JP2576232Y2 - Cable / shield gasket and shield case using the same - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention relates to a shield case accommodating a high-frequency circuit, a good electrical contact between the shield case main body and a lid to ensure an electromagnetic shield to the outside, and a unit room having a predetermined impedance. The present invention relates to a cable / shield gasket used for connection between cables.

[0002]

2. Description of the Related Art FIG. 3A shows a conventional shield case.
A relatively shallow box-shaped shield case main body 11 is divided into a plurality of unit chambers 13 and 14 by a partition wall 12, and grooves are formed in the open surface of the shield case main body 11, in this example, each wall surface on the upper surface along the longitudinal direction. 15 are formed, and the grooves 15 communicate with each other. A shield gasket 16 is embedded along the groove 15. Shield gasket 16
Is a conductive rubber or a rubber covered with a metal net. Lid 1
7, the open surface of the shield case main body 11 is covered and the shield gasket 16 is pressed, so that the inside of the shield case is electromagnetically isolated from the outside and the unit chambers 13 and 14 are closed.
The gap is electromagnetically shut off.

In order to electrically connect the unit chambers 13 and 14, that is, to electrically connect a circuit housed in the unit room 13 and a circuit housed in the unit room 14, a shield is required. A shield cable 18 is placed under the gasket 16, and both ends of the shield cable 18 are formed in small grooves 19, 21 formed in the groove wall of the groove 15.
And is introduced into the unit chambers 13 and 14 to be connected to each circuit. The shielded cable 18 has a characteristic impedance of, for example, 50Ω, and connection between circuits is performed with impedance matching.

For this reason, as shown in FIG. 3B, the groove 15 has a cable groove 15b formed along the longitudinal direction on the bottom surface of the gasket groove 15a. Alternatively, the shield gasket 16 and the shield cable 18 may be arranged in the groove 15 side by side.

[0005]

Conventionally, a shield gasket 16 and a shield cable 18 are used,
Therefore, the number of parts is large, and the workability is poor because the two lines are buried in the groove 15. Further, since the groove 15 forms the gasket groove 15a and the cable groove 15b in a two-stage configuration, a special mold is required when the groove 15 is formed by die casting.
When the shield gasket 16 and the shield cable 18 are embedded side by side, there is a disadvantage that the groove width becomes wide and the wall becomes thick.

[0006]

According to the cable / shield gasket of the present invention, the outer periphery of the center conductor is provided.
A dielectric layer is formed axially, and the dielectric layer is formed outside the dielectric layer.
An elastic conductive layer is formed axially, and the diameter of the center conductor and the diameter of the dielectric layer, that is, the thickness, are selected so as to have a predetermined characteristic impedance, and the elastic conductive layer has a relatively large elasticity in its thickness direction. Deformation is obtained , but the elastic deformation
Thus, the dielectric layer does not deform .

According to the shield case of the present invention, a cable and shield gasket is buried in a groove formed in the wall surface of the shield case body, and the cover is held down by pressing the lid.
The elastic conductive layer of the cable shield gasket is elastically deformed
And to ensure electromagnetic shield against the outside, given the both ends unit Shitsukan the cable serves shielding gasket
Electrical connection with impedance of

[0008]

FIG. 1A shows an example of a cable / shield gasket 25 according to the present invention. In the cable / shield gasket 25, a dielectric layer 27 is formed on a center conductor 26, and an elastic conductive layer 28 is formed on the dielectric layer 27.
Are formed. The diameter D ₂ of diameter D ₁ and the dielectric layer 27 of the center conductor 26 is chosen to have a predetermined characteristic impedance, e.g., 50 [Omega. The dielectric layer 27 has a small high-frequency loss. For example, a fluorine resin is used. The elastic conductive layer 28 is capable of obtaining a relatively large elastic deformation in the thickness direction, that is, in the radial direction, and is, for example, a conductive rubber or a loosely and thickly woven metal mesh.

FIG. 1B shows an example of a shield case according to the invention of claim 2, in which parts corresponding to those in FIG. 2 are denoted by the same reference numerals. In this invention, the cable and shielding gasket 2 according to the invention of FIG. 1 is shown in FIG. 1A in a groove 15 for electrically connecting the unit chambers 13 and 14.
5 are buried, and both ends thereof are introduced into the unit chambers 13 and 14 through small grooves 19 and 21, respectively, and are connected to internal electric circuits (not shown), respectively, and these electric circuits are electrically connected. Is done.

[0010] As for the portion that does not need to be connected between the unit chambers, a simple shield gasket 16 is buried in the groove 15 formed in the wall surface on the open surface of the shield case main body 11 as in the conventional case. The open surface of the shield case main body 11 is covered with a cover 17, the shield gasket 16 and the cable / shield gasket 25 are pressed by the cover 17, and the shield case is electromagnetically shielded from the outside. Be shielded. At this time, the cable / shield gasket 25 is attached to the elastic conductive layer 28.
Is elastically deformed, but the dielectric layer 27 keeps its shape.

[0011]

As described above, according to the cable / shield gasket of the present invention, the cable / shield gasket functions as a cable for electrical connection and also functions as a shield gasket. If embedded, connection between unit rooms and electromagnetic shielding can be performed. Compared with the conventional case where two cables and a shielding gasket are used, the number of parts is smaller, and mounting to a shield case is performed. The work is also easy.

In addition, since the diameter of the center conductor 26 and the diameter of the dielectric layer 27 are selected to have a predetermined characteristic impedance, impedance matching can be obtained in connection between the unit chambers. In addition, since the elastic conductive layer 28 exists outside, signal transmission is electromagnetically shielded from the outside. That is, it works well as a transmission line. Further, since the elastic conductive layer 28 is easily elastically deformed in its thickness direction, the elastic conductive layer 28 elastically comes into contact with the inner surface of the groove 15 and the surface of the lid 17. In addition, good electrical contact makes electromagnetic shielding satisfactory.

Further, the shape of the groove 15 is simple, and the shield case main body 11 can be easily formed by, for example, die casting, and its mold is also simple and can be manufactured at low cost. Further, since only one cable / shield gasket needs to be filled, the groove 15 may be thin, and the wall does not need to be thick.

[Brief description of the drawings]

FIG. 1A is a perspective view showing an embodiment of the invention of claim 1, and FIG.
FIG. 3 is an enlarged sectional view taken along line AA of FIG. 2.

FIG. 2 is an exploded perspective view showing an embodiment of the invention of claim 2;

3A is an exploded perspective view showing a partial cross section of a conventional shield case, and FIG. 3B is a view showing an example of a cross sectional shape of a groove 15. FIG.

Claims (2)

(57) [Scope of request for utility model registration] 1. A center conductor, an elastic conductive layer provided coaxially outside the center conductor, a dielectric layer filled between the center conductor and the elastic conductive layer, The diameter of the central conductor and the diameter of the dielectric layer are selected so as to have a predetermined characteristic impedance, and the elastic conductive layer can obtain relatively large elastic deformation in the thickness direction. Cable and shield gasket with almost no dielectric layer deformation. 2. The inside of the shield case main body is divided into a plurality of unit chambers by partition walls, grooves are formed along the surfaces of the walls on the open surface of the shield case main body, and the grooves are filled with a shield gasket. In a shield structure in which a lid is covered by the shield case body while pressing a shield gasket, the cable / shield gasket according to claim 1 is used as the shield gasket, and the cable is pressed by the lid to hold the cable. A shield case wherein the elastic conductive layer of the dual-purpose shield gasket is deformed, and both ends of the dual-purpose shield gasket electrically connect two different unit chambers.