JP2001167928A - Printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a coil which has a center tap and whose number of turns is large in a double-layer substrate. SOLUTION: In a printed circuit board 40, a coil is formed by developing a pattern spirally via a1 (tap 41) and a2 to c1 (tap 42), and via c1 (tap 41) and c2 to b1, (tap 43). As the inductance of the coils that are formed by the patterns of both face A and face B of the printed circuit board 40 is larger on the outer peripheral side than on the inner peripheral side, the pattern of the printed circuit board is wired so that the inner peripheral side and the outer peripheral side may be replaced by each other when the pattern moves from face A to face B or from face B to face A, and the tap 42 can be provided in an electrical midpoint between the tap 41 and the tap 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly to a coil formed by a pattern on a printed circuit board, in which the reactance is improved on a substrate having a small number of layers such as a two-layer substrate. The present invention relates to a printed circuit board in which an intermediate tap can be provided.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a coil pattern formed on a printed circuit board. As shown in FIG. 1, the coil formed on the printed circuit board is spirally formed on the printed circuit board 1 from one terminal (input terminal) a1 of the coil connected to the tap 11 toward the inner peripheral side. This is achieved by developing a pattern. Here, when the terminal (output terminal) b1 on the opposite side of the terminal a1 is to be connected to the tap 13, the pattern cannot be derived from the surface (surface A) where the pattern forming the coil is developed (the same). In the plane, so that the two patterns do not touch each other,
Since one pattern cannot jump over the other pattern), the pattern is led out from the terminal a2 of the coil on the surface A to the opposite surface (surface B) via a through hole, and the surface B is Form the pattern shown by the dashed line,
It is necessary to connect the pattern to the terminal b1 via the through hole. That is, the printed circuit board 1 has two layers (both sides).
It must be configured as a substrate. Also, in this case, the tap 12 can be prepared by connecting the terminal c2 and the terminal c1 in the middle of the coil using the surface B.

In order to reduce the board area while improving the inductance of the coil, a spiral pattern is formed on both the A and B faces of the two-layer board as shown in a printed board 20 shown in FIG. Can be expanded (that is,
It is sufficient to increase the number of turns of the coil). However, in the case of FIG. 2, the taps 21 and 22 to which both ends of the coil are connected can be easily formed. However, due to the pattern on the substrate, aerial wiring (for example, wiring using a jumper wire) is used. , The intermediate tap cannot be formed. Therefore, when it is attempted to improve the inductance with a small board area and further provide an intermediate tap, by forming an additional three-layer structure in order to form a pattern for the intermediate tap on the printed circuit board,
As in the printed circuit board 30 shown in FIG. 3, the taps 31 to 33 can be mounted without aerial wiring.
In the case of the example of FIG. 3, the input terminal a1 connected to the tap 31
And an output terminal b1 connected to the tap 33, an intermediate terminal a2 is formed. The intermediate terminal a2 is connected to the tap 32 via the terminal c1.

[0004] When a coil formed on a substrate is used for an antenna circuit used for wireless communication or electromagnetic coupling non-contact communication, for example, the power-end circuit on the transmitting side is often constituted by a push-pull circuit. In order to supply the transmission power to the coil, it is advantageous that the coil has an intermediate tap. FIG. 4 shows an example of a circuit of a transmitter in electromagnetic coupling non-contact communication using a coil having no intermediate tap (the printed circuit board 20 described with reference to FIG. 2).

A signal source V1 and a signal source V2 in FIG.
As a result, drive signals of the normal and reverse phases are transmitted. These signals are amplified in power by the transistors Q1 and Q2, and resonated at a predetermined communication frequency by the capacitor C3. The values of the capacitor C1, the capacitor C2, and the resistors R1 to R7 are determined by circuit characteristics. This transistor Q1 and transistor Q
DC voltage applied to the collector of the choke coil L1
And a junction point between the choke coil L1 and the choke coil L2 is decoupled by the choke coil L3 and the capacitor C2. Radiation of the output signal is maximum in the direction perpendicular to the printed circuit board 2. In addition, transistor Q3
The transistor Q4 is used for buffering.

[0006]

As described above,
If a coil formed by developing a pattern on a printed board is to be realized by a two-layer board, a coil (winding) having an intermediate tap and sacrificing inductance as in the printed board 1 described with reference to FIG. When selecting a small number of coils) or obtaining a large inductance, as in the case of the printed circuit board 20 described with reference to FIG.
A coil without an intermediate tap must be selected. When a coil without an intermediate tap is used for an antenna of a transmission circuit in wireless communication or electromagnetic coupling non-contact communication, for example, as shown in the circuit described with reference to FIG. Choke coil L
1 and the choke coil L2 are required, which leads to an increase in cost and an increase in circuit size. Further, in the case where a three-layer board is used to provide an intermediate tap while improving the inductance of the coil, as in the printed board 30 described with reference to FIG.
The cost of the substrate increases, and the thickness of the substrate increases, so that it is difficult to realize a thin antenna such as a card type.

The present invention has been made in view of such a situation. For example, in a printed circuit board having a small number of layers such as a two-layer board, it is possible to improve the reactance and further provide an intermediate tap. Things.

[0008]

According to a first aspect of the present invention, in the printed circuit board, a plurality of patterns forming a coil are concentrically developed on one surface and the other surface of the printed circuit board. It is characterized by.

In the printed circuit board according to the first aspect, a plurality of patterns forming a coil are concentrically developed on one surface and the other surface of the printed circuit board.

[0010]

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

FIG. 5 shows a first embodiment of a printed circuit board to which the present invention is applied. The printed board 40 is a two-layer board. FIG. 5A is a pattern diagram of the surface A of the printed board 40, and FIG.
FIG. 3 is a view of a pattern diagram of a surface seen through from an A surface side.

On the printed circuit board 40, two sets of spiral patterns, two on the side A and two on the side B, are developed concentrically. A helical pattern (the solid line pattern in FIG. 5A) from the terminal (input terminal or output terminal) a1 connected to the tap 41 toward the center (inner circumference) passes through the through-hole a2 through B A helical pattern (solid line pattern in FIG. 5B) connected to the surface and extending from the through hole a2 to the outer periphery is developed toward the through hole c1 connected to the tap 42. This pattern is connected to the surface A again through the through hole c1, and a spiral pattern from the through hole c1 toward the center (FIG. 5).
(A) (dotted line pattern) is a spiral pattern (dotted line pattern in FIG. 5 (B)) that is connected to the surface B via the through hole c2 and goes from the through hole c2 to the outer periphery.
Are developed toward a through hole (output terminal or input terminal) b1 connected to the tap 43.

FIG. 6 shows a plan view of the pattern on both sides A and B of the printed circuit board 40. That is, FIG.
5A, the pattern shown by the solid line corresponds to the coil La1-a2 in FIG. 6, and in FIG. 5A, the pattern shown by the dotted line corresponds to the coil Lc1-c2 in FIG. In FIG. 5B, the pattern shown by the solid line corresponds to the coil La2-c1 of FIG. 6, and in FIG. 5B, the pattern shown by the dotted line is the coil Lc of FIG.
This corresponds to 2-b1.

Here, when the printed circuit board 40 is used as a coil of an antenna using a push-pull circuit, the tap 42, which is an intermediate tap, must be a point that is electrically and correctly the middle point. However, the inductance of the coil generated by each of the patterns on the surface A and the surface B of the printed circuit board 40 is larger on the outer peripheral side than on the inner peripheral side (the outer peripheral side is longer than the inner peripheral side coil). . For this reason, the pattern on the printed circuit board 40 is connected such that the inner periphery and the outer periphery are switched when the pattern moves from the A surface to the B surface.

That is, from the terminal a1 to the through hole a
The pattern of the A surface up to 2 is the outer periphery, the pattern of the B surface from the through hole a2 to the through hole c1 is the inner periphery, the pattern of the A surface from the through hole c1 to the through hole c2 is the inner periphery, and the through hole The pattern on the B side from c2 to the through hole b1 is formed on the outer periphery.

The coil between the taps is composed of a coil on the A side and a coil on the B side, and is combined so that the total length of the coil between the taps is substantially equal. Therefore, as shown in FIG. 6, taps 41 to 42 and taps 42 to 43 are formed by coils on the A and B surfaces, respectively, and the patterns of the inner and outer circumferences are combined. ing. As a result, the tap 42 can be set as an electrical midpoint between the tap 41 and the tap 43.

FIG. 7 shows a circuit diagram of a transmission device in electromagnetic coupling non-contact communication using the printed circuit board 40.

In the transmission circuit of FIG. 7, similarly to the transmission circuit described with reference to FIG. 4, drive signals of positive and negative phases are transmitted by the signal sources V1 and V2, and these signals are supplied to the resistor R1 or the resistor R1. Via R2, PNP transistor
Supplied to the base of Q3 or PNP transistor Q4,
After being amplified, it is output from the emitter to which the DC bias voltage is applied via the resistor R3 or the resistor R4, respectively. This output signal is output from the resistor R12 or the resistor R11.
Is input to the base of the PNP transistor Q9 or the PNP transistor Q10, and the power is amplified. The power-amplified signal resonates at a predetermined communication frequency defined by a coil (antenna) formed by the capacitor C3 and the printed circuit board 40.

The AC component is suppressed by the tap 42 of the printed circuit board 40 by the choke coil L3, and the capacitor C2
Is applied. Based on this voltage, tap 42, tap 41, NPN transistor Q9
A bias current flows through the path of the collector-emitter of the resistor R5 or the path of the tap 42, the tap 43, the collector-emitter of the NPN transistor Q10, and the resistor R5. The capacitor C1 is for bypass.

In the transmitting circuit described with reference to FIG. 4, an external choke coil L1 and choke coil L2 are required to apply a DC voltage to the transistors Q1 and Q2.
It has been difficult to supply a stable bias voltage.
In the transmission circuit shown in FIG. 7, since power can be supplied from the tap 2 which can be an accurate electrical midpoint, the choke coil L1 and the choke coil L2 can be omitted, and the number of parts can be reduced. The circuit size can be reduced, and a stable bias voltage can be supplied.

FIG. 8 shows a printed circuit board according to a second embodiment of the present invention. The printed circuit board 50 also
It is a two-layer board like the printed board 40, and FIG.
8 is a pattern diagram of the surface A of the printed circuit board 50, and FIG.
FIG. 3B is a perspective view of the pattern diagram of the surface B of the printed circuit board 50 viewed from the surface A side.

On the printed circuit board 50, two sets of spiral patterns, three on the side A and three on the side B, are developed concentrically. Spiral pattern from terminal a1 connected to tap 51 toward the center (solid line pattern in FIG. 8A)
Is connected to the surface B through the through hole a2, and a spiral pattern (solid line pattern in FIG. 8B) from the through hole a2 toward the outer periphery is connected to the through hole c1 connected to the tap 52. Has been deployed towards. This pattern is connected to the surface A through the through hole c1, and the spiral pattern (the dotted line pattern in FIG. 8A) from the through hole c1 toward the center is the through hole c.
A spiral pattern (a dotted line pattern in FIG. 8B) connected to the surface B through the through hole 2 and extending from the through hole c2 toward the outer periphery is connected to the through hole d connected to the tap 53.
It is being rolled out towards 1. This pattern is connected to the surface A through the through hole b1, and the spiral pattern (the pattern indicated by the two-dot chain line in FIG. 8A) from the through hole d1 toward the center is changed to the B pattern through the through hole d2. A helical pattern (a two-dot chain line pattern in FIG. 8B) connected to the surface and extending from the through hole d2 toward the outer periphery is developed toward the through hole b1 connected to the tap 54.

FIG. 9 shows a plan view of the pattern on both sides A and B of the printed circuit board 50. That is, FIG.
In (A), the pattern shown by the solid line corresponds to the coil La1-a2 in FIG. 9, and in FIG. 8 (A), the pattern shown by the dotted line corresponds to the coil Lc1-c2 in FIG. In FIG. 8A, the pattern indicated by the two-dot chain line corresponds to the coil Ld1-d2 in FIG. 9, and in FIG. 8B, the pattern indicated by the solid line corresponds to the coil La2 in FIG.
8B, the pattern indicated by the dotted line in FIG. 8B corresponds to the coil Lc2-d1 in FIG.
In (B), the pattern shown by the two-dot chain line corresponds to the coil Ld2-b1 in FIG.

Here, in order for the taps 52 and 53, which are the intermediate taps, to be electrically and equally divided into three points with respect to the taps 51 and 54, the length of the pattern of the outer circumference and the inner circumference is required. On the other hand, it is sufficient that the center pattern has exactly the middle length (1/2 of the sum of the length of the outer coil and the length of the inner coil). Then, the taps are combined so that the lengths of the coils are substantially equal to each other. That is, as shown in FIG. 9, taps 51 to 52 and taps 53 to 54
, The inner and outer patterns are combined, and the central pattern is combined from tap 52 to tap 53. As a result, the taps 52 and 53 are electrically correctly divided into three points with respect to the taps 51 and 54.

Similarly, by increasing the number of patterns developed on the same surface of the printed board, the coil formed by the pattern on the printed board is provided with three or more intermediate taps. can do.

FIG. 10 shows a third embodiment to which the present invention is applied. For example, even when an intermediate tap is not required to be mounted on a coil formed on a printed circuit board in applications other than an antenna, the present invention is applied to the printed circuit board without increasing the board area and the number of board layers. The inductance of the coil formed thereon can be improved.

FIG. 10A is a pattern diagram of the surface A of the printed circuit board 60, and FIG.
FIG. 2 is a view of the pattern diagram of the B surface of No. 0 seen through from the A surface side.
The printed board 60 is a two-layer board, and the wiring of the pattern is substantially equal to that of the printed board 40 described with reference to FIG. 5, and only the tap 61 and the tap 62 are mounted, and no intermediate tap is provided. Here, two patterns are developed on the same surface, but three or more patterns may be developed on the same surface to further improve the inductance of the coil.

[0028]

According to the printed circuit board according to the first aspect, each of the one surface and the other surface of the printed circuit board has:
Since the plurality of patterns forming the coil are developed concentrically, for example, on a printed circuit board having a small number of layers such as a two-layer board, the reactance can be improved and the intermediate tap can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conventional example of a coil formed by pattern development on a printed board.

FIG. 2 is a diagram showing a conventional example of a coil formed by pattern development on a printed circuit board.

FIG. 3 is a diagram showing a conventional example of a coil formed by pattern development on a printed board.

4 is a circuit diagram of a transmission device in electromagnetic coupling non-contact communication using the printed circuit board of FIG. 2;

FIG. 5 is a diagram showing a first embodiment of a printed circuit board to which the present invention has been applied.

FIG. 6 is a diagram for explaining positions of a coil and an intermediate tap formed on the printed circuit board of FIG. 5;

7 is a circuit diagram of a transmission device in electromagnetic coupling non-contact communication using the printed circuit board of FIG.

FIG. 8 is a view showing a second embodiment of a printed circuit board to which the present invention is applied.

FIG. 9 is a diagram for explaining positions of a coil and an intermediate tap formed on the printed circuit board of FIG. 8;

FIG. 10 is a view showing a third embodiment of the printed circuit board to which the present invention is applied.

[Explanation of symbols]

40 printed circuit board, 41 to 43 taps, 50
Printed circuit board, 51 to 54 taps, 60 Printed circuit board, 61, 62 taps

Claims (4)

[Claims] 1. A printed circuit board in which a coil between an input terminal and an output terminal is formed by a spirally developed pattern, wherein the coil is formed on each of one surface and the other surface of the printed circuit board. A plurality of patterns to be developed concentrically. 2. The printed circuit board according to claim 1, wherein the coil has one or more intermediate terminals other than the input terminal and the output terminal. 3. A coil between the terminals is formed of a pattern on one surface of the substrate and a pattern on the other surface, and the entire length of the coil between the terminals is substantially equal. The printed circuit board according to claim 2, wherein the printed circuit board is combined. 4. The printed circuit board according to claim 1, wherein the coil forms an antenna.