JP2016127396A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device which suppresses reduction of a communication distance by suppressing variation of a resonant frequency of a booster antenna and an RFIC element (and a power supply coil).SOLUTION: An antenna device 101 comprises: an RFIC element 40; a power supply coil 30 connected thereto; a first coil conductor L1 including a first large diameter loop-shaped conductor 1a and a first small diameter loop-shaped conductor L1b connected thereto; and a second coil conductor L2 including a second large diameter loop-shaped conductor L2a that is disposed oppositely to the first large diameter loop-shaped conductor L1a, and a second small diameter loop-shaped conductor L2a connected thereto and disposed oppositely to the first small diameter loop-shaped conductor L1a. The first and second coil conductors L1 and L2 form a booster antenna (LC resonance circuit). The first small diameter loop-shaped conductor L1b and the second small diameter loop-shaped conductor L2b form a coupling part CP, and the number of times of winding is 1. The power supply coil 30 is disposed within a formation region of the coupling part CP in a planar view, and coupled with the coupling part CP via a magnetic field.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna device used for communication using electromagnetic field coupling such as RFID communication.

  Currently, proximity communication systems using various non-contact ICs are widely used in various fields. In such a communication system, for example, short-range wireless communication is performed by bringing a non-contact IC card, a non-contact IC tag, and the like and a card reader within a predetermined distance. Various types of non-contact IC cards, non-contact IC tags, and the like have been devised that include a module in which a wireless communication IC that is a data carrier and an antenna are integrated.

  For example, Patent Document 1 discloses an electromagnetic coupling module having a wireless communication IC and a power supply coil connected thereto, a first coil electrode and a first coil wound along the first main surface of an insulating base. An antenna module including an antenna having a second coil electrode wound along a second main surface facing the main surface is described.

  The antenna can be formed such that the coil opening of the first coil electrode and the second coil electrode is larger than the coil opening of the feeding coil of the electromagnetic coupling module, so that the antenna coil on the communication partner side (card reader side) A large amount of magnetic flux can be linked. That is, the antenna acts as a booster antenna for the electromagnetic coupling module.

Japanese Patent No. 4788850

  The degree of coupling between the booster antenna and the feeding coil of the electromagnetic coupling module (RFIC module) is as high as possible because it is related to the amount of magnetic field energy that can be received by the wireless communication IC (RFIC element) via the booster antenna. Is preferred. By increasing the degree of coupling, the communication distance in the communication system can be increased. In order to increase the degree of coupling, in Patent Document 1, the number of turns of the coupling portion of the booster antenna that electromagnetically couples with the feeding coil of the electromagnetic coupling module (RFIC module) is increased to feed the electromagnetic coupling module (RFIC module). A coil is mounted so as to overlap the coupling portion.

  The resonance frequency of the booster antenna and the RFIC module (RFIC element and the feeding coil connected thereto) is determined as a communication frequency. However, in the configuration shown in Patent Document 1, when the mounting position of the RFIC module with respect to the coupling portion of the booster antenna is deviated, the capacitance generated between the coupling portion of the booster antenna and the feeding coil and the degree of coupling change. End up. The resonance frequency is determined by an inductance (inductive reactance) and a capacity (capacitive reactance) existing in the circuit. Therefore, the resonance frequency of the booster antenna and the RFIC module (the RFIC element and the power supply coil connected thereto) fluctuates due to the change in the capacitance generated between the coupling portion of the booster antenna and the power supply coil and the degree of coupling. End up. Therefore, since these resonance frequencies deviate from the communication frequency used for communication, the communication distance in the communication system decreases.

  An object of the present invention is to suppress fluctuations in the resonance frequency of a booster antenna (LC resonance circuit) and an RFIC module (RFIC element and a feeding coil connected thereto), thereby suppressing a decrease in communication distance in a communication system. An object of the present invention is to provide an antenna device.

(1) The antenna device of the present invention
An RFIC element;
A feeding coil connected to the RFIC element;
A first coil conductor having a first large-diameter loop conductor and a first small-diameter loop conductor connected to an end of the first large-diameter loop conductor;
A second large-diameter loop conductor disposed opposite to the first large-diameter loop conductor; and a second large-diameter loop conductor disposed opposite to the first small-diameter loop conductor; A second coil conductor having a second small diameter loop conductor connected thereto;
With
The first large-diameter loop conductor is wound in a direction opposite to the winding direction of the second large-diameter loop conductor in plan view,
The first small-diameter loop-shaped conductor has a number of turns of 1, and is disposed in a formation region of the first large-diameter loop-shaped conductor in a plan view.
The second small-diameter loop conductor has a number of turns of 1, and is disposed in a formation region of the second large-diameter loop conductor in plan view,
The first coil conductor and the second coil conductor include a booster antenna having an inductance of the first coil conductor and the second coil conductor and a capacitance generated between the first coil conductor and the second coil conductor. Configure
The feeding coil is disposed in a formation region of the first small-diameter loop conductor and in a formation region of the second small-diameter loop conductor in plan view, and the first small-diameter loop conductor and the second small-diameter loop shape It is characterized by being coupled to a conductor via a magnetic field.

  With this configuration, it is possible to reduce the mutual inductance generated between the first small-diameter loop conductor, the second small-diameter loop conductor, and the feeding coil. Therefore, even if there is a slight shift in the mounting position of the feeding coil with respect to the first small-diameter loop conductor and the second small-diameter loop conductor, the variation in mutual inductance is small. As a result, fluctuations in the resonance frequency of the booster antenna (LC resonance circuit) and fluctuations in the resonance frequency of the RFIC element and the feeding coil connected thereto can be suppressed.

(2) It is preferable that the first large-diameter loop conductor and the second large-diameter loop conductor each have 1 winding. In this configuration, since the number of turns of the first large-diameter loop conductor and the second large-diameter loop conductor is small, the first large-diameter loop conductor and the second large-diameter loop shape are secured while ensuring a wide opening of the coil. The line width of the conductor can be formed wide. Therefore, even if a positional shift occurs between the first large-diameter loop conductor and the second large-diameter loop conductor that are arranged to face each other, the first large-diameter loop conductor and the second large-diameter loop conductor The fluctuation of the capacitance (capacitance) generated between and is suppressed. Therefore, the fluctuation | variation of the resonant frequency of the booster antenna (LC resonant circuit) comprised with a 1st coil conductor and a 2nd coil conductor is suppressed.

(3) The first small-diameter loop conductor is wound in the same direction as the winding direction of the first large-diameter loop conductor in plan view, and the second small-diameter loop conductor is It is preferable that the second large-diameter loop conductor is wound in the same direction as the winding direction. With this configuration, the current flowing through the first small-diameter loop conductor and the second small-diameter loop conductor is in the same direction as the first large-diameter loop conductor and the second large-diameter loop conductor. Therefore, the magnetic fields generated in the first small-diameter loop conductor and the second small-diameter loop conductor do not cancel the magnetic fields of the first coil conductor and the second coil conductor. Therefore, the effective coil opening area of the first coil conductor and the second coil conductor can be secured widely, and the communication distance can be increased.

(4) It is preferable that the RFIC element and the feeding coil are configured as an RFIC module in which these are integrated into one chip. In this configuration, an RFIC module having an RFIC element and a feeding coil connected to the RFIC element can be easily configured. In addition, the reliability of electrical connection between the RFIC element and the feeding coil can be improved.

(5) The RFIC module may include a laminated body formed by laminating a plurality of base material layers, and the feeding coil may be formed in the laminated body.

(6) A base sheet having a first main surface and a second main surface is further provided, wherein the first coil conductor is formed on the first main surface of the base sheet, and the second coil conductor is It is preferable that the RFIC module is formed on the second main surface of the base sheet, and the RFIC module is disposed on or inside the base sheet. With this configuration, the first coil conductor and the second coil conductor can be easily formed, and a booster antenna (LC resonance circuit) can be easily configured.

(7) In the first small-diameter loop-shaped conductor, the second small-diameter loop-shaped conductor, and the feeding coil, it is preferable that a winding axis is disposed on the same axis in a plan view. With this configuration, the degree of coupling between the first coil conductor and the second coil conductor and the feeding coil can be increased, and the communication distance can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, the antenna apparatus which can suppress the fluctuation | variation of the resonant frequency of a booster antenna (LC resonance circuit) and RFIC module, and can enlarge the communication distance in a communication system is realizable.

FIG. 1A is an external perspective view of the antenna device 101 according to the first embodiment, and FIG. 1B is an exploded perspective view showing a coil conductor and an RFIC module of the antenna device 101. FIG. 2A is a plan view of the antenna device 101 according to the first embodiment, and FIG. 2B is a detailed plan view showing a mounting portion of the RFIC module in the antenna device 101. FIG. 3A is a plan view showing areas where the first large-diameter loop conductor and the second large-diameter loop conductor are formed, and FIG. 3B is a first small-diameter loop conductor and a second small-diameter loop conductor. FIG. FIG. 4A is a cross-sectional view of the antenna device 101 according to the first embodiment, and FIG. 4B is a detailed cross-sectional view showing a mounting portion of the RFIC module in the antenna device 101. FIG. 5 is an exploded perspective view showing the operation principle of the antenna device 101 according to the first embodiment. FIG. 6 is an equivalent circuit diagram of the antenna device 101 according to the first embodiment. FIG. 7A is an external perspective view of the antenna device 102 according to the second embodiment, and FIG. 7B is a cross-sectional view taken along line AA in FIG.

  Hereinafter, several specific examples will be given with reference to the drawings to show a plurality of modes for carrying out the present invention. In each figure, the same reference numerals are assigned to the same portions. Each embodiment is an exemplification, and a partial replacement or combination of the configurations shown in different embodiments is possible.

<< First Embodiment >>
The antenna device according to the first embodiment will be described with reference to the drawings. FIG. 1A is an external perspective view of the antenna device 101 according to the first embodiment, and FIG. 1B is an exploded perspective view showing a coil conductor and an RFIC module of the antenna device 101. FIG. 2A is a plan view of the antenna device 101 according to the first embodiment, and FIG. 2B is a detailed plan view showing a mounting portion of the RFIC module in the antenna device 101.

  The antenna device 101 includes an RFIC module 10, a base sheet 1, a first coil conductor L1, and a second coil conductor L2. The antenna device 101 is configured as a card-sized RFID tag (IC card) having a carrier frequency band in the HF band.

  The RFIC module 10 includes an RFIC element 40, a stacked body 20 formed by stacking a plurality of base material layers, and a feeding coil 30. The feeding coil 30 is formed inside the stacked body 20 and connected to the RFIC element 40. In the present embodiment, the RFIC module 10 has a configuration in which the RFIC element 40 and the feeding coil 30 are integrated into one chip.

  The base sheet 1 is a rectangular flat plate made of an insulating material such as a resin, and has a first main surface and a second main surface. The first coil conductor L1 is formed along the first main surface of the base sheet 1 and includes a first large-diameter loop conductor L1a and a first small-diameter loop conductor L1b. The second coil conductor L2 is formed along the second main surface of the base sheet 1 and has a second large-diameter loop conductor L2a and a second small-diameter loop conductor L2b. The first coil conductor L1 and the second coil conductor L2 are patterned, for example, by etching a Cu foil or the like.

  FIG. 3A is a plan view showing areas where the first large-diameter loop conductor and the second large-diameter loop conductor are formed, and FIG. 3B is a first small-diameter loop conductor and a second small-diameter loop conductor. FIG. A large-diameter loop conductor formation region Lle in FIG. 3A indicates a formation region of the first large-diameter loop conductor in plan view and a formation region of the second large-diameter loop conductor in plan view. A small-diameter loop conductor formation region Lse in FIG. 3B shows a formation region of the first small-diameter loop conductor and the second small-diameter loop conductor in plan view.

  The first large diameter loop conductor L1a is a conductor pattern formed in a loop shape along the peripheral edge of the base sheet 1, and the first end E11 of the first large diameter loop conductor L1a is a first small diameter loop shape. It is connected to the conductor L1b. Further, as shown in FIG. 1, the first large-diameter loop conductor L1a is wound clockwise (clockwise) from the second end E12 of the first large-diameter loop conductor L1a toward the first end E11. Yes. Since the first large-diameter loop-shaped conductor L1a makes a substantially complete turn along substantially the entire circumference of the first main surface of the base sheet 1, the substantial number of turns is 1.

  The first small-diameter loop conductor L1b is a conductor pattern formed in a loop shape having an inner and outer diameter smaller than the loop-shaped conductor pattern of the first large-diameter loop conductor L1a, and extends from the first large-diameter loop conductor L1a. To be formed. The first small-diameter loop-shaped conductor L1b is disposed at the corner (the lower right corner in FIG. 1) of the rectangular base sheet 1. In other words, the first small-diameter loop conductor L1b is disposed in the formation region Lle of the first large-diameter loop conductor L1a that is substantially rounded along substantially the entire circumference of the first main surface of the base sheet 1. Further, as shown in FIG. 1 and the like, the first small-diameter loop conductor L1b rotates clockwise from the first end E11 of the first large-diameter loop conductor L1a along the first main surface of the base sheet 1 (clockwise). It is wound around (around) and goes around. Therefore, the first small-diameter loop conductor L1b is wound in the same direction as the winding direction of the first large-diameter loop conductor L1a in plan view, and the substantial number of turns (that is, the number of turns; hereinafter the same). ) Is 1.

  The second large-diameter loop conductor L2a is a conductor pattern formed in a loop shape along the peripheral edge of the base sheet 1, and the first end E21 of the second large-diameter loop conductor L2a is a second small-diameter loop shape. It is connected to the conductor L2b. Further, as shown in FIG. 1, the second large-diameter loop conductor L2a is wound counterclockwise (counterclockwise) from the second end E22 of the second large-diameter loop conductor L2a toward the first end E21. ing. Therefore, the second large-diameter loop conductor L2a is wound in a direction opposite to the winding direction of the first large-diameter loop conductor L1a in plan view. In addition, since the second large-diameter loop-shaped conductor L <b> 2 a makes substantially one turn along substantially the entire circumference of the second main surface of the base sheet 1, the substantial number of turns is one.

  The second small-diameter loop conductor L2b is a conductor pattern formed in a loop shape having an inner and outer diameter smaller than the loop-shaped conductor pattern of the second large-diameter loop conductor L2a, and extends from the second large-diameter loop conductor L2a. To be formed. The second small-diameter loop-shaped conductor L2b is disposed at a corner of the rectangular base sheet 1 (lower right corner in FIG. 1). In other words, the second small-diameter loop conductor L2b is disposed in the formation region Lle of the second large-diameter loop conductor L2a that is substantially rounded along substantially the entire circumference of the second main surface of the base sheet 1. Further, as shown in FIG. 1 and the like, the second small-diameter loop conductor L2b is clockwise (clockwise) from the first end E21 of the second large-diameter loop conductor L2a along the second main surface of the base sheet 1. It is wound around (around) and goes around. Therefore, the second small-diameter loop conductor L2b is wound in the same direction as the winding direction of the second large-diameter loop conductor L2a in plan view, and the actual number of turns is one.

  As described in detail later, the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a serve as an antenna part AP of a booster antenna (LC resonance circuit) and communicate with the communication partner side mainly through a magnetic field. Contribute to. Further, as described in detail later, the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b mainly apply a magnetic field to the feeding coil 30 of the RFIC module 10 as a coupling portion CP of a booster antenna (LC resonance circuit). It contributes to the coupling through.

  FIG. 4A is a cross-sectional view of the antenna device 101 according to the first embodiment, and FIG. 4B is a detailed cross-sectional view showing a mounting portion of the RFIC module in the antenna device 101. In FIG. 4, the structure of the antenna device 101 is simplified for easy understanding of the drawing and the principle.

  As shown in FIG. 4, the second large-diameter loop conductor L2a is disposed to face the first large-diameter loop conductor L1a with the base sheet 1 interposed therebetween, and the first large-diameter loop conductor L1a in plan view. And almost overlap. Therefore, a capacitance is generated between the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a. The second small-diameter loop conductor L2b is disposed to face the first small-diameter loop conductor L1b across the base sheet 1, and substantially overlaps the first small-diameter loop conductor L1b in plan view. Therefore, a capacitance is generated between the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b.

  Further, as shown in FIGS. 1 to 3, the RFIC module 10 is disposed in the large-diameter loop conductor formation region Lse in plan view. Furthermore, the first small-diameter loop conductor L1b, the second small-diameter loop conductor L2b, and the feeding coil 30 of the RFIC module 10 are arranged such that the winding axis is on the same axis in plan view. The first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b constitute a coupling portion CP that is coupled to the feeding coil 30 via a magnetic field.

  Further, the RFIC module 10 is disposed inside the base sheet 1. Such an RFIC module 10 is mounted on the base material sheet 1 in the following process, for example.

  First, the RFIC module 10 is mounted on the main surface of the lower holding sheet 2, and a hole for mounting the RFIC module 10 is provided in the base sheet 1. Next, the lower holding sheet 2 on which the RFIC module 10 is mounted is affixed to the second main surface of the base sheet 1 so that the RFIC module 10 can be accommodated in the hole. Next, after filling the gap portion in the hole of the base sheet 1 with the resin 5, the upper holding sheet 3 is pasted (sealed).

  Note that the RFIC element 40 is not limited to the configuration that is mounted on the upper part of the multilayer body 20 having the feeding coil 30. The feeding coil 30 may be arranged in the small-diameter loop conductor formation region Lse in a plan view, and the RFIC element 40 may be arranged outside the small-diameter loop conductor formation region Lse.

  FIG. 5 is an exploded perspective view showing the operation principle of the antenna device 101 according to the first embodiment, and shows how the feeding coil of the RFIC module 10 is coupled to the first coil conductor L1 and the second coil conductor L2. ing. FIG. 6 is an equivalent circuit diagram of the antenna device 101 according to the first embodiment.

  As shown in FIG. 5, the current i1b is induced in the first small-diameter loop conductor L1b by the current i0 flowing through the feeding coil of the RFIC module 10. That is, a current i1b in a direction (counterclockwise in FIG. 5) flows through the first small-diameter loop conductor L1b by the current i0 in a portion where the feeding coil and the first small-diameter loop conductor L1b are close to each other. Since the first small-diameter loop conductor L1b is connected to one end of the first large-diameter loop conductor L1a, the current i1b also flows through the first large-diameter loop conductor L1a (current i1a in FIG. 5). The values of current i1a and current i1b are equal.

  Further, the current i2b is induced in the second small-diameter loop conductor L2b by the current i0 flowing through the feeding coil of the RFIC module 10. That is, a current i2b in a direction (counterclockwise in FIG. 5) flows through the second small-diameter loop conductor L2b by the current i0 in a portion where the feeding coil and the second small-diameter loop conductor L2b are close to each other. Since the second small-diameter loop conductor L2b is connected to one end of the second large-diameter loop conductor L2a, this current i2b also flows through the second large-diameter loop conductor L2a (current i2a in FIG. 5). Note that the values of the current i2a and the current i2b are equal.

  As shown in FIG. 5, the current (i1a, i1b) and the current (i2a, i2b) induced by the current i0 flowing through the feeding coil of the RFIC module 10 are in the same direction (counterclockwise in FIG. 5). However, the first small-diameter loop conductor L1b is wound in a direction opposite to the winding direction of the second small-diameter loop conductor L2b, and the first large-diameter loop conductor L1a is the second large-diameter loop conductor. It is wound in a direction opposite to the winding direction of L2a. Therefore, a capacity is generated between the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b (capacitance Cb in FIG. 5), and the first large-diameter loop conductor L1a and the second large-diameter loop conductor A capacitance is generated between L2a (capacitance Ca in FIG. 5).

  The capacitances Ca and Cb (capacitance) generated between the first coil conductor L1 and the second coil conductor L2 can be designed to have desired values by changing the material and thickness of the base sheet 1. It is. Moreover, the material of the base material sheet 1 may be not only an organic sheet such as PET (polyethylene-terephthalate) or an insulating adhesive but also paper.

  As shown in FIG. 6, the first coil conductor L1 and the second coil conductor L2 include inductances (L1a, L1b, L2a, L2b) of the first coil conductor L1 and the second coil conductor L2, and the first coil conductor L1 and Capacitance generated between the second coil conductor L2 (capacity Ca generated between the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a, and the first small-diameter loop conductor L1b and the second The booster antenna 50 (LC resonance circuit) is configured by the capacitance Cb) generated between the small-diameter loop conductor L2b. The resonance frequency of the booster antenna 50 is selected to be a frequency (for example, 13.56 MHz) substantially equal to the communication frequency of the RFID system.

  In the antenna device 101 according to the present embodiment, the coil outer diameter of the feeding coil 30 of the RFIC module 10 is smaller than the coil inner diameters of the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b. The feeding coil 30 is disposed in the small-diameter loop conductor formation region Lse in plan view. That is, the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b circulate around the feeding coil 30, and all directions of the feeding coil 30 are surrounded by the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b. It becomes composition. Therefore, the entire power supply coil 30 is magnetically coupled with the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b with a high degree of coupling. Therefore, the RFIC module 10 can receive magnetic field energy from the communication partner antenna through the booster antenna 50 (LC resonance circuit) with high efficiency.

  In addition, since the feeding coil 30 does not overlap the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b in plan view, the first small-diameter loop conductor L1b, the second small-diameter loop conductor L2b, and the feeding coil 30 can be suppressed.

  The shape of the feeding coil 30 is such that all directions are surrounded by the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b, so that the first small-diameter loop conductor L1b and the second small-diameter loop shape are formed. A shape similar to that of the conductor L2b is preferable.

In the antenna device 101 according to the present embodiment, the omnidirectional portion of the feeding coil 30 is surrounded by the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b. The degree of binding _{KCP of} is high. In general, when the degree of coupling K _CP is high, magnetic field energy can be received with high efficiency, but at the same time, the mutual inductance M between the coupling part CP and the feeding coil 30 increases. By increasing the mutual inductance M, the inductance (L1a + L1b + L2a + L2b) of the booster antenna 50 as a whole changes, so that the resonance frequency of the booster antenna 50 changes.

  However, in the antenna device 101 according to the present embodiment, the inductances of the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b are small (relative to the inductance required for the first coil conductor L1 and the second coil conductor L2). Relatively small). For example, the inductance (L1b + L2b) of the coupling portion CP is 1/5 or less of the inductance (L1a + L1b + L2a + L2b) of the entire booster antenna 50. Therefore, the mutual inductance M generated by the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b and the feeding coil 30 is relative to the overall mutual inductance generated by the first coil conductor L1 and the second coil conductor L2. Relatively small.

Accordingly, the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b, RFIC module 10 as the mounting position of the (feeding coil 30) is slightly displaced mutually the whole due to the change in the degree of coupling _{K CP} Inductance variation is small. As a result, fluctuations in the resonance frequency of the booster antenna 50 (LC resonance circuit) and the RFIC module 10 (RFIC element 40 and the feeding coil 30 connected thereto) can be suppressed. That is, the rate of change of the resonance frequency of the booster antenna 50 (LC resonance circuit) and the RFIC module 10 with respect to the mounting position shift of the RFIC module 10 (feeding coil 30) becomes small.

  Specific parameters of the antenna device of the present invention are as follows.

The degree of coupling between the coupling portion CP and the feeding coil 30: K _CP = 0.1 or more and 0.6 or less (Inductance of the coupling portion CP: L1b + L2b) ≦ (Inductance of the booster antenna 50 as a whole: L1a + L1b + L2a + L2b) × 1 / 5
The degree of coupling between the booster antenna 50 and the feeding coil 30: K _AL = 0.02 or more and 0.1 or less According to this embodiment, an antenna device having the above parameters can be easily configured. The above parameter is one of the embodiments and is not limited to this value.

  According to the present embodiment, the following effects can be obtained.

(A) The mutual inductance M generated between the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b and the feeding coil 30 of the RFIC module 10 can be reduced. Therefore, even if there is a slight shift in the mounting position of the feeding coil 30 of the RFIC module 10 with respect to the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b, the fluctuation of the mutual inductance M is small, resulting in a booster antenna. 50 (LC resonance circuit) and the variation of the resonance frequency of the RFIC module 10 can be suppressed.

(B) The first small-diameter loop conductor L1b is wound in the same direction as the winding direction of the first large-diameter loop conductor L1a in plan view, and the second small-diameter loop conductor L2b is The two large-diameter loop conductors L2a are wound in the same direction as the winding direction. With this configuration, the current i1b flowing through the first small-diameter loop conductor L1b and the current i2b flowing through the second small-diameter loop conductor L2b are the current i1a flowing through the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a. In the same direction as the current i2a flowing through. Therefore, the magnetic fields generated in the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a are not canceled by the magnetic fields generated in the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b. Therefore, the effective coil opening area of the first coil conductor L1 and the second coil conductor L2 can be secured widely, and the communication distance can be increased.

(C) In the antenna device 101 according to the present embodiment, the feeding coil 30 is disposed in the small-diameter loop conductor formation region Lse in plan view. Therefore, even if the mounting position of the feeding coil 30 is slightly deviated from the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b, a rapid change in the coupling degree is suppressed. Therefore, the fluctuation of the mutual inductance due to the sudden change in the coupling degree can be reduced, and as a result, the fluctuation of the resonance frequency of the booster antenna 50 (LC resonance circuit) and the RFIC module 10 can be suppressed.

(D) In the present embodiment, the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b constituting the coupling portion CP are formed with a wide line width and the number of turns is one. Therefore, the resistance component of the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b is low. The mutual inductance Mb of the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b is small.

(E) In the antenna device 101 of the present embodiment, the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a are formed with a wide line width, and the number of turns is one. Therefore, the resistance component of the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a is low. The mutual inductance Ma of the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a is small. Further, since the number of turns of the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a is small, a wide opening of the coil can be secured. Therefore, even if a positional shift occurs between the first large-diameter loop conductor L1a and the second large-diameter loop conductor L2a that are arranged to face each other, the first large-diameter loop conductor L1a and the second large-diameter conductor Variation in the capacitance Ca (capacitance) generated between the loop-shaped conductor L2a is suppressed. Therefore, the fluctuation | variation of the resonant frequency of the booster antenna 50 (LC resonant circuit) comprised with the 1st coil conductor L1 and the 2nd coil conductor L2 is suppressed.

(F) In the present embodiment, the first coil conductor L1 (first large diameter loop conductor L1a, first small diameter loop conductor L1b) and second coil conductor L2 (second large diameter loop conductor L2a, second small diameter). The number of turns of the loop-shaped conductor L2b) is one each. Therefore, the same conductors are not adjacent to each other, and the generation of line capacitance is suppressed. Therefore, since the change in capacitance (capacitance) generated by the attachment of water droplets or the like to the booster antenna 50 (LC resonance circuit) can be suppressed, the antenna device of the present invention is a tag for a food product that is highly likely to have water droplets or the like attached thereto. Etc. can also be used.

(G) In the present embodiment, the coupling portion CP (the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b) is disposed in the large-diameter loop conductor formation region Lle in plan view. Therefore, the coil opening part of the booster antenna 50 (LC resonance circuit) with respect to the base material sheet 1 can be formed large, and the magnetic flux linked with the antenna coil on the communication partner side can be increased. That is, the communication distance can be increased.

(H) In the antenna device 101 according to the present embodiment, the first small-diameter loop conductor L1b, the second small-diameter loop conductor L2b, and the feeding coil 30 are arranged on the same axis in plan view. Therefore, the degree of coupling between the first coil conductor L1 and the second coil conductor L2 and the RFIC module 10 can be increased, and the communication distance can be increased.

(I) The RFIC module 10 of the present embodiment includes a laminated body 20 formed by laminating a plurality of base material layers, and the feeding coil 30 has a structure formed inside the laminated body 20. With this structure, the number of turns of the power feeding coil can be easily changed, so that a desired inductance value can be obtained.

(J) In this embodiment, the base sheet 1 is provided, the first coil conductor L1 is formed on the first main surface of the base sheet 1, and the second coil conductor L2 is formed on the second main surface of the base sheet 1. Is formed. With this configuration, the first coil conductor L1 and the second coil conductor L2 can be easily formed, and the booster antenna 50 (LC resonance circuit) can be easily configured.

(K) In this embodiment, static electricity (high voltage) is intentionally applied to the antenna device 101 to cause dielectric breakdown (short) of the base sheet 1, thereby destroying the function of the antenna device 101, and the RFIC module. Only 10 can create an operable state. As a result, information written in the RFIC module 10 cannot be read from a distance, and can be read only in the near field (20 mm or less).

<< Second Embodiment >>
An antenna device according to a second embodiment will be described with reference to the drawings. FIG. 7A is an external perspective view of the antenna device 102 according to the second embodiment, and FIG. 7B is a cross-sectional view taken along line AA in FIG.

  The antenna device 102 according to the second embodiment is different from the antenna device 101 according to the first embodiment in the shapes of the first coil conductor L1 and the second coil conductor L2. The antenna device 102 is different from the antenna device 101 in that the RFIC module 10 is mounted on the first main surface of the base sheet 1. Other configurations are the same as those of the antenna device 101 according to the first embodiment.

  Hereinafter, parts different from the antenna device 101 according to the first embodiment will be described.

  As shown in FIG. 7A, in the antenna device 102, the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b are one side (the base in FIG. 7A) that is the outer peripheral end of the base sheet 1. It is formed near the middle of the lower side of the material sheet 1.

  As shown in FIG. 7B, the first large-diameter loop conductor L1a has a wider line width than the second large-diameter loop conductor L2a. Further, the first small-diameter loop conductor L1b has a wider line width than the second small-diameter loop conductor L2b. That is, the first coil conductor L1 is formed to have a wider line width than the second coil conductor L2.

  The RFIC module 10 is mounted (arranged) on the first main surface (front surface) of the base sheet 1 via an adhesive layer (not shown). The adhesive layer is, for example, a double-sided pressure-sensitive adhesive tape, but may be an adhesive material or the like. The adhesive layer can be appropriately changed as long as the RFIC module 10 can be mounted on the surface of the base sheet 1. Similarly to the antenna device 101, the feeding coil 30 of the RFIC module 10 is arranged in a formation region (small-diameter loop conductor formation region) of the first small-diameter loop conductor L1b and the second small-diameter loop conductor L2b in plan view. ing.

  Even with such a configuration, the same operations and effects as the antenna device according to the first embodiment can be obtained. Thus, the position of the coupling portion between the RFIC module 10 and the booster antenna 50 (LC resonance circuit) is not limited to the corner portions of the first coil conductor L1 and the second coil conductor L2, and can be changed as appropriate.

  In the antenna device 102 according to the present embodiment, the first coil conductor L1 is formed to have a wider line width than the second coil conductor L2. With this configuration, even if a shift occurs in the formation positions of the first coil conductor L1 and the second coil conductor L2, a capacitance (first large diameter) generated between the first coil conductor L1 and the second coil conductor L2. The capacitance generated between the loop-shaped conductor L1a and the second large-diameter loop-shaped conductor L2a and the capacitance generated between the first small-diameter loop-shaped conductor L1b and the second small-diameter loop-shaped conductor L2b) are kept constant. The variation in resonance frequency can be reduced.

  Furthermore, since it is only necessary to arrange the RFIC module 10 on the surface of the base sheet 1, the manufacturing process can be reduced as compared with the antenna device 101 according to the first embodiment. In the present embodiment, the example in which the RFIC module 10 is mounted on the first main surface of the base sheet 1 (the upper side in FIG. 7B) is shown, but the present invention is not limited to this configuration. The RFIC module 10 may be configured to be mounted on the second main surface (the lower side of FIG. 7B) of the base sheet 1.

<< Other Embodiments >>
In the above-described embodiment, the example in which the shapes of the first coil conductor L1 and the second coil conductor L2 constituting the booster antenna 50 (LC resonance circuit) are rectangular in a plan view is shown. However, the present invention is not limited to this configuration. Absent. The shapes of the first coil conductor L1 and the second coil conductor L2 constituting the booster antenna 50 (LC resonance circuit) can be appropriately changed to a polygonal shape, a circular shape, an elliptical shape, etc. in plan view.

  Similarly, in the above-described embodiment, an example in which the shape of the base sheet 1 is a rectangular shape in plan view is shown, but the configuration is not limited thereto. The shape of the base sheet 1 can be appropriately changed to a polygonal shape, a circular shape, an elliptical shape, or the like in plan view. Further, the size is not limited to the card size.

  Moreover, in the above-mentioned embodiment, although the example which forms the 1st coil conductor L1 and the 2nd coil conductor L2 in the 1st main surface and 2nd main surface of the base material sheet 1 was shown, the base material sheet 1 is essential. It is not a configuration. For example, by disposing the main surface of the base plate on which the first coil conductor L1 is formed and the main surface of the base plate on which the second coil conductor L2 is formed facing each other at a predetermined interval, the first coil conductor L1 and The 2nd coil conductor L2 may be the structure which opposes and arranges via an air layer. Even in such a configuration, the capacitor generated between the first coil conductor L1 and the second coil conductor L2 is normally configured, and the LC resonance circuit is normally configured.

CP ... coupling part AP ... antenna part K _CP ... coupling degree Ca, Cb ... capacity E11 ... first end E12 ... second end E21 ... first end E22 ... second end i0, i1a, i1b, i2a, i2b ... current L1 ... 1st coil conductor L2 ... 2nd coil conductor L1a ... 1st large diameter loop conductor L1b ... 1st small diameter loop conductor L1b ... 1st large diameter loop conductor L2a ... 2nd large diameter loop conductor L2b ... 2nd Small-diameter loop conductor Lle ... Large-diameter loop conductor formation region Lse ... Small-diameter loop conductor formation regions M, Ma, Mb ... Mutual inductance 1 ... Base sheet 2 ... Lower holding sheet 3 ... Upper holding sheet 5 ... Resin 10 ... RFIC Module 20 ... Laminated body 30 ... Feeding coil 40 ... RFIC element 50 ... Booster antennas 101, 102 ... Antenna device

Claims (7)

An RFIC element;
A feeding coil connected to the RFIC element;
A first coil conductor having a first large-diameter loop conductor and a first small-diameter loop conductor connected to an end of the first large-diameter loop conductor;
A second large-diameter loop conductor disposed opposite to the first large-diameter loop conductor; and a second large-diameter loop conductor disposed opposite to the first small-diameter loop conductor; A second coil conductor having a second small diameter loop conductor connected thereto;
With
The first large-diameter loop conductor is wound in a direction opposite to the winding direction of the second large-diameter loop conductor in plan view,
The first small-diameter loop-shaped conductor has a number of turns of 1, and is disposed in a formation region of the first large-diameter loop-shaped conductor in a plan view.
The second small-diameter loop conductor has a number of turns of 1, and is disposed in a formation region of the second large-diameter loop conductor in plan view,
The first coil conductor and the second coil conductor include a booster antenna having an inductance of the first coil conductor and the second coil conductor and a capacitance generated between the first coil conductor and the second coil conductor. Configure
The feeding coil is disposed in a formation region of the first small-diameter loop conductor and in a formation region of the second small-diameter loop conductor in plan view, and the first small-diameter loop conductor and the second small-diameter loop shape An antenna device, wherein the antenna device is coupled to a conductor via a magnetic field.   2. The antenna device according to claim 1, wherein the first large-diameter loop-shaped conductor and the second large-diameter loop-shaped conductor each have 1 winding. The first small-diameter loop conductor is wound in the same direction as the winding direction of the first large-diameter loop conductor in plan view,
The antenna device according to claim 1 or 2, wherein the second small-diameter loop conductor is wound in the same direction as the winding direction of the second large-diameter loop conductor in plan view.   The antenna device according to any one of claims 1 to 3, wherein the RFIC element and the feeding coil are configured as an RFIC module in which these are integrated into one chip. The RFIC module includes a laminate formed by laminating a plurality of base material layers,
The antenna device according to claim 4, wherein the feeding coil is formed inside the laminated body. A base sheet having a first main surface and a second main surface;
The first coil conductor is formed on the first main surface of the base sheet,
The second coil conductor is formed on the second main surface of the base sheet,
The antenna device according to claim 4, wherein the RFIC module is disposed on a surface or inside of the base sheet.   The antenna device according to any one of claims 1 to 6, wherein the first small-diameter loop conductor, the second small-diameter loop conductor, and the feeding coil are arranged on the same axis in a plan view. .

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