JP2013125981A - Antenna device and communication device - Google Patents

Abstract

An antenna device capable of realizing good communication characteristics while reducing the size of a casing of the electronic device when incorporated in the electronic device.
In an antenna device, a coil wire 111 is wound on one surface of an antenna substrate 11 so as to cover the outer periphery of the antenna substrate 11 with a number of turns greater than at least 1, and a terminal portion 11b is provided. The at least one terminal 11b1, 11b2 is formed on the same surface of the antenna substrate 11 as the coil wire 11, and is perpendicular to the winding direction of the coil wire 111 and on the same surface as the coil wire 111. The position P2 of the opening portion 11c at the winding center of the coil wire 111 defined on the straight line L0 passing through the formed terminal 11b1 is formed more than the center portion P3 of the antenna substrate defined by the straight line L0. Located on the side that is not.
[Selection] Figure 4

Description

  The present invention relates to an antenna device incorporated in an electronic device and capable of communicating by receiving a magnetic field transmitted from a transmitter, and a communication device.

  In an electronic device such as a mobile phone, an antenna module for RFID (Radio Frequency Identification) is used in order to mount a short-range non-contact communication function.

  This antenna module performs communication using an inductive coupling with an antenna coil mounted on a transmitter such as a reader / writer. That is, in this antenna module, when the antenna coil receives the magnetic field from the reader / writer, the antenna coil can convert it into electric power and drive an IC that functions as a communication processing unit.

  The antenna module needs to receive a magnetic flux of a certain value or more from the reader / writer by the antenna coil in order to reliably communicate. Therefore, in the antenna module according to the conventional example, a loop coil is provided in the casing of the mobile phone, and the coil receives the magnetic flux from the reader / writer.

  For example, Patent Document 1 proposes a method of arranging a flexible cable or a flat cable around a built-in battery as a method for improving characteristics of a loop antenna built in a mobile terminal device.

JP-A-2005-303541

  Since various modules are mounted in the portable electronic device, there is a demand to reduce the width of the antenna substrate in the antenna module in which the coil wire of the antenna coil is wound on the antenna substrate. On the other hand, the terminal that pulls the coil wire to the outside needs a terminal having a certain area on the antenna substrate on which the coil wire is wound in order to ensure the connection reliability. For this reason, when the width of the antenna substrate is reduced, the line width of the coil wire formed in the vicinity of the terminal is reduced, so that the resistance value of the coil wire formed in the vicinity of the terminal becomes very high, resulting in communication. The characteristic has deteriorated.

  The present invention has been proposed in view of such circumstances, an antenna device capable of realizing good communication characteristics while reducing the size of the casing of the electronic device when incorporated in the electronic device, and An object is to provide a communication device.

  In order to solve the above-described problems, the present invention provides an antenna device that is incorporated in an electronic device and can communicate by receiving a magnetic field transmitted from a transmitter. The antenna board is formed with a communication processing unit that is driven by a flowing current and communicates with a transmitter, and a terminal unit that is connected to the transmitter, and the coil wire has an outer periphery of the antenna substrate on one surface of the antenna substrate. The terminal portion is wound at a winding number greater than 1, and the terminal portion has at least one terminal formed on the same surface of the antenna substrate as the coil wire, and is wound in the winding direction of the coil wire. The position of the opening of the winding center of the coil wire defined on a straight line passing through a terminal formed on the same plane as the coil wire is perpendicular to the center of the antenna substrate defined by the straight line. than Situated on the side child is not formed.

  Further, the present invention provides a communication device that is incorporated in an electronic device and can communicate by receiving a magnetic field transmitted from a transmitter, and a coil wire that is inductively coupled to the transmitter and a terminal portion that is connected to the coil wire. A formed antenna substrate and a communication processing unit that is driven by a current flowing in the coil wire and communicates with the transmitter are provided. The coil wire covers the outer periphery of the antenna substrate on one surface of the antenna substrate. Thus, the terminal is wound at a number of turns greater than at least 1, and at least one terminal of the terminal portion is formed on the same surface of the antenna substrate as the coil wire, with respect to the winding direction of the coil wire. The position of the opening of the winding center of the coil wire defined by a straight line passing through a terminal formed in the vertical direction and on the same plane as the coil wire is more than the center of the antenna substrate defined by the straight line. Also terminals are formed Located on the side not.

  In the present invention, the position of the opening of the winding center of the coil wire defined by a straight line passing through a terminal formed on the same plane as the coil wire is perpendicular to the winding direction of the coil wire. , Located on the side where the terminal is not formed with respect to the central portion of the antenna substrate defined by the straight line. Therefore, this invention can prevent that the line width of the coil wire which passes along the terminal part vicinity formed in the same surface of the antenna board with the coil wire becomes narrow, and can prevent deterioration of communication characteristics. .

It is a figure for demonstrating the structure of the radio | wireless communications system incorporating the antenna module to which this invention was applied. FIG. 2A is a diagram for explaining the arrangement of the antenna device to which the present invention is applied. FIG. 2B is a diagram for explaining the arrangement of the antenna device to which the present invention is applied. It is a figure for demonstrating the structure which concerns on the antenna module to which this invention was applied. It is a figure for demonstrating the structure which concerns on the antenna module to which this invention was applied. FIG. 5A is a diagram for describing a structure according to an antenna module to which the present invention is applied. FIG. 5B is a diagram for explaining a structure according to an antenna module to which the present invention is applied. 6A and 6B are diagrams for explaining a structure according to an antenna module to which the present invention is applied. FIG. 7A and FIG. 7B are diagrams for explaining a structure according to an antenna module to which the present invention is applied. FIG. 8A and FIG. 8B are diagrams for explaining a structure according to an antenna module to which the present invention is applied. FIG. 9A and FIG. 9B are diagrams for explaining a structure according to an antenna module to which the present invention is applied. FIGS. 10A, 10 </ b> B, and 10 </ b> C are diagrams for explaining the structure of the antenna module according to the comparative example. It is a graph which shows the relationship with communication distance by changing Q value by attaching resistance externally with the antenna module which has an antenna board of 12x40 mm outside shape.

  Hereinafter, embodiments 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.

  A communication apparatus to which the present invention is applied is an apparatus incorporated in an electronic device and capable of receiving communication by receiving a magnetic field transmitted from a transmitter. For example, for a radio frequency identification (RFID) as shown in FIG. It is incorporated into the wireless communication system 100 and used.

  The wireless communication system 100 includes a communication device 1 and a reader / writer 120 that accesses the communication device 1. Here, it is assumed that the communication device 1 and the reader / writer 120 are arranged to face each other on the xy plane of the three-dimensional orthogonal coordinate system xyz.

  The reader / writer 120 functions as a transmitter that transmits a magnetic field in the z-axis direction to the communication devices 1 facing each other in the xy plane. Specifically, the reader / writer 120 and an antenna 121 that transmits a magnetic field toward the communication device 1 And a control board 122 that communicates with the communication device 1 that is inductively coupled via the antenna 121.

  That is, the reader / writer 120 is provided with a control board 122 that is electrically connected to the antenna 121. A control circuit made of electronic components such as one or a plurality of integrated circuit chips is mounted on the control board 122. The control circuit executes various processes based on the data received from the communication device 1. For example, when transmitting data to the communication device 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 modulates the modulation. The signal is amplified, and the antenna 121 is driven by the amplified modulation signal. When reading data from the communication apparatus 1, the control circuit amplifies the modulation signal of the data received by the antenna 121, demodulates the modulation signal of the amplified data, and decodes the demodulated data. In the control circuit, a coding method and a modulation method used in a general reader / writer are used. For example, a Manchester coding method or an ASK (Amplitude Shift Keying) modulation method is used.

  The communication device 1 is, for example, an antenna coil that is incorporated in a housing 131 of a mobile phone 130 that is disposed so as to face the reader / writer 120 in the xy plane and that can communicate with the reader / writer 120 that is inductively coupled. The antenna module 1a having the antenna substrate 11 on which 11a is mounted, and a communication processing unit 12 that is driven by a current flowing through the antenna coil 11a and communicates with the reader / writer 120.

  On the antenna substrate 11, for example, an antenna coil 11a formed by patterning a flexible conductive wire such as a flexible flat cable, and a terminal for electrically connecting the antenna coil 11a and the communication processing unit 12 Part 11b is mounted.

  When the antenna coil 11a receives a magnetic field transmitted from the reader / writer 120, the antenna coil 11a is magnetically coupled to the reader / writer 120 by inductive coupling, receives the modulated electromagnetic wave, and performs communication processing on the received signal via the terminal portion 11b. To the unit 12.

  The communication processing unit 12 is driven by a current flowing through the antenna coil 11 a and performs communication with the reader / writer 120. 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. Further, the communication processing unit 12 reads out data to be transmitted to the reader / writer 120 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 120 via the coil 11a.

  In the wireless communication system 100 configured as described above, the antenna coil 11a of the antenna module 1a is placed between the reader / writer 120 and the electronic device such as the mobile phone 130 while reducing the size of the electronic device. From the viewpoint of realizing good communication characteristics, for example, a battery pack provided on the xy plane of a three-dimensional orthogonal coordinate system xyz as shown in FIG. 133 and the gap 132 between the inner peripheral wall 131a of the housing 131.

  Note that the antenna module includes not only the gap 132 between the battery pack 133 and the inner peripheral wall 131a of the casing 131 as described above, but also a conductor disposed inside the casing 131 such as an integrated circuit board and the inside of the casing. You may make it provide in the clearance gap with a surrounding wall. Here, for the sake of convenience, the antenna module has a plate-like conductor as an end portion 133b of the metal plate 133a facing the reader / writer 120 which is a metal case of the battery pack 133 as shown in FIG. It demonstrates as what is arrange | positioned between the inner peripheral walls 131a of the body 131. FIG.

  As shown in the cross-sectional view of FIG. 2B, the metal plate 133a, which is the metal casing of the battery pack 133 disposed in the mobile phone 130, flows electricity relatively well. An electric current is generated and the magnetic field is rebounded. Examining the magnetic field distribution when an AC magnetic field is applied from the outside, the magnetic field at the end 133b of the metal plate 133a of the battery pack 133 facing the reader / writer 120 is strong.

  In order to realize good communication characteristics by utilizing the magnetic field strength characteristics inside the casing 131 of the mobile phone 130, the antenna coil 11a of the antenna module 1a is parallel to the z-axis as shown in FIG. 3, for example. The opening 11c at the winding center of the antenna coil 11a is located in the gap 132 between the end 133b of the metal plate 133a and the inner peripheral wall 131a of the housing 131, and the coil wire is wound around the gap 132. Is.

  Here, FIG. 3 shows only the antenna coil 11a in which the number of turns of the coil wire is larger than at least 1 as a configuration of the antenna substrate 11 for convenience, but the antenna substrate 11 is provided with the terminal portion 11b as described above. Have. Such a terminal portion 11b is formed on the same surface of the antenna substrate 11 as the antenna coil 11a. When the number of turns of the coil wire is greater than at least 1, the coil wire passes through the vicinity of the terminal portion, but the resistance value increases due to the narrow wire width of the coil wire, and the communication characteristics deteriorate.

  For example, as shown in FIG. 4, the antenna module 1 a according to the present embodiment is perpendicular to the winding direction of the coil wire 111 in a region other than the region where the terminal portion 11 b is formed (hereinafter, the terminal portion formation area 11 b 0). The position P1 of the opening 11c passing through the straight line L0 is the intersection of the center line C of the antenna substrate 11 and the straight line L0. From the viewpoint of preventing the above-described deterioration in communication characteristics, the opening in the terminal portion formation area 11b0 The shape of the part 11c is as follows. That is, in the terminal portion formation area 11b0, the coil wire 111 defined on the straight line L1 passing through the terminal 11b1 formed in the direction perpendicular to the winding direction of the coil wire 111 and on the same plane as the coil wire 111. The position P2 of the opening 11c at the winding center is located on the side where the terminal 11b1 is not formed with respect to the center P3 of the antenna substrate 11 defined by the intersection of the straight line L1 and the center line C. Hereinafter, for convenience, in the terminal portion formation area 11b0, a region from the center portion P3 to the position P2 is defined as a region where the coil protrudes from the center portion P3, that is, a protruding portion 11d.

  In this way, in the antenna coil 11a, since the protruding portion 11d is formed in the terminal portion forming area 11b0, the coil wire that passes through the vicinity of the terminal portion as compared with an antenna module according to a comparative example as described later, for example. Therefore, it is possible to prevent the communication characteristics from being deteriorated.

  In the antenna module to which the present invention is applied, for example, the magnetic flux in the outer peripheral portion of the casing 131 such as the gap 132 between the battery pack 133 and the inner peripheral wall 131a of the casing 131 is efficiently drawn into the antenna coil. In the antenna module 1b shown in FIG. 5A and FIG. 5B, the magnetic sheet 13 is more than the antenna coil 11a in the traveling direction of the magnetic field oriented by the metal plate 133a facing the reader / writer 120, that is, upstream in the y-axis direction. Also, the antenna coil 11a is arranged on the reader / writer 120 side with respect to the magnetic sheet 13 in the traveling direction of the oriented magnetic field, that is, on the downstream side in the y-axis direction. As shown, the magnetic sheet 13 is wound around the winding center of the antenna coil 11a formed on the antenna substrate 11. Those plugged into the mouth portion 11c.

  Here, the substantially convex magnetic sheet 13 as shown in FIG. 6A, that is, the width of the sheet side 13a on the terminal 11b1, 11b2 side of the antenna substrate 11 after insertion is larger than the width of the opposing sheet side 13b. The antenna module 1b can be manufactured using a small one as shown in FIG. 6 (B).

  In addition, the T-shaped magnetic sheet 13 as shown in FIG. 7A, that is, the sheet side 13a on the side of the terminals 11b1 and 11b2 of the antenna substrate 11 after insertion is wider than the width of the opposing sheet side 13b. As shown in FIG. 7B, the antenna module 1b can be manufactured.

  Furthermore, the magnetic sheet 13 as shown in FIG. 8A, that is, the sheet side 13a on the side of the terminals 11b1 and 11b2 of the antenna substrate 11 after insertion is the same as the width of the opposing sheet side 13b. Thus, as shown in FIG. 6B, the antenna module 1b can be manufactured.

  As described above, in the antenna module to which the present invention is applied, in addition to the antenna module 1b as described above, terminals 11b1 and 11b2 are simply formed as shown in FIGS. 9A and 9B. The magnetic sheet 13 can be laminated so as to overlap the surface of the antenna substrate 11 that has not been formed.

  Next, the performance of the antenna module to which the present invention is applied is evaluated in comparison with the antenna module 2a according to the comparative example as shown in FIG.

  Here, in the antenna module 2a according to the comparative example, as shown in FIG. 10A, the terminal portion forming area 21b0 where the terminal portion 21b is formed and all other areas are wound around the coil wire 211. The position P0 of the opening 21c passing through the straight line L0 perpendicular to the direction is located on the center line C of the antenna substrate 11. That is, the antenna module 2a is such that no protruding portion is formed on the antenna substrate 21 like the antenna module 1a. Further, the antenna module 2a has a substantially convex magnetic sheet 23 as shown in FIG. 10B, that is, the sheet side 23a that becomes the terminal 21b1, 21b2 side of the antenna substrate 21 after insertion has an opposite sheet side. A sheet having a width smaller than 23b is inserted into the opening 11c at the winding center of the antenna coil 11a as shown in FIG. 10C.

  Next, communication characteristics between the antenna module to which the present invention is applied and the antenna module 2a according to the comparative example are evaluated.

  First, specific evaluation conditions are defined as follows. The external dimensions of the antenna substrate defined by the xy plane were 50 mm × 9 mm. In addition, the opening at the winding center of the antenna coil was set to have a y-axis width of 1 mm and an x-axis width of 40 mm. Each terminal size defined by the xy plane of the terminal portion was 3 mm × 3 mm. The number of windings was three. Further, as a magnetic sheet, a T-shaped ferrite having a thickness of 200 μm, specifically, a magnetic sheet that has been softened by covering the periphery with a PET film, and an opening at the winding center of the antenna coil is provided. It was assumed that it was plugged in.

  When the opening 21c of the antenna module 2a according to the comparative example is designed with the coil wire width and the L / S between the coil wires being 3: 1, the coil in the portion parallel to the outer periphery of the antenna substrate 21 is formed in the terminal portion formation area 21b0. The width is 0.263 mm, and outside the terminal portion formation area 21b0 is 0.925 mm. Therefore, in the terminal part formation area 21b0, the resistance value of the coil wire is slightly more than three times larger than that outside the terminal part formation area 21b0.

  On the other hand, in the antenna module 1a to which the present invention is applied, in the terminal portion formation area where the protruding portion is formed, the width at which the coil can be formed on the terminal side is 0.7 mm, and the winding center of the coil wire is The width on which the coil on the opposite side of the terminal can be formed across the opening is 3.7 mm, and the coil width for the three turns on the opposite side to the two turns on the terminal side is equal. The width of 2 turns was increased.

  Here, (0.7 mm + 3.7 mm) / (2 + 3) is the width for one turn. The width of the coil forming part on the terminal side is (0.7 mm + 3.7 mm) × [2 / (2 + 3)], and the opposite side is (0.7 mm + 3.7 mm) × [3 / (2 + 3)], that is, 1.76 mm and 2.64 mm. In this case, the line width of the coil wire is 0.667 mm for both two turns on the terminal side and three turns on the opposite side.

  In the terminal portion formation area, by forming the protruding portion, the line width of the coil 2 turns on the terminal portion side is increased from 0.264 mm to 0.666 mm, and the line width of the coil 3 turns on the opposite side is 0. Narrow from 924 mm to 0.666 mm.

  Here, since the resistance is proportional to the reciprocal of the line width of the coil wire and to the number of turns, if the coil length is constant, the overall resistance varies as follows between the conventional example and the embodiment.

Conventional example Terminal portion: 2 × (1 / 0.263) + 3 × (1 / 0.925) = 10.86
Example Terminal side opposite side: 2 × (1 / 0.667) + 3 × (1 / 0.667) = 5 / 0.66 = 7.50
Therefore, the resistance change rate in the pattern change area is 7.5 / 10.86 = 0.69, which is a reduction in resistance of about 30%.

  Further, the 3-turn area where the pattern is not changed is about 7 times as long as the terminal area.

  In the conventional example, 2 × (1 / 0.263) + 3 × (1 / 0.925) + 3 × (7 / 0.925) = 33.86.

  The example is 2 * (1 / 0.667) + 3 * (1 / 0.667) + 3 * (7 / 0.925) = 30.50.

  Therefore, overall, 30.5 / 33.86 = 0.90, resulting in a 10% resistance reduction.

  Since the area excluding the opening at the winding center of the antenna coil is not changed between the conventional example and the example, the coupling coefficient k is considered to be constant. Further, the inductance value of the coil hardly changes. On the other hand, since the coil resistance is reduced by 10%, the Q value is increased by 10%, and the communication distance of the antenna is proportional to the Q value, so that the communication performance is improved.

  Here, the graph of FIG. 11 is an antenna module having an antenna substrate having an outer shape of 12 × 40 mm, and shows a relationship with a communication distance by changing the Q value with an external resistor. An antenna module is placed 1 mm above the metal plate (SUS plate) for measurement. As a reader / writer, 461C manufactured by Sony Corporation was used.

  From this result, for example, when the Q value increases by 20 to 10%, that is, becomes 22, the communicable distance increases by 1.5 mm. Even from the viewpoint of clearing the standard of communication distance, the effect that the communicable distance increases by 1.5 mm is very large.

  As described above, the antenna modules 1a and 1b to which the present invention is applied can prevent the line width of the coil wire passing through the vicinity of the terminal portion from being narrowed and can prevent the deterioration of the communication characteristics. . In particular, it is preferable in that the resistance value can be reduced more effectively by setting the line width of the coil wire passing through the vicinity of the terminal portion to an equal width as in the above-described embodiment.

  1 communication device, 1a, 1b, 2a antenna module, 11, 21 antenna board, 11a antenna coil, 11b, 21b terminal part, 11b0, 21b0 terminal part forming area, 11b1, 11b2, 21b1, 21b2 terminal, 11c, 21c opening part 11d, protruding portion, 13a, 133b end, 111 central axis, 12 communication processing unit, 13, 23 magnetic sheet, 13a, 13b, 23a, 23b sheet side, 100 wireless communication system, 111, 211 coil wire, 120 reader / writer , 121 antenna, 122 control board, 130, 230 mobile phone, 131 housing, 131a inner peripheral wall, 131b outer peripheral wall, 132 gap, 133 battery pack, 133a metal plate, 133b end, 133c central portion

Claims (5)

In an antenna device that is incorporated in an electronic device and can communicate by receiving a magnetic field transmitted from a transmitter,
An antenna substrate formed with a coil wire that is inductively coupled to the transmitter, and a terminal unit that is connected to a communication processing unit that is driven by a current flowing in the coil wire to communicate with the transmitter;
The coil wire is wound on one surface of the antenna substrate at a number of turns greater than at least 1 so as to cover the outer periphery of the antenna substrate,
The terminal portion has at least one terminal formed on the same surface of the antenna substrate as the coil wire,
The position of the opening at the winding center of the coil wire defined on a straight line passing through a terminal formed on the same plane as the coil wire in a direction perpendicular to the winding direction of the coil wire, An antenna device, wherein the antenna device is located on a side where the terminal is not formed with respect to a central portion of the antenna substrate defined by the straight line.   The coil wire is arranged such that an opening at the winding center of the coil wire is positioned in a gap between the end of the conductor facing the transmitter inside the housing of the electronic device and the inner peripheral wall of the housing. The antenna device according to claim 1, wherein the antenna device is wound around the antenna. A magnetic sheet for drawing a magnetic field transmitted from the transmitter to the coil wire;
The magnetic sheet is inserted into an opening at the winding center of the coil wire formed on the antenna substrate, so that the upstream side in the traveling direction of the magnetic field oriented by the housing surface facing the transmitter An arrangement condition in which the magnetic sheet is located closer to the transmitter than the coil wire, and an arrangement condition in which the coil wire is located closer to the transmitter than the magnetic sheet on the downstream side in the traveling direction of the oriented magnetic field. The antenna device according to claim 2, wherein the coil wire and the magnetic sheet are superimposed on each other so as to satisfy both of the arrangement conditions. A magnetic sheet for drawing a magnetic field transmitted from the transmitter to the coil wire;
The antenna device according to claim 1, wherein the coil wire and the magnetic sheet are superposed on each other so that the coil wire satisfies a condition of being located closer to the transmitter than the magnetic sheet. In a communication device that is incorporated in an electronic device and can communicate by receiving a magnetic field transmitted from a transmitter,
An antenna substrate formed with a coil wire inductively coupled to the transmitter, and a terminal portion connected to the coil wire;
Driven by the current flowing in the coil wire, and equipped with a communication processing unit for communicating with the transmitter,
The coil wire is wound on one surface of the antenna substrate at a number of turns greater than at least 1 so as to cover the outer periphery of the antenna substrate,
The terminal portion has at least one terminal formed on the same surface of the antenna substrate as the coil wire,
The position of the opening at the winding center of the coil wire defined on a straight line passing through a terminal formed on the same plane as the coil wire in a direction perpendicular to the winding direction of the coil wire, A communication device, wherein the communication device is located on a side where the terminal is not formed with respect to a central portion of the antenna substrate defined by the straight line.

Images