JPH0132726Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an improvement of an air-core coil used for assembling a high frequency circuit such as a television tuner.

Conventional technology Conventionally, air-core coils that are assembled into high-frequency circuits such as VHF and UHF (30MHz to 900MHz) suffer from inductance after assembly due to variations in the electrical characteristics of electrically connected transistors and variations in capacitors (CPF). are forced to adjust. Because of this need, this type of air-core coil is usually attached to a printed circuit board or the like in its bare form, consisting of only a spirally wound conductor such as a copper wire.

Problems that the invention aims to solve However, this method is not only unstable in shape, but is also incompatible with automatic mounting, so the reality is that each installation is done manually, which takes time and effort.

Another object of the present invention is to provide an air-core coil whose inductance can be adjusted even after assembly, and which is also suitable for automatic mounting.

Means for Solving the Problems In the air-core coil according to the present invention, external electrodes are provided on opposing sides of a partially open case, and the end surface of each external electrode exposed inside the case is connected to the terminal side. It is constructed by attaching a spirally wound conductive wire to the inside of the case.

Function This air-core coil has conductive wires attached inside the case, so it can be mounted with stability in terms of shape.If the case is held, it is not only suitable for automatic mounting, but also can be mounted from the open part of the case. Since the magnetic path length can be changed by inserting a tool, the inductance can be adjusted even after mounting.

Embodiments The following description will be made with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, this air-core coil is constructed by installing a conductive wire 1 in a manner that it is suspended inside cases 2 and 2'. As the conductive wire 1, a conductive material such as a copper wire wound several times in a spiral shape is used. Also, case 2,
As 2', a substantially groove-shaped or housing-shaped one with an open upper surface is used, and external electrodes 3 and 4 are attached to each opposing side surface. These external electrodes 3,
4 is provided in the case with its end surface exposed, and the conductive wire 1 is connected between each of the external electrodes 3 and 4 by bringing the terminal side into contact with each end surface and fixing it by soldering. The external electrodes 3 and 4 can be formed as a surface-mounted air-core coil by embedding a conductive material near the lower side of the case, and by drawing out the end of the conductive wire 1 or attaching a separate lead wire. It can also be formed into a lead type. The cases 2 and 2' can be formed into any shape as long as they are partially open and allow the conductive wire 1 to be incorporated therein, and can be formed using a polymeric resin such as epoxy as the molding material. be able to.

In the air-core coil configured in this way, the cases 2 and 2' are placed on the printed circuit of the printed circuit board,
The external electrodes 3 and 4 can be attached by soldering and fixing them. Even if automatic mounting is applied at that time, since the conductive wire 1 is installed inside the cases 2, 2', the conductive wire 1 can be easily attached without causing deformation or the like. In addition, the inductance L (μH), which is an electrical characteristic of this air-core coil, is L = μ・S/l・N ² (μ: magnetic permeability, S: cross-sectional area of the coil, l: magnetic path length, N: coil length). The electrical characteristics are determined by the number of turns), but since the cases 2 and 2' are formed in the shape of a generally groove-shaped frame with a partially open part or in the shape of a casing with the top open, By adjusting the magnetic path length by changing the winding gap of the conductive wire 1 using a jig such as an insulated screwdriver that is inserted, fine adjustment can be made even after mounting and mounting.

Incidentally, the cases 2 and 2' can be made of a resin material that is a mixture of epoxy and ferrite powder. In this case, the inductance can be kept at a predetermined value even if it is constructed as a small device such as a chip type. Alternatively, they may be formed of a sintered body of ferrite magnetic material, and in this case, a constant inductance can be obtained even if the cases 2, 2' are made smaller.

Effects of the invention As described above, according to the air-core coil according to the present invention, not only can the electrical characteristics be easily adjusted even after installation in relation to other assembly parts, but also it can be easily installed on a printed circuit board, etc. This makes it possible to perform mounting work efficiently since it is compatible with automatic mounting.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of an air-core coil according to the present invention, and FIG. 2 is a perspective view showing another embodiment of the air-core coil. 1: Spiral conductive wire, 2, 2': Case,
3, 4: External electrode.

Claims (1)

[Claims for Utility Model Registration] (1) External electrodes are provided on opposite sides of a partially open case, and the end surface of each external electrode exposed inside the case is connected to the terminal side to form a spiral shape. An air-core coil that is made by wrapping a wound conductive wire inside a case. (2) The air-core coil according to claim 1, wherein the case is made of a resin material that is a mixture of epoxy and ferrite powder. (3) The air-core coil according to claim 1, wherein the case is formed of a ferrite sintered body.