JPH05166623A - Small fixed coil - Google Patents

Abstract

PURPOSE:To provide a small fixed coil which allows high mounting freedom on a printed board without inductance characteristic fluctuation and that permits small waste in occupying volume on the printed board. CONSTITUTION:The cross-section along the wire coiling plane of a bobbin 10, which is a core material, is permitted to be approximately elliptical. The width, height and length of a coil main body which has the bobbin 10 coiled with the wire 20 have different dimensions and the coil main body is molded in rectangular parallelopiped by resin 30 according to the shape of the bobbin 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small fixed coil used in a high frequency circuit such as a small wireless device.

[0002]

2. Description of the Related Art A small fixed coil basically has a structure in which a wire is wound around a core material made of synthetic resin or magnetic material.
Recently, in order to support automation of component mounting on a printed circuit board, recently, in many cases, a coil body in which a wire is wound around a core is further molded with a synthetic resin.

FIGS. 6, 7 and 8 and 9 respectively show a conventional small fixed coil in which the coil body is molded with a synthetic resin. The shape of the core material 1 is a cylindrical shape in FIGS. 6 and 7 and a quadrangular prism shape with a square vertical cross section in FIGS. 8 and 9, but they are different from each other, but the final resin-molded overall shape is It has a simple rectangular cross section and a square pole shape because of material savings, easy manufacturing, and easy handling.

[0004]

However, in the conventional small fixed coil, the shape of the core material is originally a cylindrical shape or a quadrangular prism shape having a square cross section, so that the whole is not molded with a synthetic resin. Regardless, the width x and the height z have the same dimension. Therefore, there are only two types of conventional small fixed coils mounted on the printed circuit board as shown in FIG. 10 or FIG.
There was a problem that the degree of freedom in mounting was low.

Further, the prior art in which the core material 1 shown in FIGS. 8 and 9 has a quadrangular prism shape is box-shaped as compared with the prior art in which the core material 1 shown in FIGS. 6 and 7 has a cylindrical shape. Therefore, there is little waste in the volume occupied on the printed circuit board, and when molding the whole into a quadrangular prism having a square cross section, there is an advantage that there is little waste in the molding portion, but on the contrary, there are the following drawbacks. That is, the quadrangular prism-shaped core material 1 shown in FIGS.
Unlike the cylindrical core material 1 shown in FIGS. 6 and 7, there is a corner portion a and a flat portion b, and the surface curvature of the core material changes abruptly. Cannot be adhered. Since the rate at which the wire 2 is separated from the flat part b cannot be made constant due to the material, processing accuracy, etc., in the conventional small fixed coil in which the core is a square pole, the winding state of the wire is different for each product. However, there is a problem in that the inductance characteristics vary.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is a small-sized compact which has a high degree of freedom in mounting on a printed circuit board, a small variation in inductance characteristics, and a small volume occupied on the printed circuit board. To provide a fixed coil.

[0007]

In order to achieve the above object, in the small fixed coil according to the present invention, the cross-sectional shape of the bobbin, which is the core material, is substantially elliptical along the wire winding surface. The width of the coil body with the wire wound around the bobbin,
The height and the depth are different from each other.

According to the second aspect, the coil body is resin-molded into a rectangular parallelepiped shape matching the bobbin shape.

[0009]

[Function] Since the cross section of the core material along the winding surface of the wire material is substantially elliptical, there is no portion where the wire material is separated from the surface of the core material, and the winding condition of the wire material does not differ for each product. There is little variation in inductance characteristics.

Since the width, height, and depth of the coil body are formed to have different dimensions, there are three different mounting forms on the printed circuit board.

Since the cross section of the core material along the winding surface of the wire is substantially elliptical, the volume occupied on the printed circuit board is less wasteful than in the prior art in which the core material is cylindrical.

According to the second aspect of the present invention, since the coil main body is molded with resin to form a rectangular parallelepiped shape in which the entire shape is matched with the bobbin shape, there is little waste in the molded portion.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view of a small fixed coil which is an embodiment of the present invention, FIG. 2 is a cross sectional view of the same, FIG.
4 and 5 are perspective views showing different mounting configurations of the same coil on a printed circuit board.

In these drawings, reference numeral 10 indicates a column-shaped core material having an oval cross section, and a coil body in which a wire material 30 is wound along a curved side surface of the core material 10. Is molded with synthetic resin 30 to form a small fixed coil having a rectangular parallelepiped overall shape.

Since the small fixed coil in the shape of a rectangular parallelepiped is a solid body composed of three different rectangles with different dimensions of width X, height Z, and depth Y, these three different rectangles are printed respectively. By setting the mounting surface on the substrate 50, three different mounting configurations shown in FIGS. 3, 4, and 5 can be taken on the printed circuit board 50.

That is, the external dimensions are height Z <width X <depth Y.
In the mounting form shown in FIG. 3, for example, in the mounting form shown in FIG. 3, the small fixed coil of the present embodiment has the largest area on the substrate 50 in X and Y, but the smallest height in Z. . On the other hand, in the mounting form shown in FIG. 5, the area occupied on the substrate 50 is the smallest in Z · X, but the height is the largest in Y. Moreover, in the mounting form shown in FIG.
The area occupied on the top is ZY and the height of the back is X.
The area occupied on 0 and the height of the back are respectively intermediate values between the case of FIG. 3 and the case of FIG.

In this embodiment, the cross section of the core material 10 along the wire winding surface is oval, but it may be oval.

Further, in this embodiment, the wire rod 3 is attached to the core member 10.
The coil body wound with 0 is further molded with the synthetic resin 30, but the coil body formed so as to have different width, height, and depth dimensions is directly printed on the printed circuit board 50.
It may be mounted on top, and in this case as well,
As shown in FIGS. 4 and 5, three different mounting configurations can be adopted.

[0020]

As is apparent from the above description, according to the present invention, since there is little variation in the inductance characteristic,
When used in a high-frequency circuit or the like, the circuit characteristics are constant and the adjustment work is reduced, the work time is shortened, and the manufacturing cost of the small wireless device is reduced.

There are three different mounting forms of the small fixed coil on the printed circuit board, and the degree of freedom in mounting on the printed circuit board is higher than in the prior art in which the mounting form is limited to two. Therefore, it is possible to increase the mounting density of components, more effectively avoid electrical mutual interference with other electrical components mounted on the printed circuit board, and use it in high-frequency circuits such as small radio equipment. Therefore, it is possible to provide a high-performance and small-sized wireless device.

[Brief description of drawings]

FIG. 1 is a perspective view of a small fixed coil according to an embodiment of the present invention.

FIG. 2 is a cross sectional view of the coil.

FIG. 3 is a perspective view showing a mounting form of the coil on a printed circuit board.

FIG. 4 is a perspective view showing a mounting form of the coil on a printed circuit board.

FIG. 5 is a perspective view showing a mounting form of the coil on a printed circuit board.

FIG. 6 is a perspective view of a conventional small fixed coil.

FIG. 7 is a cross sectional view of the coil.

FIG. 8 is a perspective view of another conventional small fixed coil.

FIG. 9 is a transverse sectional view of the coil.

FIG. 10 is a perspective view showing a mounting form of a conventional small fixed coil on a printed circuit board.

FIG. 11 is a perspective view showing a mounting form of a conventional small fixed coil on a printed circuit board.

[Explanation of symbols]

 10 core material 20 wire material 30 synthetic resin mold part

Claims (2)

[Claims] 1. A bobbin which is a core member has a substantially elliptical cross-section along a wire winding surface, and the width, height, and depth of a coil body in which the wire is wound around the bobbin are different from each other. A small fixed coil characterized by being formed. 2. The small fixed coil according to claim 1, wherein the coil body is resin-molded into a rectangular parallelepiped shape matching a bobbin shape.