JP3469312B2 - Thin transformer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin transformer for an IC card size communication interface, and more particularly to a small thin transformer such as a low frequency transformer or a pulse transformer which is surface-mounted on a substrate.

[0002]

2. Description of the Related Art Conventionally, in this type of thin transformer,
In order to obtain the required inductance value, it is necessary to use a material with a high magnetic permeability as the core material. Generally, cores made by punching a nickel alloy into an E shape or the like are laminated alternately or ferrite cores are used. ing.

FIG. 5 is a conventional example of this transformer, and FIG. 6 is a sectional view of its core portion. That is, 1'in these figures is a core half made of a nickel alloy or ferrite, and a short columnar central leg 2'is formed in the central portion, and both legs 3'are formed on both sides thereof, and the cross section is Figure 6
It is E-shaped as shown in FIG. Further, in FIG. 5, reference numeral 5'denotes a coil bobbin having a coil 6 ', which coil bobbin 5'is positioned in a concave bobbin accommodating portion 7'formed in the lower core half body 1', and the upper core half The transformer is assembled by, for example, joining the body 1'face to face.

Among the small and thin transformers thus constructed, particularly low frequency transformers and pulse transformers are required to be thinner, for example, for surface mounting, and the core having high magnetic permeability as described above is used. Has been adapted to miniaturization.

[0005]

However, if the core material is a single ferrite core or a single structure in which only nickel alloys are punched out and laminated, a reduction in inductance may cause a decrease in inductance and magnetic saturation. There was a challenge to come.

In order to solve this problem, the floor area of the core may be increased, but the mounting area of the transformer becomes large, which hinders high-density mounting and hinders miniaturization.

The present invention has been proposed in view of the above, and an object thereof is to prevent magnetic saturation even if the size of the central leg of the core is made of a different material having a high magnetic permeability. And to provide a thin transformer capable of improving electric characteristics.

[0008]

The present invention SUMMARY OF THE INVENTION, in thin transformer to the coil bobbin which a coil is wound to a compact comprising incorporating a ferrite core, from the ferrite in the center of the central leg of the ferrite core A magnetic body made of a magnetic material having a high magnetic permeability is arranged, and the magnetic body is an amorphous material.
A thin plate of magnetic material such as fuss or nickel alloy can be cylindrical
The above-mentioned object is achieved by constructing it in a cylindrical shape . Furthermore, the magnetic body is the center of the central leg .
The central leg has a composite structure by being inserted into and housed in a magnetic body housing portion formed of an annular or columnar recess formed in the portion.

[0009]

According to the present invention, as described above, a part of the central leg of the ferrite core is formed by winding a thin plate of amorphous or nickel alloy, which is a magnetic material having a higher magnetic permeability than the ferrite core, into a cylindrical or cylindrical shape. Since a part of the central leg is made of a magnetic material with high magnetic permeability, it is possible to obtain higher inductance than in the case of a ferrite core alone, and prevent magnetic saturation and transmission loss characteristics while maintaining miniaturization.
The electrical characteristics such as impedance characteristics and waveform distortion rate characteristics are improved.

[0010]

First Embodiment FIG. 1 is an exploded perspective view of a first embodiment of the present invention,
FIG. 2 is a sectional view in the assembled state.

In these drawings, reference numerals 1 and 1 denote E-shaped core halves each made of ferrite having the same shape, and a ferrite core body is formed by joining two core halves 1 and 1 to each other.

Each core half 1 has a central leg 2 and both legs 3 and has an E-shaped cross section. Further, the center leg 2 is formed of a substantially cylindrical protrusion 2a at the center thereof and an annular portion 2b formed by leaving a space between the protrusion 2a and the protrusion 2a.
That is, the annular recess 2c is provided between the protrusion 2a and the annular portion 2b.
In other words, the center leg 2 is formed with an annular recess 2c.

Reference numeral 4 denotes an annular magnetic body having a hole a accommodated in the magnetic body accommodating portion composed of the annular recess 2c. The magnetic body 4 is formed by winding a thin plate of an amorphous or nickel alloy magnetic material, which is a magnetic material having a magnetic permeability higher than that of ferrite, into a cylindrical shape.

Reference numeral 5 denotes a coil bobbin formed of a resin molded product, and a body portion 5a having an annular hollow portion a ', and this body portion 5
flanges 5b and 5c respectively formed on both ends of a,
A thick portion 5d is formed on both sides of the outer end of the one flange 5c, and a plurality of terminals 5e having a bent structure for surface mounting are planted in each thick portion 5d.

Upon assembly, predetermined primary and secondary coils 6 are wound around the outer periphery of the body portion 5a. Further, the hole a is formed in the magnetic body containing portion formed by the annular recess 2c of the lower core half body 1.
The lower half part of the magnetic body 4 having is accommodated around the protrusion 2a. Then, the coil bobbin 5 is arranged around the central leg 2 via the annular hollow portion a ′, and the coil bobbin 5 is positioned in the concave bobbin accommodating portion 7 formed between the central leg 2 and both legs 3. Then, the upper core half body 1 is covered, and the upper half portion of the magnetic body 4 and the coil bobbin 5 are housed inside and bonded to the lower core half body 1, thereby forming a thin transformer.

According to this thin transformer, however, a part of the central leg 2 of the ferrite core is combined with a magnetic material having a higher magnetic permeability, so that even if the size is reduced, the magnetic saturation is maintained while maintaining a high inductance. Prevention and improvement of electrical characteristics can be achieved.

[0017]

Second Embodiment FIG. 3 is an exploded perspective view of a second embodiment of the present invention,
FIG. 4 is a sectional view of the assembled state.

In this embodiment, the ferrite core is E.I.
It is different from the above-mentioned embodiment in that it is composed of the mold cores 11 and 12, and the bobbin shape, the magnetic body 13 and the like correspond thereto.

That is, the central leg 11a of the E-shaped core 11 is formed with a cylindrical recess 11b, and the cylindrical magnetic body 13 having a shape corresponding to the recess 11b is inserted and accommodated. There is.

The magnetic body 13 is formed by winding a thin plate of an amorphous or nickel alloy, which is a magnetic material having a high magnetic permeability, in a cylindrical shape, as in the above-mentioned embodiment.

In this example, the body portion 14a of the coil bobbin 14 has a substantially rectangular tubular shape, and the flanges 14b, 1
4c and the like also have a corresponding shape.

At the time of assembly, the magnetic body 13 is housed in the magnetic body housing formed by the recess 11b of the central leg 11a,
The coil bobbin 14 around which the coil 15 is wound has an E.I.
A transformer can be constructed by incorporating the mold cores 11 and 12 in a known manner.

[0023]

As described above, according to the present invention, in a thin transformer in which a ferrite core is incorporated in a coil bobbin, a magnetic body made of a magnetic material having a magnetic permeability higher than that of the ferrite core is provided at the center of the central leg of the ferrite core. Place and
The magnetic material is an amorphous or nickel alloy magnetic material.
It consists of a thin sheet of material rolled into a cylindrical or cylindrical shape.
Was therefore obtained high inductance than ferrite alone is an effect of obtaining aims to improve the prevention and electrical properties of the magnetic saturation while maintaining the miniaturization.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a thin transformer according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the assembled state of the first embodiment of the present invention.

FIG. 3 is an exploded perspective view of a thin transformer according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a second embodiment of the present invention in an assembled state.

FIG. 5 is an exploded perspective view of a conventional example of a thin transformer.

FIG. 6 is a sectional view of the above conventional example in an assembled state.

[Explanation of symbols]

1 core half 2 central leg 2a protrusion 2b annular part 2c annular recess 3 legs 4 magnetic material 5 coil bobbins 5a body 5b, 5c flange 5d thick part 5e terminal 6 coils 7 Bobbin housing a hole 11 E type core 11a central leg 11b recess 12 type I core 13 Magnetic material 14 coil bobbins 14a body 14b, 14c flange 14d thick part

Claims (2)

(57) [Claims] 1. A small and thin transformer comprising a coil bobbin having a coil wound around and incorporating a ferrite core, wherein the central part of the center leg of the ferrite core has a higher magnetic permeability than ferrite. A magnetic body made of magnetic material
Arranged and said magnetic material is amorphous or nickel alloy
A thin plate of magnetic material is rolled into a cylinder or cylinder
A thin transformer characterized in that 2. The thin transformer according to claim 1, wherein the magnetic material is inserted and accommodated in a magnetic material accommodating portion formed of an annular or cylindrical recess formed in the central portion of the central leg.