JPH0543456Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a variable air-core coil that allows fine adjustment.

Coils used in various filters in the several 100 MHz band generally have minute inductance and the inductance is variable.
There is a need for a configuration that allows easy fine adjustment of the inductance of such a small coil.

[Conventional technology]

A conventional high-frequency coil with variable inductance, for example, as shown in FIG. By connecting to the coil to form a coil with a desired inductance, and by providing three or more terminals, it is also possible to derive a tap from the coil.

The number of turns of the conducting wire 22 is, for example, approximately 1 turn when an inductance of 0.018 μH is required, and approximately 21/2 turns when an inductance of 0.046 μH is required.

Also, when adjusting the inductance by selecting taps, the taps are about 1/2 turn, so the inductance can be adjusted in steps of 1/2 of the inductance by one turn of the conductor 22, but smaller adjustments are not possible. be.

Therefore, a configuration is adopted in which the inductance is finely adjusted by screwing the magnetic trimmer 25 into the screw hole at the center of the bobbin 21 to take advantage of the fact that the inductance increases.

[Problem that the invention attempts to solve]

As mentioned above, when finely adjusting the inductance using the magnetic material trimmer 25, it is desired that the inductance can be adjusted within the inductance step range of 1/2 winding of the conductor wire 22. It is necessary to increase the size of the trimmer 25 or increase its magnetic permeability. In this way, increasing the size of the magnetic material trimmer 25 or increasing its magnetic permeability increases the inductance, so it is necessary to reduce the number of windings of the conductor 22 from the beginning, making it easy to manufacture. The disadvantage is that it no longer works.

The object of the present invention is to make it easy to manufacture and to easily finely adjust the inductance.

[Means to solve the problem]

The variable air core coil of the present invention has a configuration in which the inductance of the air core coil can be easily varied without using a magnetic trimmer or the like, and will be explained with reference to FIG. 1.

A coil portion 4 in which a conducting wire 3 is wound around a spiral groove 2 formed on the outer periphery of the bobbin 1 so that the outer periphery of the conducting wire 3 protrudes, and one end 3a of the conducting wire 3 is led out in the direction of the central axis of the bobbin 1; A spiral groove 5 into which the outer periphery of the conducting wire 3 of the section 4 is screwed is formed on the inner periphery, and a terminal 6 that contacts a part of the outer periphery of the conducting wire 3 and a terminal 7 that contacts one end 3a of the conducting wire 3 are provided. It is equipped with a terminal block 8.

[Effect]

By screwing the coil part 4 into the spiral groove 5 of the terminal block 8, the conductor 3 of the coil part 4 comes into contact with the terminal 6.
As a result, the number of windings between the terminal 7 and the one end 3a of the conducting wire 3 of the coil portion 4 that contacts the terminal 7 changes.
That is, by gradually screwing the coil part 4,
The number of windings of the conducting wire 3 between the terminals 6 and 7 can be adjusted steplessly. Therefore, the range of fine adjustment can be expanded without using a magnetic trimmer.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an exploded explanatory view of the embodiment of the present invention. The bobbin 1 and the terminal block 8 are made of an insulating material such as synthetic resin, and the bobbin 1 has a spiral groove 2 formed on its outer periphery, as shown on the upper left side of FIG. The depth of the spiral groove 2 is selected so that the conductor 3 is wound around the helical groove 2, and the outer circumference of the conductor 3 protrudes from the outer circumference of the bobbin 1, as shown in the upper right side of FIG. There is. Also, one end 3a of the conducting wire 2 is led out in the direction of the central axis of the bobbin 1, and the other end is not shown,
It is fixed within the spiral groove 2. This fixing can be done with adhesive or the like.

A coil portion 4 in which a conductive wire 3 is wound around a bobbin 1 is screwed into a center hole of a terminal block 8. A spiral groove 5 having the same pitch as the spiral groove 2 of the bobbin 1 is formed in the center hole of the terminal block 8, and a contact portion 6a at the tip of the terminal 6 is formed in the window 9 so that a part of the outer periphery of the conductor 3 is elastically connected. The contact portion 7a of the terminal 7 is arranged so as to be in contact with the conductor 3.
It is arranged in the center hole 10 so as to be in elastic contact with one end 3a of the. The outer periphery of the conductive wire 3 of the coil portion 4 becomes a screw portion and is screwed into the spiral groove 5 of the terminal block 8 as shown in FIG.

Therefore, the number of turns of the coil in the coil section 4 between the terminals 6 and 7 can be adjusted steplessly, making it possible to widen the variable range of inductance and making fine adjustment easier. After adjustment, the contact part 6
The parts a and 7a can be connected and fixed using solder, conductive adhesive, etc. to prevent the adjustment from shifting.

The pitch of the spiral grooves 2 and 5 can be selected depending on the required inductance and adjustment range, and the cross-sectional shape of the conductor 22 can be not only circular but also any shape. It is sufficient to form the spiral grooves 2 and 5 in a shape corresponding to the cross-sectional shape.

[Effect of idea]

As explained above, in the present invention, the conductive wire 3 is wound around the helical groove 2 of the bobbin 1 so that its outer periphery protrudes, and the resulting threaded portion is inserted into the helical groove 2 of the terminal block 8.
a terminal 6 that is screwed into the terminal 6 and contacts the outer periphery of the conductor 3;
There is an advantage that the inductance of the coil portion 4 between the terminal 7 that contacts one end 3a of the conducting wire 3 can be adjusted steplessly over a relatively wide range from one turn or less to several turns.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is an exploded explanatory view of the embodiment of the present invention, and FIG. 3 is a cross-sectional view of essential parts of a conventional example. 1 is a bobbin, 2 is a spiral groove, 3 is a conducting wire, 3a is one end of the conducting wire, 4 is a coil portion, 5 is a spiral groove, 6 and 7 are terminals, and 8 is a terminal block.

Claims (1)

[Claims for Utility Model Registration] A conducting wire 3 is wound around a spiral groove 2 formed on the outer periphery of the bobbin 1 so that the outer periphery of the conducting wire 3 protrudes, and one end 3a of the conducting wire 3 is wound in the direction of the central axis of the bobbin 1. a terminal 6 having a spiral groove 5 formed in its inner circumference into which the outer circumference of the conductor 3 of the coil portion 4 is screwed in as a screw portion and contacting a part of the outer circumference of the conductor 3; A variable air core coil characterized by comprising a terminal block 8 provided with a terminal 7 that contacts one end 3a of a conducting wire 3.