JPH02130000A - Noise reducing device - Google Patents

Abstract

PURPOSE:To achieve an improved noise reducing effect by coating a conductor with a ferrite resin composition. CONSTITUTION:Compositions 8a-8c consisting of a mixture of a synthetic resin or a natural resin and a ferrite powder are used to coat an electrical conductor 7. Thus, the electrical conductor 7 can be in high-impedance at a desired frequency range and noise elements passing through the electrical conductor 7 can be reduced. Also, generation of noise of electrical conductor due to intrusion of electromagnetic wave from outside due to electromagnetic wave absorption loss operation of the ferrites 8a-8b and radiation of unneeded electromagnetic wave from the electrical conductor 7 to the outside can be reduced.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to noise countermeasures for conductors for transmitting electrical and electronic signals (hereinafter referred to as electrical signals) within and between various electronic devices. be.

[Conventional technology]

Electrical signals in electronic circuits configured on a printed wiring board and electronic circuit components not incorporated in the printed wiring board are connected and transmitted by cables provided on each.

In recent years, with the tightening of regulations on electromagnetic noise generated from these cables, etc., various measures have been implemented as noise countermeasures.

FIG. 4 shows an indirect wrapping type connector for mounting on a printed circuit board in which this noise countermeasure has been implemented, in which (a) is a plan view, (a) is a front view, and (a) is a side view.

In the figure, reference numeral 1 denotes a contact which serves as a point of contact for an electric signal passing through the connector 2, and is made of a conductor such as a copper alloy. 3 is this contact! Fixed array at regular intervals,
In addition, the entire connector 2 is molded with a synthetic resin or the like with a shape-retaining housing. 4 is a ferrite bead core inserted into each contact 1 whose one end is molded in the housing 3, and small bead cores made of ferrite are used.

In order to suppress connector noise, a ferrite bead core 4 is inserted into each contact 1 to add appropriate impedance.

Furthermore, when the frequency band of the noise is different, one dimension of the material of the ferrite used for the ferrite bead core 4 is changed to adjust the frequency characteristics of the impedance.

Another conventional example is a noise reduction device shown in FIG. 5, which is disclosed in Japanese Utility Model Application Publication No. 63-102298.

In this device, a printed circuit board 5 near a terminal is surrounded by ferrite cores from the front and back to form a high frequency impedance 6, thereby serving as a noise filter.

[Problem to be solved by the invention]

In this way, conventional noise countermeasures require replacing ferrite cores one by one, and noise countermeasures include connectors,
Since it is limited to the vicinity of the terminals and does not cover the entire area of the conductors connected to these terminals, there is a problem in that the conductors act as antennas and unnecessary electromagnetic radiation is generated.

This invention was made in order to solve such problems, and it is an object of the present invention to provide a noise reduction device that does not require removing the ferrite core one by one and can take measures against noise over the entire conductor. be.

[F stage for solving problems]

In order to achieve the -F2 objective, the present invention configures a noise reduction device as follows.

That is, the electrical conductor is coated with a composition consisting of a mixture of synthetic resin or natural resin and ferrite powder.

(Function) With this configuration, the electrical conductor becomes high impedance in the desired frequency range, reducing noise components passing through the electrical conductor, and due to the electromagnetic wave absorption loss effect of the ferrite, noise is generated in the electrical conductor due to electromagnetic wave intrusion from the outside. , radiation of unnecessary electromagnetic waves from the electrical conductor to the outside is reduced.

〔Example〕

This invention will be explained below with reference to Examples.

FIG. 1 is a perspective view of a noise reduction device that is an embodiment of the present invention.

In the figure, 7 is a conductor such as copper, 8a is a shielding material covering this conductor, and the device is manufactured by the method described below.

First, ferrite which has been calcined with the addition of N 1-Zn components is ground to an average particle size of about 10 μm. Next, silicone resin and hardening agent are added to this ferrite powder.

Add surface treatment agent etc. and knead. This mixture contained ferrite powder in an amount of 85% by weight, and the remainder consisted of silicone resin and the like.

This mixture was formed into a tube using an extruder, and a conductor was passed through the formed tube to obtain a product.

Using the noise reduction device according to this example, we measured the attenuation characteristics against noise in the range of lO to 100,100O, and found that the attenuation was 5 dB more than the conventional connector with ferrite beads. An attenuation effect of 1 OdB was observed compared to the case where the conductor was connected directly.

In the above example, the ferrite resin composition was combined with a tube-shaped conductor such as the rear body, but it is of course possible to mold the ferrite resin composition and the conductor simultaneously. Needless to say.

Furthermore, from the standpoint of convenience in noise countermeasures, a method of dividing a tube-shaped object into two and attaching it to the conductor 7 (8b) is recommended.
There is also a method of wrapping a ribbon-shaped shielding material 8C around the conductor (see FIG. 3). These two examples make it possible to deal with noise without having to redo the wiring when it is discovered that noise has occurred after the electrical wiring has been completed and a countermeasure is required.

In addition, an example in which a mixture of silicone resin and ferrite powder is used as the ferrite resin composition has been described, but any resin material such as urethane or nylon, or a flexible natural resin material may be used in the same manner as in the above embodiment. Deepen the effect.

Furthermore, it is possible to control the frequency characteristics of impedance by changing the ferrite composition, so if the frequency band of the noise you want to attenuate is known in advance, instead of adding Ni-Zn components, Mn
, Fe, Cu.

Components such as Mg and Co can be added and selected to optimize impedance.

〔Effect of the invention〕

As described above, according to the present invention, by coating a conductor with a ferrite resin composition, it is possible to reduce conduction noise and absorb unnecessary electromagnetic radiation generated when the conductor acts as an antenna.
Alternatively, an excellent noise reduction effect can be obtained by absorbing electromagnetic waves from the outside.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the invention, FIG. 2 is a perspective view showing another embodiment, and FIG. 3 is a perspective view showing still another embodiment. Fig. 4 shows a conventional example, in which (a) is a plan view, (b) is a front view, and (ii) is a side view.
The figure is a wiring diagram showing another conventional example. In the figure, 7 is a conductor, and 8a to 8C are shielding materials (a composition made of a mixture of synthetic resin or natural resin and ferrite powder). Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A noise reduction device characterized in that an electric conductor is coated with a composition made of a mixture of synthetic resin or natural resin and ferrite powder.