JP2010161618A - Antenna structure, communications apparatus, and method of manufacturing the antenna structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna structure incorporated by efficiently using the space of an apparatus for communication and excelling in characteristics while restraining cost. <P>SOLUTION: An antenna coil 11 incorporated in a cellular phone 200 and becoming communicatable, by being inductively-coupled to a reader/writer 2 emitting a magnetic field, is formed by winding a flat cable 111 with one rectangular wire 301 covered with an insulator 302, around the side faces 202a of a secondary battery putting-in part 202 of a secondary battery incorporated in the cellular phone 200, while being stuck by an insulating adhesive 112. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antenna structure, a communication device, and a method for manufacturing the antenna structure that are communicable by electromagnetic induction generated with a transmitter that transmits a magnetic field.

  The following several types of antenna modules for RFID (Radio Frequency Identification) have been conventionally used. First, there is an antenna module in which a coil pattern is created on a plane using an FPC (Flexible Printed Circuit) or a rigid substrate. Secondly, there is an antenna module in which a coil is formed by winding a round wire. Third, there is an antenna module in which an FPC, FFC (Flexible Flat Cable) or the like is used as a harness, and the harness is formed in a ring shape to form a coil.

  The above-described antenna module is appropriately selected by a design that takes into account the arrangement and shape of components, and is used by being incorporated in an electronic device.

  Moreover, as a function requested | required of the antenna module integrated in the IC card using RFID, it is preferable that it can be used on both surfaces of the card. Further, in a form incorporated in an electronic device such as a mobile phone, in consideration of the arrangement of other components, it may be arranged as a ribbon-like antenna coil on the side surface of the device. (For example, see Patent Document 1).

  When placing an antenna coil in an electronic device, a magnetic sheet having a relatively high magnetic permeability is used for the antenna coil or its coil so as not to be affected by the metal used in the metal casing or internal parts of the electronic device. It is attached around. More specifically, by attaching a magnetic sheet having a magnetic frequency of about 30 to 80 at a typical frequency of 13.56 MHz and used for RFID to the antenna coil or its periphery, the antenna coil In order to prevent the generation of eddy currents in the metal disposed around the magnetic field generated from the magnetic field and to obtain good communication performance, the shape, combination, etc. are optimized.

JP 2004-364199 A

  As described above, the antenna module has been conventionally designed in consideration of the shape of the electronic device and the influence of parts such as metal, but the size of the antenna module has been increased due to the complexity and miniaturization of the device shape. May not be sufficient. As a result, since the communication performance does not satisfy the requirements, an antenna module with better communication characteristics is demanded.

  More specifically, a change in electrical characteristics such as the inductance of the antenna coil causes a shift in communication frequency in a parallel resonant circuit composed of the antenna coil and the IC circuit, resulting in a deterioration in communication performance. Therefore, from such a viewpoint, a design that enhances reliability performance is required in the sense that there is little change in electrical characteristics.

  In addition, the price of the antenna module is required to be reduced, and it is required to develop a high-performance antenna module from a more general-purpose material.

  The present invention has been proposed in view of such a situation, and can be built by efficiently using the space of a communication device in which various members are integrated, and has good characteristics while suppressing costs. An object of the present invention is to provide an antenna structure, a communication device in which the antenna structure is built, and a method for manufacturing the antenna structure.

  As means for solving the above-described problems, the present invention provides a metal incorporated in a communication device in an antenna structure incorporated in a communication device and capable of communicating by being inductively coupled to a transmitter that transmits a magnetic field. It is formed by winding a flat cable in which a single flat wire is covered with an insulator on the side surface of the member while being bonded with an insulating adhesive.

  Further, the present invention provides a method for manufacturing an antenna structure that is built in a communication device and is inductively coupled to a transmitter that transmits a magnetic field to enable communication. An antenna structure is formed by winding a flat cable in which a flat wire is covered with an insulator while being bonded with an insulating adhesive.

  Further, the present invention provides a communication device including an antenna structure that is inductively coupled to a transmitter that transmits a magnetic field to enable communication. The communication device includes a metal member built in the device, and the antenna structure includes a metal member. It is formed by winding a flat cable in which a single flat wire is covered with an insulator on the side surface thereof while being bonded with an insulating adhesive.

  The present invention stabilizes the shape by winding a flat cable in which a single flat wire is covered with an insulator on the side surface of a metal member incorporated in a communication device while being bonded with an insulating adhesive. Can be formed. Therefore, the present invention can suppress a change in the electrical characteristics of the antenna coil due to, for example, deformation using a general-purpose material, and as a result, an antenna structure having good characteristics while suppressing costs. It is possible to incorporate the communication device in which various members are integrated by efficiently using the space.

It is a figure which shows the whole structure of a radio | wireless communications system. It is a perspective view which shows the shape of the mobile telephone in which an antenna module is integrated. It is a figure for demonstrating the shape of a flexible flat cable. It is a figure for demonstrating the shape of an antenna coil. It is a figure which shows the change of the communication characteristic according to the film thickness of an insulating adhesive agent. It is a perspective view which shows the shape of the mobile telephone in which the antenna module which concerns on a 1st comparative example is integrated. It is a figure for demonstrating the communication characteristic which concerns on an antenna coil when carrying out inductive coupling between reader-writers.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention.

<Wireless communication system>
An antenna module to which the present invention is applied is a device that is in a communicable state by electromagnetic induction generated with a transmitter that transmits electromagnetic waves. For example, the antenna module for RFID (Radio Frequency Identification) as shown in FIG. It is incorporated into the wireless communication system 100 and used.

  The wireless communication system 100 includes an antenna module 1 to which the present invention is applied, and a reader / writer 2 that accesses the antenna module 1.

  The reader / writer 2 functions as a transmitter that transmits a magnetic field to the antenna module 1, and specifically, an antenna 2a that transmits a magnetic field toward the antenna module 1, and an antenna module 1 that is inductively coupled via the antenna 2a. And a control board 2b for performing communication.

  That is, the reader / writer 2 is provided with a control board 2b that is electrically connected to the antenna 2a. A control circuit composed of electronic components such as one or a plurality of integrated circuit chips is mounted on the control board 2b. The control circuit executes various processes based on the data received from the antenna module 1. For example, when writing data to the antenna module 1, the control circuit encodes the data, modulates a carrier wave of a predetermined frequency (for example, 13.56 MHz) based on the encoded data, and amplifies the modulated modulation signal Then, the antenna 2a is driven by the amplified modulation signal. Further, when reading data from the antenna module 1, the control circuit amplifies the modulation signal of the data received by the antenna 2a, demodulates the modulation signal of the amplified data, and decodes the demodulated data. In the control circuit, an encoding method and a modulation method used in a general reader / writer are used. For example, a Manchester encoding method or an ASK (Amplitude Shift Keying) modulation method is used.

  The antenna module 1 incorporated in the electronic device in this manner is connected between the reader / writer 2 that is driven by the current flowing through the antenna coil 11 and the antenna coil 11 that can communicate with the reader / writer 2 that is inductively coupled. And a communication processing unit 12 for performing communication.

  When the antenna coil 11 is held by a user or the like so as to receive a magnetic field transmitted from the reader / writer 2, the antenna coil 11 is magnetically coupled to the reader / writer 2 by inductive coupling, and receives a modulated electromagnetic wave. A received signal is supplied to the communication processing unit 12 via the connection terminal 11a.

  The communication processing unit 12 is driven by a current flowing through the antenna coil 11 and communicates with the reader / writer 2. Specifically, the communication processing unit 12 demodulates the received modulation signal, decodes the demodulated data, and writes the decoded data in the internal memory of the communication processing unit 12. The communication processing unit 12 reads data to be transmitted to the reader / writer 2 from the internal memory, encodes the read data, modulates a carrier wave based on the encoded data, and is magnetically coupled by inductive coupling. The modulated radio wave is transmitted to the reader / writer 2 via the coil 11.

  In the wireless communication system 100 configured as described above, the antenna module 1 according to the present embodiment can be incorporated by efficiently using the space of a portable communication device in which various members are integrated, In order to ensure good communication characteristics while suppressing costs, the configuration shown in FIG. 2 is provided. Below, it demonstrates paying attention to the composition concerning antenna module 1.

<Configuration of antenna module>
As for the antenna coil 11 of the antenna module 1 according to the present embodiment, in a mobile phone 200 as shown in FIG. 2, a battery pack 204 provided in the vicinity of a control board 201 that controls the operation of the mobile phone 200 is inserted. It is incorporated between the side surface 202 a of the secondary battery charging unit 202 and the wall surface 203 of the casing of the mobile phone 200. The connection terminal 11 a of the antenna coil 11 is incorporated in the control board 201. The antenna module 1 according to this embodiment is incorporated in a space provided between the secondary battery insertion unit 202 and the wall surface 203, but is a metal incorporated in a portable communication device such as the cellular phone 200. If there is a space that can be secured on the side surface of the member, such a space may be incorporated.

  As described above, the antenna module 1 according to the present embodiment forms the antenna coil 11 on the side surface of the metal member such as the secondary battery insertion unit 202, so that the mobile phone 200 such as the mobile phone 200 in which various members are integrated. Can be built in efficiently using the space of the type of communication equipment.

  In the present embodiment, as a specific shape of the mobile phone 200, the outer shape of the secondary battery insertion unit 202 is a substantially rectangular shape of 40 [mm] × 35 [mm], and the side surface and the housing of the secondary battery insertion unit 202 are arranged. There is a space having a width of about 1 [mm] between the body wall surface 203 and the antenna coil 11 is incorporated in the space restricted in shape.

  Further, the antenna coil 11 is made of a general-purpose material, and, for example, a flat cable 111 is attached to the side surface 202a of the secondary battery insertion unit 202 in order to suppress changes in the electrical characteristics of the antenna coil 11 due to deformation or the like. It is formed by winding while being bonded with an insulating adhesive.

  Here, as shown in FIG. 3A, the single flat cable 111 includes a plurality of signal lines in which a single flat wire 301 is covered with an insulator 302 as a general-purpose material. It is obtained by processing the flexible flat cable 300 into a single wire.

  In this embodiment, from the viewpoint of ensuring good communication characteristics, considering that the cross-sectional shape of the rectangular wire 301 is preferably 0.3 × 0.1 [mm], FIG. A flexible flat cable 300 having a cross-sectional shape as shown is used.

  That is, in the flexible flat cable 300, as shown in FIG. 3B, the long side of the flat wire 301 is 0.3 [mm], and the line interval between the flat wires 301 and 301 adjacent to each other through the insulator 302 is set. Is 0.35 [mm].

  Further, the flexible flat cable 300 has a short side of the flat wire 301 of 0.1 [mm], and an insulator having a film thickness of 0.05 [mm] with respect to a plane parallel to the long side direction of the flat wire 301. The flat wire 301 is covered on both sides. That is, the flexible flat cable 300 has a thickness of 0.2 [mm] on its outer shape.

  With respect to the flexible flat cable 300 having such a shape, cut lines C1, C2, and C3 having a width of 0.65 [mm] are set so as to be equally spaced in the long side direction. Then, by cutting the flexible flat cable 300 along the cut lines C1, C2, and C3 into a single wire, a plurality of the above-described single flat cable 111 is formed.

  Thus, the single flat cable 111 can be easily formed with good workability by cutting the flexible flat cable 300, which is a general-purpose material, into a single wire.

  As shown in FIG. 4A, the flat cable 111 formed by making the flexible flat cable 300 as a single wire as described above has a substantially rectangular shape with an outer shape of 40 [mm] × 35 [mm]. The antenna coil 11 is formed by being wound on the side surface 202a of the secondary battery charging unit 202 while being bonded with an insulating adhesive 112 such as an acrylic resin adhesive (ADH).

  Here, when the antenna coil 11 is arranged, as shown in FIG. 4A, the surface of the battery pack 204 and the antenna coil to be inserted into the secondary battery insertion unit 202 arranged inside the antenna coil 11 11 is preferably 0.5 [mm] or more from the viewpoint of ensuring good communication characteristics.

  Specifically, there are two types of methods of winding the flat cable 111 around the side surface 202a of the secondary battery insertion unit 202, the following type 1 and type 2.

  First, FIG. 4B shows a cross-sectional view of the antenna coil 11 formed with the number of windings 3 by the method according to the type 1. Here, FIG. 4B is a diagram showing a cross-sectional shape when cut in the A-A ′ direction shown in FIG.

  That is, while the antenna coil 11 is bonded to the flat cable 111 with the insulating adhesive 112 so that the side surface 202a and the long side of the flat wire 301 of the flat cable 111 are parallel by the method according to type 1. It is formed by winding with 3 windings.

  A cross-sectional view of the antenna coil 11 formed by the method according to type 2 is shown in FIG. Here, FIG. 4C is a diagram showing a cross-sectional shape when cut in the A-A ′ direction shown in FIG.

  That is, the antenna coil 11 is bonded by the insulating adhesive 112 so that the long side of the flat wire 301 of the flat cable 111 is perpendicular to the side surface 202a by the method according to type 2. However, it is formed by winding with 3 windings.

  In this way, the antenna coil 11 is formed by winding the flat cable 111 while being bonded with the insulating adhesive 112, so that the shape can be stabilized and the flat wire 301 inside the flat cable 111 can be obtained. Can be adjusted with high accuracy. In particular, in the method according to type 1, since the long side of the flat wire 301 and the side surface 202a are parallel to each other, compared to the method according to type 2, it is easier to route close to the side surface 202a and more easily in a constrained space The antenna coil 11 can be formed.

  If the flat cable 111 can be wound in the space between the side surface 202a and the wall surface 203 of the housing and good communication characteristics can be secured, the number of windings is not limited to 3 described above. For example, the number of windings is You may make it select from 2-6 suitably.

  As described above, the antenna coil 11 can adjust the line spacing of the flat wires 301 inside the flat cable 111 with high accuracy by winding the flat cable 111 while being bonded with the insulating adhesive 112.

That is, in the antenna coil 11, the rectangular wire 301 of the flat cable 111 forming the antenna coil 11 is used as a space material having a thickness of 0.05 [mm] with respect to the surface parallel to the long side, 302 is covered. Furthermore, the antenna coil 11 is wound while being adhered to the surface of the insulator 302 covered with the flat wire 301 by the insulating adhesive 112 as a space material having a film thickness d1 with respect to the surface of the insulator 302. Thereby, the line interval of the flat wire 301 inside the flat cable 111 can be adjusted with high accuracy. Therefore, in the antenna coil 11, the line interval d of the flat wire 301 is defined by the following equation.
d = 0.1 [mm] + d1
Here, changes in the communication characteristics of the antenna coil 11 when the thickness of the insulating adhesive 112 is changed and the line interval d of the flat wire 301 is changed will be described with reference to Table 1 below.

  Note that communication characteristics are evaluated using a Q value, which is a value expressed by ωL / R, as an evaluation index. ω [rad / s] is the resonance frequency of the antenna coil 11, L [H] is the reactance value of the antenna coil 11, and R [Ω] is the resistance value of the antenna coil 11. The frequency of the magnetic field transmitted from the reader / writer 2 is 13.56 MHz, which is a representative magnetic field used in short-range wireless communication such as RFID. In such a communication environment, the upper limit value of the distance at which the antenna coil 11 can be separated from the reader / writer 2 for communication is defined as the maximum communicable distance. Further, it is assumed that the battery pack 204 is inserted in the secondary battery insertion unit 202.

上記の表１から明らかなように、フラットケーブル１１１の平角線３０１の線間隔ｄを変化させることでアンテナコイル１１の特性を変化させることができる。このような結果に基づいて、絶縁性接着剤１１２の膜厚ｄ１を横軸にとって、Ｑを縦軸にとって変化させたとき、図５のように通信特性が変化する。このように、平角線３０１の線間隔ｄを大きくすることによって最大通信可能距離Ｔが向上するのは、隣接する平角線３０１の線間隔ｄが大きくなると近接効果を低減することができ、結果としてアンテナコイル１１の抵抗値が減少してＱ値を高くすることができるからである。

As apparent from Table 1 above, the characteristics of the antenna coil 11 can be changed by changing the line interval d of the flat wire 301 of the flat cable 111. Based on such a result, when the film thickness d1 of the insulating adhesive 112 is changed on the horizontal axis and Q is changed on the vertical axis, the communication characteristics change as shown in FIG. As described above, the maximum communicable distance T is improved by increasing the line interval d of the rectangular wires 301. The proximity effect can be reduced as the line interval d of the adjacent rectangular wires 301 is increased. This is because the resistance value of the antenna coil 11 can be decreased and the Q value can be increased.

  For example, as a preferable communication condition, when the Q value is 41.50 or more, the flat cable 111 has a film thickness d1 of the insulating adhesive 112 on the side surface 202a of the secondary battery insertion unit 202 of 50 [μm] or more. Thus, the antenna coil 11 having good characteristics can be formed by being wound. However, when the film thickness d1 of the insulating adhesive 112 is set to 150 [μm] or more, the outer shape of the antenna coil 11 is increased, which is not preferable from the viewpoint of being incorporated in a space of about 1 [mm]. Therefore, the film thickness d1 of the insulating adhesive is selected within the range of 50 to 150 [μm], that is, the line interval d of the flat wires 301 is selected within the range of 150 to 250 [μm]. Thus, it is possible to form the antenna coil 11 having good characteristics while satisfying the geometrical constraints.

  In addition, the communication characteristics of the antenna module 1 according to the present embodiment are evaluated in comparison with the following comparison target.

  The antenna module according to the first comparative example is an antenna formed by winding a wire cable 400 having a circular cross-sectional shape on a side surface 202a of a secondary battery insertion portion 202 as shown in FIG. A coil 401 is provided.

  The antenna module according to the second comparative example is a flexible flat cable in which three flat wires of 0.3 × 0.1 [mm] are arranged in parallel via an insulating material, and the long side direction of the flat wire is secondary. It is wound so as to be orthogonal to the side surface of the battery insertion portion. Furthermore, since this flexible flat cable draws the magnetic field transmitted from the reader / writer into the antenna coil on the surface opposite to the direction in which the magnetic field is radiated, μ ′ is 40 and μ ″ is 1 at a frequency of 13.56 MHz. A magnetic sheet having magnetic permeability characteristics and having a film thickness of 250 μm is attached.

  The antenna module according to the third comparative example is one in which no magnetic sheet is provided with respect to the antenna module according to the second comparative example.

  In contrast to such a comparative example, as an example of the present embodiment, an antenna module 1 including an antenna coil 11 formed by the method according to types 1 and 2 so that the Q value is 42 or more is respectively Example 2 is used.

  Table 2 below shows the characteristics of antenna coils of a total of five types of antenna modules including three types of comparative examples and two types of examples.

まず、第１の比較例に係るアンテナモジュールは、上述した好適なＱ値を実現することができない。これは、捲回される導線の線間隔に応じてアンテナコイルの特性が変化する点を考慮すると、ワイヤーケーブルをハーネス上に絡ませて導線の間隔を密にしても、所望とする特性を実現するように精度良くこの間隔を調整することができないからである。

First, the antenna module according to the first comparative example cannot realize the preferable Q value described above. In consideration of the fact that the characteristics of the antenna coil change according to the line spacing of the conductors to be wound, the desired characteristics are realized even if the wire cables are entangled on the harness and the conductors are closely spaced. This is because the interval cannot be adjusted with high accuracy.

  Further, when comparing the second comparative example and the third comparative example, the antenna module according to the second comparative example provided with the magnetic sheet can realize a suitable Q value. However, the antenna modules according to the second and third embodiments have a width of about 2 mm on the outer shape, and satisfy the shape restriction that the space must be formed at 1 [mm] as described above. I can't. In addition, the antenna module according to the second comparative example is costly because of the magnetic sheet.

  In contrast to these comparative examples, the antenna modules according to the first and second embodiments can be 1 [mm] or less in size and outer width. In addition, the antenna modules according to the first and second embodiments have a characteristic that the inductance increases due to the structure in which the rectangular wires are overlapped, and the resistance value R can be set by adjusting the line spacing d appropriately. As a result, suitable communication characteristics can be realized without attaching a magnetic sheet.

  Next, communication characteristics when inductively coupled with a reader / writer will be described with reference to FIG. Here, the horizontal axis represents the frequency of the magnetic field used for communication, and the vertical axis represents the maximum communicable distance corresponding to the frequency. The frequency of the magnetic field transmitted from the reader / writer is 13.56 MHz as described above. However, when communication is performed by inductive coupling, the magnetic field is higher than 13.56 MHz, for example, up to 13.86 MHz. Communication is performed using up to these components.

  As is clear from FIG. 7, the antenna modules according to the first and second examples tend to be higher in characteristics in all frequency bands that are measurement targets than the antenna module according to the first comparative example. is there. As described above, the antenna modules according to the first and second embodiments are more densely wound by adjusting the conductor spacing more accurately than the antenna module according to the first comparative example. Because it can be done.

  In addition, the antenna module according to the first and second examples achieves the same communication characteristics as the antenna module according to the second comparative example provided with the magnetic sheet. Therefore, the antenna modules according to the first and second embodiments can obtain good communication characteristics without providing a magnetic sheet, and can further reduce costs compared to an antenna module using a magnetic sheet. .

  As described above in the first and second examples, the antenna module 1 according to this embodiment uses a general-purpose material, and changes in the electrical characteristics of the antenna coil due to deformation or the like, for example. As a result, it is possible to incorporate an antenna structure having good characteristics while reducing costs while efficiently using the space of a portable communication device in which various members are integrated.

  DESCRIPTION OF SYMBOLS 1 Antenna module 11, 401 Antenna coil, 11a Connection terminal, 111 flat cable, 112 Insulating adhesive, 12 Communication processing part, 2 Reader writer, 2a Antenna, 2b Control board, 100 Wireless communication system, 200 Mobile phone, 201 Control board, 202 Secondary battery insertion part, 202a side surface, 203 wall surface, 204 battery pack, 300 flexible flat cable, 301 flat wire, 302 insulator, 400 wire cable

Claims (5)

In an antenna structure that is built in a communication device and can be communicated by being inductively coupled with a transmitter that transmits a magnetic field,
An antenna structure formed by winding a flat cable in which a single flat wire is covered with an insulator on a side surface of a metal member built in the communication device while being bonded with an insulating adhesive. The insulating adhesive is an acrylic resin adhesive,
The rectangular wire has a long side of about 0.3 [mm] and a short side of about 0.1 [mm],
The conducting wire interval in the flat cable bonded by the insulating adhesive is 150 to 250 [μm],
It is formed by winding a flat cable in which a single flat wire is covered with an insulator on the side surface of the secondary battery insertion portion while being bonded with an insulating adhesive, and the transmission frequency is 13.56 [MHz]. The antenna structure according to claim 1, wherein the antenna structure is capable of communicating by being inductively coupled to the transmitter that transmits the magnetic field.   The flat cable is wound while being adhered with an insulating adhesive so that the thickness direction of the flat wire of the flat cable is perpendicular to the side surface of the metal member built in the communication device. The antenna structure according to claim 1 or 2, wherein the antenna structure is formed as described above. In the manufacturing method of an antenna structure that is built in a communication device and is inductively coupled to a transmitter that emits a magnetic field, thereby enabling communication.
An antenna structure in which a flat cable in which a single flat wire is covered with an insulator is wound on a side surface of a metal member built in the communication device while being bonded with an insulating adhesive to form the antenna structure. Body manufacturing method. In communication equipment with an antenna structure that is inductively coupled to a transmitter that emits a magnetic field and can communicate,
Comprising a metal member built into the device,
The antenna structure is a communication device formed by winding a flat cable in which a single flat wire is covered with an insulator on a side surface of the metal member while being bonded with an insulating adhesive.

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