JPS62257707A - Chip coil - Google Patents

Abstract

PURPOSE:To decrease eddy current produced in external electrodes and to increase values of sharpness Q and of inductance, by arranging external electrodes to which a winding is connected, at a distance from the end faces of a cylindrical core on which the winding is wound. CONSTITUTION:Electrode shafts 11 of a conductor are inserted into recesses formed at the ends of a cylindrical core 10. External electrodes 12, 12 are inserted into the respective electrode shafts and fixed at a predetermined distance from the ends of the core 10. A winding 13 is wound on the periphery of the core 10 and the ends of the winding are connected to the respective electrodes 11, 11. The winding 13 is sheathed with a sheathing material 14 such as resin or the like and the spaces 12a are filled also with the sheathing material 14. When a chip coil is energized, magnetic flux is produced as shown by the point-and-dash lines. Most of the magnetic flux passes through the spaces 12a but little magnetic flux passes through the external electrodes 12. Accordingly, eddy current which would be otherwise produced within the external electrodes 12, 12 is decreased substantially.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a chip coil, and more particularly to a chip coil having a columnar core and having external electrodes arranged at both ends thereof.

<Prior Art> Conventionally, a chip coil as shown in FIG. 4 has been known. This is a columnar core 20 with two windings.
and external electrodes 22 and 22 are placed on both ends of this core 20.
, and both ends of the winding 21 are connected to the external electrodes 22 and 22, respectively. Note that the external electrode 22
．． 22 is formed by applying conductive paint or fitting a metal cap, and the winding 21 is wound.
The outer periphery is covered with an exterior material such as resin so that it is not exposed.

<Problems to be solved by the invention> By the way, in a chip coil with such a configuration,
There were the following problems. That is, when this chip coil is energized, a magnetic flux as shown by the "dotted chain line" in FIG. 4 is generated. Since this magnetic flux is focused at both ends of the core 20, most of it crosses the external electrodes 22, 22 formed at these positions. Therefore, when this magnetic flux changes, eddy currents are generated in the external electrodes 22, 22, which are conductors, due to electromagnetic effects.

This eddy current flows through the short-circuited external electrode 22.2.
2, the current value is extremely large, and even the slightest resistance generates Joule heat. This Joule heat is then dissipated to the outside. In this way, since the change in magnetic flux is naturally lost as energy, the sharpness Q of the chip coil becomes small.

In addition, magnetic flux is generated by the eddy current generated in the external electrodes 22, 22, and this magnetic flux acts to prevent changes in the magnetic flux due to the chip coil itself, so that the inductance of the chip coil is reduced and the inductance is large. becomes.

In view of these conventional problems, an object of the present invention is to increase the sharpness Q and the inductance value by reducing the eddy current generated in the external electrode.

Means for Solving the Problems In the present invention, in order to achieve the above object, external electrodes are arranged at positions spaced apart from both end faces of a columnar core around which a winding is wound. It is characterized by a configuration in which a winding is connected to an external electrode.

<Operation> According to the above configuration, most of the magnetic flux generated in the chip coil passes between the end face of the core and the external electrode, so only a small portion of the magnetic flux crosses the external electrode, and the eddy current generated within the external electrode decreases significantly.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a sectional view of the chip coil, and FIG. 2 is a perspective view of its core and external electrodes. In these figures, the code 10 is the core, t 1.1 t is the electrode axis, l 2,
12 is an external electrode. The core 10 is made of ferrite and has a cylindrical shape, and a recess is formed in the center of both end surfaces. In these recesses, one end portion 1 of each electrode shaft 1'l, 11 made of a cylindrical conductor such as metal is provided.
1a and lla are inserted and fixed.

On the other hand, the external electrode 12.12 is made of a disc-shaped conductor such as metal, and has a hole formed in the center of its surface. These external electrodes 12.12 are inserted into each electrode shaft 11.11 by respective holes, and are arranged at positions spaced apart from both end faces of the core IO by a predetermined distance. Note that the reference numeral 12a is a gap formed between the end surface of the core 10 and the external electrode 12. and external electrode 12.12
is electrically connected to the electrode shaft 11.11 by adhesive means such as soldering. In addition, the core IO and electrode axis 11
The cross section of the external electrode 12 and the shape of the external electrode 12 are not limited to a circular shape, but may be any shape such as a rectangular shape.

Further, a winding 13 is wound around the outer peripheral surface of the core 10, and both ends of the winding 13 are connected to each electrode shaft 11°. The outer periphery of the wound wire 13 is covered with a sheathing material 14 such as resin so that the winding I3 is not exposed, and the void 12a is filled with the sheathing material 14.

When such a chip coil is energized, a magnetic flux as shown by the "dotted chain line" in FIG. 1 is generated. This magnetic flux is focused at both ends of the core IO, but most of it passes through the air gap 12a between the core IO and the external electrode 12.12. Therefore, in such a chip coil, only a small portion of the generated magnetic flux is transmitted to the external electrode 12.12.
, the eddy currents occurring in the outer electrode 12.12 are significantly reduced.

Next, FIG. 3 is a perspective view showing another embodiment of the core and external electrodes. In this figure, reference numeral 15.15 is an external electrode. In this external electrode 15, a protrusion 15b is formed at the center of the surface of an electrode portion 15a made of a disc-shaped conductor such as metal. And this protrusion 15
The tip of b is brought into contact with and fixed to the end surface of the core IO. Note that this electrode portion 15a is not limited to a disk shape, but may be hemispherical or the like.

Note that the core 10 and the external electrode 12 are separated by a member made of the same material as the external electrode 12, such as the electrode shaft 11, but this separating member may be an insulating material, and its material and shape may vary. It is not limited to the examples.

<Effects of the Invention> As described above, according to the present invention, most of the magnetic flux generated in the chip coil passes between the core and each external electrode, so only a small part of the magnetic flux crosses the external electrode. Eddy currents generated in the external electrode are significantly reduced. Therefore, the generation and dissipation of Joule heat is reduced, so the sharpness Q
As the inductance becomes larger, the generation of a magnetic field due to eddy current is suppressed, so the inductance value becomes larger and the variation becomes smaller.

Additionally, if the external electrode is provided on the end face of the core via a shaft-shaped metal member, the process of attaching this shaft-shaped metal member to the core is almost the same as the process of attaching the external lead terminal to the core in an axial type coil. Since they are the same, it can be easily implemented by only partially changing the manufacturing process of the axial type coil.

[Brief explanation of drawings]

1 and 2 show one embodiment of the present invention, FIG. 1 is a sectional view of the chip coil, FIG. 2 is a perspective view of the core and external electrodes, and FIG. 3 is a diagram showing another embodiment of the present invention. FIG. 3 is a perspective view of such a core and external electrodes. Moreover, FIG. 4 is a sectional view according to a conventional example. IO... Core, 11.11... Electrode axis, 12.12... External electrode, 15.15... External electrode. Applicant: Sokoku Seisakusho Co., Ltd. Agent: Patent Attorney Oka 1) Hide Kazu Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A chip coil characterized by comprising a columnar core around which a winding is wound, and external electrodes each disposed at a distance from both end faces of the core and to which the winding is connected. .