JP2019192951A - Antenna device and electronic apparatus - Google Patents

Abstract

To provide an antenna device having high communication performance with a communication partner in a configuration with a plurality of coils and suppressing variations in the communication performance caused by a positional relationship between the plurality of coils.SOLUTION: An antenna device includes a coil antenna 101, or the like. The coil antenna 101 includes an insulating base member 10, a plurally wound first coil L1 configuring a part of a first resonant circuit, and a plurally wound second coil L2 configuring a part of a second resonant circuit. The first coil L1 is connected to a feeder circuit. A wound axis AX1 of the first coil L1 and a wound axis AX2 of a second coil L2 are parallel to each other. At least a part of the first coil L1 and the second coil L2 extend in parallel to each other when viewed in a wound axis AX1 direction (Z-axis direction) of the first coil, and are alternately arranged in a radial direction of the first coil L1. The first coil L1 and the second coil L2 are electromagnetic-field coupled in a manner such that revolving directions of currents flowing through the first coil L1 and the second coil L2 are the same direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an antenna device, and more particularly to an antenna device including a plurality of coils and an electronic apparatus including the antenna device.

  Conventionally, an antenna device including a coil antenna and a booster antenna that is magnetically coupled to the coil antenna is known.

  For example, Patent Document 1 discloses an antenna device including a first coil (chip coil) connected to a power feeding circuit and a second coil (booster antenna) that is magnetically coupled to the first coil. The antenna device disclosed in Patent Document 1 is a multi-resonant antenna in which a circuit to which a first coil is connected and a circuit to which a second coil is connected resonate.

JP 2013-243666 A

  However, in the configuration shown in Patent Document 1, since the degree of coupling between the first coil and the second coil is low, the communication performance of the antenna is low. Further, the degree of coupling between the coils may vary depending on the positional relationship between the first coil and the second coil, and there is a possibility that the communication characteristics of the antenna device may vary.

  An object of the present invention is to provide an antenna device that has high communication performance with a communication partner in a configuration including a plurality of coils and suppresses variations in communication characteristics due to the positional relationship between the plurality of coils.

The antenna device of the present invention is
An insulating substrate;
A first coil connected to the power supply circuit, constituting a part of the first resonance circuit, formed on the insulating substrate, and wound in a plurality
A second coil that forms part of the second resonant circuit, is formed on the insulating substrate, and is wound a plurality of times;
With
The winding axis of the first coil and the winding axis of the second coil are parallel,
At least a part of the first coil and the second coil are parallel to each other when viewed from the winding axis direction of the first coil, and the first coil is the second coil in the radial direction of the first coil. And the second coils are alternately arranged so as to sandwich the first coil,
The first coil and the second coil are characterized in that the circulation directions of currents flowing through the first coil and the second coil are the same direction and are electromagnetically coupled to each other.

  According to this configuration, since the first coil and the second coil are both formed on the insulating base material, the first coil and the second coil are compared with the case where the first coil and the second coil are formed on different members. Variations in the positional relationship between the two coils are unlikely to occur. For this reason, fluctuations in the coupling degree due to variations in the positional relationship between the coils are suppressed, and variations in communication characteristics can be suppressed.

  Moreover, according to this structure, since the 1st coil and the 2nd coil run mutually in parallel and are arrange | positioned alternately at radial direction, the distance between a 1st coil and a 2nd coil can be shortened. Therefore, compared with the case where a 1st coil and a 2nd coil are each formed in a different member, the coupling | bonding of coils can be improved and the communication characteristic of an antenna apparatus can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, in the structure provided with a several coil, the communication performance with a communicating party is high, and the antenna apparatus which suppressed the dispersion | variation in the communication characteristic resulting from the positional relationship of several coils is realizable.

FIG. 1A is a plan view of the coil antenna 101 according to the first embodiment, and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 is a circuit diagram of an electronic device 401 including the antenna device 301 in the first embodiment. FIG. 3 is a perspective view showing the positional relationship between the coil antenna 101 and the communication partner antenna 500. FIG. 4 is a diagram showing how the coil antenna 101 and the communication partner antenna 500 shown in FIG. FIG. 5 is a circuit diagram showing a coupling state between the coil antenna 101 and the communication partner antenna. 6A is a plan view of a one-resonant coil antenna 100A as a comparative example, and FIG. 6B is a plan view of a coil antenna 100B as another comparative example. Figure 7 is a graph showing the relationship between the resonance frequency f _R and the coefficient alpha. FIG. 8 is a diagram showing the relationship between the first impedance Z1 and the second impedance Z2 and the frequency. FIG. 9A is a circuit diagram of an electronic device 402A according to the second embodiment, and FIG. 9B is a circuit diagram of another electronic device 402B according to the second embodiment. FIG. 10 is a circuit diagram of another electronic device 402C according to the second embodiment. FIG. 11 is a cross-sectional view of the coil antenna 103 according to the third embodiment. FIG. 12A is a plan view of an antenna device 304A according to the fourth embodiment, and FIG. 12B shows the positional relationship between the antenna device 304A shown in FIG. It is a perspective view. 13A is a plan view of another antenna device 304B according to the fourth embodiment, and FIG. 13B is a positional relationship between the antenna device 304B and the communication partner antenna 500 shown in FIG. FIG. 14A is a plan view of another antenna device 304C according to the fourth embodiment, and FIG. 14B is a positional relationship between the antenna device 304C and the communication partner antenna 500 shown in FIG. FIG. FIG. 15A is a perspective view showing the positional relationship between the coil antenna 100 and the measurement coil 600, and FIG. 15B is a front view showing the positional relationship between the coil antenna 100 and the measurement coil 600. FIG. 16 is a plan view of the coil antenna 100. FIG. 17 is a diagram showing a coupling coefficient k ₁₃ ^EQ between the coil antenna 100 and the measurement coil 600. FIG. 18A is a plan view showing the structure inside the housing of the electronic device 405 according to the fifth embodiment, and FIG. 18B is a cross-sectional view taken along line BB in FIG. FIG. 19 is a cross-sectional view illustrating the structure inside the housing of the electronic device 406 according to the sixth embodiment.

  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. In consideration of ease of explanation or understanding of the main points, the embodiments are shown separately for convenience, but the components shown in different embodiments can be partially replaced or combined. In the second and subsequent embodiments, description of matters common to the first embodiment is omitted, and only different points will be described. In particular, the same operation effect by the same configuration will not be sequentially described for each embodiment.

  The “antenna device” shown in each embodiment can be applied to either a signal (or power) transmission side (power transmission side) or a reception side (power reception side). Even when this “antenna device” is described as an antenna that radiates magnetic flux, the antenna device is not limited to being a magnetic flux generation source. Even when the transmission counterpart antenna device receives (links) the generated magnetic flux, that is, even if the transmission / reception relationship is reversed, the same effect is obtained.

  The “antenna device” shown in each embodiment is an antenna device used for near-field communication using electromagnetic field coupling (magnetic field coupling and electric field coupling) with a communication counterpart antenna device, or a power transmission counterpart antenna and an electromagnetic field. It is an antenna device used for power transmission in the near field using coupling. In the case of communication, it is applied to a communication system such as NFC (Near Field Communication). In the case of power transmission, for example, the present invention is applied to a power transmission system using electromagnetic coupling such as an electromagnetic induction method or a magnetic resonance method.

  The “antenna device” shown in each embodiment is used in, for example, the HF band, particularly 13.56 MHz, 6.78 MHz, or a frequency band in the vicinity thereof. The size of the antenna device is sufficiently smaller than the wavelength λ at the used frequency, and the radiation efficiency of electromagnetic waves is low in the used frequency band. The size of the antenna device is λ / 10 or less. More specifically, the length of the current path of the antenna device is λ / 10 or less. In addition, the wavelength here is an effective wavelength in consideration of the wavelength shortening effect due to the dielectric property and permeability of the base material on which the conductor is formed.

  In each embodiment, the “electronic device” refers to a mobile phone terminal such as a smartphone or a feature phone, a wearable terminal such as a smart watch or a smart glass, a portable PC such as a notebook PC or a tablet PC, a camera, a game machine, a toy, etc. It refers to various electronic devices such as information devices, IC tags, SD cards, SIM cards, and information media such as IC cards.

<< First Embodiment >>
FIG. 1A is a plan view of the coil antenna 101 according to the first embodiment, and FIG. 1B is a cross-sectional view taken along line AA in FIG. FIG. 2 is a circuit diagram of an electronic device 401 including the antenna device 301 in the first embodiment. In FIG. 1A, the second coil L2 is indicated by a broken line for easy understanding of the structure. The coil antenna 101 is used for a reader / writer or a tag in an RFID system that performs communication using NFC, for example.

  The coil antenna 101 includes an insulating base material 10, a first coil L1, and a second coil L2.

  The insulating substrate 10 is a rectangular flat plate made of an insulating material. The insulating base 10 has a first main surface VS1 (front surface) and a second main surface VS2 (back surface) that face each other. The insulating substrate 10 is a sheet of thermoplastic resin such as polyimide (PI) or liquid crystal polymer (LCP).

  The first coil L1 is a rectangular spiral conductor pattern of about 2 turns (two turns) formed on the first main surface VS1 of the insulating base 10, and has a first end E11 and a second end E12. As will be described in detail later, the first coil L1 constitutes a part of the first resonance circuit. The first coil L1 is a conductor pattern such as a Cu foil, for example.

  The second coil L2 is a rectangular spiral conductor pattern of about two turns (two turns) formed on the first main surface VS1 of the insulating base 10, and has a first end E21 and a second end E22. As will be described in detail later, the second coil L2 constitutes a part of the second resonance circuit. The second coil L2 is a conductor pattern such as a Cu foil, for example.

  The winding axis AX1 of the first coil L1 and the winding axis AX2 of the second coil L2 are the same. However, the winding axis AX1 and the winding axis AX2 do not necessarily need to coincide with each other and may be in parallel. In this specification, “the winding axis AX1 and the winding axis AX2 are parallel” does not mean that the winding axis AX1 and the winding axis AX2 are strictly parallel. Is a range of 0 ° to less than ± 30 °.

  As shown in FIGS. 1A and 1B, at least a part of the first coil L1 and the second coil L2 is viewed from the Z-axis direction (the direction of the winding axis AX1 of the first coil L1), They are parallel to each other and are alternately arranged in the radial direction of the first coil L1. In the present embodiment, substantially the whole of the first coil L1 and the second coil L2 are parallel to each other when viewed from the Z-axis direction.

  In this specification, “the first coil L1 and the second coil L2 are alternately arranged in the radial direction of the first coil” means that the first coil L1 is the second coil in the radial direction of the first coil L1. A relationship in which the second coil L2 sandwiches the first coil L1 in the radial direction of the first coil L1 with the L2 sandwiched therebetween. That is, the first coil L1 and the second coil are arranged in the order of the first coil L1, the second coil L2, the first coil L1, and the second coil L2 (or the second coil L2, around the winding axis AX1). The first coil L1, the second coil L2, and the first coil are wound in this order.

  Only a part of the first coil L1 and the second coil L2 may be alternately arranged in the radial direction of the first coil L1. For example, when each of the first coil L1 and the second coil L2 has three turns, the first coil L1, the first coil L1, the second coil L2, in the radial direction of the first coil L1 around the winding axis AX1, The first coil L1, the second coil L2, and the second coil L2 may be wound in this order. However, it is preferable that the entire first coil L1 and second coil L2 are alternately arranged in the radial direction of the first coil L1. For example, when each of the first coil L1 and the second coil L2 has three turns, the first coil L1, the second coil L2, the first coil L1, in the radial direction of the first coil L1 around the winding axis AX1, Order of second coil L2, first coil L1, second coil L2 (or order of second coil L2, first coil L1, second coil L2, first coil L1, second coil L2, first coil L1) In any part, it is preferable that the first coils L1 or the second coils L2 are not adjacent to each other in the radial direction of the first coil L1.

  FIG. 2 is a circuit diagram of an electronic apparatus 401 including the antenna device 301 according to the first embodiment.

  As shown in FIG. 2, the electronic device 401 includes an antenna device 301, an RFIC 9, and the like. Note that other components are also mounted on the electronic device 401. The antenna device 301 includes a coil antenna 101, first inductors L10a and L10b, first capacitors C10a, C10b, C11a, C11b, C12a, C12b, and a second capacitor C20. The first inductors L10a and L10b are, for example, chip inductors. The first capacitors C10a, C10b, C11a, C11b, C12a, C12b and the second capacitor C20 are, for example, chip capacitors. The first capacitor and the second capacitor may be a line capacitance of the coil.

  In the present embodiment, the RFIC 9 is an example of the “feed circuit” in the present invention.

  The first end E11 and the second end E12 of the first coil L1 are connected to the RFIC 9 via a matching circuit MC (described in detail later). The RFIC 9 has a balanced input / output. As shown in FIG. 2, the first capacitors C10a and C10b connected in series are connected in parallel to the first end E11 and the second end E12 of the first coil L1. The connection point of the first capacitors C10a and 10b is connected to the ground. The first end E21 and the second end E22 of the second coil L2 are connected to the second capacitor C20. The first coil L1 and the second coil L2 are electromagnetically coupled.

  As shown in FIG. 2, the first resonance circuit RC1 is configured including at least the first coil L1 and the first capacitors C10a and C10b. The second resonance circuit RC2 is configured including at least the second coil L2 and the second capacitor C20.

  In the present embodiment, the first resonance circuit RC1 is configured by the first coil L1 and the first capacitors C10a and C10b. However, the first resonance circuit RC1 may include other circuit components. Good. In the present embodiment, the second resonance circuit RC2 is configured by the second coil L2 and the second capacitor C20. However, the second resonance circuit RC2 may include other circuit components.

  As shown in FIG. 2, the matching circuit MC is connected between the coil antenna 101 and the RFIC 9. The matching circuit MC includes first inductors L10a and L10b and first capacitors C10a, C10b, C11a, C11b, C12a, and C12b. In particular, the first inductors L10a and L10b also function as a filter for EMC (Electro-Magnetic Compatibility).

  FIG. 3 is a perspective view showing the positional relationship between the coil antenna 101 and the communication partner antenna 500. FIG. 4 is a diagram showing how the coil antenna 101 and the communication partner antenna 500 shown in FIG. FIG. 5 is a circuit diagram showing a coupling state between the coil antenna 101 and the communication partner antenna. In FIG. 5, the communication partner antenna 500 shown in FIG. 3 and the like is represented by an inductor L3. In FIG. 4, the first coil L1 and the second coil L2 are coupled with a coupling coefficient k12, and the second coil L2 and the communication partner antenna 500 are coupled with a coupling coefficient k23. Furthermore, the first coil L1 and the communication partner antenna 500 are coupled with a coupling coefficient k13. Communication partner antenna 500 (inductor L3 shown in FIG. 5) is connected to the communication partner side IC (or a communication circuit including the IC; IC 8 shown in FIG. 5).

  The first resonance circuit RC1 resonates at a first frequency (the resonance frequency of the first resonance circuit RC1), and a resonance current flows through the first coil L1 that is a part of the first resonance circuit RC1. The second resonance circuit RC2 resonates at a second frequency (the resonance frequency of the second resonance circuit RC2), and a resonance current flows through the second coil L2 that is a part of the second resonance circuit RC2. At this time, the circulation direction of the current flowing through the first coil L1 that is a part of the first resonance circuit RC1 is the same as the circulation direction of the current flowing through the second coil L2 that is a part of the second resonance circuit RC2. For example, see the arrow in FIG. That is, the first coil L1 and the second coil L2 are electromagnetically coupled to each other so that the circulation directions of the flowing currents are the same. In other words, the first coil L1 and the second coil L2 are magnetically coupled to each other so that the magnetic fluxes generated by the flowing currents are in phase.

  The antenna device 301 (coil antenna 101) according to this embodiment has the following operational effects.

(A) In the present embodiment, both the first coil L1 and the second coil L2 are formed on the insulating base material 10. According to this configuration, the positional relationship between the first coil L1 and the second coil L2 is less likely to vary than when the first coil L1 and the second coil L2 are formed on different members. That is, since the relative positional shift factor between the first coil L1 and the second coil L2 is reduced, the variation in the coupling degree due to the variation in the positional relationship between the coils is suppressed, and the antenna has stable communication characteristics. A device is obtained.

(B) In the present embodiment, at least a part of the first coil L1 and the second coil L2 run in parallel with each other and are alternately arranged in the radial direction of the first coil L1. According to this structure, the distance between the 1st coil L1 and the 2nd coil L2 can be shortened compared with the case where the 1st coil L1 and the 2nd coil L2 are formed in a respectively different member. Therefore, the coupling between the coils can be enhanced, and the communication characteristics of the antenna device can be enhanced.

  In addition, when the 1st coil L1 and the 2nd coil L2 are formed in a respectively different member, there exists a possibility that coils may not fully couple | bond depending on the positional relationship of the 1st coil L1 and the 2nd coil L2. In addition, if the coils are to be sufficiently coupled together, the positional relationship between the first coil L1 and the second coil L2 may be limited. On the other hand, according to the said structure, the coupling | bonding of the 1st coil L1 and the 2nd coil L2 can be improved, without receiving the restriction | limiting of the positional relationship between coils.

(C) Moreover, in this embodiment, the substantially whole of the 1st coil L1 and the 2nd coil L2 are mutually running in parallel. The coupling coefficient between the first coil L1 and the second coil L2 increases as the distance between the portions where the first coil L1 and the second coil L2 are close to each other is longer. Therefore, it is preferable that the number of turns of the first coil L1 and the number of turns of the second coil L2 are substantially the same in terms of increasing the coupling coefficient between the first coil L1 and the second coil L2.

(D) In the present embodiment, the winding axis AX1 of the first coil L1 and the winding axis AX2 of the second coil L2 are parallel. With this configuration, an antenna device 301 having a higher coupling coefficient k12 between the first coil L1 and the second coil L2 can be obtained as compared with the case where the winding axis AX1 of the first coil L1 is oriented in the Y-axis direction, for example.

  Here, an effect of improving the coupling coefficient by the configuration of the present invention (the configuration in which the first coil L1 and the second coil run in parallel with each other and are alternately arranged in the radial direction) (see (b) above) will be described.

  6A is a plan view of a one-resonant coil antenna 100A as a comparative example, and FIG. 6B is a plan view of a coil antenna 100B as another comparative example. The coil antenna 100 </ b> A is different from the coil antenna 101 according to the first embodiment in that only the first coil L <b> 1 a having about four turns (four turns) is formed on the surface of the insulating base material 10. The coil antenna 100B differs from the coil antenna 101 in that a second coil L2b of about 2 turns (2 turns) is disposed inside the first coil L1b of about 2 turns (2 turns). The sizes and other configurations of the coil antennas 100A and 100B are the same as those of the coil antenna 101.

  The values of the coupling coefficients of the coil antennas 100A and 100B of the comparative example and the coil antenna 101 according to the present embodiment are as follows.

  Each coupling coefficient shown in Table 1 is as follows.

k ₁₂ : Coupling coefficient between the first coil and the second coil
k ₁₃ : Coupling coefficient between first coil and communication partner antenna
k _23: coupling coefficient between communication partner antenna and the second coil
k ₁₃ ^EQ : Equivalent coupling coefficient between the first coil including the second resonance circuit and the communication partner antenna
k ₁₃ ^EQ is obtained by the following equation.

The coefficient α is a coefficient obtained from the resonance frequency f _R (either the first frequency or the second frequency) and the third frequency f (the carrier frequency to be used).

  The coefficient α is obtained by the following formula.

Figure 7 is a graph showing the relationship between the resonance frequency f _R and the coefficient alpha. In FIG. 7, the third frequency f is 13.56 MHz. As shown in FIG. 7, when the resonance frequency f _R is higher than the third frequency f, the coefficient α is a negative value. Therefore, the second term of the numerator on the right side of Equation (1) becomes a positive value and k ₁₃ ^EQ increases. That is, communication characteristics can be improved by the synergistic effect of multiple resonances. On the other hand, as shown in FIG. 7, when the resonance frequency f _R is lower than the third frequency f, the coefficient α is a positive value, and therefore the second term of the numerator on the right side of the equation (1) is a negative value. K ₁₃ ^EQ becomes positive and small, or k ₁₃ ^EQ becomes negative. That is, the effect of improving the communication characteristics due to the double resonance cannot be obtained. From the above, it is preferable to set the resonance frequency f _R to be higher than the third frequency f so that the coefficient α becomes a negative value.

Thus, the first coil L1 and the second coil and extending parallel to each other, by being arranged alternately in the radial direction of the first coil L1, the coupling coefficient k ₁₂ of the first coil L1 and the second coil L2 And the coupling coefficient k ₁₃ ^EQ is improved.

Further, the resonance frequency f _R (either the first frequency f ₁ or the second frequency f ₂ ) is preferably higher than the third frequency f. This improves the coupling coefficient k ₁₃ ^EQ .

  Moreover, in order to improve the communication performance with the communication partner antenna, it is preferable to satisfy the following conditions. FIG. 8 is a diagram showing the relationship between the first impedance Z1 and the second impedance Z2 and the frequency.

For example, the first frequency f ₁ and the second frequency f ₂ are preferably not less than 0.5 times the third frequency f and not more than twice the third frequency f (0.5f ≦ f ₁ ≦ 2f). ) (0.5f ≦ f ₂ ≦ 2f). Further, for example, (the impedance of the second resonance circuit in the second frequency f2) second impedance Z2, the first impedance Z1 (impedance of the first resonant circuit at the first frequency _{f 1)} of 0.5 times or more, and, the It is preferable that the impedance is not more than twice the impedance Z1 (0.5Z1 ≦ Z2 ≦ 2Z1).

  Accordingly, the first coil that is a part of the first resonance circuit and the second coil that is a part of the second resonance circuit are strongly coupled, and as a result, the communication characteristics with the communication partner antenna are enhanced.

<< Second Embodiment >>
In the second embodiment, an electronic device having a circuit configuration different from that of the electronic device 401 according to the first embodiment is illustrated.

  FIG. 9A is a circuit diagram of an electronic device 402A according to the second embodiment, and FIG. 9B is a circuit diagram of another electronic device 402B according to the second embodiment. FIG. 10 is a circuit diagram of another electronic device 402C according to the second embodiment.

  The electronic devices 402A, 402B, and 402C are different from the electronic device 401 according to the first embodiment in the circuit configuration of the antenna device. In this embodiment, the RFIC 9 is a single end type. Other configurations of the electronic devices 402A, 402B, and 402C are substantially the same as those of the electronic device 401.

  Hereinafter, parts different from the electronic device 401 according to the first embodiment will be described.

  As shown in FIG. 9A, the electronic device 402A includes an antenna device 302A and an RFIC 9. The antenna device 302A includes a coil antenna 101, a first inductor L10, first capacitors C10, C11, C12, and a second capacitor C20. The first inductor L10 and the first capacitor C11 are connected in series between the first coil L1 and the RFIC9. The first capacitor C10 is connected in parallel to the first end E11 and the second end E12 of the first coil L1. The first capacitor C12 is connected in parallel to the input / output of the RFIC 9 (or the first end E11 and the second end E12 of the first coil L1).

  In the electronic device 402A, the first resonance circuit RC1 is configured including the first coil L1 and the first capacitors C10 and C11.

  As shown in FIG. 9B, the electronic device 402B includes an antenna device 302B and an RFIC 9. The antenna device 302B includes a coil antenna 101, a first inductor L10, first capacitors C11 and C12, and a second capacitor C20. The first inductor L10 and the first capacitor C11 are connected in series between the first coil L1 and the RFIC9. The first capacitor C12 is connected in parallel to the input / output of the RFIC 9 (or the first end E11 and the second end E12 of the first coil L1).

  In the electronic device 402B, the first resonance circuit RC1 is configured including the first coil L1 and the first capacitors C11 and C12.

  As illustrated in FIG. 10, the electronic device 402C includes an antenna device 302C and an RFIC 9. The antenna device 302C includes a first inductor L10, first capacitors C11a, C11b, C12, and a second capacitor C20. The first inductor L10 and the first capacitors C11a and C11b are connected in series between the first coil L1 and the RFIC9. The first capacitor C12 is connected in parallel to the input / output of the RFIC 9 (or the first end E11 and the second end E12 of the first coil L1).

  In the electronic device 402C, the first resonance circuit RC1 is configured including the first coil L1 and the first capacitors C11a, C11b, and C12.

  Thus, the present invention can also be applied to a single-ended type communication circuit.

<< Third Embodiment >>
In 3rd Embodiment, the antenna apparatus (coil antenna) shows the example which has a magnetic body.

  FIG. 11 is a cross-sectional view of the coil antenna 103 according to the third embodiment.

  The coil antenna 103 is different from the coil antenna 101 according to the first embodiment in that it further includes a magnetic body 5. Other configurations of the coil antenna 103 are the same as those of the coil antenna 101.

  Hereinafter, a different part from the coil antenna 101 which concerns on 1st Embodiment is demonstrated.

  As shown in FIG. 11, the magnetic body 5 is attached to the second main surface VS <b> 2 of the insulating base material 10. The magnetic body 5 is, for example, a magnetic ferrite plate.

  The coil antenna 103 according to the present embodiment has the following effects in addition to the effects described in the first embodiment.

(E) The coil antenna 103 according to the present embodiment includes the magnetic body 5. With this configuration, a coil antenna having a predetermined inductance can be obtained without increasing the size of the coil antenna 103. Further, the magnetic flux collection effect of the magnetic body 5 increases the magnetic field coupling between the first coil L1 and the second coil L2, and the magnetic field coupling between the first coil L1 and the communication partner antenna.

(F) In the coil antenna 103 according to the present embodiment, the magnetic body 5 is disposed on the second main surface VS2 side of the insulating base 10. According to this configuration, the magnetic shield effect of the magnetic body 5 can suppress the magnetic field from the coil antenna 103 from being radiated to the second main surface VS2 side. Therefore, even when another conductor is close to the second main surface VS2 side of the insulating base material 10, unnecessary coupling between the other conductor and the coil antenna is suppressed.

<< Fourth Embodiment >>
In the fourth embodiment, an example of an antenna device further including a conductor plate is shown.

  FIG. 12A is a plan view of an antenna device 304A according to the fourth embodiment, and FIG. 12B shows the positional relationship between the antenna device 304A shown in FIG. It is a perspective view. The antenna device 304 </ b> A includes the coil antenna 101 and the conductor plate 2. The antenna device 304A includes a configuration other than the coil antenna 101 and the conductor plate 2, but is not illustrated in FIGS. 12A and 12B.

  The antenna device 304A is different from the antenna device 301 according to the first embodiment in that the antenna device 304A further includes a conductor plate 2 close to the coil antenna 101. The coil antenna 101 is the same as that described in the first embodiment. The other configuration of the antenna device 304A is the same as that of the antenna device 301. Hereinafter, a different part from 1st Embodiment is demonstrated.

  The conductor plate 2 is a rectangular flat plate. The conductor plate 2 is a ground conductor formed on a part of a housing of an electronic device made of, for example, metal or graphite, or on a circuit board. As will be described later, the conductor plate 2 may be, for example, a metal portion (conductor portion) of a battery pack housed inside the casing of the electronic device. Moreover, the conductor plate 2 may be a member including a metal such as a shield plate housed inside the housing of the electronic device. Moreover, the conductor plate 2 does not necessarily need to be rectangular, and may be, for example, a circular shape.

  As shown in FIG. 12A, the conductor plate 2 of the antenna device 304A overlaps the first coil L1 and the second coil L2 when viewed from the Z-axis direction (direction of the winding axis AX1 of the first coil L1). And a portion that does not overlap the first coil L1 and the second coil L2. The conductor plate 2 is located in the −Z direction with respect to the first coil L1 and the second coil L2 (insulating base material 10).

  13A is a plan view of another antenna device 304B according to the fourth embodiment, and FIG. 13B is a positional relationship between the antenna device 304B and the communication partner antenna 500 shown in FIG. FIG. The antenna device 304B includes the coil antenna 101 and the conductor plate 2. The antenna device 304B includes a configuration other than the coil antenna 101 and the conductor plate 2, but is not shown in FIGS. 13A and 13B.

  In the antenna device 304B, the position of the conductor plate 2 is different from the antenna device 304A described above. Hereinafter, parts different from the antenna device 304A will be described.

  As shown in FIG. 13A, the conductor plate 2 of the antenna device 304B is located in the + Z direction with respect to the first coil L1 and the second coil L2 (insulating base material 10). In other words, the conductor plate 2 is disposed between the first coil L1 and the second coil L2 and the communication partner antenna in the Z-axis direction.

  14A is a plan view of another antenna device 304C according to the fourth embodiment, and FIG. 14B is a positional relationship between the antenna device 304C and the communication partner antenna 500 shown in FIG. FIG. The antenna device 304 </ b> C includes the coil antenna 101 and the conductor plate 2. The antenna device 304B includes a configuration other than the coil antenna 101 and the conductor plate 2, but is not illustrated in FIGS. 14A and 14B.

  In the antenna device 304C, the position of the conductor plate 2 is different from the antenna devices 304A and 304B described above. Hereinafter, parts different from the antenna devices 304A and 304B will be described.

  As shown in FIG. 14A, the conductor plate 2 of the antenna device 304C does not overlap the first coil L1 and the second coil L2 (insulating base material 10) when viewed from the Z-axis direction. The conductor plate 2 is disposed in the vicinity of the first coil L1 and the second coil L2.

  According to the present embodiment, the conductor plate 2 is coupled to the first coil L1 and the second coil L2, and the conductor plate 2 functions as a booster antenna for the first coil L1 and the second coil L2. Rise.

  Next, the influence of the conductor plate on the coupling coefficient with the communication partner antenna will be described. FIG. 15A is a perspective view showing the positional relationship between the coil antenna 100 and the measurement coil 600, and FIG. 15B is a front view showing the positional relationship between the coil antenna 100 and the measurement coil 600. FIG. 16 is a plan view of the coil antenna 100.

  The coil antenna 100 includes a first coil L1, a second coil L2, and an insulating substrate 10A. The first coil L1 and the second coil L2 are formed on the first main surface VS1 of the insulating base 10A. The insulating base 10A is a rectangular flat plate whose longitudinal direction matches the Y-axis direction. The conductor plate 2 is provided on the first main surface VS1 side of the insulating base 10A. As shown in FIG. 16, the outer edges of the first coil L1 and the second coil L2 coincide with a part of the outer edge of the insulating base 10A.

  In FIG. 15 (B) and FIG. 16, the dimension of each part is as follows.

X1 (length in the X-axis direction of the first coil L1 and the second coil L2): 45 mm
X2 (the length of the conductor plate 2 in the X-axis direction): 70 mm
Y1 (the length of the conductor plate 2 in the Y-axis direction): 130 mm
Y2 (distance in the Y-axis direction from the outer edge of the insulating base 10A to the outer edge of the conductor plate 2): 15 mm
D1 (diameter of measuring coil 600): φ70 mm
D2 (the length of the first coil L1 and the second coil L2 in the Y-axis direction): 9 to 30 mm
H1 (distance between the first coil L1 and the second coil L2 and the measuring coil 600): 25 mm
FIG. 17 is a diagram illustrating a coupling coefficient k ₁₃ ^EQ between the coil antenna 100 and the measurement coil. FIG. 17 shows the relationship between the coil antenna 100 and the measurement coil when D2 (the length of the first coil L1 and the second coil L2 in the Y-axis direction) is changed from 9 mm to 30 mm (see the arrow in FIG. 16). The coupling coefficient is shown. In FIG. 17, for comparison, the coupling coefficient between the coil antenna that does not include the conductor plate 2 and the measurement coil is also illustrated.

As shown in FIG. 17, the coil antenna 100 including the conductor plate 2 generally has a higher coupling coefficient k ₁₃ ^EQ with the measurement coil (600) than the coil antenna not including the conductor plate 2. . From this, it can be seen that the presence of the conductor plate 2 adjacent to the coil antenna contributes to the improvement of the coupling coefficient k ₁₃ ^EQ .

Since Y2 = 15 mm, when D2 exceeds 15 mm, the first coil L1 and the second coil L2 overlap the conductor plate 2. Even when D exceeds 15 mm, the coupling coefficient k ₁₃ ^EQ between the coil antenna 100 and the measurement coil (600) is improved. From this, the direction in which the first coil L1 and the second coil L2 partially overlap the conductor plate 2 is compared with the case where the first coil L1 and the second coil L2 do not overlap the conductor plate 2. It can be seen that the coupling coefficient k ₁₃ ^EQ with the measuring coil (600) is high.

  Therefore, as in the coil antennas 104A and 104B according to the present embodiment, the conductor plate 2 overlaps the first coil L1 and the second coil L2 as viewed from the Z-axis direction, and the first coil L1 and the second coil L2. And a portion that does not overlap the coil L2.

  In addition, the conductor plate 2 of the present embodiment is not formed with slits or openings, but the conductor plate 2 may be formed with slits or openings. Thereby, the function as a booster antenna of the conductor board 2 can be improved more.

<< Fifth Embodiment >>
In the fifth embodiment, an example of an electronic apparatus including the antenna device of the present invention is shown.

  FIG. 18A is a plan view showing the structure inside the housing of the electronic device 405 according to the fifth embodiment, and FIG. 18B is a cross-sectional view taken along line BB in FIG.

  The electronic device 405 includes a housing 50, an antenna device (coil antenna 101), a circuit board 60, a device 61, a battery pack 62, a display 63, a power feeding circuit (not shown), and the like. Although the antenna device includes a configuration other than the coil antenna 101, it is not shown in FIGS. 18A and 18B.

  The coil antenna 101, the circuit board 60, the device 61, the battery pack 62, the display 63 and the like are housed in the housing 50. The coil antenna 101 is attached to the inner surface of the housing 50 and connected to a power feeding circuit (not shown). A device 61 or the like is mounted on the circuit board 60. The device 61 is a device such as a camera module, a flash, a speaker, an earphone jack, a card slot, a terminal such as a USB, a button, or a sensor.

  Although not shown, the battery pack 62 includes a conductor portion (for example, a metal portion such as an exterior). As shown in FIG. 18A, the first coil L1 and the second coil L2 include a portion overlapping the battery pack 62 as viewed from the Z-axis direction (the direction of the winding axis AX1 of the first coil L1), and the battery pack. And a portion that does not overlap with 62.

  In the present embodiment, the conductor portion (metal portion) included in the battery pack 62 corresponds to the “conductor plate” in the present invention.

  Thus, as the “conductor plate” in the present invention, a conductor portion of a component provided in an electronic device may be used. According to this configuration, it is not necessary to separately provide a conductor plate, so that the antenna device can be easily manufactured and the cost can be reduced.

  In the present embodiment, the conductor portion of the battery pack 62 is used as the “conductor plate”, but the present invention is not limited to this. For example, a conductor provided on the back surface of the display may be used as the “conductor plate”. Further, for example, a conductor pattern formed on a circuit board may be used as a “conductor plate”.

<< Sixth Embodiment >>
In the sixth embodiment, an example of an electronic device using a part of a housing as a conductor plate is shown.

  FIG. 19 is a cross-sectional view illustrating the structure inside the housing of the electronic device 406 according to the sixth embodiment.

  The electronic device 406 is different from the electronic device 405 according to the fifth embodiment in that the electronic device 406 includes a housing 50A. Other configurations of the electronic device 406 are the same as those of the electronic device 405. Hereinafter, parts different from the electronic device 405 will be described.

  The casing 50 </ b> A includes a resin casing 51 and a conductor plate 52. As shown in FIG. 19, the conductor plate 52 includes a portion that overlaps the first coil L1 and the second coil L2 and the first coil L1 when viewed from the Z-axis direction (the direction of the winding axis AX1 of the first coil L1). And a portion that does not overlap the second coil L2.

  Even with such a configuration, the same operational effects as those of the electronic apparatus 405 according to the fifth embodiment can be obtained.

<< Other Embodiments >>
In each embodiment shown above, it is not limited to this structure which showed the example whose insulating base material is a rectangular flat plate. The shape of the insulating substrate can be changed as appropriate within the scope of the effects and effects of the present invention. For example, the planar shape may be polygonal, circular, elliptical, L-shaped, crank-shaped, T-shaped, Y-shaped, or the like. The insulating substrate is not limited to a flat plate, and may be a rectangular parallelepiped, a cube, a polygonal column, a cylinder, an elliptical column, or the like. Furthermore, the insulating base material may be a laminated body formed by laminating a plurality of insulating layers. A protective film such as a solder resist film or a coverlay film may be formed on the surface of the insulating substrate.

  In each of the embodiments described above, an example in which the insulating base material is a thermoplastic resin sheet has been described. However, the present invention is not limited to this configuration. The insulating substrate may be a sheet of a thermosetting resin such as an epoxy resin. Further, the insulating base material may be a dielectric ceramic of, for example, a low temperature co-fired ceramic (LTCC).

  In addition, the shape and the number of turns of the first coil L1 and the second coil L2 in the present invention are not limited to the configurations of the embodiments described above, and are appropriately changed within the scope of the operation and effect of the present invention. Is possible. The shape of the first coil L1 and the second coil L2 is not limited to a rectangular spiral shape, and may be, for example, a circular spiral shape or an elliptical spiral shape. Further, the number of turns of the first coil L1 and the second coil L2 may be more than two turns. In each of the embodiments described above, the example in which the number of turns of the first coil L1 and the number of turns of the second coil L2 are substantially the same is shown, but the present invention is not limited to this configuration. The number of turns of the first coil L1 and the second coil L2 may be different. However, in order to increase the coupling coefficient between the first coil L1 and the second coil L2, the difference between the number of turns (n) of the first coil L1 and the number of turns (m) of the second coil L2 must be within ± 1. Is preferable (n-1 ≦ m ≦ n + 1).

  In each embodiment shown above, although the example in which the 1st coil L1 and the 2nd coil L2 were formed in the 1st main surface VS1 of the insulating base material 10 was shown, it is not limited to this structure. That is, the first coil L1 and the second coil L2 are not limited to those formed in the same plane. For example, the first coil L1 is formed on the first main surface VS1 of the insulating base 10, and the second The coil L2 may be formed on the second main surface VS2.

  Finally, the description of the above embodiment is illustrative in all respects and not restrictive. Modifications and changes can be made as appropriate by those skilled in the art. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention includes modifications from the embodiments within the scope equivalent to the claims.

AX1 ... winding axis AX2 of first coil ... winding axis C10, C10a, C10b, C11, C11a, C11b, C12, C12a, C12b ... first capacitor C20 ... second capacitor E11 ... first coil of the second coil the second end E21 ... first end E22 ... second end _{f 1} ... the first frequency _{f 2} ... second frequency f ... third frequency _{f R} of the second coil of the second coil of the first end E12 ... first coil ... Resonant frequency (either the first frequency or the second frequency)
k ₁₂ , k ₁₃ , k ₂₃ ... coupling coefficient
k ₁₃ ^EQ ... coupling coefficients L1, L1a, L1b ... first coils L2, L2b ... second coils L10, L10a, L10b ... first inductor L3 ... inductor MC ... matching circuit RC1 ... first resonance circuit RC2 ... second resonance circuit VS1 ... first main surface VS2 of insulating base material ... second main surface Z1 of insulating base material ... first impedance Z2 ... second impedance 2 ... conductor plate 5 ... magnetic material 8 ... IC
9 ... RFIC
DESCRIPTION OF SYMBOLS 10, 10A ... Insulation base material 50, 50A ... Case 51 ... Resin case 52 ... Conductor board 60 ... Circuit board 61 ... Device 62 ... Battery pack 63 ... Display 100, 100A, 100B, 101, 103, 104A, 104B ... Coil antennas 301, 302A, 302B, 304A, 304B, 304C ... Antenna devices 401, 402A, 402B, 402C, 405, 406 ... Electronic equipment 500 ... Communication partner antenna 600 ... Measurement coil

Claims (10)

An insulating substrate;
A first coil connected to the power supply circuit, constituting a part of the first resonance circuit, formed on the insulating substrate, and wound in a plurality
A second coil that forms part of the second resonant circuit, is formed on the insulating substrate, and is wound a plurality of times;
With
The winding axis of the first coil and the winding axis of the second coil are parallel,
At least a part of the first coil and the second coil are parallel to each other when viewed from the winding axis direction of the first coil, and the first coil is the second coil in the radial direction of the first coil. And the second coils are alternately arranged so as to sandwich the first coil,
In the first coil and the second coil, the circulation directions of the currents flowing in the first coil and the second coil are the same direction, and are electromagnetically coupled to each other.
An antenna device characterized by the above.   The antenna device according to claim 1, further comprising a first capacitor connected to the first coil and constituting a part of the first resonance circuit.   The antenna device according to claim 1, further comprising a second capacitor connected to the second coil and constituting a part of the second resonance circuit.   The antenna device according to claim 1, further comprising a magnetic body. The resonance frequency of the first resonance circuit is a first frequency, the impedance of the first resonance circuit at the first frequency is a first impedance,
The resonance frequency of the second resonance circuit is the second frequency, the impedance of the second resonance circuit at the second frequency is the second impedance,
When the carrier frequency to be used is the third frequency,
The first frequency and the second frequency are not less than 0.5 times and not more than twice the third frequency,
5. The antenna device according to claim 1, wherein the second impedance is not less than 0.5 times and not more than twice the first impedance. 6. A conductor plate;
The conductor plate includes a portion that overlaps the first coil and the second coil and a portion that does not overlap the first coil and the second coil when viewed from the winding axis direction of the first coil. The antenna device according to claim 1, comprising: A housing, an antenna device, and a feeding circuit;
The antenna device is
An insulating substrate;
Constituting a part of the first resonance circuit, formed on the insulating base material, and a first coil that is wound a plurality of times;
A second coil that forms part of the second resonant circuit, is formed on the insulating substrate, and is wound a plurality of times;
Have
The winding axis of the first coil and the winding axis of the second coil are parallel,
At least a part of the first coil and the second coil are parallel to each other when viewed from the winding axis direction of the first coil, and the first coil is the second coil in the radial direction of the first coil. And the second coils are alternately arranged so as to sandwich the first coil,
In the first coil and the second coil, the circulation directions of the currents flowing in the first coil and the second coil are the same direction, and are electromagnetically coupled to each other.
The first coil is connected to the power feeding circuit.
An electronic device characterized by that. A conductor plate;
The conductor plate includes a portion that overlaps the first coil and the second coil and a portion that does not overlap the first coil and the second coil when viewed from the winding axis direction of the first coil. The electronic device according to claim 7.   The electronic device according to claim 8, wherein the conductor plate is a part of the housing.   The electronic device according to claim 8, wherein the conductor plate is a metal portion of a battery pack housed in the electronic device.

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