JP2012019302A - Antenna module and non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna module and non-contact power transmission which allow the same antenna to be used for electric power transmission and communication even if magnetic field resonance is used.SOLUTION: An antenna 10 comprises a first coil 11 and a second coil 12 which is placed outside the first coil 11 and adjusted to any resonance frequency by LC resonance. The first coil 11 is connected to a reception power circuit 14 and the second coil 12 is connected with a communication circuit 15. The antenna module switches between electric power transmission and communication by controlling the impedance of the communication circuit 15.

Description

  The present invention relates to an antenna module and a non-contact power transmission device, and more particularly to an antenna module and a non-contact power transmission device suitable for portable devices such as a mobile phone, a headset, a digital camera, and a digital video.

  In non-contact power transmission using electromagnetic induction, non-contact power transmission is possible by combining a simple planar coil as an antenna, and non-contact power charging devices, non-contact IC cards, reader / writers, etc. are practical. It has become.

  However, when electromagnetic induction is used, the power transmission efficiency changes greatly depending on the positional relationship between the power transmission side antenna and the power reception side antenna. Therefore, in order to maintain high efficiency power transmission, It is necessary to provide a mechanism that makes the positional relationship of the power receiving antenna always constant. For such a problem, for example, means using magnetic field resonance as disclosed in Patent Document 1 is disclosed.

  FIG. 4 is a diagram illustrating an example of a conventional antenna module. As shown in FIG. 4, the conventional antenna 50 includes two coils, and has a resonance at a specific frequency connected to a first coil 51 including a loop coil connected to the power receiving circuit 54 and a capacitor 53. The second coil 52 is configured. When the electric power having a specific frequency is input to the first coil 51, the second coil 52 is excited and can transmit electric power from the second coil 52. According to the method using magnetic resonance, even when the positional relationship between the power transmission side antenna and the power reception side antenna is more deviated than when electromagnetic induction is used, power can be transmitted with high efficiency. It is not necessary to provide a mechanism that always keeps the positional relationship between the antenna and the power receiving antenna constant.

  In addition, in order to transmit power safely, it is necessary to perform communication such as authentication of a portable device to be charged. However, if the charging antenna and the communication antenna are separated, the mounting space increases or the antenna It is desirable that power transmission and communication can be performed with a single antenna.

Special table 2009-501510

  However, in the prior art described in Patent Document 1, when trying to perform power transmission and communication using the same frequency band, an antenna for performing power transmission using magnetic resonance does not perform power transmission with high efficiency. Although possible, communication such as RF-ID communication cannot be performed. This is because the magnetic resonance antenna requires a high Q value, whereas a low Q value is required when used as a communication antenna for RF-ID communication or the like. The satisfactory Q value required for the above cannot be obtained.

  Therefore, even in non-contact power transmission using magnetic field resonance, it is desirable that power transmission and communication can be performed using the same antenna.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an antenna module capable of performing power transmission and communication with the same antenna even when magnetic resonance is used, and contactless power transmission Is to provide.

  According to the present invention, the antenna includes a first coil and a second coil disposed outside or inside the first coil and adjusted to an arbitrary resonance frequency by LC resonance. Is connected to the power receiving circuit, the second coil is connected to the communication circuit, and the impedance at both ends of the second coil is controlled in the communication circuit or between the communication circuit and the second coil. It is possible to obtain an antenna characterized by including a control circuit capable of changing the frequency.

  That is, according to the present invention, the antenna includes a loop-shaped first coil and a loop-shaped second coil arranged inside or outside the first coil, and the first coil receives power. An antenna module connected to a circuit, wherein the second coil is adjusted to an arbitrary resonance frequency, and is connected to a communication circuit, and the impedance of the communication circuit is controlled to switch between power transmission and communication. Is obtained.

  In addition, according to the present invention, the antenna module described above is characterized in that the communication circuit has a reactance component and the frequency is different between power transmission and communication.

  According to the present invention, the antenna module described above is characterized in that a magnetic material is disposed on the antenna.

  According to the present invention, there is obtained the antenna module as described above, wherein a shield plate is disposed on the antenna.

  Further, according to the present invention, there is obtained the above antenna module characterized in that the power receiving circuit is replaced with a power transmission circuit to be a power transmission device.

  In addition, according to the present invention, the antenna module described above, wherein a plurality of the antennas are arranged, is obtained.

  In addition, according to the present invention, a non-contact power transmission device using the above antenna module can be obtained.

  As described above, according to the present invention, it is possible to provide an antenna module and non-contact power transmission that can perform power transmission and communication with the same antenna even when using magnetic field resonance.

  According to the present invention, at the time of power transmission, the impedance of the communication circuit viewed from the second coil is sufficiently increased so that current does not flow from the second coil to the communication circuit as much as possible. The impedance of the antenna takes a minimum value at the resonance point of the antenna, has a high Q value, and can be driven as a magnetic resonance antenna for power transmission with high efficiency. Further, at the time of communication, the Q characteristic required as a communication antenna is reduced by reducing the Q value by the amount that the communication circuit is loaded on the second coil by sufficiently reducing the impedance of the communication circuit viewed from the second coil. Therefore, the antenna can be driven as a communication antenna.

It is a figure explaining an example of the antenna module by this invention. It is a figure explaining the antenna module in Example 1 of this invention. FIG. 2A shows a plan view. FIG. 2B is a diagram showing a bottom surface. It is a figure explaining the antenna module in Example 2 of this invention. It is a figure explaining an example of the antenna module by a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of the configuration of an antenna module according to the present invention. As shown in FIG. 1, the antenna module of the present invention includes an antenna 10, a power receiving circuit 14, and a communication circuit 15. The antenna 10 includes a first coil 11 and a second coil 12 disposed outside the first coil 11. The resonance frequency of the second coil 12 is adjusted to an arbitrary frequency, and the first coil 11 is connected to the power receiving circuit 14. The second coil 12 is connected to the communication circuit 15 and further controls the impedance of both ends of the second coil 12 by a control circuit installed in the communication circuit 15 or between the communication circuit and the second coil. It is configured to switch between power transmission and communication by controlling the impedance to the communication circuit 15. Switching between power transmission and communication is performed by disconnecting the communication circuit 15 and the second coil 12 in an equivalent circuit during power transmission and connecting the communication circuit 15 and the second coil 12 during communication. Note that the second coil 12 may be disposed inside the first coil 11.

  Similarly to the communication circuit 15, the power reception circuit 14 has a function of controlling the impedance at both ends of the first coil 11, and the impedance of the power reception circuit 14 viewed from the first coil 11 is sufficiently large during communication. By doing so, interference from the first coil 11 to the second coil 12 can be suppressed, and communication characteristics can be improved.

  The antenna 10 is manufactured on a flat substrate such as an FPC or FR-4 substrate. Or it can also produce only with a winding.

  The LC resonance of the second coil 12 is adjusted by connecting the second coil 12 and the capacitor 13 in parallel, and is caused by the self-resonance of the second coil 12 and the overlap of the copper foil pattern on the substrate. Other capacitive components can also be used.

  By providing the power receiving circuit or the communication circuit with a reactance component and changing the resonance frequency of the antenna, different frequencies can be used for power transmission and communication.

  The power receiving circuit can be replaced with a power transmission circuit and used as a power transmission device.

  You may arrange | position a magnetic body on the back surface of an antenna. The magnetic material is preferably made of a material having a low loss even at a high frequency such as NiZn ferrite. Moreover, the composite material which combined the magnetic material with a several different magnetic permeability may be sufficient.

  A shield material may be disposed on the back surface of the magnetic body.

  A plurality of antennas may be used in combination.

  Hereinafter, an example of the configuration of the module in the embodiment of the present invention will be described.

  2A and 2B are diagrams illustrating the antenna module according to the first embodiment of the present invention. FIG. 2A is a diagram illustrating a plan view, and FIG. 2B is a diagram illustrating a bottom surface. In FIG. 2A, the receiving circuit and the communication circuit are omitted. As shown in FIG. 2, the antenna 30 includes a loop-shaped first coil 31 and a loop-shaped second coil 32. The size of the antenna 30 was 40 mm × 20 mm, and was produced on an FR-4 substrate. The second coil 32 is arranged from the outside of the antenna 30, and the first coil 31 is arranged inside the second coil 32. The first coil 31 was formed of a one-turn planar coil, and was produced inside the second coil 32 with a coil pattern width of 0.5 mm. The second coil 32 was composed of a 4-turn coil, and was produced with a coil pattern width of 0.5 mm and a coil pattern gap of 0.3 mm. The second coil 32 was connected to the capacitor 33, had LC resonance, and the resonance frequency was adjusted to 13.56 MHz. The end portions 31a and 31b of the first coil 31 on the plane (front surface) and the end portions 32a and 32b of the second coil 32 are respectively connected to the end portions 31c and 31d and the end portions 32c and 32d on the bottom surface (back surface). It is connected through a through hole in the substrate. As long as the resonance frequency is adjusted, a plurality of capacitors 33 may be provided as necessary.

  In the antenna 30, the first coil 31 is connected to the power receiving circuit 34 via the terminal 38 in FIG. 2B. The power receiving circuit 34 includes a first semiconductor switch, and the first semiconductor switch is controlled by IC control. The open and short of the terminal of the first coil 31 can be switched. The second coil 32 is connected to a communication circuit 35 via a terminal 39, and the communication circuit 35 includes a second semiconductor switch. The second semiconductor switch is controlled by IC control to open the second coil 32 terminal. The short can be switched. Thus, each impedance control circuit is composed of an IC and a semiconductor switch.

  The operation of the antenna module of the present invention having the antenna 30 configured as described above will be described.

  When power transmission is performed, the first semiconductor switch is short-circuited and the second semiconductor switch is opened by IC control. At this time, the first coil 31 and the second coil 32 are coupled by magnetic field coupling. When the antenna 30 is placed in a 13.56 MHz magnetic field, the second coil 32 is excited by the magnetic field and can receive power with high efficiency due to LC resonance. This electric power is taken out by the first coil 31 and transmitted to the power receiving circuit, whereby electric power transmission becomes possible. As described above, the reason for opening the second semiconductor switch is that when both the first semiconductor switch and the second semiconductor switch are short-circuited, a part of the power received by the second coil 32 is obtained. Since it flows to the communication circuit, the power transmission efficiency is reduced, and the voltage generated at both ends of the second coil 32 is applied to the communication circuit. This is because there is a possibility of destruction.

  When communication is performed, control is performed by IC control so that the first semiconductor switch is open and the second semiconductor switch is short-circuited. At this time, the first coil 31 does not function as a coil, and magnetic field coupling does not occur between the first coil 31 and the second coil 32. When the antenna 30 is placed in a 13.56 MHz magnetic field, the second coil 32 is excited by the magnetic field, and the voltage generated at both ends of the second coil 32 is applied to the communication circuit to enable communication. As described above, the reason for opening the first semiconductor switch is that when both the first semiconductor switch and the second semiconductor switch are short-circuited, the second coil 32 is inhibited from being excited. Since one coil 31 is excited, the communication characteristics deteriorate. However, the first semiconductor switch is not necessarily required when the deterioration of the communication characteristics is slight.

  By using the antenna described in Embodiment 1 as one unit and arranging a plurality of units of antennas as shown in FIG. 3, a power transmission device or a power reception device can be configured. FIG. 3 is a diagram illustrating an antenna module according to the second embodiment of the present invention. As illustrated in FIG. 3, the antenna module according to the second embodiment includes an antenna 40 including three antenna units each including a first coil 41 and a second coil 42.

  In the case where a plurality of antennas are arranged, the arrangement is not limited to the arrangement in which the antennas are adjacent to each other.

  The antenna module for power transmission can be arbitrarily changed in units of one antenna, and may have a structure that can be detached for each unit of antenna.

  The maximum transmitted power that can be transmitted from the antenna module for power transmission can be adjusted by the number of antennas constituting the antenna module for power transmission. For example, assuming that 1 W of power can be transmitted per unit of antenna, a power transmitting antenna device configured of four antenna units can transmit power up to a maximum of 4 W.

  Further, by adding a control system that can select an antenna to be excited among the antennas of the antenna module for power transmission, it is possible to perform power transmission using a part of the antenna of the power transmission device.

  Further, the power transmission antenna module can transmit power to a plurality of power receiving antenna modules as long as the total transmitted power is equal to or less than the maximum transmitted power.

  The maximum received power of the power receiving antenna module can be adjusted by the number of antennas constituting the antenna module. For example, if it is possible to receive 1 W of power per unit of antenna, a power receiving antenna module composed of 4 units of antennas can receive power up to 4 W.

  As mentioned above, although embodiment and Example of this invention were described using drawing, this invention is not limited to these examples, In the range which does not deviate from the summary of this invention, a member and a structure change are possible. Even if it exists, it is included in this invention. For example, the configuration of the antenna is not limited to that shown in FIG. 1, and various modifications such as omitting some of the components, adding other components, and changing the connection relationship are possible. It is. In addition, a mechanical switch can be used instead of the semiconductor switch. The resonance frequency of the coil can be set to an arbitrary frequency. That is, various modifications and corrections that can naturally be made by those skilled in the art are also included in the present invention.

10, 30, 40 Antenna 11, 31, 41, 51 First coil 12, 32, 42, 52 Second coil 13, 33, 53 Capacitor 14, 34, 54 Power receiving circuit 15, 35 Communication circuit 31a, 31b, 31c, 31d, 32a, 32b, 32c, 32d End 38, 39 Terminal 50 Conventional antenna

Claims (7)

  A loop-shaped first coil; and an antenna composed of a loop-shaped second coil disposed inside or outside the first coil, wherein the first coil is connected to a power receiving circuit, and the second coil The antenna module is adjusted to an arbitrary resonance frequency, connected to a communication circuit, and switches between power transmission and communication by controlling impedance of the communication circuit.   The antenna module according to claim 1, wherein a reactance component is provided in the communication circuit, and the frequency is different between power transmission and communication.   The antenna module according to claim 1, wherein a magnetic material is disposed on the antenna.   The antenna module according to claim 1, wherein a shield plate is disposed on the antenna.   The antenna module according to any one of claims 1 to 4, wherein the power reception circuit is replaced with a power transmission circuit to be a power transmission device.   The antenna module according to claim 1, wherein a plurality of the antennas are arranged.   A non-contact power transmission apparatus using the antenna module according to claim 1.

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