JP2000353622A - Noise-absorbing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noise-absorbing device, the noise absorbability of which is enhanced by preventing the positional deviation between a pair of ferrite cores which are faced to each other on both sides of a cable and which can be manufactured inexpensively. SOLUTION: A noise-absorbing device is provided with a pair of ferrite cores 1A and 1B, which are faced to each other on both sides of a cable and the internal surfaces of which are brought into close contact with each other so as to surround the cable. Each ferrite core 1A and 1B has coupling sections 3 and 4 respectively, having a projecting section (projecting stripe) 5 and a recessed section (recessed stripe) 6 on their closely contacting surface, so that the cores 1A and 1B do not cause positional deviation between, them when the cores 1A and 1B are brought into close contact with each other by inserting the projecting sections 5 into the recessed sections 6. Therefore, the declined in the noise absorbing ability of the noise-absorbing device caused by the positional deviation between the cores 1A and 1B can be prevented, and the device can which is effective in absorbing noise is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise absorbing device for absorbing noise superimposed on a signal transmitted through a cable, and more particularly to a device for preventing a relative displacement of a pair of ferrite cores attached to a cable. And a noise absorbing device having an improved noise absorbing effect.

[0002]

2. Description of the Related Art In electronic equipment handling digital signals, such as a computer, if noise is superimposed on a signal transmitted through a cable and enters the equipment, the equipment may malfunction. Therefore, in recent years, a noise absorbing device using a ferrite core has been proposed. For example,
As a noise absorber for flat cables,
No. 2,754. This technology includes a pair of flat ferrite cores 101A and 101B having a shallow groove 102 through which a flat cable FC can be inserted, as shown schematically in FIG. 7A. 7 (b), these ferrite cores 10
1A and 101B, both ends of the shallow groove 102 are opposed to each other so as to be in close contact with each other, and a flat cable F is inserted into a gap formed by the two shallow grooves 102.
C, and both ferrite cores 101A,
101B is clamped or band-shaped holding member 11
This is a technique for setting the connection state to 0. In such a noise absorbing device, a noise current flowing through the flat cable FC is absorbed in a closed circuit composed of a pair of ferrite cores 101A and 101B so as to surround the flat cable FC, and the noise current is transmitted through the flat cable. Can be prevented.

[0003]

In such a conventional noise absorbing device, a pair of ferrite cores 101A and 101A are used.
1B has flat surfaces that are in close contact with each other, so that when a noise absorbing device is attached to a cable, or when an external force is applied to the noise absorbing device after attachment, for example,
As shown in FIG. 7C, both ferrite cores 101A,
Slippage in the planar direction may occur on the close contact surface of the flat cable 101B, and a shift may occur between the ferrite cores 101A and 101B in the length direction of the flat cable FC as shown in the drawing or in a direction crossing the flat cable FC. As described above, the ferrite cores 101A and 101B are connected to the flat cable F.
Although a noise current is absorbed by forming a closed circuit of a ferrite core around C, it is advantageous to increase the cross-sectional area of the closed circuit in order to enhance the noise absorbing effect.
However, as described above, both ferrite cores 101
When a displacement occurs between A and 101B, the area of the close contact surface between both ferrite cores is reduced, whereby the cross-sectional area in the closed circuit described above is reduced, and the effect of absorbing noise is reduced. When the displacement is large, the ferrite cores 101A and 101B by the holding member 110 are used.
Is lost, and the assembled state of the noise absorbing device is destroyed.

For this reason, conventionally, it has been considered to prevent the displacement of the two ferrite cores by devising a holding member. However, in this technique, the displacement of the two ferrite cores is prevented via the holding member. Therefore, when the holding member itself is deformed or its shape is deteriorated, it is difficult to effectively prevent the displacement of the two ferrite cores. Further, as another technique, it has been considered that a pair of ferrite cores are respectively provided in a case and mounted on a cable using the case, but this type of case is usually formed by resin molding. For,
This is disadvantageous in reducing the manufacturing cost. In addition, it is necessary to prepare various types of cases corresponding to a plurality of types of ferrite cores having different shapes and dimensions, which is disadvantageous in reducing the cost of the noise absorbing device.

It is an object of the present invention to provide a noise absorbing device that can prevent a positional shift between a pair of ferrite cores and increase noise absorption efficiency, and can be manufactured at low cost.

[0006]

A noise absorbing device according to the present invention comprises a pair of ferrite cores which face each other with a cable interposed therebetween and whose inner surfaces are in close contact with each other so as to surround the cable. A holding member for holding the cable in a sandwiched state, wherein the pair of ferrite cores have, on surfaces that are in close contact with each other, a convex portion on a close contact surface of one of the ferrite cores; A concave portion is formed in the close contact surface, and the relative position shift of the pair of ferrite cores on the close contact surface is prevented in a state where the convex portion and the concave portion are engaged. Here, the ferrite core is
The two sides sandwiching the cable are in close contact with each other, and the close surface on one side is provided with the convex portion, and the close surface on the other side is provided with the concave portion. Alternatively, the convex portion and the concave portion are provided on the close contact surface on one side, and the convex portion and the concave portion are provided on the close contact surface on the other side in a direction opposite to the one close contact surface.

In the noise absorbing device according to the present invention, the protrusion provided on one of the close contact surfaces of the pair of ferrite cores and the recess provided on the other engage with each other, so that the two ferrite cores are relatively positioned on the close contact surfaces. Movement of the two ferrite cores is prevented. For this reason, it is possible to prevent a decrease in the noise absorption effect due to the displacement between the two ferrites, and to obtain a noise absorption device having a high noise absorption effect. In addition, there is no need to provide a holding member for holding both ferrite cores with a configuration to prevent displacement of both ferrite cores, and since both ferrite cores can be of the same shape, manufacturing costs are reduced. It is also possible to do.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is an external perspective view of a first embodiment of the noise absorbing device of the present invention. Each of the pair of ferrite cores 1A and 1B is formed in a rectangular thick plate shape, and has a shallow groove 2 extending in the short side direction in a central region in the long side direction on each inner surface. And these ferrite cores 1A and 1B are:
The thick end regions sandwiching the shallow groove 2 in the long side direction are respectively formed as connecting portions 3 and 4, and the inner surfaces of the connecting portions 3 and 4 are brought into close contact with each other as an adhesion surface, so that both ferrites are formed. The cores 1A and 1B are formed in a flat rectangular tube shape, and a flat cable to be subjected to noise absorption can be inserted into a flat gap formed by the shallow grooves 2 of both ferrites 1A and 1B. Of the joints 3 and 4 of each of the ferrite cores 1A and 1B, a protruding ridge 5 extending in the short side direction protrudes from a close contact surface of one joint 3 and a close contact surface of the other joint 4. Is formed with a concave ridge 6 with which the convex ridge 5 can be engaged. Here, these ridges 5 and concave ridges 6 need to have their respective ends in the length direction and width direction terminated in the respective close contact surface regions of the coupling portions 3 and 4, respectively. As a result, when the two ferrite cores face each other as shown in FIG. 1B, the ridges 5 and the ridges 6 of one ferrite core 1A (1B) become the ridges 6 of the other ferrite core 1B (1A). And ridges 5
And the ferrite cores 1A and 1B are not relatively moved in a plane direction parallel to the close contact surface by the engagement of the ridges 5 and the concave ridges 6.

The ferrite core 1 configured as described above
As shown in FIG. 2, in the noise absorbing device including A and 1B, the pair of ferrite cores 1A and 1B face each other so as to be sandwiched from both sides of the flat cable FC.
Then, the bonding surfaces 3 and 4 of both ferrite cores 1A and 1B are brought into close contact with each other. As a result of this close work, the ridges 5 and the ridges 6 of one ferrite core 1A (1B) are engaged with the ridges 6 and the ridges 5 of the other ferrite core 1B (1A). , 1B can prevent the occurrence of slippage between the close surfaces of the connecting portions 3 and 4. Therefore, thereafter, as shown in the figure, both ferrite cores 1A, 1A are clamped by a clamper 10 made of a metal material bent into a U shape or a resin material formed into a U shape.
By clamping B at both ends, the ferrite cores 1A and 1B can be attached to the flat cable FC while maintaining the combined state.

Thus, both ferrite cores 1A, 1B
The ferrite cores 1A and 1B are prevented from being displaced on the close surfaces while the inner surfaces of the joints 3 and 4 are kept in close contact by the clamper 10 while the close surfaces are kept close to each other. Even when an external force or the like is applied when the core is mounted or in a state after that, the displacement of the ferrite cores 1A and 1B can be prevented. Therefore, the cross-sectional area of the closed circuit surrounding the flat cable FC composed of the ferrite cores 1A and 1B is not reduced, and a high noise absorbing effect is obtained. In addition, even when the clamper 10 has a general configuration that has been conventionally used, the displacement of the ferrite cores 1A and 1B can be prevented, so that the cost of the noise absorbing device increases. There is no such thing.

The pair of ferrite cores 1A, 1A
B is a ridge 5 on each of the coupling surfaces 3 and 4 when used.
When the ferrite core is turned 180 degrees in the plane direction, it can be seen that both ferrite cores 1A and 1B have exactly the same shape. Therefore, since the two ferrite cores 1A and 1B can be formed of the same ferrite core, a ferrite core having one shape may be manufactured when forming the noise absorbing device. As a result, only one type of die is required for manufacturing the ferrite core of the present invention, and a manufacturing process such as manufacturing the ferrite core while changing the die is not required. There is no increase.

In the first embodiment, the U-shaped clamper 10 is used as a holding member for connecting the ferrite cores 1A and 1B. However, as shown in FIG. The ferrite cores 1A and 1B may be maintained in a connected state by being wound around the ferrite cores 1A and 1B. In this case, the displacement of the ferrite cores 1A and 1B during the operation of winding the adhesive tape 11 can be prevented, and the mounting operation becomes easy, and even when the adhesive force of the adhesive tape 11 decreases over time. There is no displacement between the ferrite cores 1A and 1B, and a noise absorbing device having a high noise absorbing effect and a low cost can be obtained. In the case of this example, the cable to be subjected to noise absorption is a connection cable N formed by integrally molding a plurality of single-wire cables in parallel.
C is used.

FIGS. 4A and 4B are a perspective view and a sectional view of a second embodiment of the present invention. Note that parts equivalent to those in the first embodiment are denoted by the same reference numerals. In the second embodiment, the basic structure of the pair of ferrite cores 1A and 1B is the same as that of the first embodiment, but is formed on the close surfaces of the joints 3 and 4 of each ferrite core for preventing misalignment. As a structure, here, on the close surface of the connecting portion 3 at one end,
A cylindrical or frustoconical projection 7 at one position in the short side direction
And a circular or inverted truncated cone-shaped engaging hole 8 with which the protrusion 7 is engaged is formed at the other position in the short side direction. On the contrary, the coupling portion 4 at the other end portion
A cylindrical or truncated cone-shaped projection 7 is protruded at the other position in the short side direction, and a circular or inverted cone with which the projection 7 is engaged at one position in the short side direction. A trapezoidal engagement hole 8 is formed.

The ferrite core 1 constructed as described above
As shown in FIG. 5A, the noise absorbing device including the pair of ferrite cores 1A and 1B includes, for example, the pair of ferrite cores 1A and 1B.
B are respectively housed in a case 20 having a hinge structure formed of resin. The case 20 includes a pair of case portions 21 and 22.
Are connected to each other by hinges 23, and the ferrite cores 1A and 1B are housed in the case portions 21 and 22, respectively. Then, if the hinge 23 is bent after the case 20 is arranged so as to sandwich it from both sides of the flat cable FC, as shown in FIG. 5B, the pair of case portions 21 and 22 face each other. And each case part 2
By connecting the two case portions 21 and 22 at the connection portions 24 and 25 provided on the first and second 22, respectively, the connecting surfaces of the pair of ferrite cores 1A and 1B provided inside the case 20 are brought into close contact with each other. It can be attached to the flat cable FC. Then, in the state of being mounted in this manner, the protrusion 7 of one ferrite core 1A (1B)
And the engaging hole 7 are engaged with the engaging hole 8 and the projection 7 of the other ferrite core 1B (1A).
It is possible to prevent the occurrence of slippage between the close contact surfaces of A and 1B.

Therefore, as in the first embodiment, both ferrite cores 1A and 1B are held in close contact with each other by the holding member, while both ferrite cores 1A and 1B are Since the displacement on the close contact surface is prevented, the ferrite cores 1A, 1
Even when external force or the like is applied at the time of mounting B or afterwards, both ferrite cores 1A,
1B can be prevented from shifting. Therefore, the cross-sectional area of the closed circuit surrounding the flat cable FC composed of the ferrite cores 1A and 1B is not reduced, and a high noise absorbing effect is obtained. Further, even if the above-described case 20 has a general configuration that has been used in the past, the displacement of the ferrite cores 1A and 1B can be prevented, so that the cost of the noise absorbing device increases. There is no such thing. Also in the second embodiment, the pair of ferrite cores 1A and 1B
Are point-symmetrical with respect to their respective centers.
It can be composed of ferrite cores of the same shape, and the cost of the noise absorbing device can be reduced.

Since the ferrite cores 1A and 1B of the first and second embodiments are chamfered at the corners, chipping and cracking at the corners can be prevented. The volume of is not reduced,
A reduction in the noise absorption effect can be prevented. In addition, cracks and chips do not cause foreign substances in the electronic device as foreign substances. Further, in the first and second embodiments, an example in which the cable is mounted on a flat cable is shown. However, a plurality of cables are arranged in parallel on a plane, and the plurality of cables are collectively surrounded. It is also possible to adopt a configuration in which noise absorption is simultaneously performed on the cables.

The present invention is not limited to the above-described noise absorbing device for a flat cable.
For example, as shown in FIG. 6, the present invention is also applied to a ferrite core having a configuration in which a pair of semi-cylindrical ferrite cores 1C and 1D used for a single-wire cable, a coaxial cable, or the like are closely faced to face each other to absorb noise. be able to. In the same figure, (a) shows the same convex ridges 5 and concave ridges 6 as in the first embodiment formed on the close surface of the ferrite core having a semi-cylindrical shape as described above, and the misalignment of both ferrite cores. (B) shows a projection in which the same projections 7 and locking holes 8 as in the second embodiment are formed to prevent displacement. Usually, this type of ferrite cores 1C and 1D are attached to the cable using a semi-cylindrical case having a hinge structure made of resin, similarly to the case used in the second embodiment. Also, in this case, by providing the locking structure for preventing the displacement of the ferrite core with respect to the ferrite core, a structure for preventing the displacement of the ferrite core with respect to the case is not required, and the same as in the above embodiments. The noise absorption effect can be improved and the cost can be reduced.

[0018]

As described above, according to the present invention, of a pair of ferrite cores facing each other in a state of being in close contact with a cable interposed therebetween, one of the ferrite cores has a protruding portion on the close contact surface and the other ferrite core has a close contact surface. A recess is formed in the
Since the relative displacement of the pair of ferrite cores on the close contact surface can be prevented in a state where the protrusions and the recesses are engaged, a reduction in the noise absorption effect due to the displacement of both ferrites is prevented. As a result, a noise absorbing device having a high noise absorbing effect can be obtained. In addition, there is no need to provide a holding member for holding both ferrite cores with a configuration to prevent displacement of both ferrite cores, and since both ferrite cores can be of the same shape, manufacturing costs are reduced. It is also possible to do.

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view of a ferrite core according to a first embodiment of a noise absorbing device of the present invention.

FIG. 2 is a perspective view of the first embodiment with a cable attached.

FIG. 3 is a perspective view showing a state in which a cable is mounted in a different form of the second embodiment.

FIG. 4 is a perspective view and a sectional view of a ferrite core according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a second embodiment before and after a cable is mounted.

FIG. 6 is a perspective view of a ferrite core according to another embodiment of the present invention.

FIG. 7 is a perspective view illustrating a ferrite core of a conventional noise absorbing device, a cable attached state thereof, and a problem thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1A, 1B, 1C, 1D Ferrite core 2 Shallow groove 3, 4 Joining part 5 Convex ridge 6 Concave ridge 7 Projection 8 Engagement hole 10 Clamper 11 Adhesive tape 20 Case 21, 22, Case part 23 Hinge FC Flat cable

Claims (3)

[Claims] A pair of ferrite cores which are opposed to each other with a cable interposed therebetween and whose inner surfaces are in close contact with each other so as to surround the cable, and a holding member which holds the ferrite core with the cable interposed therebetween. In the noise absorbing device including: the pair of ferrite cores, on the surfaces that are in close contact with each other, a convex portion is formed on the close contact surface of one ferrite core, and a concave portion is formed on the close contact surface of the other ferrite core; A noise absorbing device for preventing a relative displacement of the pair of ferrite cores on the close contact surface in a state in which the concave portion is engaged. 2. The ferrite core is closely contacted with each other on both sides of the cable, the convex portion is provided on the close contact surface on one side, and the concave portion is provided on the close contact surface on the other side. The noise absorbing device according to claim 1, wherein: 3. The ferrite core is closely contacted with each other on both sides of the cable, the convex portion and the concave portion are provided on the close contact surface on one side, and the one close contact surface is provided on the close contact surface on the other side. The noise absorbing device according to claim 1, wherein the convex portion and the concave portion are provided in a direction opposite to a surface.