JPH1167297A - Method for preventing noise radiation of coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing noise radiation of a coaxial cable connecting with a housing made of insulating material. SOLUTION: A housing 1 made of insulating material capable of attaching and detaching is attached to a device such as a printed circuit board 20 or the like and on an inner surface of a cable connection hole 3 of the housing 1 an inner surface conductive part contacting with an outer conductor of a coaxial cable 10 is arranged when connecting the coaxial cable 10 to the device through the cable connection hole 3 of the housing 1. A facing part of the device to the housing 1 is for example a grounded conductive surface that is a resist removing part of the printed circuit board 20. A metal leaf spring contacting the inner surface conductive part and the said grounded conductive surface is inserted between the housing 1 and the said device and the shielding effect is produced by connecting the outer conductor of the coaxial cable 10 to the grounded conductive surface of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing noise radiation from a coaxial cable, and more particularly to a method for preventing noise radiation from a coaxial cable connected to a printed board with a housing made of an insulating material.

[0002]

2. Description of the Related Art Referring to FIG. 5, in connecting a coaxial cable 10 to a printed circuit board 20, a housing (hereinafter referred to as a housing) 1 for a coaxial connector plug made of an insulating material for one or more coaxial cables. The coaxial cable 10 is inserted into the
The transmission and reception of signals to and from the printed circuit board 20 are performed. In this case, there is a problem that the shield for the core of the coaxial cable 10 is lowered inside the housing 1 and unnecessary noise is radiated to the environment.
A solution is required as a problem of tromagnetic compatibility).

[0003]

As a countermeasure against EMC at the connection portion of the coaxial cable, the connection connector itself is made of metal and, for example, a grounded frame (such as an EMC-compatible BNC connector) of a housing or printed board. Frame ground, F
The connector itself can be brought into contact with G) to shield the outer conductor of the coaxial cable 10 with a low impedance FG.

[0004] However, metal coaxial cable connectors are not always suitable, and use of general-purpose EMC-compatible BNC connectors or other metal connectors may be inappropriate. In such a case, E
MC measures need to be taken.

Accordingly, an object of the present invention is to provide a method for preventing noise radiation of a coaxial cable connected by a housing made of an insulating material.

[0006]

The inventor of the present invention has conducted experiments and researches to achieve the above object. As a result, the coaxial cable 10 is provided with noise mitigation measures at both ends of the coaxial cable 10.
The present invention was completed by paying attention to the fact that the outer conductor of (1) acts as a shield against noise radiation.

Referring to FIGS. 1 and 2, a method for preventing noise emission of a coaxial cable according to the present invention is described in, for example, a printed circuit board 20.
In order to prevent the noise radiation of the coaxial cable 10 connected to the device by the cable connection hole 3 of the insulating material housing 1 detachable from the device, the coaxial cable 10 Outer conductor (not shown)
An inner conductor member 6 is provided to be in contact with the housing 1 of the device.
The part opposite to
23, a grounded conductive surface, and a metal leaf spring 15 that is in contact with the inner conductor member 6 of the housing 1 and the grounded conductive surface is inserted between the housing 1 and the device. .

The above-mentioned equipment may be not only the printed board 20 and various electric machines and instruments but also a housing or a frame.

Preferably, as shown in FIG.
15, an elastic tongue that engages with a grounded conductive surface such as a fitting protrusion 16 and a resist removing portion 23 fitted with the inner conductor member 6;
17 is provided.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of FIG. 1, when the housing 1 in which the coaxial cable 10 is inserted via the inner conductor member 6 is attached to a grounded conductive surface such as a resist removing portion 23, metal A leaf spring 15 contacts the inner conductor member 6 of the housing 1 and the grounded conductive surface. Preferably,
The fitting projection 16 of the metal leaf spring 15 fits with the inner conductor member 6 and the elastic tongue 17 elastically engages with a grounded conductive surface such as the resist removing portion 23, so that the metal leaf spring 15 The contact between the inner conductor member 6 and the grounded conductive surface is ensured. However, the present invention is not limited to the use of the fitting protrusion 16 and the elastic tongue 17. An outer conductor (not shown) of the coaxial cable 10 is provided with a resist removing portion via an inner conductor member 6 and a metal leaf spring 15 in the coaxial cable connection hole 3 of the housing 1.
Since it is connected to a grounded conductive surface such as 23, it has a low impedance ground plane against noise. That is, the coaxial cable 10 has a shielding effect equivalent to that of the shielded cable, and radiation of unnecessary noise from the coaxial cable 10 can be prevented. Moreover, the housing 1 to which the coaxial cable 10 is detachably fixed is made of an insulating material instead of a metal.

Accordingly, the object of the present invention is to provide a "method of preventing noise emission of a coaxial cable connected by a housing made of an insulating material".

However, if the device is not provided with the EMC countermeasure, noise radiation from the device cannot be avoided even if the coaxial cable 10 has the function of preventing noise radiation according to the present invention.

[0013]

In the embodiment shown in FIG. 1, a portion of the coaxial cable 10 to be inserted into the housing 1 is made of a conductive metal in order to ensure contact between the outer conductor of the coaxial cable 10 and the inner conductor member 6. Connector plug 11 is attached. But,
The present invention is not limited to the use of this connector plug 11.
The structure of the connector plug 11 itself may be configured to fulfill the function of the inner conductor member 6. When the surface of the printed circuit board 20 is a grounded conductive surface, the housing contact portion 21 of the printed circuit board 20 may be the original conductive surface, and it is not necessary to provide the resist removing portion 23.

The housing 1 shown in FIGS. 2 and 3 has two guide pins 5 for positioning, and a guide pin insertion hole 25 into which these pins fit into the printed board 20 is formed. Further, in order to fix the housing 1, an appropriate bolt (not shown) is inserted into the mounting screw hole 4 of the housing 1 and the mounting screw insertion hole 26 of the printed board 20, and then a nut (not shown) is screwed into the nut. Can be nervous. The silk line 24 in FIG. 3 indicates the range of the housing contact portion 21 or its mounting position.

[0015]

As described above, according to the method for preventing noise radiation of a coaxial cable of the present invention, the outer conductor of the coaxial cable is brought into contact with the ground plane of the device to exhibit a shielding effect and prevent noise radiation. This has a remarkable effect of preventing noise radiation from the equipment connection portion of the cable and the coaxial cable itself. Furthermore, EM of various devices having coaxial cables
It can be widely applied as C countermeasure technology.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a housing used in the present invention.

FIG. 3 is a plan view of a coaxial cable connection portion of a printed board.

FIG. 4 is a plan view, a side view, and a cross-sectional view showing details of a metal leaf spring.

FIG. 5 is an explanatory diagram of a connection between a conventional coaxial cable and a printed board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Housing main body 3 ... Coaxial cable connection hole 4 ... Mounting screw hole 5 ... Guide pin 6 ... Inner circumference conductor member 10 ... Coaxial cable 11 ... Connector plug 15 ... Metal plate spring 16 ... Fitting protrusion 17 ... Elastic tongue Piece 20… Printed board 21… Housing contact part 22… Coaxial cable connection hole 23… Resist removal part 24… Silk wire 25… Guide pin insertion hole 26… Mounting screw insertion hole

Claims (6)

[Claims] 1. A method for preventing noise radiation of a coaxial cable connected to a device by a cable connection hole of an insulating material housing detachable from the device, wherein an outer conductor of the coaxial cable is provided on an inner periphery of the cable connection hole of the housing. An inner conductor member that is in contact with the housing, a portion facing the housing of the device is a grounded conductive surface, and is in contact with the inner conductor member of the housing and the grounded conductive surface between the housing and the device. A method of preventing noise radiation from a coaxial cable, which inserts a metal leaf spring. 2. The noise of a coaxial cable according to claim 1, wherein said metal leaf spring is provided with a fitting projection fitted with said inner conductor member and an elastic tongue piece engaged with said grounded surface. Radiation prevention method. 3. The method according to claim 1, wherein said apparatus is a printed board, and wherein said apparatus is a printed board. 4. The method according to claim 1, wherein said apparatus is a resist-coated printed board, and a grounded conductive surface is opposed to said housing by removing the resist at a printed board surface portion facing said housing. A method of preventing noise radiation from coaxial cables. 5. The method according to claim 1, wherein said equipment has a frame ground, and a surface of said equipment facing said housing is used as said frame ground. 6. A method according to claim 1, wherein said inner conductor member serves as a connector plug to be attached to the coaxial cable.