JPH0513979A - Electromagnetic shielding body - Google Patents

Abstract

PURPOSE:To provide an electromagnetic shielding body around the joint or the door of a metal case so as to prevent electromagnetic wave from leaking out of the metal case concerned. CONSTITUTION:An electromagnetic shielding body 1 is of integral structure composed of a conductor rod 5 provided with a groove U-shaped in cross section and a magnetic substance 2 formed of a rod-like magnetic substance 3 and a rod-like magnet 4 and filled into the groove provided to the conductor 5. As the rod-like magnet 4 is magnetized in a direction vertical to the lengthwise direction, the rod-like magnetic substance 3 kept in contact with the rod-like magnet 4 is magnetized in a crosssectional direction. Therefore, the shielding body 1 becomes high in magnetic permeability to a magnetic component in the lengthwise direction of the magnetic substance, so that it enables leakage electromagnetic waves possessed of a magnetic field component in the same direction to be much attenuated. Therefore, a metal case mounted with an electromagnetic shielding body of this design is not required to be equipped with a special structure so as to come into tight contact with the shielding body and has an enough shielding effect to a electromagnetic wave source of low impedance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic shield for suppressing unnecessary electromagnetic waves radiated from electronic equipment and for preventing electromagnetic waves from leaking or entering by being used in an electromagnetic shield room, and more particularly to a joint portion of a metal casing or The present invention relates to an electromagnetic shield that is used in a door portion of an electromagnetic shield room to suppress electromagnetic waves leaking from a seam or a gap around the door.

[0002]

2. Description of the Related Art When electromagnetic shielding is performed, the conductivity of a conductor such as a metal is generally low at a portion of the conductor.
Electromagnetic waves tend to leak, and it is necessary to install an electromagnetic shield at the contact portion between conductors such as metals to suppress the leaking electromagnetic waves.

A conventional electromagnetic shield of this type is shown in FIG.
1A is a cross-sectional view and FIG. 1B is a perspective view.
A conductive electromagnetic shielding material such as an EMI gasket 52 in which a conductive rubber is tubular as shown in the sectional view of FIG. 5 (a) and the perspective view of (b) is known (“Key points of electromagnetic shield and earth system”). , See Japan Industrial Technology Center). The electromagnetic shield shown in FIG. 14 utilizes the spring action of a metal piece, and the electromagnetic shield shown in FIG. 15 utilizes the elasticity of conductive rubber. Both of them are interposed between the contact portions of the conductors and are used for improving the conductivity thereof.

[0004]

However, the conductive electromagnetic shield material shown in FIGS. 14 and 15 is the shield finger 51, the gasket 52 and the housing, the mounting portion of the electromagnetic shield chamber, or the shield finger 51 and the gasket 5.
Since the magnitude of the contact resistance between the conductor portion 2 and the conductor portion that contacts 2 influences the leakage effect of electromagnetic waves, a mechanism for strengthening the contact was necessary. Furthermore, shield finger 5
1. When the gasket 52 is used, there is a problem that the secular change in spring action and elasticity causes a decrease in the shielding effect.

Further, the shielding effect is reduced in the low frequency band with respect to the electromagnetic wave source of large current and small voltage type and low impedance (Technical Research Report of IEICE, EMCJ9).
0-48).

An object of the present invention is to provide an electromagnetic shield for suppressing leakage of electromagnetic waves, which is used around a joint portion of a metal housing or a door, and in particular, does not require a special mechanism for strengthening the contact and has a low impedance. Another object of the present invention is to provide an electromagnetic shield that can sufficiently shield the electromagnetic wave source in the low frequency band.

[0007]

In order to achieve the above object, the electromagnetic shield according to the first invention is an electromagnetic shield having a conductor and a magnetic body, the conductor comprising:
It is rod-shaped or plate-shaped, with grooves formed in its lengthwise direction,
The magnetic body is arranged in the groove of the conductor, and a magnetic field in a direction perpendicular to the length direction of the groove is applied.

In the second aspect of the invention, there is provided an electromagnetic shield having a conductor and a magnetic body, wherein the conductor and the magnetic body are rod-shaped and arranged alternately, and the magnetic bodies are the length of the conductor. A magnetic field in a direction perpendicular to the direction is applied.

According to the third aspect of the invention, there is provided an electromagnetic shield having a conductor, a magnet, and a magnetic body, wherein the conductor is rod-shaped or plate-shaped, and a groove is formed in the longitudinal direction thereof. The magnet and the magnetic body are combined with the structure, embedded in the groove of the conductor and integrated with the conductor, and the magnet is magnetized in a direction perpendicular to the length direction of the groove. The magnetic body is disposed in contact with the magnetized surface of the magnet.

According to a fourth aspect of the present invention, there is provided an electromagnetic shield having a conductor, a magnet and a magnetic body, wherein the conductor has a rod or plate shape, and the magnet and the magnetic body have a rod or plate structure. The magnet is magnetized in a direction perpendicular to the longitudinal direction of the conductor, and the magnet is magnetized by the magnet. It is arranged in contact with the surface.

In the fifth invention, part or all of the conductor of the fourth invention is an electromagnetic shielding material having elasticity.

Further, in the sixth invention, an electromagnetic shield having a conductor, a magnet, and a magnetic body, wherein the conductor has a conductive electromagnetic shield having elasticity in at least a part thereof. And the conductive electromagnetic shielding material is
Part of it has one or more rows of grooves, the magnet and magnetic body are combined with the structure and embedded in the groove of the conductive electromagnetic shielding material, and the magnet is perpendicular to the length direction of the groove. The magnetic body is magnetized in any direction, and the magnetic body is disposed in contact with the magnetized surface of the magnet.

According to the seventh aspect of the invention, there is provided an electromagnetic shield having a conductor and a magnetic body, the conductor being a magnet having conductivity, and the magnetic body having a rod shape or a plate shape.
The magnet having conductivity is arranged so as to sandwich a magnetic body, and two opposing surfaces sandwiching the magnetic body are magnetized to have polarities different from each other.

Further, in the eighth aspect of the present invention, there is provided an electromagnetic shield having a conductor, a magnetic body and a magnet, wherein the conductor is rod-shaped or plate-shaped, and has a groove in its lengthwise direction.
The magnetic body and the magnet are combined into a structure and embedded in the groove of the conductor, the magnet is a magnet having conductivity, and is magnetized in a direction perpendicular to the longitudinal direction of the groove, and the magnetic body is The magnetic body and a part of the surface of the magnet having conductivity are in contact with the magnetized surface of the magnet having conductivity, and are exposed on the surface of the conductor.

According to a ninth aspect of the invention, the conductor of the eighth aspect of the invention or a part of a magnet having electrical conductivity that electrically contacts the conductor has a conductive electromagnetic shielding material, The conductive electromagnetic shielding material is one that is electrically contacted directly or through the magnet having the conductivity.

In the present invention, the cross section of the rod-shaped or plate-shaped conductor or magnetic material constituting the electromagnetic shield and the cross section of the groove are rectangular, rectangular, elongated rectangular, circular, elliptical, triangular, polygonal, etc. Can be freely designed according to.
For example, a U-shaped, H-shaped, or L-shaped conductor can be used.

[0017]

As shown in FIG. 13A, a structure 44 in which rod-shaped conductors 46 and rod-shaped magnetic bodies 42 are alternately arranged, or a conductive electromagnetic shield having elasticity as shown in FIG. 13B. Structure 41 in which a groove is provided in 43 and a magnetic body 42 is embedded
The electromagnetic shield of (1) is effective as a shield for a gap in a metal casing having a low-impedance wave source. It is known that the shielding effect of this type of electromagnetic shield largely depends on the magnetic permeability characteristics of the embedded magnetic body, and the greater the magnetic permeability, the greater the shielding effect (Technical Research Report of IEICE, EMCJ90). -48).

On the other hand, when DC magnetization is applied to a magnetic material such as a ferrite sintered body, the high frequency magnetic permeability corresponding to the magnetic field component in the direction perpendicular to the magnetization increases (Technical Research Report of the Institute of Electronics, Information and Communication Engineers, EMCJ87-82). reference).

Therefore, as shown in FIG.
If a DC magnetic field 47 or 48 can be applied parallel to the cross-sectional direction of the magnetic body as shown in (b), the high-frequency magnetic permeability with respect to the magnetic field in the longitudinal direction of the magnetic body becomes large, and the leakage electromagnetic wave 49 having a magnetic field component in the same direction 49. It is possible to enhance the shielding effect against.

[0020]

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

(Embodiment 1) FIG. 1 is a perspective view showing a first embodiment of the present invention. The electromagnetic shield 1 of this embodiment is
This is a structure in which a bar-shaped conductor 5 having a U-shaped cross section is embedded and integrated with a magnetic body portion 2 composed of a bar-shaped magnetic body 3 and a bar-shaped magnet 4 so as to match the recess.

As shown in the cross-sectional view of FIG. 2, the bar-shaped magnet 4 is magnetized perpendicularly to the longitudinal direction, so that the bar-shaped magnet 4 is
The rod-shaped magnetic body 3 in contact with is also magnetized in the cross-sectional direction.
Therefore, the magnetic permeability of the magnetic substance with respect to the magnetic field component in the length direction is increased, and the attenuation of the leaked electromagnetic wave having the magnetic field component in the same direction can be increased.

The magnetic body portion 2 may have a structure in which a plurality of bar-shaped magnetic bodies 3 and a plurality of bar-shaped magnets 4 are alternately arranged as shown in the sectional view of FIG. At this time, the rod-shaped magnets 4 are arranged so that the rod-shaped magnetic bodies 3 are magnetized in the cross-sectional direction such that the surfaces of the rod-shaped magnetic bodies 3 facing each other have different polarities.
Further, as shown in FIG. 3B, the magnetic body portion 2 may have a structure in which the boundary surface between the rod-shaped magnetic bodies 3 is perpendicular to the bottom of the recessed portion of the rod-shaped conductor 5. Or the boundary surface is
It may be oblique as in (c). Also, the rod-shaped conductor 5
May have an L-shaped cross section, or may have an H-shaped cross section and have a structure in which the magnetic body portions 2 are embedded in both recesses.

FIG. 4 shows an example of an electromagnetic shield having a structure in which the magnetic material portions 2 and the rod-shaped conductors 6 are alternately arranged. A structure in which a plurality of magnetic body portions 2 and a plurality of rod-shaped conductors 6 are alternately arranged may be adopted. The rod-shaped magnetic body 3 is composed of a sintered ferrite material, a polymer material mixed with ferrite powder, or a magnetic alloy such as a magnetic amorphous alloy or permalloy. A sintered ferrite material with a small decrease is suitable. The rod-shaped magnet 4 may have a rod-shaped structure in which a plurality of magnets are arranged in a line so that the directions of the magnetic poles are the same.

FIG. 5 shows an electromagnetic shield 8 having a structure in which a conductive electromagnetic shield 7 having elasticity is provided on a part of the rod-shaped conductor 5.
FIG. In this structure, the conductive electromagnetic shield 7
By closing the gap generated between the conductors, the shielding characteristics in the high frequency band are improved, and a wideband shielding effect can be obtained. The conductive electromagnetic shield 7 is made of a conductive gasket material having a structure in which conductive rubber or polyurethane foam material is coated with silver, or a conductive material having elasticity such as conductive fingers.

Further, in the structure shown in FIG. 4, the same effect can be obtained even if some or all of the rod-shaped conductors 6 are replaced with a conductive electromagnetic shielding material. Unlike the conventional conductive electromagnetic shield material, the electromagnetic shield 8 has little influence on the shield effect in the contact state.

(Second Embodiment) FIG. 6 is a perspective view showing a second embodiment of the present invention. Electromagnetic shield 11 of this embodiment
Is a structure in which a magnetic material portion 12 composed of a rod-shaped magnetic body 13 and a rod-shaped magnet 14 is incorporated and integrated in a conductive electromagnetic shield 15 having a U-shaped cross-section and having elasticity so as to match the recess. . The bar magnet 14 is magnetized perpendicularly to the length direction. The rod-shaped magnetic body 13 is the rod-shaped magnet 1
Since it is arranged in contact with the magnetic field surface of No. 4, it is magnetized in the cross-sectional direction. Therefore, the magnetic permeability with respect to the magnetic field in the length direction increases, and the leaked electromagnetic wave having the magnetic field component in the same direction is significantly attenuated. The magnetic body portion 12 includes a plurality of rod-shaped magnetic bodies 13
And a plurality of bar-shaped magnets 14 may be alternately arranged. In this case, the rod-shaped magnets 14 are arranged such that the magnetic poles on the surfaces facing each other sandwiching the rod-shaped magnetic body 13 are different from each other so that the magnetization direction of the rod-shaped magnetic body 13 is the cross-sectional direction.

Further, as shown in FIG. 7, the rod-shaped magnetic body 13
The boundary surface between the bar magnet 14 and the bar-shaped magnet 14 may be arranged so as to be perpendicular to the bottom of the recess of the conductive electromagnetic shield 15. The conductive electromagnetic shielding material 15 may be one having an H-shaped cross section, and the magnetic material portion 12 may be embedded in each recess. When the electromagnetic shield 11 according to the present embodiment is applied to a gap portion such as a case made of metal or a good conductor, it has a contact portion with a conductor wall surface forming the gap and a portion in which the magnetic body portion 12 is embedded. By arranging so that they coincide with each other, a low frequency band can be shielded by the action of the magnetic material, and a high frequency band can be shielded by the effect of conductive contact, so that a broadband shielding effect can be obtained.

(Third Embodiment) FIG. 8 is a perspective view showing a third embodiment of the present invention. The electromagnetic shield 21 of this embodiment
Is a structure in which the rod-shaped magnetic body 22 is sandwiched between a pair of conductive rod-shaped magnets 23 and integrated. Since the bar-shaped magnet 23 has conductivity, it is effective as a low-frequency electromagnetic shield for a low-impedance wave source.

Further, as shown in the sectional view of FIG. 9, the two bar-shaped magnets 23 sandwiching the bar-shaped magnetic body 22 are magnetized perpendicularly to the longitudinal direction, and the surfaces having different polarities face each other. Since the bar-shaped magnets 23 are arranged, the bar-shaped magnets 23 are magnetized in the cross-sectional direction, the magnetic permeability in the longitudinal direction is increased, and the shielding property of the leaked electromagnetic wave having the magnetic field component in the same direction can be significantly improved. The rod-shaped magnet 23 may be formed by arranging a plurality of magnets in a rod shape so that the directions of the magnetic poles thereof are aligned with each other. The rod-shaped magnet 23 is made of a conductive magnet such as a samarium-cobalt magnet, but a non-conductive magnet having conductive plating such as metal plating may be used.

Further, as shown in the perspective view of FIG. 10, a part of the conductive bar magnet 23 has a conductive electromagnetic shield 25.
The electromagnetic shield 24 having a structure in which the bar-shaped magnet 23 having conductivity and the conductive electromagnetic shield 25 are in electrical contact with each other.
Is arranged so as to close the gap generated between the conductors by the conductive electromagnetic shielding material 25, so that the high frequency characteristics are improved,
Wideband shielding characteristics can be obtained. Unlike the conventional conductive electromagnetic shield material, the electromagnetic shield 24 has little influence on the shielding effect in the contact state.

(Fourth Embodiment) FIG. 11 is a perspective view showing a fourth embodiment of the present invention. Electromagnetic shield 31 of this embodiment
Is a rod-shaped magnet 34 having a U-shaped cross-section in the concave portion of the rod-shaped conductor 35, having a cross-section that matches the concave portion, and magnetized in a direction perpendicular to the longitudinal direction, and the rod-shaped magnet 34. This is a structure in which a magnetic body portion 32 formed by alternately arranging and integrating rod-shaped magnetic bodies 33 contacting the magnetized surface of 34 is incorporated. The boundary surface between the rod-shaped magnetic body 33 and the rod-shaped magnet 34 having conductivity is perpendicular to the bottom of the recess of the rod-shaped conductor 35. The rod-shaped magnet 34 is arranged such that two surfaces facing each other with the rod-shaped magnetic body 33 sandwiched therebetween have polarities different from each other, and magnetizes the rod-shaped magnetic body 33 in a direction perpendicular to the longitudinal direction. Therefore, the magnetic permeability of the rod-shaped magnetic body 33 with respect to the magnetic field in the longitudinal direction increases, and the effect of shielding leaked electromagnetic waves having a magnetic field component in the same direction increases. The rod-shaped magnetic body 33 is divided into a number of small pieces so as to have a small cross-sectional area, and the rod-shaped magnets 34 are alternately arranged to reduce the effect of the demagnetizing field, suppress the effective decrease in magnetic permeability, and provide a good shielding effect. Can be kept.
The conductive bar-shaped magnet 34 is composed of a conductive magnet such as a samarium-cobalt magnet, but a non-conductive magnet plated with conductive material such as metal plating may be used. Further, a large number of conductive magnets may be arranged so that the directions of the magnetic poles are aligned to form a rod shape.

In FIG. 12, a conductive conductive electromagnetic shield 37 having elasticity is provided on a part of the bar-shaped conductor 35 or the bar-shaped magnet 34 having conductivity, and the bar-shaped conductor 35 and the bar-shaped magnet 34 having conductivity are electrically connected to each other. 3 is a perspective view of an electromagnetic shield 36 having a structure in which a conductive electromagnetic shield 37 is in electrical contact with the electromagnetic shield 36. FIG. When this electromagnetic shield 36 is applied to the gap of the housing,
If the conductive electromagnetic shielding material 37 is arranged so as to close the gap between the conductors, the high frequency characteristic is improved and the broadband shielding characteristic is obtained. Unlike the conventional conductive electromagnetic shield material, the electromagnetic shield 36 has little influence on the shielding effect in the contact state.

In this embodiment, a bar magnet or the like is used as a means for applying a magnetic field to the magnetic material, but an electromagnet may be used.
Further, the structure may be such that a spacer is sandwiched between the magnetic body and the magnet, and it is not necessary that both are in contact with each other.

The present invention can be applied to general electronic equipment such as computers, exchanges, communication equipment racks, pressure bodies such as cabinets, electronic component modules and chassis.

[0036]

As described above, according to the electromagnetic shield according to the present invention, the influence of the contact is small. Therefore, a mechanism for strengthening the contact when applied to a gap or a joint portion of a metal housing is provided. It has the effect that effective shielding measures can be taken without the need. Further, the shield according to the present invention has a greater effect of suppressing the leakage current as compared with the conventional conductive electromagnetic shield material, so that the shield of the low impedance wave source where an induced current is likely to occur is significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view of the first embodiment.

3 (a), (b) and (c) are diagrams showing an arrangement example of magnetic bodies.

FIG. 4 is a diagram showing another example of a combined structure of a magnetic body portion and a rod-shaped conductor.

FIG. 5 is a diagram showing an example in which a conductive shield having elasticity is provided on a part of a rod-shaped conductor.

FIG. 6 is a perspective view showing a second embodiment.

FIG. 7 is a diagram showing another example of a combination of a rod-shaped magnetic body and a rod-shaped magnet.

FIG. 8 is a diagram showing a third embodiment.

FIG. 9 is a sectional view of a third embodiment.

FIG. 10 is a diagram showing an example in which a conductive electromagnetic shielding material is attached.

FIG. 11 is a diagram showing a fourth embodiment.

FIG. 12 is a view showing an example in which an elastic conductive electromagnetic shield material is attached.

FIG. 13 is a diagram showing the operation of the present invention.

FIG. 14 is a diagram showing a conventional electromagnetic shield.

FIG. 15 is a view showing a conventional electromagnetic shield.

[Explanation of symbols]

1 Electromagnetic shield 2 Magnetic part 3 Rod-shaped magnetic material that constitutes the magnetic material part 4 Bar-shaped magnets that make up the magnetic body 5 Bar-shaped conductor with a U-shaped cross section 6 Rod-shaped conductor 7 Conductive electromagnetic shielding material 11 Electromagnetic shield 12 Magnetic part 13 Rod-shaped magnetic material that constitutes the magnetic material part 14 Rod-shaped magnets that form the magnetic body 15 Conductive electromagnetic shielding material with elasticity 21 Electromagnetic shield 22 Rod-shaped magnetic body 23 Conductive bar magnet 24 Electromagnetic shield 25 Conductive electromagnetic shielding material 31 Electromagnetic shield 32 Magnetic part 33 Rod-shaped magnetic body that constitutes the magnetic body part 34 Conductive bar-shaped magnet that constitutes the magnetic body 35 Rod-shaped conductor with U-shaped cross-section 36 Electromagnetic shield 37 Conductive electromagnetic shielding material 41 Electromagnetic shield 42 Rod-shaped magnetic body 43 Elastic Conductive Electromagnetic Shielding Material with Grooves 44 Electromagnetic shield 46 Bar conductor 47,48 Magnetization direction 49 Leaked electromagnetic wave

Claims (9)

[Claims] 1. An electromagnetic shield having a conductor and a magnetic body, wherein the conductor is rod-shaped or plate-shaped, and a groove is formed in a longitudinal direction thereof. The magnetic body is provided in the groove of the conductor. An electromagnetic shield, which is arranged and to which a magnetic field in a direction perpendicular to the longitudinal direction of the groove is applied. 2. An electromagnetic shield having a conductor and a magnetic body, wherein the conductor and the magnetic body are rod-shaped and are alternately arranged. The magnetic bodies are magnetic fields in a direction perpendicular to the length direction of the conductor. An electromagnetic shield characterized by being applied. 3. An electromagnetic shield having a conductor, a magnet, and a magnetic body, wherein the conductor has a rod shape or a plate shape, and a groove is formed in a length direction thereof, and the magnet and the magnetic body have a structure. The magnet is combined with the body and embedded in the groove of the conductor to be integrated with the conductor, the magnet is magnetized in a direction perpendicular to the length direction of the groove, and the magnetic body is An electromagnetic shield, which is arranged in contact with a magnetized surface of a magnet. 4. An electromagnetic shield having a conductor, a magnet and a magnetic body, wherein the conductor has a rod shape or a plate shape, and the magnet and the magnetic body are combined in a rod shape or a plate shape structure,
The conductor and the structure are alternately arranged and integrated, the magnet is magnetized in a direction perpendicular to the length direction of the conductor, and the magnetic body is arranged in contact with the magnetized surface of the magnet. An electromagnetic shield characterized by being installed. 5. The electromagnetic shield according to claim 4, wherein a part or all of the conductor is an elastic electromagnetic shield material. 6. An electromagnetic shield including a conductor, a magnet and a magnetic body, wherein the conductor has a conductive electromagnetic shield having elasticity at least in a part thereof. The material has one or more rows of grooves in a part thereof, the magnet and the magnetic body are combined with the structure and embedded in the groove of the conductive electromagnetic shielding material, and the magnet has the length of the groove. An electromagnetic shield, wherein the magnetic body is magnetized in a direction perpendicular to the vertical direction, and the magnetic body is arranged in contact with the magnetized surface of the magnet. 7. An electromagnetic shield having a conductor and a magnetic material, wherein the conductor is a magnet having conductivity, the magnetic material has a rod shape or a plate shape, and the magnet having conductivity is a magnetic material. An electromagnetic shield, wherein the two opposing surfaces sandwiching the magnetic material are magnetized to have polarities different from each other. 8. An electromagnetic shield having a conductor, a magnetic body, and a magnet, wherein the conductor is rod-shaped or plate-shaped, and has a groove in its lengthwise direction. Embedded in the groove of the conductor combined with the structure, the magnet is a magnet having conductivity, magnetized in a direction perpendicular to the length direction of the groove, the magnetic body of the magnet having conductivity. An electromagnetic shield, which is in contact with a magnetized surface, and a part of the surface of a magnet having a magnetic substance and conductivity is exposed on the surface of a conductor. 9. A conductive electromagnetic shielding material is provided on a part of the conductor or a magnet having electrical conductivity that electrically contacts the conductor, and the conductor and the conductive electromagnetic shielding material are directly or The electromagnetic shield according to claim 8, which is electrically contacted through a magnet having conductivity.