JP2009164265A - Electromagnetic wave shield housing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave shield housing that is given a function of blocking electromagnetic waves by simple technique when a nonconductive material is used for a housing body. <P>SOLUTION: The electromagnetic wave shield housing includes a nonconductive housing body (comprising a case 11 and a cover 12) forming a closed space, and conductive nonwoven fabric or conductive woven fabric (made of carbon fiber, brass fiber, stainless steel fiber, or aluminum fiber as a suitable material applied to the nonwoven fabric or woven fabric) to be stuck on the entire inner wall surface of the housing body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shielding casing used for electronic equipment and the like.

  In electronic devices, a housing having a function of shielding electromagnetic waves may be used. Such a casing is generally made of a conductive material such as metal. However, in order to reduce the weight and reduce the cost, a non-conductive material such as a resin may be used as the material of the housing body. In this case, the entire body of the casing is provided with a function of shielding electromagnetic waves by plating with a conductive material, attaching a metal foil, or fixing a metal plate.

However, when these methods are adopted, it is necessary to require specialized techniques and advanced techniques, and a technique for providing a function of shielding electromagnetic waves more easily is demanded. In addition, as a related technique, there exists what was disclosed by patent documents 1-3.
JP 11-274793 A JP-A-11-68376 JP 2000-133980 A

  An object of the present invention is to provide an electromagnetic wave shielding housing capable of providing a function of shielding electromagnetic waves with a simple technique when a non-conductive material is used as a material of the housing body.

  The present invention employs the following means in order to solve the above problems.

That is, the electromagnetic wave shielding casing of the present invention is
A non-conductive housing body forming a closed space;
Conductive non-woven fabric or conductive woven fabric affixed to the entire inner wall surface of the casing body (note that carbon fibers, brass fibers, stainless steel fibers, aluminum fibers are applicable to these non-woven fabrics or woven fabrics) As a suitable example)
It is characterized by providing.

  According to the present invention, the housing body is non-conductive, but the conductive nonwoven fabric or the conductive woven fabric is attached to the entire inner wall surface of the housing body, thereby providing a function of shielding electromagnetic waves. Can do. As a result, a lightweight and inexpensive material such as a resin material can be employed as the housing body. And according to the present invention, it is only necessary to affix the conductive nonwoven fabric or the conductive woven fabric to the inner wall surface of the housing body, so that it is possible to easily shield electromagnetic waves without requiring specialized techniques or advanced techniques. Can be given. In addition, since the conductive nonwoven fabric or conductive woven fabric can be cut into an appropriate shape and attached to the inner wall surface of the housing body, the case where the housing body shape is complicated or the electronic components are complicated in the housing Even in the case of being placed in, it can be easily handled.

The housing body is provided with an insertion hole through which an electric wire is inserted,
When the conductive grommet that seals the gap between the inner wall surface of the insertion hole and the electric wire is attached to the insertion hole in a state of being electrically connected to the conductive nonwoven fabric or the conductive woven fabric. Good.

  By doing so, even if a hole is formed in the housing body, the function of shielding electromagnetic waves can be sufficiently exerted. Also in this case, the conductive non-woven fabric or the conductive woven fabric only needs to be cut at the portion through which the electric wire passes, so that it does not take time for processing.

  The conductive nonwoven fabric or the conductive woven fabric may be subjected to a treatment for forming an insulating film in a region including a region where a conductive portion of an electronic component housed in the housing body can come into contact.

  By doing so, it is possible to suppress a problem caused by a short circuit of an electronic component housed in the housing body while providing the housing with a function of shielding electromagnetic waves.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, when a non-conductive material is used as the material of the housing body, it is possible to provide a function of shielding electromagnetic waves with a simple technique.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
With reference to FIGS. 1-10, the electromagnetic wave shielding housing | casing which concerns on the Example of this invention is demonstrated.

<Basic configuration of electromagnetic shielding case>
With reference to FIGS. 1-5, the fundamental structure of the electromagnetic wave shielding housing | casing which concerns on the Example of this invention is demonstrated. FIG. 1 is a perspective view showing a state before assembly of an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 2 is an exploded view of a case constituting the casing body of the electromagnetic wave shielding casing according to the embodiment of the present invention. FIG. 3 is an exploded view of a lid constituting the casing body of the electromagnetic wave shielding casing according to the embodiment of the present invention. FIG. 4 is a plan view of a conductive nonwoven fabric or a conductive woven fabric attached to the case according to the embodiment of the present invention. FIG. 5 is a plan view of a conductive nonwoven fabric or a conductive woven fabric attached to the lid according to the embodiment of the present invention.

  The electromagnetic wave shielding housing 10 according to the present embodiment includes a housing body including a case 11 and a lid 12. Both the case 11 and the lid 12 are made of a non-conductive material (for example, resin). FIG. 1 shows a state before assembling the case 11 and the lid 12 constituting the casing main body, and the casing main body forming the closed space is obtained by attaching the lid 12 to the case 11.

  Conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 are attached to the inner wall surface of the case 11 and the inner wall surface of the lid 12, respectively. In addition, as a material applied to these nonwoven fabrics or woven fabrics, carbon fibers, brass fibers, stainless steel fibers, and aluminum fibers can be cited as preferred examples.

The conductive nonwoven fabric (or conductive woven fabric) 21 is configured to include a portion having the same shape and size as the inner wall surface of the case 11 so as to be attached to the entire inner wall surface of the case 11. In FIG. 4, a portion surrounded by a dotted line is a portion corresponding to the inner wall surface of the case 11. Similarly, the conductive non-woven fabric (or conductive woven fabric) 22 is configured to include a portion having the same shape and size as the inner wall surface of the lid 12 so as to be attached to the entire inner wall surface of the lid 12. Has been. In FIG. 5, a portion surrounded by a dotted line is a portion corresponding to the inner wall surface of the lid 12.

  The conductive nonwoven fabric (or conductive woven fabric) 21 is configured to be slightly larger than the inner wall surface of the case 11. That is, in FIG. 4, the outer portion 21 a of the portion surrounded by the dotted line is configured to be larger than the inner wall surface of the case 11. The conductive nonwoven fabric (or conductive woven fabric) 22 is also configured to be slightly larger than the inner wall surface of the lid 12. That is, in FIG. 5, the outer portion 22 a of the portion surrounded by the dotted line is configured to be larger than the inner wall surface of the lid 12.

  Here, these conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 can be easily obtained by, for example, cutting a sheet-like conductive nonwoven fabric (or conductive woven fabric) into a desired shape. Can do.

  The conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 configured as described above are attached to the inner wall surface of the case 11 and the inner wall surface of the lid 12, respectively. At this time, the portions surrounded by dotted lines in the conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 are attached so as to overlap the inner wall surface of the case 11 and the inner wall surface of the lid 12, respectively. In the state where the conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 are attached to the inner wall surface of the case 11 and the inner wall surface of the lid 12, respectively, the conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 are attached. Needless to say, these are bent along the inner wall surface of the case 11 and the inner wall surface of the lid 12.

  In this way, the conductive nonwoven fabrics (or conductive woven fabrics) 21 and 22 are attached to the entire inner wall surface of the case 11 and the entire inner wall surface of the lid 12, respectively. In addition, as an affixing method, it can employ | adopt appropriate methods, such as using a double-sided tape, using a staple, using a bis | screw etc.

  When the lid 12 is attached to the case 11, the outer portion 21a of the conductive nonwoven fabric (or conductive woven fabric) 21 and the outer portion 22a of the conductive nonwoven fabric (or conductive woven fabric) 22 are overlapped with each other. . As a result, the conductive nonwoven fabric (or conductive woven fabric) is provided over the entire inner wall surface of the electromagnetic wave shielding casing 10, and a closed space surrounded by the conductive material is formed. Therefore, the electromagnetic wave shielding housing 10 has a function of shielding electromagnetic waves, can prevent electromagnetic waves emitted from electronic components housed inside the housing from leaking to the outside of the housing, and the housing from the outside. It is possible to prevent electromagnetic waves from entering the inside.

<When providing an insertion hole through which the electric wire is inserted in the housing>
In an electronic device, in general, it may be necessary to draw an electric wire such as a power supply line or a signal line from the inside of the housing to the outside of the housing. In this case, an insertion hole for inserting the electric wire is required in the housing. Such a case will be described with reference to FIGS. FIG. 6 is a part of a front view showing a state before an electric wire is inserted when an insertion hole is provided in an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 7 is a part of a schematic cross-sectional view showing a state before an electric wire is inserted when an insertion hole is provided in an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 8 is a part of a front view showing a state where an insertion hole is provided in the electromagnetic wave shielding casing according to the embodiment of the present invention and a state where the electric wire is inserted. FIG. 9 is a part of a schematic cross-sectional view showing a state where an insertion hole is provided in the electromagnetic wave shielding casing according to the embodiment of the present invention and a state where the electric wire is inserted.

In the present embodiment, a case where the insertion hole 11a is provided in the case 11 among the constituent members of the housing body will be described. As shown in FIG. 7, the case 11 is provided with an insertion hole 11 a for inserting the electric wire 30. The conductive nonwoven fabric (or conductive woven fabric) 21 affixed to the inner wall surface of the case 11 is provided with a radial cut 21b at a portion corresponding to the opening of the insertion hole 11a. This notch 21b may be formed before or after attaching the conductive nonwoven fabric (or conductive woven fabric) 21 to the inner wall surface of the case 11.

  Moreover, in order to seal the clearance gap between the inner wall face of the penetration hole 11a, and the electric wire 30, the electroconductive grommet 40 is provided. The grommet 40 includes a through hole having a diameter smaller than the outer diameter of the electric wire 30. The electric wire 30 is inserted into the through hole, and the inner peripheral surface of the through hole and the outer peripheral surface of the electric wire 30 are in close contact with each other. . Further, the grommet 40 is provided with stopper portions 41a and 41b having an outer diameter larger than the inner diameter of the insertion hole 11a at both ends of the cylindrical body portion 41 having an outer diameter smaller than the inner diameter of the insertion hole 11a of the case 11. ing. Thus, when the grommet 40 is fitted into the insertion hole 11a, the outer peripheral edge portions of the stopper portions 41a and 41b are in contact with the inner wall surface side edge and the outer wall surface side edge of the insertion hole 11a. The grommet 40 is fixed to the insertion hole 11a (see FIG. 9).

  Further, in a state where the grommet 40 is fitted, the plurality of substantially triangular portions obtained by the cuts 21b of the conductive nonwoven fabric (or conductive woven fabric) 21 are bent toward the inner side of the case 11 so that the grommet 40 It will be in the state closely_contact | adhered to the outer peripheral surface of the stopper part 41a (refer FIG.8 and FIG.9). In the present embodiment, by mounting the O-ring 50, the plurality of substantially triangular portions are more reliably brought into close contact with the outer peripheral surface of the stopper portion 41a of the grommet 40. Thereby, the conductive nonwoven fabric (or conductive woven fabric) 21 and the grommet 40 are electrically connected.

  As described above, even when an insertion hole for inserting an electric wire through the housing is necessary, it is possible to form a closed space surrounded by a conductive material as much as possible. As described above, by making the grommet 40 conductive, even when the insertion hole 11a for allowing the wire 30 to be inserted into the case 11 is provided, it is surrounded by a conductive material as much as possible with a simple configuration. The closed space can be formed, and electromagnetic waves can be effectively shielded. However, it is also possible to adopt a non-conductive material for the grommet 40. However, in this case, when the conductive grommet 40 is employed by covering the grommet 40 with the conductive nonwoven fabric (or conductive woven fabric) 21 as indicated by a dotted line 21X in FIG. It is desirable to exhibit an electromagnetic wave shielding effect equivalent to the above.

<Short-circuit countermeasures using electronic components>
Depending on the usage environment, the conductive part of the electronic component housed in the housing may come into contact with the conductive non-woven fabric or the conductive woven fabric due to, for example, vibration or impact, causing a short circuit. In particular, when a high-voltage electronic component (for example, a regulator) is short-circuited, other low-voltage electronic components may be damaged. Therefore, a countermeasure for preventing such a problem will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view showing a short countermeasure part in the electromagnetic wave shielding casing according to the embodiment of the present invention.

  When the electromagnetic shielding case 10 is applied to a case of an electronic device or the like, a plurality of electronic components are accommodated therein. FIG. 10 schematically shows a case where a high-voltage electronic component 70 and two low-voltage electronic components 71 and 72 are arranged.

  In this embodiment, the conductive portion of the high-voltage electronic component 70 in the conductive nonwoven fabric (or conductive woven fabric) 21 attached to the inner wall surface of the case 11 has some influence (vibration or shock). ), A process of forming the insulating film 60 in the contactable region is performed. Specifically, an insulating material such as rubber or resin is impregnated near the surface of the conductive nonwoven fabric (or conductive woven fabric) 21. Note that the insulating film 60 may be formed so as to include a region where the conductive portion of the electronic component 70 can contact, or may be formed partially or over the entire region.

Moreover, like the electronic components 71 and 72, the conductive part is a conductive nonwoven fabric (or conductive woven fabric).
If contact with 21 does not cause a problem, the insulating film as described above may not be formed in a region where these conductive portions can contact.

<Excellent points of this embodiment>
As described above, according to the electromagnetic wave shielding casing 10 according to the present embodiment, the casing main body including the case 11 and the lid 12 is non-conductive, but the conductive nonwoven fabric (or conductive woven fabric) 21 and 22. Can be attached to the entire inner wall surface of the housing body to provide a function of shielding electromagnetic waves. As a result, the case 11 and the lid 12 constituting the housing body can be made of a lightweight and inexpensive material such as a resin material.

  And according to a present Example, since it is only necessary to affix the electroconductive nonwoven fabric (or electroconductive woven fabric) 21 and 22 to the inner wall surface of the case 11 and the lid | cover 12, respectively, it does not require a special technique and an advanced technique. It can easily have a function of shielding electromagnetic waves.

  Here, the conductive nonwoven fabric (or conductive woven fabric) can be cut into the shape of the inner wall surface of the housing body and pasted on the inner wall surface of the housing body. Even in the case where electronic parts are arranged in a complicated manner in the housing, it can be easily handled. For example, even if there are small irregularities on the inner wall surface of the casing body, the conductive nonwoven fabric (or conductive woven fabric) is flexible, so that the conductive nonwoven fabric can follow the irregularities without any special processing. (Or conductive woven fabric) can be attached. In addition, if the unevenness is large, the conductive nonwoven fabric (or conductive woven fabric) is divided into a plurality of sheets, and each is electrically connected to each other so as to be applied to the entire inner wall surface of the housing body. That's fine.

  In this way, the conductive nonwoven fabric (or conductive woven fabric) can be divided into a plurality of pieces and pasted so as to be electrically connected to each other. Even if the body body is very large, even if electronic parts are arranged in a complicated manner in the housing, it can be easily handled.

  Moreover, when providing the insertion hole through which the electric wire is inserted in the housing, as described above, the conductive grommet that seals the gap between the inner wall surface of the insertion hole 11a and the electric wire 30 in the insertion hole 11a. What is necessary is just to mount | wear in the state which electrically connected 40 to the conductive nonwoven fabric (or conductive woven fabric) 21.

  By doing so, even if a hole is formed in the housing body (case 11 in this embodiment), the function of shielding electromagnetic waves can be sufficiently exhibited. Also in this case, the conductive nonwoven fabric (or conductive woven fabric) 21 only needs to have a cut 21b in the portion through which the electric wire 30 passes, so that the processing is not time-consuming.

  Further, as described above, as a countermeasure against a short circuit of the electronic component housed in the housing, as described above, of the conductive nonwoven fabric (or conductive woven fabric) 21, the electronic component housed in the housing body (high in this embodiment) What is necessary is just to perform the process which forms the insulating film 60 in the area | region including the area | region which the conductive part of the electronic component 70) for voltage can contact. By doing so, it is possible to suppress a problem caused by a short circuit of an electronic component housed in the housing body while providing the housing with a function of shielding electromagnetic waves.

  In addition, electromagnetic wave shielding performance can be easily improved by sticking on the inner wall surface of a housing | casing main body in the state which piled up the conductive nonwoven fabric (or conductive woven fabric) several sheets.

<Experimental example>
Specific experimental contents and results will be described. As the case body, a rectangular parallelepiped resin product with an inner size of 225 × 150 × 40 mm and a thickness of 5 mm is used, and a metal woven fabric with a thickness of 200 μm is attached to the entire inner wall surface with a double-sided tape, and an electromagnetic wave. A shielded housing was made. As the electromagnetic shielding casing, a casing and a lid were used as in the above-described embodiment. Then, in the vicinity of the joint between the case and the lid, the metal woven fabric is exposed so that they are securely electrically connected.

  Further, the housing body is provided with an insertion hole for inserting the cable of the oscillation antenna, and the cable is pulled out from the inside of the housing with the conductive grommet attached to the insertion hole. The conductive grommet and the metal woven fabric were electrically connected.

  Using the sample configured as described above, an electromagnetic wave was oscillated from the antenna, and the electric field strength leaked to the outside of the housing was measured. The shield characteristics were evaluated based on the difference from the radiated electric field strength measured with a resin casing (without metal woven cloth and with conductive grommets). As a result, the shield characteristic was 50-60 dB, and it was confirmed that electromagnetic waves were reduced.

FIG. 1 is a perspective view showing a state before assembly of an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 2 is an exploded view of a case constituting the casing body of the electromagnetic wave shielding casing according to the embodiment of the present invention. FIG. 3 is an exploded view of a lid constituting the casing body of the electromagnetic wave shielding casing according to the embodiment of the present invention. FIG. 4 is a plan view of a conductive nonwoven fabric or a conductive woven fabric attached to the case according to the embodiment of the present invention. FIG. 5 is a plan view of a conductive nonwoven fabric or a conductive woven fabric attached to the lid according to the embodiment of the present invention. FIG. 6 is a part of a front view showing a state before an electric wire is inserted when an insertion hole is provided in an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 7 is a part of a schematic cross-sectional view showing a state before an electric wire is inserted when an insertion hole is provided in an electromagnetic wave shielding casing according to an embodiment of the present invention. FIG. 8 is a part of a front view showing a state where an insertion hole is provided in the electromagnetic wave shielding casing according to the embodiment of the present invention and a state where the electric wire is inserted. FIG. 9 is a part of a schematic cross-sectional view showing a state where an insertion hole is provided in the electromagnetic wave shielding casing according to the embodiment of the present invention and a state where the electric wire is inserted. FIG. 10 is a schematic cross-sectional view showing a short countermeasure part in the electromagnetic wave shielding casing according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electromagnetic shielding case 11 Case 11a Insertion hole 12 Lid 21 Conductive nonwoven fabric (or conductive woven fabric)
22 Conductive nonwoven fabric (or conductive woven fabric)
30 Electric wire 40 Grommet 41 Body portion 41a, 41b Stopper portion 50 O-ring 60 Insulating film 70, 71, 72 Electronic parts

Claims (3)

A non-conductive housing body forming a closed space;
A conductive nonwoven fabric or a conductive woven fabric, which is affixed to the entire inner wall surface of the casing body;
An electromagnetic wave shielding housing comprising: The housing body is provided with an insertion hole through which an electric wire is inserted,
A conductive grommet that seals a gap between the inner wall surface of the insertion hole and the electric wire is attached to the insertion hole in a state of being electrically connected to the conductive nonwoven fabric or the conductive woven fabric. The electromagnetic wave shielding housing according to claim 1, wherein:   The conductive nonwoven fabric or the conductive woven fabric is subjected to a process of forming an insulating film in a region including a region where a conductive part of an electronic component housed in the housing body can contact. The electromagnetic wave shielding casing according to claim 1.

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