JP2570669B2 - Non-reciprocal circuit device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to non-reciprocal circuit devices, such as isolators and circulators, used in VHF, UHF and high-frequency portions of a microwave band. The present invention relates to a reduction in component costs by simplifying a manufacturing process. Hereinafter, the present invention will be described using an isolator as an example.

[Conventional technology]

Lumped-constant isolators and circulators have a function of causing little attenuation in the signal transmission direction and increasing attenuation in the opposite direction, and are indispensable components for microwave equipment.

Conventionally, such an isolator has a structure shown in FIG. In the isolator 1, a dielectric substrate 4 is connected to a bottom of a rectangular parallelepiped magnetic metal case 2 via an earth plate 3, and a ferrite assembly 5 is inserted into a central hole of the dielectric substrate 4, and Case 2 ceiling wall
The permanent magnet 6 is bonded inside the 2a. In the ferrite assembly 5, three center conductors 9 are arranged so as to cross each other between a pair of ferrites 7 with an insulating sheet 8 interposed therebetween. Is connected to the impedance matching electrode film 4a on the upper surface of the dielectric substrate 4. The cut and raised connection pieces are connected to a shield plate 10, whereby the shield plate 10 is connected to the ground plate 3 to be at a ground potential.

The isolator 1 is configured to apply a DC bias magnetic field to the ferrite 7 by the permanent magnet 6 in the vertical direction in the drawing. In order to apply a DC magnetic field to the ferrite 7, a permanent magnet 6 (a sintered magnet such as a ferrite magnet) is disposed in the ceiling wall 2a of the case 2 (or both the ceiling wall and the bottom wall). A method of using the case 2 as a yoke is adopted. That is, the above case 2
Is used as a yoke for a magnetic circuit while protecting the ferrite assembly 5 and the like from external forces.
It also serves to prevent the DC magnetic field from leaking outside.

However, in the above-described conventional isolator 1, since the case 2 and the permanent magnet 6 need to be aligned and bonded together with an adhesive, the number of manufacturing steps and the number of parts increase, and the cost increases. There's a problem.

Therefore, as an example of an isolator capable of reducing the cost, there is one disclosed in Japanese Utility Model Laid-Open Publication No. 6-136604. This is because the case part and the permanent magnet part are integrally formed of magnetic resin,
The cost is reduced by reducing the number of parts.

[Problems to be solved by the invention]

However, in the isolator according to the above publication, although the step of attaching the magnet to the case is not required, the magnetic force leaks out of the case in this state,
In order to prevent this leakage, it is necessary to bond an iron plate for magnetic flux focusing.In the end, the increase in the number of attaching steps of the iron plate offsets the reduction in the magnet attaching step, and the effect of reducing the cost can be obtained so much. There is a problem that not.

An object of the present invention is to provide a non-reciprocal circuit device capable of reliably preventing leakage of magnetic force without employing an iron plate for converging magnetic flux, reducing the number of manufacturing steps and the number of parts, and reducing costs.

[Means for solving the problem]

Therefore, the present inventors considered preventing the leakage of magnetic force without using an iron plate in order to realize the above object, and integrally forming the ceiling wall portion and the permanent magnet portion with a magnetic resin having magnetic anisotropy. And found that by controlling the magnetic anisotropy of each part, leakage of magnetic force can be prevented without employing the iron plate,
The present inventors have conceived that cost reduction can be realized by this, and have made the present invention.

That is, the present invention provides a non-reciprocal circuit device in which a ferrite assembly is disposed in a case and a direct current magnetic field is applied to the ferrite of the assembly by a permanent magnet disposed on a ceiling wall of the case. At least the ceiling wall portion and the permanent magnet portion of the case are formed integrally with a magnetic resin having magnetic anisotropy, and the direction of large magnetic permeability, that is, the anisotropic direction, the permanent magnet portion is in the DC magnetic field direction, The ceiling wall portion is characterized by being directed in a direction orthogonal to the DC magnetic field.

Here, the above-mentioned at least the ceiling wall portion and the permanent magnet portion include a case where the four side walls or the bottom wall portion in addition to the two portions are integrally formed.

[Action]

According to the non-reciprocal circuit device according to the present invention, the ceiling wall portion and the permanent magnet portion are formed integrally with the magnetic resin, and the direction of the magnetic anisotropy of the magnetic resin is directed to the DC magnetic field direction. Therefore, a bias magnetic field can be applied to the ferrite, and the ceiling wall portion is oriented in a direction orthogonal to the DC magnetic field, so that the ceiling wall portion forms a magnetic circuit as it is, and magnetism leaks outward. Can be prevented. As a result, the iron plate for magnetic flux focusing described in the above publication can be dispensed with, and the number of parts and the number of manufacturing steps can be reduced.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 to 3 show an isolator according to an embodiment of the present invention, in which the same reference numerals as in FIG. 6 denote the same or corresponding parts.

The isolator 1 of the present embodiment is configured by housing a ferrite assembly 5 in which a pair of ferrites 7 sandwich three center conductors 9 arranged in an intersecting manner via an insulating sheet 8 in a case 15. The basic structure is almost the same as the conventional one.

The case 15 of the present embodiment has a metal frame 16 having a bottom wall 16a integrally formed with four side walls 16b, and a plastic magnet 17 having a ceiling wall 17a and a permanent magnet portion 17b integrally formed of a magnetic resin. And a combination thereof. The ceiling wall 17a of the plastic magnet 17 is formed in a rectangular plate shape, and the permanent magnet portion 17b is formed by projecting a central portion of the ceiling wall 17a downward in a columnar shape. The diameter of the permanent magnet portion 17b is not limited to the illustrated example, and may be, for example, the same diameter as the ceiling wall 17a.

Permanent magnet part 17b of the plastic magnet 17
Is that the magnetic permeability in the axial direction of the ferrite 7 is much larger than the magnetic permeability in the direction perpendicular thereto, that is, the magnetic anisotropy of the permanent magnet portion 17b is oriented in the axial direction of the ferrite 7. (See arrow A in FIG. 2).
On the other hand, the ceiling wall 17a is formed so that the magnetic permeability in the direction orthogonal to the axis of the ferrite 7 is increased, that is, the magnetic anisotropy of the ceiling wall 17a is orthogonal to the DC magnetic field to the ferrite 7. (See arrow B in FIG. 2).

Here, the control of the magnetic anisotropy is performed, for example, as follows. That is, a magnetic resin obtained by mixing ferromagnetic powder in the resin is used, and during injection molding, the direction of magnetization is in the direction of arrow B on the ceiling wall 17a, and the direction of arrow A is on the permanent magnet portion 17b. What is necessary is just to set the direction of the magnetic field applied for magnetizing so that it may become a direction.

 Next, the operation and effect of this embodiment will be described.

The isolator 1 according to the present embodiment is disposed, for example, between a transmission unit of a car phone and a duplexer for transmission and reception, and has a function of preventing a backflow of a transmission output from the transmission unit.

And according to the isolator 1 of the present embodiment, the ceiling wall
Since the 17a and the permanent magnet part 17b are formed integrally with the plastic magnet 17, the work of bonding the conventional metal case and the permanent magnet while positioning them can be omitted. As a result, the number of manufacturing steps and the number of parts are reduced, and the cost is reduced. it can.

In addition, since the magnetic anisotropy of the permanent magnet portion 17b is oriented in the direction of the DC magnetic field and the magnetic anisotropy of the ceiling wall 17a is oriented in the direction orthogonal to the DC magnetic field, the DC is applied to the ferrite 7 by the permanent magnet portion 17b. A magnetic field can be applied, and a magnetic circuit is formed by the ceiling wall 17a and the isotropic magnetic metal frame 16, and as a result, the leakage of the magnetic field can be prevented without using the conventional magnetic flux focusing iron plate, The number of parts and the number of manufacturing steps can be reduced.

In the above embodiment, the case where the ceiling wall 17a and the permanent magnet portion 17b are integrally formed is described as an example.
In the present invention, by integrally forming the case including the side wall and the bottom wall, and by controlling the direction of magnetic anisotropy, a magnetic circuit can be formed to prevent leakage of magnetism.

4 and 5 are views showing a modification of the above embodiment. FIG. 4 shows a ceiling wall 18a, four side walls 18b and a permanent magnet portion 18c.
FIG. 5 shows an example in which a ceiling wall 19a, four side walls 19b, a bottom wall 19c, and a permanent magnet portion 19d are integrally formed of a magnetic resin. In any of the above-described modifications, the magnetic force can be prevented from leaking by setting the direction of the magnetic anisotropy in the direction of the arrow in the drawing, and the same effect as in the above-described embodiment can be obtained.

Further, in the above embodiment, the isolator has been described as an example, but the present invention can of course be applied to a circulator,
Further, the present invention can be applied to a non-reciprocal circuit device used for another high frequency component.

〔The invention's effect〕

As described above, according to the non-reciprocal circuit device according to the present invention,
At least the ceiling wall portion and the permanent magnet portion of the case are integrally formed of a magnetic resin having magnetic anisotropy, and the direction of the magnetic anisotropy is set in the direction of the DC magnetic field in the permanent magnet portion and in the direction of the DC magnetic field in the ceiling wall portion. Is oriented in the orthogonal direction,
There is an effect that the leakage of magnetism can be reliably prevented without adding a magnetic metal such as an iron plate, and the number of manufacturing steps and the number of parts can be reduced to reduce costs.

[Brief description of the drawings]

1 to 3 show an isolator according to an embodiment of the present invention. FIG. 1 is a sectional side view, FIG. 2 is a front view showing the direction of magnetic anisotropy, and FIG. 4 (a) and 4 (b) are a perspective view and a sectional view showing a modification of the above embodiment, respectively. FIG. 5 is a sectional view showing another modification, and FIG. FIG. 3 is a cross-sectional side view showing a conventional isolator. In the figure, 1 is an isolator (non-reciprocal circuit element), 5
Is a ferrite assembly, 7 is a ferrite, 9 is a center conductor,
15 is a case, 17 is a plastic magnet (magnetic resin), 17a is a ceiling wall, 17b is a permanent magnet part, and A and B are arrows indicating the direction of magnetic anisotropy.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hiroshi Tokudera 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-62-33404 (JP, A) Sho 61-136604 (JP, U) JP-B Sho 59-24524 (JP, B2)

Claims (1)

(57) [Claims] 1. A ferrite assembly comprising a pair of ferrites sandwiching a plurality of central conductors arranged in an electrically insulated state and crossing each other in a case. In a non-reciprocal circuit device configured to apply a DC magnetic field by a permanent magnet disposed in, at least the ceiling wall portion and the permanent magnet portion of the case are integrally formed of a magnetic resin having magnetic anisotropy, A nonreciprocal circuit device characterized in that the direction of the large magnetic permeability is oriented in the direction of the DC magnetic field in the permanent magnet portion and in the direction orthogonal to the DC magnetic field in the ceiling wall portion.