JPH021846Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a coil used in communication devices, radios, televisions, etc., and more specifically to a coil for a single-tuned circuit that utilizes a through hole provided in a printed circuit board.

Traditionally, communication devices, radios, televisions, etc. have become smaller,
In order to save money and improve reliability, printed circuit boards are used in which circuits such as amplifiers are patterned.
To create a single-tuned circuit coil directly on this printed circuit board, a circular spiral or rectangular spiral pattern was printed on one side of the insulating substrate of the printed circuit board to have the desired inductance. .

However, printed coils printed in this way require a relatively large area on the printed circuit board, which limits the miniaturization of the printed circuit board to a certain extent, and also causes variations in the inductance of the obtained coils. There were some drawbacks such as:

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and aims to provide a single-tuned circuit coil that requires a small area on a printed circuit board and has less variation in inductance. This method utilizes a through hole that connects the back surface pattern and the back surface pattern, and will be explained below with reference to the drawings.

The figure is a perspective view illustrating an embodiment of a single-tuned circuit coil according to the present invention. A through hole 3 having a through hole diameter is formed, and a divided annular conductive film 5 having an opening 6 made of copper, for example, is provided on the inner peripheral wall 4 of the through hole 3 by plating. In this case, both ends 5 sandwiching the opening 6 of the divided annular conductive film 5
In a and 5b, connection conductive films 7a and 7b, which are conductor portions of the printed circuit board 1, are plated integrally with the divided annular conductive film 5 in such a manner that they are drawn out from the divided annular conductive film 5. As a result, a single tuned circuit coil having a predetermined inductance value can be obtained by using the divided annular conductive film 5 provided on the inner peripheral wall 4 of the through hole 3 and using the connecting conductive films 7a and 7b as connection terminals.

The single-tuned circuit coil formed in this way is an air-core coil, and is a coil formed of one divided annular conductive film 5 and has one turn, so its inductance value is mainly determined by the through-hole. It depends on the diameter of 3. Therefore, a coil for a single tuned circuit with less variation in inductance value can be obtained.

To form a single-tuned circuit using this coil, for example, a ceramic trimmer can be connected as a resonant capacitor to each of the connecting conductive films 7a and 7b and housed in the through hole 3. A circuit is obtained.

For example, if the diameter of through hole 3 is 8 mmφ, the inductance value of this coil is approximately 0.01 μH.
is obtained, and the maximum value as a resonant capacitor is 2PF.
This trimmer can be used as a single tuning circuit for high frequency receivers in the UHF band.

Further, if you want to increase the inductance value of the coil for a single tuned circuit, prepare another insulating substrate body having a through hole similar to the through hole 3 having the above-mentioned divided annular conductive film 5, and connect this through hole to the printed circuit board 1. The required number of conductive films may be stacked in the through-hole 3 of , and the connecting conductive films may be connected so that each divided annular conductive film forms a spiral shape.

In the above description, a case has been described in which the divided annular conductive film 5 having an opening 6 is provided in the through hole 3, but instead of the opening 6, a notch (not shown) may be provided using a mold or the like. Of course. As described above, the single-tuned circuit coil according to the present invention includes a split annular conductive film provided on the inner circumferential wall of a through hole formed in an insulating substrate body of a printed circuit board, and a split annular conductive film provided at both ends of the split annular conductive film. Since the coil is made of a connected conductive film that has been drawn out, the coil is formed flat, and the resonant capacitor can be stored in the through hole that forms the coil. There are advantages such as requiring less space, making the printed circuit board more compact, and reducing variations during manufacturing since the inductance of the coil depends on the diameter of the through hole.

[Brief explanation of the drawing]

The figure is a perspective view showing an embodiment of a single-tuned circuit coil according to the present invention. 1...Printed circuit board, 2...Insulating board body, 3...
... Through hole, 4 ... Inner peripheral wall, 5 ... Divided annular conductive film, 6 ... Opening, 5a, 5b ... End, 7
a, 7b... Connection conductive film.

Claims (1)

[Scope of utility model registration request] a divided annular conductive film provided on the inner peripheral wall of a through hole drilled in an insulating substrate body of a printed circuit board;
A coil for a single-tuned circuit, comprising connecting conductive films led out from both ends of the divided annular conductive film.