JP5093412B2 - Antenna coil and antenna device - Google Patents

Description

  The present invention relates to an antenna coil and an antenna device used for an RFID (Radio Frequency Identification) system that communicates with an external device via an electromagnetic field signal.

  In recent years, in an RFID system whose use has been expanded, an antenna for information communication is mounted on each of a mobile communication terminal and a reader / writer to exchange data with each other. Among these, antennas mounted on portable electronic devices are particularly demanded for high performance, low cost, and downsizing. As an attempt to achieve these, a magnetic antenna having a magnetic core is disclosed in Patent Document 1, It is disclosed in Patent Document 2 and Patent Document 3.

  1A is a perspective view of a magnetic antenna disclosed in Patent Document 1, and FIG. 1B is a plan view thereof. In the antenna device 23 shown in FIGS. 1A and 1B, an antenna coil 22 is mounted on a circuit board 21. The antenna coil 22 is mounted on the circuit board 21 so that the lateral end of the antenna coil 22 and the lateral end of the circuit board 21 overlap each other.

  In the antenna coil 22, the first magnetic core 24a and the first magnetic core 24a are aligned with the second magnetic core 24b juxtaposed at a distance from each other, and the axial direction of the coil coincides with the winding direction. Are reversed so that the first coil portion 22a and the second coil portion 22b are wound.

Patent Document 2 includes an air-core coil formed in a spiral shape in a plane and a flat magnetic core member inserted into the air-core coil so as to be substantially parallel to the plane of the air-core coil. A configuration in which the magnetic core member is provided is disclosed.
Patent Document 3 discloses a configuration in which a magnetic body is installed under a loop-shaped coil.

Japanese Patent No. 3957000 JP 2002-325013 A JP 2002-298095 A

  In the antenna device disclosed in Patent Document 1, when the gap between the circuit board 21 and the antenna coil 22 is increased, the ratio of the magnetic flux transmitted in the axial direction of the coil is reduced, and the magnetic field interlinked with the coil is reduced. There is a problem that the coupling coefficient deteriorates.

  In the antenna device shown in Patent Document 2, since only the magnetic flux that escapes to one side of the metal plate is linked to the coil, sufficient communication performance cannot be obtained.

  In the antenna device shown in Patent Document 3, if there is a conductor plate under the antenna, the self-inductance of the coil that does not contribute to the coupling increases, so the coupling coefficient deteriorates.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna coil and an antenna device that can ensure a high coupling coefficient even when the gap between the conductor plate and the antenna coil becomes large.

In order to solve the above problems, an antenna coil and an antenna device of the present invention are configured as follows.
(1) a first coil conductor and a second coil conductor formed in a spiral shape each having a winding opening as a conductor opening;
A magnetic core having a first main surface and a second main surface opposite to the first main surface, each inserted into a conductor opening of the first coil conductor and a conductor opening of the second coil conductor And comprising
The first coil conductor and the second coil conductor include a first conductor portion close to the first main surface of the magnetic core and a second conductor close to the second main surface of the magnetic core. Part of the magnetic core is not overlapped when viewed from the normal direction of the first main surface or the second main surface of the magnetic core, and the first coil conductor formation region and the second coil conductor The formation region is at a position that does not overlap when viewed from the normal direction of the first main surface or the second main surface of the magnetic core,
Compared with the first conductor portion, the second conductor portion of the first coil conductor and the second conductor portion of the second coil conductor, respectively, the first coil conductor and the second coil conductor, It is characterized by being arranged so as to be closer to the end of the outer shape of the formation region.
With this configuration, since the magnetic field radiated from the antenna of the communication partner is easily interlinked with the antenna coil, the characteristic deterioration due to the variation or variation in the distance between the conductor plate and the antenna coil is small.

(2) The magnetic core may be thicker at the end where the magnetic flux enters and exits than the other part.
This reduces the magnetic resistance of the magnetic path and increases the coupling coefficient with the counterpart antenna.

(3) It is preferable that the first coil conductor and the second coil conductor are formed on a flexible substrate.

(4) The flexible substrate includes a conductor opening side through-hole through which the magnetic core penetrates the conductor opening, and a coil conductor outside through-hole through which the magnetic core penetrates outside the coil conductor forming area. A hole, and
Each of the magnetic cores passes through the conductor opening side through hole from the first main surface of the flexible substrate, and passes through the coil conductor forming region outer through hole from the second main surface of the flexible substrate. It is good also as a structure provided in the state. That is, two holes for inserting the magnetic core into the flexible substrate are provided for each magnetic core (coil conductor).
With this configuration, the flexible substrate and the magnetic core can be bonded with a single adhesive layer, and the cost of members such as double-sided tape can be reduced.

(5) The magnetic core inserted into the conductor opening of the first coil conductor and the magnetic core inserted into the conductor opening of the second coil conductor are formed of a single magnet. You may comprise a body core.
As a result, the number of parts is reduced, so that the manufacturing cost and the part cost can be reduced.

  According to the present invention, since the magnetic field radiated from the antenna of the communication partner is easily interlinked with the antenna coil, it is possible to configure an antenna device in which the characteristic deterioration due to the variation or variation in the distance between the conductor plate and the antenna coil is small.

1A is a perspective view of a magnetic antenna disclosed in Patent Document 1, and FIG. 1B is a plan view thereof. It is an expanded view of the flexible substrate 32 which is one of the components of the antenna device which concerns on 1st Embodiment. 3A is a plan view of the antenna device 101, FIG. 3B is a front view of the antenna device 101, and FIG. 3C is a right side view of the antenna device 101. 4 (A) and 4 (B) are diagrams showing how the magnetic flux of the counterpart antenna passes through the antenna device 101. FIG. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a figure which shows the relationship of the coupling coefficient with respect to X1 / X2 when the clearance gap between the circuit board 31 and the antenna coil 91 is changed. It is a block diagram of the antenna coil 92 which is a component of the antenna apparatus which concerns on 2nd Embodiment. 12A is a plan view of the antenna coil 92 before assembly, FIG. 12B is a top view of the antenna coil 92, FIG. 12C is a cross-sectional view of the antenna coil 92, and FIG. FIG. FIG. 13A is a plan view of the antenna device 102 according to the second embodiment, and FIG. 3B is a front view of the antenna device 102. It is a block diagram of the antenna coil 93 which is a component of the antenna apparatus which concerns on 3rd Embodiment. 14A is a plan view before assembly of the antenna coil 93, FIG. 14B is a top view of the antenna coil 93, FIG. 14C is a cross-sectional view of the antenna coil 93, and FIG. 14D is the antenna coil. 93 is a bottom view of FIG. It is a block diagram of the antenna coil 94 which is a component of the antenna apparatus which concerns on 4th Embodiment. FIG. 15A is a plan view of the antenna coil 94 before assembly, FIG. 15B is a top view of the antenna coil 94, and FIG. 15C is a bottom view of the antenna coil 94. It is a block diagram of the antenna coil 95 which is a component of the antenna apparatus which concerns on 5th Embodiment. 16A is a plan view of the antenna coil 95 before assembly, FIG. 16B is a top view of the antenna coil 95, and FIG. 16C is a bottom view of the antenna coil 95.

<< First Embodiment >>
The antenna device according to the first embodiment will be described with reference to FIGS.
FIG. 2 is a development view of the flexible substrate 32 which is one of the components of the antenna device according to the first embodiment.

  As shown in FIG. 2, the flexible substrate 32 is formed with spiral coil conductors 34-1 and 34-2 having the winding centers as conductor openings CW-1 and CW-2, respectively. Through holes 32W-1 and 32W-2 into which the magnetic cores are inserted are formed in the respective conductor openings CW-1 and CW-2.

  The two coil conductors 34-1 and 34-2 are arranged in such a direction that currents generated by magnetic fluxes passing through the conductor openings CW-1 and CW-2 of the two coil conductors 34-1 and 34-2 are in phase. Two coil conductors 34-1 and 34-2 are connected in series, and one end of each is formed as coil conductor connection portions 34-1A and 34-2A.

  3A is a plan view of the antenna device 101, FIG. 3B is a front view of the antenna device 101, and FIG. 3C is a right side view of the antenna device 101. The antenna device 101 includes an antenna coil 91 and a circuit board 31. As shown in FIG. 2, the antenna coil 91 includes a flexible substrate 32 on which a coil conductor is formed and magnetic cores 33-1 and 33-2. The magnetic cores 33-1 and 33-2 are inserted into the through holes 32W-1 and 32W-2 of the flexible substrate 32, respectively.

  The first coil conductor 34-1 and the second coil conductor 34-2 are disposed near both ends of the circuit board (conductor plate) 31 in the short direction.

  For example, a circuit of a mobile communication terminal is configured on the circuit board 31. The circuit board 31 corresponds to a conductor plate according to the present invention. The circuit board 31 is provided with electrodes for electrically connecting the antenna coil 91, and these electrodes and the coil conductor connecting portions 34-1A and 34-2A of the antenna coil 91 are shown in FIG. As shown, they are connected via two pins 35.

  4 (A) and 4 (B) are diagrams showing how the magnetic flux of the counterpart antenna passes through the antenna device 101. FIG. A broken line in the figure represents a typical magnetic flux contributing to the coupling between the antenna device 101 and the counterpart antenna.

  The first coil conductor 34-1 includes a first conductor portion 34-11 adjacent to the first main surface of the magnetic core 33-1, and a second conductor portion close to the second main surface of the magnetic core 33-1. The conductor portion 34-12 is in a position that does not overlap when viewed from the normal direction of the first main surface or the second main surface of the magnetic core 33-1, and similarly, the second coil conductor 34-2 is The first conductor portion 34-21 close to the first main surface of the magnetic core 33-2 and the second conductor portion 34-22 close to the second main surface of the magnetic core 33-2 are: It exists in the position which does not overlap seeing from the normal line direction of the 1st main surface or the 2nd main surface of the magnetic body core 33-2. The second conductor portion 34-12 of the first coil conductor 34-1 and the second conductor portion 34-22 of the second coil conductor 34-2 are respectively connected to the first conductor portions 34-11 and 34-. Compared to 21, the first coil conductor 34-1 and the second coil conductor 34-2 are arranged so as to be closer to the end of the outer shape of the formation region.

  Because of this structure, even if the distance D between the antenna coil 91 and the circuit board 31 is increased as shown in FIG. 4A, the antenna coil 91 and the circuit board 31 are used as shown in FIG. As in the case where the distance D between the coil conductors 34-1 and 34-2 is small, a large proportion of the coil conductors 34-1 and 34-2 passing through the conductor winding center (the conductor opening) can be secured, so that the characteristic deterioration is small.

  That is, even if the distance D between the circuit board (conductor plate) 31 and the antenna coil 91 is large, the magnetic field generated by the communication partner is easily linked to the coil, and therefore the characteristic deterioration is small. When considering the case of mounting on a normal mobile communication terminal, the gap between the conductor plate varies for each mobile communication terminal, but by using the antenna device of the present invention, good communication performance is obtained in any mobile terminal. It becomes possible.

  5 to 11 are diagrams showing the relationship of the coupling coefficient with respect to X1 / X2 when the gap between the circuit board 31 and the antenna coil 91 is changed. Here, X1 is the width of the antenna coil 91 shown in FIG. 3, and X2 is the width of the circuit board 31 shown in FIG. Further, the polygonal line of the triangular mark is the characteristic of the antenna device according to the first embodiment, the polygonal line of the rhombus mark is the characteristic of the antenna device according to Patent Document 1, and the polygonal line of the square mark is the characteristic of the antenna device according to Patent Document 3. .

  From this result, when X1 / X2> 0.7 and the gap with the conductor plate is 6 mm or less, the antenna device according to the first embodiment of the present invention is compared with the antenna device according to Patent Document 1 and Patent Document 3. It can be seen that a large coupling coefficient is obtained.

<< Second Embodiment >>
FIG. 12A, FIG. 12B, FIG. 12C, and FIG. 12D are configuration diagrams of an antenna coil 92 that is a component of the antenna device according to the second embodiment. 12A is a plan view of the antenna coil 92 before assembly, FIG. 12B is a top view of the antenna coil 92, FIG. 12C is a cross-sectional view of the antenna coil 92, and FIG. FIG. As shown in FIG. 12C, the magnetic cores 33-1 and 33-2 are bonded to the flexible substrate 32 via the adhesive layer 36.
FIG. 13A is a plan view of the antenna device 102, and FIG. 3B is a front view of the antenna device 102.

What is different from the example shown in FIGS. 2 and 3 in the first embodiment is the shape of the magnetic cores 33-1 and 33-2. In the second embodiment, the magnetic cores 33-1 and 33-2 have thicker end portions where magnetic flux enters and exits than other portions.
This structure reduces the magnetic resistance of the magnetic path and increases the coupling coefficient with the counterpart antenna.

<< Third Embodiment >>
FIG. 14A, FIG. 14B, FIG. 14C, and FIG. 14D are configuration diagrams of an antenna coil 93 that is a component of the antenna device according to the third embodiment. 14A is a plan view before assembly of the antenna coil 93, FIG. 14B is a top view of the antenna coil 93, FIG. 14C is a cross-sectional view of the antenna coil 93, and FIG. 14D is the antenna coil. 93 is a bottom view of FIG.

  The difference from the first and second embodiments is the shape of the flexible substrate 32 and the assembly structure of the magnetic cores 33-1 and 33-2 with respect to the flexible substrate 32.

  On the flexible substrate 32, spiral coil conductors 34-1 and 34-2 are respectively formed. Conductor opening side through holes 32W-11 and 32W-21 are formed in the winding center portions of the coil conductors 34-1 and 34-2, respectively. Further, outside the coil conductor formation region through-holes 32W-12 and 32W-22 through which the magnetic cores 33-1.33-2 pass are formed outside the formation regions of the coil conductors 34-1 and 34-2.

  The magnetic core 33-1 passes through the conductor opening side through hole 32W-11 from the first main surface of the flexible substrate 32, and passes through the coil conductor formation region outer hole from the second main surface of the flexible substrate 32. It is provided in a state of penetrating 32W-12, and is arranged so that the first main surface side of the flexible substrate 32 faces the circuit board side. Similarly, the magnetic core 33-2 penetrates the conductor opening side through hole 32W-21 from the first main surface of the flexible substrate 32, and the coil conductor formation region extends from the second main surface of the flexible substrate 32. It is provided in a state of penetrating the outer through hole 32W-22, and is arranged so that the first main surface side of the flexible substrate 32 faces the circuit substrate side.

  As shown in FIG. 14C, the magnetic cores 33-1 and 33-2 are bonded to the flexible substrate 32 via the adhesive layer 36. With this configuration, the flexible substrate 32 and the magnetic cores 33-1 and 33-2 can be bonded by the single adhesive layer 36, and the cost of members such as double-sided tape can be reduced.

<< Fourth Embodiment >>
FIG. 15A, FIG. 15B, and FIG. 15C are configuration diagrams of an antenna coil 94 that is a component of the antenna device according to the fourth embodiment. FIG. 15A is a plan view of the antenna coil 94 before assembly, FIG. 15B is a top view of the antenna coil 94, and FIG. 15C is a bottom view of the antenna coil 94.

  In the fourth embodiment, a single magnetic core 33 is provided. The configuration of the flexible substrate 32 is the same as that shown in the first embodiment. The magnetic core 33 is provided in a state of penetrating the through hole 32W-1 from the first main surface of the flexible substrate 32 and penetrating the through hole 32W-2 from the second main surface of the flexible substrate 32. The board 32 is arranged so that the first main surface side faces the circuit board side.

  Since the number of parts is reduced by this configuration, the manufacturing cost and the part cost can be reduced.

<< Fifth Embodiment >>
16A, 16B, and 16C are configuration diagrams of an antenna coil 95 that is a component of the antenna device according to the fifth embodiment. 16A is a plan view of the antenna coil 95 before assembly, FIG. 16B is a top view of the antenna coil 95, and FIG. 16C is a bottom view of the antenna coil 95.

In the fifth embodiment, a single magnetic core 33 is provided. The configuration of the flexible substrate 32 is the same as that shown in the third embodiment.
The magnetic core 33 penetrates the conductor opening side through hole 32W-11 from the first main surface of the flexible substrate 32, and the coil conductor formation region outer through hole 32W- from the second main surface of the flexible substrate 32. 12 through the coil conductor forming region outer through hole 32W-22 from the first main surface of the flexible substrate 32, and the conductor opening side through hole 32W-21 from the second main surface of the flexible substrate 32. It is provided in the state which penetrates. And it arrange | positions so that the 1st main surface side of the flexible substrate 32 may face the circuit board side.
Since the number of parts is reduced by this configuration, the manufacturing cost and the part cost can be reduced.

31 ... Circuit board 32 ... Flexible boards 32W-1, 32W-2 ... Through holes 32W-12, 32W-22 ... Coil conductor formation region outer through holes 32W-11, 32W-22 ... Conductor opening side through holes 33, 33 -1, 33-2 ... magnetic cores 34-1 and 34-2 ... coil conductors 34-1A and 34-2A ... coil conductor connecting portions 34-11 and 34-21 ... first conductor portions 34-12 and 34 -22 ... 2nd conductor part 35 ... Pin 36 ... Adhesive layers 91-95 ... Antenna coils 101, 102 ... Antenna device

Claims (5)

A first coil conductor and a second coil conductor formed in a spiral shape each having a winding opening as a conductor opening;
A magnetic core having a first main surface and a second main surface opposite to the first main surface, each inserted into a conductor opening of the first coil conductor and a conductor opening of the second coil conductor And comprising
The first coil conductor and the second coil conductor include a first conductor portion close to the first main surface of the magnetic core and a second conductor close to the second main surface of the magnetic core. Part of the magnetic core is not overlapped when viewed from the normal direction of the first main surface or the second main surface of the magnetic core, and the first coil conductor formation region and the second coil conductor The formation region is at a position that does not overlap when viewed from the normal direction of the first main surface or the second main surface of the magnetic core,
Compared with the first conductor portion, the second conductor portion of the first coil conductor and the second conductor portion of the second coil conductor, respectively, the first coil conductor and the second coil conductor, An antenna coil arranged so as to be closer to the end of the outer shape of the formation region of the.   The antenna coil according to claim 1, wherein the magnetic core has a thicker end where magnetic flux enters and exits than other portions.   The antenna coil according to claim 1, wherein the first coil conductor and the second coil conductor are formed on a flexible substrate. The flexible substrate includes a conductor opening side through hole through which the magnetic core passes through the conductor opening, a coil conductor forming region outer through hole through which the magnetic core penetrates outside the coil conductor forming region, With
Each of the magnetic cores penetrates the conductor opening side through hole from the first main surface of the flexible substrate, and penetrates the coil conductor formation region outer through hole from the second main surface of the flexible substrate. The antenna coil according to claim 3, which is provided in a state.   The magnetic core inserted into the conductor opening of the first coil conductor and the magnetic core inserted into the conductor opening of the second coil conductor are a single magnetic core. The antenna coil according to any one of claims 1 to 4, wherein the antenna coil is configured.

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