JP3431495B2 - Noise absorber using composite magnetic material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device mounted around a cable to suppress electromagnetic interference noise, and particularly to a power supply line of electronic equipment such as digital equipment, a signal line connecting equipment, a control line, and the like. The present invention relates to a noise absorbing device using a composite magnetic material that suppresses unnecessary electromagnetic interference noise that is conducted on the cable and that prevents electromagnetic interference noise that enters from the outside through the cable from entering and entering the equipment.

[0002]

2. Description of the Related Art Conventionally, unnecessary electromagnetic interference noise that is conducted through power lines of electronic devices, signal lines connecting devices, control lines, etc. is suppressed, and unnecessary electromagnetic waves that are induced or intruded into the above lines from the outside. In order to prevent noise caused by an interfering wave, a noise absorbing device having a structure in which a pair of ferrite magnetic bodies opposed to each other and detachably combined is mounted around a cable is used. As a conventional technology of this type of noise absorbing device, there is a Japanese Utility Model Publication No. 62-14770.
There is one described in the issue.

FIG. 11 shows an example of a noise absorbing device which is used by being mounted around a cable of this type. A pair of semi-annular (semi-cylindrical) ferrites 2 are held by a plastic case 1 having a hinge portion. By fitting the cable 3 on the inner circumference of the ferrite 2 and closing the case 1, a pair of semi-annular (semi-cylindrical) ferrites 2 are made to abut each other to form a closed loop magnetic path around the cable. Is.

FIG. 12 shows an example of use of the noise absorbing device 5 as shown in FIG. 11. In this figure, a personal computer, auxiliary equipment and various peripheral equipment (keyboard, CRT) are shown.
A noise absorbing device 5 is attached to each cable connecting a display, a printer, an MO driver, etc.).

[0005]

By the way, as the frequency of circuit operation in electronic equipment becomes higher, the frequency component of electromagnetic interference noise that is generated and leaks has reached the GHz band, and further, external The noise caused by the electromagnetic interference wave that is induced and penetrates into the GHz band. In the case of a conventional Ni-Zn ferrite having a spinel type crystal structure,
3 As can be seen from the frequency characteristics of the complex relative permeability of the ferrites of Samples A, B, and C, the frequency dispersion of the permeability in the MHz band −
The disappearance of the real part μr ′ of the complex relative permeability, followed by the imaginary part μr ″
Disappears, and the function of suppressing electromagnetic interference noise in the GHz band deteriorates.

In view of the above points, a first object of the present invention is to
It is an object of the present invention to provide a noise absorbing device using a composite magnetic material having a capability of suppressing and blocking electromagnetic interference noise from the MHz band to the GHz band.

A second object of the present invention is to provide a noise absorbing device using a composite magnetic material whose structure is improved because the magnetic body used can be formed by a molded body.

Other objects and novel features of the present invention will be clarified in the embodiments described later.

[0009]

In order to achieve the above object, a noise absorbing device using the composite magnetic material of the present invention is
Includes 50% by weight or more of a Si—Fe based metal magnetic powder in the form of scales having a length of 40 to 50 μm as a main component and at 1 GHz
Of complex relative permeability (μr′-jμr ″) of 3 is 3
As described above, at least a part of the composite magnetic material having an imaginary part μr ″ of 2 or more is provided, and a pair of magnetic bodies having a shape obtained by dividing an annular body is provided on each of the openable and closable holding members. A portion formed of the composite magnetic material while the set of magnetic materials constitutes a closed loop magnetic path when closed.
Is a closed loop magnetic path .

Further, in the noise absorbing device using the composite magnetic material, a part of a set of magnetic bodies having a shape obtained by dividing the annular body may be made of ferrite.

Further, it is preferable that a set of magnetic bodies having a shape obtained by dividing the annular body is integrally molded with the holding member.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a noise absorbing device using a composite magnetic material according to the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. In these figures, 10 is a shape obtained by dividing an annular shape (cylindrical shape) into two, that is, a semi-annular shape (semi-cylindrical shape) composite magnetic material, and Si-Fe-based metal magnetic material powder (scale shape and width 10 μm, length 40-50 μm, thickness 1
(0 μm) and a thermoplastic resin (for example, polyester resin) powder as a binder are mixed and kneaded, and a molded body of a composite magnetic material is obtained by heating and molding into a semi-ring shape by a plastic molding method.

Reference numeral 20 denotes a plastic case as a holding member, and first and second case portions 21 and 22 for accommodating and holding the semi-annular composite magnetic body 10, respectively.
A hinge portion 23 that connects the first and second case portions 21 and 22 so as to be openable and closable, and the first and second case portions 21 and 22.
The locking portions 24 and 25 respectively formed on the opening and closing edge portions of are molded integrally with a flexible nylon resin or the like. For example, a locking hole 24a is formed in the locking portion 24 on the first case portion 21 side, and a locking convex portion 25a is formed in the locking portion 25 on the second case portion 22 side. Inside the first and second case parts 21 and 22, semi-cylindrical recesses 21a and 2 are formed.
2a is formed, on which the semi-annular composite magnetic body 10 is fixedly arranged. In the present embodiment, the fixing protrusions 26 for preventing the composite magnetic body 10 from falling off protrude inside the first and second case portions 21 and 22, respectively. Case part 2
It is held so that it does not fall into the inside of 1, 2 or 22.

The composite magnetic body 10 has a complex relative magnetic permeability (μr'-jμ) at high frequencies (MHz band to GHz band).
The composite magnetic material using a magnetic material powder of a scale-like Si-Fe-based alloy with a large r ″) and an inexpensive polyester-based resin or the like, which has moldability and thermal stability, as the binder (predetermined shape) In the case of (1), it is used after being heated and cured into a semi-circular shape. However, when the composite magnetic body 10 is preheated and molded, the upper limit of the weight ratio of the Si—Fe based metal magnetic body powder is:
Due to the restrictions from the molding surface of the plastic molding method, it is expected that the binder powder is about 20% with respect to the magnetic powder of 80%. The lower limit of the mixing ratio of the magnetic powder is required to be 50% by weight or more in order to secure a sufficient amount of attenuation. If it is less than 50% by weight, the properties as a magnetic material are significantly deteriorated.

The frequency characteristic of the complex relative permeability of the composite magnetic body 10 (80% by weight of the magnetic powder, 20% by weight of the binder powder) is as shown in FIG. 3, and the complex complex of the ferrite shown in FIG. It can be seen that the frequency dispersion phenomenon of the magnetic permeability can be made higher than that of the frequency characteristic of the relative magnetic permeability. The complex relative permeability (μr′−jμr ″) shown in FIG.
In terms of the amount of attenuation in the Hz band, it is required to show as large a value as possible in the high frequency region, and the real part μr ′ of the complex relative permeability is 1 or more and the imaginary part μr ″ is 2 or more at 1 GHz. Is preferred.

When actually using the noise absorbing device using the composite magnetic material shown in FIGS. 1 and 2, the case 20 is used.
1 and 2, the cable 3 is fitted to the inner circumference of the composite magnetic body 10 as shown by the phantom line in FIG. 2 in a state where the solid line is opened, and then the first and second case portions 21 of the case 20, 22
Close. That is, the locking portion 24 on the first case portion 21 side
The locking convex portion 25a provided on the locking portion 25 on the second case portion 22 side is fitted into the locking hole 24a provided on the second case portion 22 to keep the closed state. Thereby, the composite magnetic body 1 provided in each of the first and second case portions 21 and 22
The set of 0s are butted against each other to form a closed loop magnetic path.

FIG. 4 shows a solder-plated copper wire having a wire diameter of 1.0 mm,
It is a frequency characteristic of impedance when a pair of composite magnetic bodies 10 (however, a molded product of the composite magnetic material of the magnetic body powder 80% by weight and the binder powder 20% by weight) are butted against each other, and is sufficient in the GHz band. It shows a large impedance. However, the measurement sample of FIG. 4 has an inner diameter of 10 mm, an outer diameter of 26 mm, and a sample length of 3 of the pair of composite magnetic bodies 10.
0 mm, Z is impedance, R is resistance component, and X is reactance component.

According to the first embodiment, Si-F
A case 2 in which a set of semi-annular composite magnetic bodies 10 made of a composite magnetic material containing e-based metal magnetic powder as a main component can be freely opened and closed.
Since the cable 3 is attached to surround the outer circumference of the cable 3, electromagnetic interference noise from the MHz band to the GHz band can be suppressed / prevented. In particular, the composite magnetic body 10 can shift the frequency dispersion of the magnetic permeability to a high frequency region as compared with the ferrite, and the imaginary part (μr ″) of the complex relative magnetic permeability which is related to the absorption of electromagnetic interference noise in the GHz band. ) Is large, the resistance component (= ωμr ″ Lo, where ω:
It is possible to configure a noise absorbing device having a large angular frequency, Lo: the inductance of a conductive wire corresponding to the length of the noise absorbing device, that is, a high impedance value in the GHz band (a large noise absorbing effect). The cable 3 referred to here also includes a cord of an AC power supply line and a DC adapter (converts AC100V to DC12V or the like).

5 and 6 show a second embodiment of the present invention. In this case, after heating and molding the pair of composite magnetic bodies 10 into a semi-annular shape (semi-cylindrical shape) by the plastic molding method, the first and second case portions 21 and 22 and the first and second case portions 21 and 22 are formed.
And a hinge portion 23 that connects the second case portions 21 and 22 so as to be openable and closable, and locking portions 24 and 25 that are formed at the opening and closing edges of the first and second case portions 21 and 22, respectively. The case 20 is integrally molded with a flexible nylon resin or the like so as to cover the outer periphery of each composite magnetic body 10 (which is molded using a so-called two-step molding method). The rest of the configuration is the same as that of the first embodiment described above.

In this case, the case 20 can be integrally molded with the composite magnetic body 10 by using the fact that the composite magnetic body 10 is a molded product containing a resin, and the fall prevention means for the composite magnetic body 10 and the like can be used as the case 20. There is an advantage that it is not necessary to provide it on the side, and the manufacturing process and the case structure can be simplified. Other functions and effects are similar to those of the above-described first embodiment.

FIG. 7 shows a third embodiment of the present invention,
A semi-annular composite magnetic body 10A and a semi-annular ferrite magnetic body 3 are used as a magnetic body obtained by dividing the annular shape into two.
The combination structure 40A with 0A is used. In the present embodiment, half of the axial dimension of the magnetic body is the composite magnetic body 1
At 0A, the other half is the ferrite magnetic body 30A. The material of the composite magnetic body 10A is the same as that of the composite magnetic body 10 shown in the first embodiment. Other configurations such as the case are the same as those in the second embodiment.

According to the third embodiment, by utilizing the characteristics of the ferrite magnetic body 30A having a large magnetic permeability in the MHz band, the impedance is increased in a wide frequency range from the MHz band to the GHz band and noise is increased. It is possible to improve the absorption effect.

FIG. 8 shows the frequency characteristics of the impedance of the noise absorbing device shown in the third embodiment, up to a lower frequency than the characteristics of FIG. 4 in the case of the composite magnetic body alone.
It can be seen that the impedance shows a large value. However, in the measurement sample of FIG. 8, the pair of composite magnetic body 10A and ferrite magnetic body 30A each have an inner diameter of 10 mm and an outer diameter of 26 mm.
mm, sample length 15 mm, Z is impedance, R is resistance component, and X is reactance component.

FIG. 9 shows a fourth embodiment of the present invention,
A semi-annular composite magnetic body 10B and a semi-annular ferrite magnetic body 3 are used as a magnetic body in which the annular shape is divided into two.
The combination structure 40B with 0B is used. In the present embodiment, the outer peripheral side is the composite magnetic body 10B and the inner peripheral side is the ferrite magnetic body 30B. The material of the composite magnetic body 10B is the composite magnetic body 1 shown in the first embodiment.
The same as 0. The configuration of other cases is the same as the above-mentioned second.
This is the same as the embodiment.

According to the fourth embodiment, MHz
By utilizing the characteristics of the ferrite magnetic body 30B having a large magnetic permeability in the band, it is possible to increase the impedance in a wide frequency range from the MHz band to the GHz band and improve the noise absorption effect.

FIG. 10 shows a fifth embodiment of the present invention, in which a semi-annular composite magnetic body 10C and a semi-annular ferrite magnetic body 30C are used as a magnetic body obtained by dividing an annular shape into two. And the combined structure 40C is used. In the present embodiment, the inner peripheral side is the composite magnetic body 10C and the outer peripheral side is the ferrite magnetic body 30C. The material of the composite magnetic body 10C is the same as that of the composite magnetic body 10 shown in the first embodiment. Other configurations such as the case are the same as those in the second embodiment.

According to the fifth embodiment as well, MHz
By utilizing the characteristics of the ferrite magnetic body 30C having a large magnetic permeability in the band, it is possible to increase the impedance in a wide frequency range from the MHz band to the GHz band and improve the noise absorption effect.

In each of the embodiments, the set of magnetic bodies to be used is exemplified to form a ring (cylindrical) at the time of butting, but it can be appropriately changed according to the cable shape, for example, a flat cable. On the other hand, a shape such as a rectangular tube may be formed at the time of butting. In short, there is no problem as long as the pair of magnetic bodies has a shape obtained by dividing an annular body that constitutes a closed loop magnetic path. Further, it is desirable to use a Ni—Zn system suitable for a high frequency band as the ferrite magnetic body.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to these and various modifications and changes can be made within the scope of the claims. Ah

[0031]

As described above, according to the noise absorbing device using the composite magnetic material according to the present invention, it can be attached to the power line of electronic equipment, the signal line connecting the equipment, the control line and the like. Thus, it is possible to suppress unnecessary electromagnetic interference noise that is conducted on the cable, and to prevent electromagnetic interference noise that enters from the outside through the cable from entering and entering the equipment. Especially, in the GHz band, the electromagnetic interference noise can be prevented. GHz by using a composite magnetic material having a large imaginary part of the complex relative permeability that is related to absorption of
The impedance value in the band can be increased to increase the noise absorption effect.

When combined with a ferrite magnetic material having a high impedance value in the MHz band, it is possible to realize a noise absorbing device having a wide impedance (a large noise absorbing effect) in a wide band capable of covering the MHz band to the GHz band. .

Further, when the case is integrally molded with the composite magnetic body from plastic, the case structure can be simplified.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a noise absorbing device using a composite magnetic material according to the present invention with an open case.

FIG. 2 is a front view of the same.

FIG. 3 is a graph showing frequency characteristics of complex relative permeability of the composite magnetic body used in the first embodiment.

FIG. 4 is a graph showing frequency characteristics of impedance of the noise absorbing device according to the first embodiment.

FIG. 5 is a plan view showing a second embodiment of the present invention with a case opened.

FIG. 6 is a front view of the same.

FIG. 7 is a plan view showing a third embodiment of the present invention with a case opened.

FIG. 8 is a graph showing frequency characteristics of impedance of a noise absorbing device in which ferrite and a composite magnetic body are combined.

FIG. 9 is a plan view showing a fourth embodiment of the present invention with a case opened.

FIG. 10 is a plan view showing a fifth embodiment of the present invention with a case opened.

FIG. 11 is a perspective view showing a method of mounting the noise absorbing device on a cable.

FIG. 12 is an explanatory diagram showing a usage example of a noise absorbing device using a composite magnetic material.

FIG. 13 is a graph showing frequency characteristics of complex relative permeability of ferrite.

[Explanation of symbols]

1,20 cases 2,30A, 30B, 30C Ferrite magnetic material 3 cables 5 noise absorber 10,10A, 10B, 10C composite magnetic body 21,22 Case part 23 Hinge part 24, 25 locking part

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Akachi, 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation (56) References JP-A-5-29152 (JP, A) JP-A-7 -211532 (JP, A) JP-A-7-273485 (JP, A) JP-A-11-273924 (JP, A) JP-A-11-273925 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) H01F 17/04 H01F 1/14 H01F 1/34 H05K 9/00

Claims (3)

(57) [Claims] 1. A scale-shaped Si having a length of 40 to 50 μm.
-Fe based metal magnetic powder as a main component, containing 50 wt% or more
The complex relative permeability (μr'-jμr ") at 1 GHz
At least a part is made of a composite magnetic material having several parts μr ′ of 3 or more and an imaginary part μr ″ of 2 or more. And a set of the magnetic bodies forming a closed loop magnetic path when the holding member is closed, and the composite magnetic material.
A noise absorbing device using a composite magnetic material, characterized in that a part consisting of a magnetic field constitutes a closed loop magnetic path . 2. The noise absorbing device using the composite magnetic material according to claim 1, wherein a part of a set of magnetic bodies having a shape obtained by dividing the annular body is made of ferrite. 3. A noise absorbing device using a composite magnetic material according to claim 1, wherein a pair of magnetic bodies each having a shape obtained by dividing the annular body is integrally molded with the holding member.