 ... Cable

Claims (1)

[Claims] 1. A belt-shaped conductive rubber containing a metal powder, a conductive filler, etc., has a set of two or more sheets arranged in parallel so that respective sides thereof are in contact with each other. An electromagnetic wave shield characterized in that the rubbers are superposed so that they are arranged in different directions, and that a cable can be inserted between the conductive rubbers of each pair of sheets that intersect each other.