JP6213992B2 - ANTENNA DEVICE AND ELECTRONIC DEVICE - Google Patents

Description

  The present invention relates to an antenna device that is incorporated in an electronic device and communicates with an external device via an electromagnetic field signal, and an electronic device in which the antenna device is incorporated.

  2. Description of the Related Art Conventionally, an RFID (Radio Frequency Identification) antenna module has been used in an electronic device such as a mobile phone, a smartphone, and a tablet PC in order to mount a near field non-contact communication (NFC) 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 the antenna device, when the antenna coil receives the magnetic field from the reader / writer, the antenna coil can convert the power into electric power and drive the IC functioning 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 device 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. The antenna module incorporated in an electronic device such as a cellular phone has a magnetic flux from the reader / writer rebounded due to an eddy current generated when a metal such as a substrate or a battery pack inside the device receives a magnetic field from the reader / writer. End up. For example, when considering the surface of a mobile phone case, the magnetic field coming from the reader / writer tends to be strong at the outer peripheral portion of the case surface and weak near the center of the case surface.

  In the case of an antenna using a normal loop coil, the loop coil is located in the central portion of the mobile phone where the opening portion cannot receive a magnetic field passing through the outer peripheral portion of the housing surface described above. For this reason, in the antenna using a normal loop coil, the efficiency which receives a magnetic field has deteriorated. Therefore, an antenna device in which a loop antenna is arranged on the outer peripheral portion of the surface of the casing where the magnetic field coming from the reader / writer is strong, and an antenna device in which the magnetic sheet is used to increase the magnetic flux to improve the performance have been proposed. . In these antenna devices, the loop antenna has a rectangular shape and is installed so that its long side is along the outer peripheral edge of the housing surface (see, for example, Patent Documents 1 to 3).

Japanese Patent No. 4883125 Japanese Patent No. 48949945 Japanese Patent No. 5135450

  As described above, in the RFID antenna module built in the portable terminal device, a method for improving the characteristics by using the magnetic field shielding effect by a metal plate such as a substrate has been proposed. For example, in Japanese Patent Application No. 2013-021616, the applicant of the present invention is a first antenna device that is provided inside a casing of an electronic device and faces an external device. A metal plate, an antenna coil provided in the electronic device casing and inductively coupled to the external device, and a first conductor provided in the electronic device casing and serving as a main metal plate are superimposed or contacted. In addition, an antenna device is proposed that includes a surface of the antenna coil opposite to the surface facing the external device and a sheet-like second conductor at least partially overlapping.

  However, the positional relationship between the antenna device and the first conductor serving as a main metal plate of the electronic device including the antenna device differs depending on the structure of the electronic device. Accordingly, the size of the second conductor to be attached to the antenna device varies depending on the distance from the first conductor, and it is difficult to standardize the antenna module including the second conductor. It was. In addition, when the distance between the first conductor and the antenna device is large, the size of the second conductor provided in the antenna device increases, and the degree of freedom in designing the electronic device when installing the antenna module is increased. It was constrained and difficult to handle. In the antenna devices of Patent Documents 1 to 3, although communication characteristics are enhanced by using a metal plate such as a substrate, the standardization of the antenna module including the second conductor and the solution of the design flexibility are mentioned. Not done.

  The present invention has been made in view of the above problems, and includes an improvement in the stable communication function of an antenna device including a second conductor and the second conductor, regardless of the internal structure of the electronic device. It is an object of the present invention to provide a new and improved antenna device and electronic apparatus capable of realizing standardization of an antenna module and ensuring design flexibility.

  One embodiment of the present invention is an antenna device that is incorporated in an electronic device and communicates with the external device via an electromagnetic field signal, and is provided inside the housing of the electronic device and faces the external device. A conductor, a loop antenna provided around an antenna coil that is inductively coupled to the external device, and a loop antenna provided around the first conductor, the loop being provided at a predetermined interval; Provided between the first conductor and the second conductor, a sheet-like second conductor partially overlapping or contacting the surface opposite to the surface facing the external device of the antenna A sheet-like third conductor in which one end overlaps or contacts the first conductor and a part of the other end overlaps or contacts the second conductor; Prepare.

  According to one embodiment of the present invention, it is possible to facilitate standardization of an antenna module including the second conductor and to ensure design flexibility of the antenna module while improving a stable communication function of the antenna device.

  At this time, in one aspect of the present invention, the loop antenna is divided into one side and the other side via a longitudinal center line, and the second conductor is the antenna coil of the loop antenna. The conductive wire of the antenna coil may overlap with one side portion that circulates in one direction, and the conductive wire of the antenna coil may not overlap with the other side portion that circulates in the other direction.

  In this way, by partially overlapping the second conductor with the loop antenna, the magnetic flux can be concentrated in the non-superimposed region, and efficient power generation in the region can be promoted.

  In the aspect of the invention, the second conductor may be overlapped over the entire length of the one side portion of the loop antenna.

  In this way, the second conductor suppresses inductive coupling on one side of the loop antenna via the third conductor, and the current amount in the opposite direction to the current generated on the other side is relative. In addition, the magnetic flux can be induced from one side of the loop antenna to the other side of the loop antenna, the coupling at the other side can be promoted, and communication characteristics can be improved.

  In the aspect of the invention, the second conductor may have a size in the longitudinal direction that is substantially the same as a size in the longitudinal direction of the loop antenna.

  In this way, since the second conductor can be made the minimum size necessary for improving the communication characteristics of the antenna device, the standardization of the antenna module including the second conductor can be realized. The design flexibility can be improved.

  In the aspect of the invention, the other side portion of the loop antenna may be disposed at a position facing the third conductor via the second conductor.

  In this way, the second conductor is partially overlapped with the loop antenna, so that the magnetic field in the overlap region is bounced back via the third conductor to suppress the inductive coupling in the overlap region. It is possible to efficiently transmit a current generated in a non-existing region.

  In one embodiment of the present invention, the third conductor may be provided with a hole, and the third conductor may be divided into a plurality of parts. It is good also as being comprised so that it may overlap with or contact the side part of one conductor. Further, the third conductor may be configured to overlap or contact one surface of the first conductor facing the external device or a part of the surface opposite to the one surface. Good.

  Thus, by providing the third conductor, the degree of freedom in designing the antenna module including the second conductor is improved.

  Another aspect of the present invention is an electronic device in which any of the antenna devices described above is incorporated and can communicate with an external device via an electromagnetic field signal.

  According to another aspect of the present invention, it is possible to improve the communication characteristics of an electronic device with respect to an external device while realizing standardization of an antenna module including the second conductor and improving design flexibility.

  As described above, according to the present invention, regardless of the internal structure of the electronic device, the stable communication function of the antenna device including the second conductor is improved, and the antenna module including the second conductor is improved. Standardization and design freedom can be secured.

1 is a perspective view illustrating a schematic configuration of a wireless communication system to which an antenna device according to an embodiment of the present invention is applied. It is a perspective view showing the composition of the antenna device concerning one embodiment of the present invention. It is a perspective view which shows an example of the modification of the 3rd conductor with which the antenna apparatus which concerns on one Embodiment of this invention is equipped. It is a perspective view which shows an example of the other modification of the 3rd conductor with which the antenna apparatus which concerns on one Embodiment of this invention is equipped. It is a partial side view which shows an example of the other modification of the 3rd conductor with which the antenna apparatus which concerns on one Embodiment of this invention is equipped. (A), (B) is a partial side view which shows an example of the installation aspect of the 3rd conductor with which the antenna apparatus which concerns on one Embodiment of this invention is equipped. It is a perspective view which shows an example of the inside of the electronic device to which the antenna device which concerns on one Embodiment of this invention is applied. It is a partial side view which shows an example of the inside of the electronic device to which the antenna device which concerns on one Embodiment of this invention is applied.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

  First, a configuration of an antenna device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view illustrating a schematic configuration of a wireless communication system to which an antenna device according to an embodiment of the present invention is applied, and FIG. 2 is a perspective view illustrating a configuration of the antenna device according to an embodiment of the present invention. FIG.

  The antenna device 1 according to the present embodiment is a device that is incorporated in an electronic device and communicates with an external device via an electromagnetic field signal. For example, the antenna device 1 is incorporated in an RFID wireless communication system 100 as illustrated in FIG. Used.

  The wireless communication system 100 includes an antenna device 1 provided in an electronic device and a reader / writer 120 serving as an external device that accesses the antenna device 1. Here, it is assumed that the antenna 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 antenna devices 1 that face each other in the xy plane, and specifically, an antenna 121 that transmits a magnetic field toward the antenna device 1 And a control board 122 that communicates with the antenna 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 antenna device 1.

  For example, when transmitting data to the antenna 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 antenna device 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. In the following description, the antenna device and the like in the non-contact communication system will be described, but the same can be applied to a non-contact charging system such as Qi (Chi).

  The antenna device 1 is incorporated in a casing of an electronic device such as a mobile phone that is disposed so as to face the reader / writer 120 in the xy plane during communication, and communicates with an external device via an electromagnetic field signal. As shown in FIG. 1, the antenna device 1 of the present embodiment includes an antenna module 2, a metal plate 3, an antenna metal foil 4, and a connection metal foil 5. In this embodiment, the antenna device 1 includes a part of the antenna module 2 superimposed on the antenna metal foil 4, and the antenna module 2 including the antenna metal foil 4 is provided at a predetermined interval from the metal plate 3. The metal plate 3 and the antenna metal foil 4 are connected by a connection metal foil 5.

  The antenna module 2 is provided inside the housing of the electronic device and communicates with the reader / writer 120 that is inductively coupled. In this embodiment, as shown in FIG. 1, the antenna module 2 includes a loop antenna 11, a communication processing unit 13, and a connection unit 14, and a part of the loop antenna 11 is superimposed on the antenna metal foil 4. doing.

  The loop antenna 11 is provided inside the housing of the electronic device, and the antenna coil 12 that can communicate with the reader / writer 120 circulates by being inductively coupled to the reader / writer 120 serving as an external device. The loop antenna 11 includes, for example, an antenna coil 12 formed by patterning a flexible conductive wire such as a flexible flat cable, and a terminal portion that electrically connects the antenna coil 12 and the communication processing unit 13. 14 is implemented.

  The loop antenna 11 has a substantially rectangular shape as shown in FIG. 2, and one conductor wire of the antenna coil 12 is circulated along the outer shape. In the present embodiment, the loop antenna 11 has a substantially rectangular shape, but the shape may be other shapes such as an ellipse. Further, in this specification, the “longitudinal direction” of the loop antenna 11 indicates a direction in which the length or outer diameter shows the maximum value, and in the case of a substantially rectangular shape, the long side direction, and in the case of a substantially elliptical shape, the long axis. The direction shall be indicated.

  As shown in FIG. 2, the loop antenna 11 is arranged such that the main surface around which the antenna coil 12 circulates faces the reader / writer 120 in the xy plane during communication. The loop antenna 11 has a first side portion 11a and a second side portion 11b with a center line 12a in the longitudinal direction as a boundary. On the other hand, the side portion 11a has a direction in which the direction of current flowing along the longitudinal direction of the conducting wire of the antenna coil 12 is the same as the direction of circulation. The other side portion 11b has the conducting wire of the antenna coil 12 in the direction of circulation in which the direction of current along the longitudinal direction flows in the opposite direction. The loop antenna 11 is arranged with one side edge along the longitudinal direction facing the metal plate 3 side, that is, one of the one side portion 11a and the other side portion 11b facing the metal plate 3 side.

  When the antenna coil 12 receives a magnetic field transmitted from the reader / writer 120, the antenna coil 12 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 unit 14. To the unit 13.

  The communication processing unit 13 is driven by a current flowing through the antenna coil 12 and communicates with the reader / writer 120. Specifically, the communication processing unit 13 demodulates the received modulation signal, decodes the demodulated data, and writes the decoded data in the internal memory of the communication processing unit 13. The communication processing unit 13 reads the data to be transmitted to the reader / writer 120 from the internal memory, encodes the read data, modulates the carrier wave based on the encoded data, and is magnetically coupled by inductive coupling. The radio wave modulated via the coil 12 is transmitted to the reader / writer 120. Note that the communication processing unit 13 may be driven not by power flowing through the antenna coil 12 but by power supplied from a power supply unit such as a battery pack or an external power source incorporated in the electronic device.

  The metal plate 3 is provided in the housing of the electronic device and serves as a first conductor facing the reader / writer 120 serving as an external device. The metal plate 3 is provided in a housing of an electronic device such as a mobile phone, a smartphone, or a tablet PC, for example, and constitutes a first conductor that faces the reader / writer 120 during communication of the antenna module 2. The first conductor is provided on, for example, a metal cover affixed to the inner surface of the smartphone casing, a metal casing of a battery pack housed in the smartphone, or the back surface of the liquid crystal module of the tablet PC. Corresponds to a metal plate or the like.

  The metal foil for antenna 4 is provided at a predetermined distance from the metal plate 3 serving as the first conductor, and a part of the surface of the loop antenna 11 opposite to the surface facing the reader / writer 120 is overlapped or contacted. This is a sheet-like second conductor. In the present embodiment, the antenna metal foil 4 overlaps over the entire length of the one side portion 11 a of the loop antenna 11 as shown in FIG. 2, and preferably the size in the longitudinal direction is the length of the loop antenna 11. They are formed so as to be substantially the same slightly larger than the size in the direction. That is, since the antenna metal foil 4 has a minimum size necessary for improving the communication characteristics of the antenna device 1, the standardization of the antenna module 2 including the antenna metal foil 4 and the degree of design freedom are realized. Can be improved.

  In addition, in this embodiment, although the metal foil 4 for antennas has comprised the substantially rectangular shape, the shape is good also as other shapes, such as an ellipse. Further, in this specification, the “longitudinal direction” of the metal foil 4 for an antenna indicates a direction in which the length or outer diameter shows the maximum value, and in the case of a substantially rectangular shape, the long side direction, and in the case of a substantially elliptical shape, The major axis direction shall be indicated.

  The connecting metal foil 5 is a sheet-like third conductor provided between the metal plate 3 serving as the first conductor and the antenna metal foil 4 serving as the second conductor. In the present embodiment, the connecting metal foil 5 has one end portion 5 a overlapping or contacting the metal plate 3 and a part of the other end portion 5 b overlapping or contacting the antenna metal foil 4.

  Thus, by providing the connection metal foil 5 between the metal plate 3 and the antenna metal foil 4, the antenna metal foil 4 can be separated from the metal plate 3 of the electronic device. The antenna module 2 superimposed on the metal foil 4 can use the magnetic shielding effect by the metal plate 3 via the connection metal foil 5. That is, the connecting metal foil 5 connects the metal plate 3 and the antenna metal foil 4 so that the antenna device 1 such as a small NFC antenna using the magnetic shield effect by the metal plate 3 is used regardless of the internal structure of the electronic device. To maximize the performance. Further, the connecting metal foil 5 connects the metal plate 3 and the antenna metal foil 4, thereby improving the degree of design freedom of the electronic device including the antenna module 2.

  As described above, in the present embodiment, a sheet-like second conductor is formed between the loop antenna 11 and the metal plate 3 via the connecting metal foil 5 that overlaps or contacts the metal plate 3. An antenna metal foil 4 is provided. The metal foil for antenna 4 partially overlaps the surface of the loop antenna 11 opposite to the surface facing the reader / writer 120. The antenna metal foil 4 is superimposed on a part of the loop antenna 11, thereby suppressing inductive coupling in the overlapping region by repelling the magnetic field in a part of the overlapping loop antenna 11, and a region not overlapping. Enhancing the concentration of magnetic flux to improve communication performance.

  That is, in the loop antenna 11, the magnetic flux from the reader / writer 120 that passes through the antenna coil 12 that circulates around the main surface of the substrate is connected to the one side portion 11a in which the conductor of the antenna coil 12 circulates in one direction and The other side portion 11b that circulates in the other direction generates a current in the opposite direction, and as a result, cannot be efficiently coupled.

  Therefore, in the antenna device 1 of the present embodiment, the antenna metal foil 4 is partially overlapped with the surface of the loop antenna 11 opposite to the surface facing the reader / writer 120, thereby repelling the magnetic field in the overlap region. The inductive coupling in can be suppressed, and the current generated in the non-overlapping region can be transmitted efficiently. Further, the antenna device 1 partially superimposes the antenna metal foil 4 on the surface opposite to the surface facing the reader / writer 120 of the loop antenna 11, thereby concentrating the magnetic flux on the non-superimposed region. Efficient power generation in can be promoted.

  Further, the antenna device 1 includes the antenna metal foil 4 without leaking the magnetic flux from the metal plate 3 through the connection metal foil 5 when the metal foil 4 for antenna overlaps or contacts the metal foil 5 for connection. 4 can be guided to the area of the loop antenna 11 on which no superposition 4 is superimposed, and efficient inductive coupling can be performed. That is, a structure in which the end 3 a of the metal plate 3 is equivalently disposed on the center line 12 a of the antenna coil 12 of the loop antenna 11 is realized. Further, in the antenna device 1, the antenna metal foil 4 overlaps with the connection metal foil 5, so that the antenna metal foil 4 is overlapped by the leakage magnetic flux from the metal plate 3 through the connection metal foil 5. Generation of current due to inductive coupling can be prevented in the portion.

  The metal foil for antenna 4 and the metal foil for connection 5 are preferably good conductors such as copper foil, but are not necessarily good conductors. That is, the antenna metal foil 4 and the connection metal foil 5 may be formed of at least a material such as a conductive metal. Also, the thickness of the metal foil for antenna 4 and the metal foil for connection 5 is appropriately determined according to the communication frequency between the antenna device 1 and the reader / writer 120. For example, at a communication frequency of 13.56 MHz, the thickness is 20 to 30 μm. Metal foil can be used.

  Note that the antenna metal foil 4 is not necessarily in contact with the connection metal foil 5 or the loop antenna 11 if it overlaps. However, the closer to the connection metal foil 5 and the loop antenna 11, the more advantageous the coupling coefficient of the metal foil for antenna 4 is, so it is preferable that the metal foil for antenna 4 is close or in contact.

  Further, as shown in FIG. 2, the antenna metal foil 4 is preferably overlapped from the end of one side portion 11 a of the loop antenna 11 to the center line 12 a of the antenna coil 12. Thereby, the metal foil 4 for antenna suppresses the coupling | bonding in the one side part 11a of the loop antenna 11, and makes the electric current amount of the direction opposite to the electric current which generate | occur | produces in the other side part 11b relatively low. At the same time, the magnetic flux is induced from the one side portion 11a of the loop antenna 11 to the other side portion 11b, the coupling at the other side portion 11b is promoted, and the communication characteristics can be improved.

  Further, as shown in FIG. 2, the antenna metal foil 4 has a width equal to or greater than the longitudinal direction of the one side portion 11a of the loop antenna 11, and the one side portion 11a of the loop antenna 11 is entirely overlapped in the longitudinal direction. It is preferable to do. Also by this, the antenna metal foil 4 suppresses inductive coupling in the one side portion 11a of the loop antenna 11 via the third conductor 5, and the current in the direction opposite to the current generated in the other side portion 11b. Make the amount relatively low. At the same time, it is possible to induce magnetic flux from the one side portion 11a of the loop antenna 11 to the other side portion 11b, promote the coupling at the other side portion 11b, and improve communication characteristics.

  In addition, the loop antenna 11 has the number of the antenna coils 12 on the other side portion 11b on which the antenna metal foil 4 is not superimposed more than the number (for example, three) of the antenna coils 12 on the one side portion 11a on which the antenna metal foil 4 is superimposed. You may make it circulate so that a number (for example, four) may increase. That is, by making the start and end of the conductor of one antenna coil the other side portion 11b, the other side portion 11b of the loop antenna 11 is located more than the one side portion 11a across the center line 12a of the antenna coil 12. It can be formed so that many coil conductors circulate. Thereby, the number of coils inductively coupled with the magnetic flux from the reader / writer 120 can be increased, and good communication characteristics can be realized.

  In the antenna device 1, a plurality of antenna metal foils 4 divided into two or more may be superimposed between the connection metal foil 5 and the loop antenna 11. Thus, for example, when the lens foil of the camera module cannot be provided, for example, when the lens barrel of the camera module is disposed between the connection metal foil 5 and the loop antenna 11, the lens barrel etc. Communication characteristics can be improved by providing the antenna metal foil 4 at a position avoiding the above member. Further, the antenna device 1 may use a metal foil 4 for an antenna in which an opening (not shown) or a notch (not shown) corresponding to another member such as a lens barrel is formed.

  Further, as shown in FIG. 3, the antenna device 1 includes a plurality of connecting metal foils 5 divided into two or more pieces between the antenna metal foil 4 and the metal plate 3 superimposed on the loop antenna 11. You may superimpose. In this manner, the connection metal foil 5 is divided into a plurality of parts, so that, for example, the lens barrel 6 of the camera module is interposed between the metal foil 4 for antenna and the metal plate 3 superimposed on the loop antenna 11. Even when the connecting metal foil 5 cannot be provided as it is, the antenna metal foil 4 and the metal plate 3 on which the loop antenna 11 is superimposed are arranged so as to bypass the lens barrel 6. Can connect. That is, by providing the connecting metal foil 5 divided into a plurality at positions avoiding other members such as the lens barrel 6, it is possible to improve the communication characteristics while ensuring the function of the members. Note that FIG. 3 shows the case where the connecting metal foil 5 is divided into two parts, but the number is increased to three or more depending on the number of installations and installation locations of other members such as the lens barrel 6. It is good also as a divided | segmented structure.

  Further, as shown in FIG. 4, the antenna device 1 uses a connection metal foil 5 in which an opening 5 c and a notch (not shown) corresponding to other members such as a lens barrel 6 are formed. Also good. Further, as shown in FIG. 5, the connecting metal foil 5 may be configured to overlap or contact the side surface portion 3b of the metal plate 3 serving as the first conductor. At this time, the connecting metal foil 5 is formed by being bent into a substantially L shape, and the loop antenna 11 has an opening formed in the center line 12a of the antenna coil 12 in the longitudinal direction, and a magnetic property is formed in the opening. The sheet 20 may be inserted. Further, as shown in FIG. 6A, the connecting metal foil 5 may be configured to overlap or contact a part of the one surface 3c of the metal plate 3 facing the external device 120. Further, as shown in FIG. 6B, the connecting metal foil 5 is configured to overlap or contact a part of the surface 3d opposite to the one surface 3c facing the external device 120 of the metal plate 3. It is good to be. Thus, by providing the connecting metal foil 5 between the antenna metal foil 4 and the metal plate 3, the degree of freedom in designing the antenna module 2 (see FIG. 1) including the antenna metal foil 4 is improved. .

  In the present embodiment, by providing the connecting metal foil 5 between the metal plate 3 and the antenna metal foil 4 superimposed on the antenna module 2, the antenna metal foil 4 is separated from the metal plate 3 of the electronic device. Even in this configuration, the magnetic shield effect by the metal plate 3 of the antenna module 2 superimposed on the antenna metal foil 4 can be used. That is, regardless of the internal structure of the electronic device, the performance of the antenna device 1 using the magnetic shield effect by the metal plate 3 is maximized, and the degree of design freedom of the electronic device including the antenna module 2 is improved.

  Further, in the present embodiment, the connecting metal foil 5 is provided between the metal plate 3 and the antenna metal foil 4 superimposed on the antenna module 2, so that the reliability is ensured regardless of the size of the antenna metal foil 4. It is possible to connect the antenna module 2 superimposed on the metal plate 3 and the metal foil 4 for antenna. That is, even if the antenna metal foil 4 superimposed on the antenna module 2 is unified to a predetermined size, the metal plate 3 and the antenna module 2 can be reliably connected regardless of the internal structure of the electronic device. Therefore, standardization of the antenna module 2 including the antenna metal foil 4 can be facilitated.

  Further, in the present embodiment, the performance of the antenna device 1 using the magnetic shield effect by the metal plate 3 is maximized regardless of the internal structure and metal parts of the electronic device such as a portable terminal. In addition, it is possible to reduce changes in electrical characteristics such as inductance before and after mounting the antenna. For this reason, it can greatly contribute to simplification of the resonance frequency adjustment of the antenna device 1 such as an NFC antenna.

  Next, an example of an electronic apparatus to which the antenna device according to an embodiment of the present invention is applied will be described with reference to the drawings. FIG. 7 is a perspective view showing an example of the inside of an electronic apparatus to which the antenna device according to one embodiment of the present invention is applied, and FIG. 8 is an electronic diagram to which the antenna device according to one embodiment of the present invention is applied. It is a partial side view which shows an example of the inside of an apparatus.

  In the following description, a smart phone 133 is mainly used as an electronic device, and the main surface of the metal casing 135 of the battery pack 134 housed in the smart phone 133 that faces the reader / writer 120 during communication constitutes the first conductor. The metal plate 3 will be described.

  When the loop antenna 11 of the antenna module 2 is incorporated in the smartphone 133, the smartphone 133 is reduced in size, and from the viewpoint of realizing good communication characteristics with the reader / writer 120, as shown in FIG. On the xy plane of the three-dimensional orthogonal coordinate system xyz, for example, it is arranged in a space 142 between the battery pack 134 provided in the outer casing 141 of the smartphone 133 and the inner peripheral wall 141a of the outer casing 141. Specifically, the loop antenna 11 is between the end 3a of the metal plate 3 facing the reader / writer 120 of the metal casing 135 of the battery pack 134 and the inner peripheral wall 141a of the outer casing 141 as shown in FIG. Is arranged.

  Here, as shown in FIG. 8, the metal plate 3 constituting the metal casing of the battery pack 134 disposed in the smartphone 133 flows electricity relatively well, so that an eddy current is generated when an AC magnetic field is applied from the outside. Then, 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 3a of the metal plate 3 of the battery pack 134 facing the reader / writer 120 is strong.

  In order to realize good communication characteristics using the magnetic field strength characteristics inside the housing 131 of the smartphone 130, the loop antenna 11 of the antenna module 2 is, for example, as shown in FIG. The center 12a of the parallel antenna coil 12 passes through the space 142 between the end portion 3a of the metal plate 3 and the inner peripheral wall 141a of the outer casing 141, and one side edge in the longitudinal direction faces the end portion 3a side of the metal plate 3. In other words, the one side portion 11 a is arranged toward the end portion 3 a side of the metal plate 3.

  In the present embodiment, the loop antenna 11 is provided at a separated position without contacting the end 3 a of the metal plate 3. As described above, the antenna device 1 spans the metal plate 3 and the loop antenna 11 even when the metal plate 3 and the loop antenna 11 are spaced apart from each other due to layout restrictions in the housing of the electronic device. Good communication characteristics can be obtained by connecting the metal foil for antenna 4 and the metal foil for connection 5 superimposed. That is, by incorporating the antenna device 1 according to the present embodiment into an electronic device such as a smartphone 130, communication with an external device such as the reader / writer 120 is performed using the concentration of magnetic flux due to the magnetic shield effect of the metal plate 3 such as a substrate. The characteristics can be enhanced.

  Although one embodiment and each example of the present invention have been described in detail as described above, it will be understood by those skilled in the art that many modifications that do not substantially depart from the novel matters and effects of the present invention are possible. It will be easy to understand. Therefore, all such modifications are included in the scope of the present invention.

  For example, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. In addition, the configurations and operations of the antenna device and the electronic device are not limited to those described in the embodiment and examples of the present invention, and various modifications can be made.

DESCRIPTION OF SYMBOLS 1 Antenna apparatus, 2 Antenna module, 3 Metal plate (1st conductor), 3a edge part, 3b Side surface part, 3c One surface, 3d Opposite side surface 4 Metal foil for antennas (2nd conductor), 5 Metal foil for connection (third conductor), 5a one end, 5b the other end, 5c hole, 11 loop antenna, 11a one side, 11b other side, 12 antenna coil, 12a center line, 13 communication processing unit, 14 terminal unit, 120 reader / writer (external device), 121 antenna, 122 control board, 133 smart phone (electronic device), 134 battery pack, 135 metal casing (first conductor), 141 outer casing Body (housing), 141a inner peripheral wall, 142 space

Claims (10)

An antenna device incorporated in an electronic device and communicating with an external device via an electromagnetic field signal,
A first conductor provided inside the casing of the electronic device and facing the external device;
A loop antenna provided inside the casing of the electronic device and around which an antenna coil that is inductively coupled with the external device;
A sheet-like second conductor that is provided at a predetermined interval from the first conductor, and a part of the loop antenna that overlaps or contacts a surface opposite to the surface facing the external device;
Provided between the first conductor and the second conductor, one end of which overlaps or contacts the first conductor, and a part of the other end is the second conductor An antenna device comprising: a sheet-like third conductor that overlaps or contacts the conductor. The loop antenna is divided into one side and the other side via a longitudinal center line,
The said 2nd conductor is superimposed on the one side part which the conducting wire of the said antenna coil of the said loop antenna circulates in one direction, and does not overlap the other side part which the said conducting wire of the said antenna coil circulates in another direction. The antenna device according to 1.   The antenna device according to claim 2, wherein the second conductor is overlapped over the entire length of the one side portion of the loop antenna.   The antenna device according to claim 3, wherein the second conductor has a size in the longitudinal direction substantially the same as a size in the longitudinal direction of the loop antenna.   5. The antenna device according to claim 2, wherein the other side portion of the loop antenna is disposed at a position facing the third conductor via the second conductor. 6.   The antenna device according to claim 1, wherein the third conductor is divided into a plurality of parts.   The antenna device according to claim 1, wherein a hole is formed in the third conductor.   The antenna device according to any one of claims 1 to 7, wherein the third conductor is configured to overlap or contact a side surface portion of the first conductor.   The third conductor is configured to overlap or contact one surface of the first conductor facing the external device or a part of the surface opposite to the one surface. The antenna device according to any one of the above.   An electronic device in which the antenna device according to any one of claims 1 to 9 is incorporated and can communicate with an external device via an electromagnetic field signal.

Images