JP6336761B2 - 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

  The NFC antenna module with enhanced communication characteristics due to the magnetic shielding effect of the main metal plate of the electronic device equipped with the antenna device may have a mounting position close to the outer edge of the metal plate in order to fully exhibit its performance. is important. However, electronic devices such as portable terminals are becoming smaller and more multifunctional, and accordingly, various electronic components such as cameras are mounted in the electronic device at high density. For this reason, there is a problem that the performance of the communication characteristics of NFC enhanced by the magnetic shield effect by the metal plate cannot be sufficiently exhibited. Although the antenna devices of Patent Documents 1 to 3 use a metal plate such as a substrate to improve the characteristics, problems remain regarding further improvements in NFC communication characteristics of electronic devices that are becoming smaller and more multifunctional. .

  The present invention has been made in view of the above problems, and can improve the communication characteristics of NFC more reliably by utilizing the magnetic shielding effect of the main metal plate of electronic devices that are becoming smaller and more multifunctional. It is an object of the present invention to provide a new and improved antenna device and electronic apparatus that are possible.

  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 in any of the vicinity of the outer edge of the first conductor, and an antenna coil that is inductively coupled to the external device, and a magnetic material, and a center of the loop antenna. A magnetic sheet that is unfolded from the outer edge toward the opposite end of the outer edge facing the loop antenna.

  According to one aspect of the present invention, since the first conductor is shielded by the magnetic sheet provided so as to expand from the vicinity of the outer edge portion provided with the loop antenna, the magnetic flux from the external device is collected and the loop is collected. Guided to the center of the antenna. For this reason, the communication characteristic of the NFC can be improved more reliably by utilizing the magnetic shield effect by the main metal plate of the electronic device.

  At this time, in one embodiment of the present invention, the first conductor may be a metal cover that covers the housing.

  In this way, when the first conductor is a metal cover, the NFC communication characteristics are obtained by using the magnetic shield effect of the main metal plate of the electronic device, particularly by shielding the metal cover with a magnetic sheet. Can be enhanced.

  In one embodiment of the present invention, an opening may be formed in any part of the metal cover.

  In this way, when an opening is formed in the metal cover, the NFC communication is performed by utilizing the magnetic shield effect of the main metal plate of the electronic device, particularly by shielding the metal cover with a magnetic sheet. The characteristics can be enhanced.

  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 magnetic sheet is arranged on the one side from the center of the loop antenna. And a second magnetic sheet that extends from the center portion of the loop antenna toward the opposing end portion, and a first magnetic sheet that extends to an end portion in the width direction of the first and second side portions. The first magnetic sheet has one end disposed above the one side as viewed from the external device, and a portion excluding the one end is located below the other side as viewed from the external device. It is good also as being provided so that it may be arrange | positioned.

  If it does in this way, the magnetic flux from the external apparatus collected with the 2nd magnetic sheet can be sent to the center part of a loop antenna via the 1st magnetic sheet.

  In the aspect of the invention, the second magnetic sheet may have a configuration in which at least one of a hole and a notch is formed.

  In this way, it can be applied according to the specifications of the electronic device on which the antenna device is mounted.

  In the aspect of the invention, the hole may be formed in a portion facing the opening and have an outer diameter smaller than that of the opening.

  In this way, the magnetic flux around the opening sent from the external device can be reliably sent to the center of the loop antenna.

  In one embodiment of the present invention, the first magnetic sheet and the second magnetic sheet may be integrally formed.

  If it does in this way, the magnetic sheet which collects the magnetic flux received from an external apparatus more reliably can be easily manufactured as a simple structure.

  In one embodiment of the present invention, the first magnetic sheet and the second magnetic sheet may be separately molded and connected.

  In this way, the degree of freedom in designing the magnetic sheet that can more reliably collect the magnetic flux received from the external device 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, communication characteristics can be improved by utilizing the magnetic shield effect of the main metal plate of the electronic device regardless of the mounting position of the antenna module including the loop antenna.

  As described above, according to the present invention, the first conductor provided in the electronic device is shielded by the magnetic sheet provided so as to expand from the vicinity of the outer edge portion provided with the loop antenna. Can be collected more reliably and guided to the center of the loop antenna. For this reason, the communication characteristics of the NFC can be improved by utilizing the magnetic shield effect of the main metal plate of electronic devices that are becoming smaller and more multifunctional.

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 explanatory drawing which shows the arrangement | positioning relationship between the loop antenna of the antenna apparatus which concerns on one Embodiment of this invention, and a magnetic sheet, (A) is a perspective view, (B) is a side view. It is explanatory drawing which shows an example of an electronic device provided with the antenna device which concerns on one Embodiment of this invention, (A) is a perspective view, (B) is a top view. It is explanatory drawing which shows the arrangement | positioning relationship of the loop antenna and magnetic sheet in the modification of the antenna apparatus which concerns on one Embodiment of this invention, (A) is a perspective view, (B) is a side view. It is a perspective view which shows the arrangement | positioning relationship between the loop antenna and magnetic sheet in the other modification of the antenna device which concerns on one Embodiment of this invention. It is a perspective view which shows the arrangement | positioning relationship between the loop antenna and magnetic sheet in the other modification of the antenna device which concerns on one Embodiment of this invention. It is a perspective view which shows the arrangement | positioning relationship between the loop antenna and magnetic sheet in the other modification of the antenna device which concerns on one Embodiment of this invention. It is a perspective view which shows the arrangement | positioning relationship between the loop antenna and magnetic sheet in the other modification of the antenna device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the arrangement | positioning relationship of the loop antenna and magnetic sheet in the other modification of the antenna apparatus which concerns on one Embodiment of this invention, (A) is a perspective view, (B) is a side view. It is explanatory drawing which shows the arrangement | positioning relationship of the loop antenna and magnetic sheet in the other modification of the antenna apparatus which concerns on one Embodiment of this invention, (A) is a perspective view, (B) is a side view. It is a perspective view which shows an example of the antenna apparatus used as a comparative example. It is a graph which shows the change of the coupling coefficient which concerns on Example 1 and the comparative example 1 of the antenna apparatus which concerns on one Embodiment of this invention. It is a graph which shows the change of the coupling coefficient which concerns on Example 2 and the comparative example 2 of the antenna apparatus which concerns on one Embodiment of this invention.

  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 showing 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 diagram showing a loop antenna and magnetic properties of the antenna device according to an embodiment of the present invention. It is explanatory drawing which shows the arrangement | positioning relationship with a sheet | seat, (A) is a perspective view, (B) is a side view. 3A and 3B are explanatory views showing an example of an electronic apparatus including the antenna device according to the embodiment of the present invention, where FIG. 3A is a perspective view and FIG. 3B is a plan view.

  The antenna device 1 according to the present embodiment is a device that is incorporated in an electronic device 30 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 shown in FIG. Used.

  As illustrated in FIG. 1, the wireless communication system 100 includes an antenna device 1 provided in an electronic device 30 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 housing 32 (see FIG. 3A) of an electronic device 30 such as a mobile phone that is disposed so as to face the reader / writer 120 in the xy plane during communication, and becomes an external device. It communicates with the reader / writer 120 via an electromagnetic field signal. The antenna device 1 of the present embodiment includes an antenna module 2, a metal plate 3, and a magnetic sheet 20 (see FIG. 2).

  The antenna module 2 is provided inside the housing 32 of the electronic device 30 and communicates with the reader / writer 120 that is inductively coupled. In the present 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.

  The loop antenna 11 is provided inside the housing 32 of the electronic device 30 and has an antenna coil 12 (see FIG. 2) that can communicate with the reader / writer 120 by being inductively coupled to the reader / writer 120 serving as an external device. Go around. In the present embodiment, as shown in FIGS. 3A and 3B, the loop antenna 11 is provided in any of the vicinity of the outer edge portion 3a of the metal plate 3 serving as the first conductor. That is, the loop antenna 11 is provided in the vicinity of one side 3a1 in the outer edge portion 3a of the metal plate 3 as shown in FIG. As shown in FIG. 1, the loop antenna 11 includes an antenna coil 12 formed by patterning a flexible conductive wire such as a flexible flat cable, and the antenna coil 12 and the communication processing unit 13 are electrically connected. The terminal part 14 connected to the is mounted. In the present specification, “in the vicinity of the outer edge portion 3a of the metal plate 3” refers to a spatial region including a region close to the outer edge portion 3a from a position immediately above the outer edge portion 3a of the metal plate 3.

  As shown in FIG. 2A, the loop antenna 11 has a substantially rectangular shape, and one conductor wire of the antenna coil 12 is circulated along the outer shape, and the central portion 12a is an opening. 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. 2A, the loop antenna 11 is disposed so 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 12b 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 30 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 when the antenna module 2 communicates. As the first conductor, for example, a metal cover affixed to the inner surface of the smartphone casing, a metal casing of a battery pack stored 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 magnetic sheet 20 has a function of guiding the magnetic flux sent from the reader / writer 120 during communication of the antenna module 2 to the central portion 12 a of the loop antenna 11 in order to improve the communication characteristics of the antenna module 2. The magnetic sheet 20 is formed of a magnetic material such as iron oxide, chromium oxide, cobalt, or ferrite. In this embodiment, as shown in FIGS. 3 (A) and 3 (B), the magnetic sheet 20 is formed from the central portion 12a of the loop antenna 11. One of the outer edges 3 a of the conductor 3 is provided so as to expand toward the opposite end 3 a 2 facing the loop antenna 11. That is, as shown in FIG. 3B, out of the outer edge 3a of the metal plate 3 where the loop antenna 11 is provided, from one side 3a1 where the loop antenna 11 is provided toward the opposite side 3a2 facing the one side 3a1, The metal plate 3 is provided so as to be shielded.

  In the present embodiment, the magnetic sheet 20 includes a first magnetic sheet 21 that is inserted into an opening formed in the center portion 12 a of the loop antenna 11 in the longitudinal direction, and an opposite end portion from the center portion 12 a of the loop antenna 11. And a second magnetic sheet 22 developed toward 3a2. That is, with respect to the first magnetic sheet 21 inserted into the center portion 12 a of the loop antenna 11, the second magnetic sheet 22 faces the loop antenna 11 from the center portion 12 a to the outer edge portion 3 a of the metal plate 3. It is provided so that it may expand | deploy toward the opposing edge part 3a2 which has in the position to do. In the present embodiment, the first magnetic sheet 21 and the second magnetic sheet 22 are integrally molded in order to make the magnetic sheet 20 simple and easy to manufacture.

  In the present specification, the “opposing end portion” indicates a portion or a region of the outer edge portion 3 a that is located at a position facing the portion where the loop antenna 11 is provided in the outer edge portion 3 a of the metal plate 3. That is, in the example shown in FIG. 3 (B), the opposite side 3a2 that is located at a position facing the one side 3a1 that is a portion where the loop antenna 11 is provided in the outer edge portion 3a of the substantially rectangular metal plate 3 is shown.

  In the present embodiment, the second magnetic sheet 22 is expanded toward the facing end 3 a 2 facing the loop antenna 11 in the outer edge 3 a of the metal plate 3. Is provided. Specifically, as shown in FIG. 3 (B), the second magnetic sheet 22 has a side opposite to the one side 3a1 from one side 3a1 where the loop antenna 11 is provided in the outer edge portion 3a of the metal plate 3. The metal plate 3 is provided so as to be shielded toward 3a2.

  In the present embodiment, the second magnetic sheet 22 shields the metal plate 3 from the center portion 12a of the loop antenna 11 to a portion in the middle from the one side 3a1 to the opposite side 3a2 of the outer edge portion 3a of the metal plate 3. ing. However, in order to more reliably collect the magnetic flux from the reader / writer 120 and send it to the central portion 12a of the loop antenna 11, the second until the opposite side 3a2 that is the opposite end of the one side 3a1 of the outer edge 3a is reached. It is preferable to develop the magnetic sheet.

  As described above, in the present embodiment, the magnetic sheet 20 provided so as to expand from the portion 3a1 where the loop antenna 11 is provided to the opposing end 3a2 in the outer edge portion 3a of the metal plate 3 is used as the first. The metal plate 3 serving as the conductor is shielded. For this reason, the magnetic flux sent from the reader / writer 120 when the antenna device 1 provided in the electronic device 30 performs near-field non-contact communication with the reader / writer 120 is provided so as to shield the metal plate 3. It is collected by the magnetic sheet 22. Then, the magnetic flux from the reader / writer 120 collected by the second magnetic sheet 22 is drawn into the central portion 12 a of the loop antenna 11 via the first magnetic sheet 21. In this way, a large electromotive force is generated in the antenna coil 12 by the magnetic flux guided to the central portion 12a of the loop antenna 11 via the second magnetic sheet 22 and the first magnetic sheet 21, and therefore the antenna device 1 The communication characteristics by NFC are further improved.

  That is, in the present embodiment, when viewed from the reader / writer 120, the center portion 12a of the loop antenna 11 provided on the one side 3a1 that is the outer edge portion 3a of the metal plate 3 extends to the opposite side 3a2 that is the opposite end portion of the outer edge portion 3a. The metal plate 3 is shielded by a second magnetic sheet 22 that is additionally provided with respect to the first magnetic sheet 21 so as to unfold. In other words, the second magnetic sheet 22 is provided on the upstream side of the flow of magnetic flux received from the reader / writer 120 to shield the metal plate 3. For this reason, the outer edge portion 3a of the metal plate 3 provided in the antenna module 2 provided in the antenna module 2 is built in the electronic device 30 such as a portable terminal and uses the magnetic flux concentration due to the magnetic shield effect of the metal plate 3 such as the substrate. Communication characteristic performance is improved.

  In other words, in the present embodiment, the second magnetic sheet 22 provided so as to shield the metal plate 3 reliably collects the magnetic flux sent from the reader / writer 120 toward the metal plate 3, The magnetic flux can be sent to the central portion 12 a of the loop antenna 11 through the first magnetic sheet 21. For this reason, even if the electronic device 30 is downsized and multifunctional, the antenna module 2 having high-performance communication characteristics can be realized by utilizing the magnetic shielding effect of the main metal plate 3. In particular, when the metal plate 3 serving as the first conductor is a metal cover that covers the casing 32 of the electronic device 30, the metal cover is shielded by the second magnetic sheet 22, thereby reducing the size and multifunction. The NFC communication characteristics can be enhanced by utilizing the magnetic shield effect of the main metal plate 3 of the electronic device 30 that is becoming increasingly popular.

  As described above, in order to improve communication characteristics by utilizing the concentration of magnetic flux due to the magnetic shielding effect of the metal plate 3 such as a substrate, the magnetic flux from the reader / writer 120 collected by the second magnetic sheet 22 is used as the first magnetic material. The sheet 21 needs to be sent to the central portion 12a of the loop antenna 11 via the sheet 21. For this reason, in the present embodiment, the first magnetic sheet 21 has one end thereof (in the present embodiment, the first magnetic sheet 21 and the second magnetic sheet 22 are integrally molded, so the second magnetic sheet 22) is arranged above the one side portion 11a when viewed from the reader / writer 120, and a portion excluding the one end (a tip side portion of the first magnetic sheet 21 in the Y direction shown in FIG. 2B) is the reader / writer 120. As seen from the other side 11b.

  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 according to the embodiment of the present invention described above, the first magnetic sheet 21 and the second magnetic sheet 22 constituting the magnetic sheet 20 are integrally molded. It is also possible to have a configuration of That is, the antenna device 1 of the present embodiment can be applied to the following modified examples according to the specifications of the electronic device 30 to be mounted.

  For example, in order to increase the degree of freedom in designing the magnetic sheet, as shown in FIGS. 4A and 4B, the first magnetic sheet 21a and the second magnetic sheet 22a constituting the magnetic sheet 20a are separately molded. Then, it is good also as a connected structure. In this way, by forming the first magnetic sheet 21a and the second magnetic sheet 22a separately and then connecting them, a more suitable shape and size according to the specifications and configuration of the electronic device 30. The second magnetic sheet 22a can be provided.

  Moreover, in order to make it applicable according to the specification of the electronic device 30 which mounts the antenna device 1 which concerns on one Embodiment of this invention, as shown in FIG. 5, a camera, a microphone, etc. are shown in the 2nd magnetic sheet 22b. A hole 22b1 for using an electronic component or a notch 22c1 as shown in FIG. 6 may be formed. The hole 22b1 of the second magnetic sheet 22b is formed at a portion facing the opening 3g1 provided in the metal plate 3 (see FIGS. 10A and 10B). The hole 22b1 preferably has a smaller outer diameter than the opening 3g1 in order to reliably collect the magnetic flux around the opening 3g1 and send it to the center 12a of the loop antenna 11.

  Further, as shown in FIG. 7, the second magnetic sheet 22d is configured to be narrower than the loop antenna 11 or the first magnetic sheet 21d, or as shown in FIG. One magnetic sheet 21e may be off-center.

  Further, the mounting portion of the antenna device 1 according to the embodiment of the present invention is not limited to the planar metal plate 3. For example, the antenna device 1 can be mounted on a bent metal cover 3f having a slope 3f1 as shown in FIG. At this time, as shown in FIG. 9B, the first magnetic sheet 21f and the second magnetic sheet 22f are formed by integral molding, but the first magnetic sheet 21g and the second magnetic sheet 22g are separately formed. It may be molded and pasted with the body.

  Furthermore, as shown in FIG. 10A, the antenna device 1 can be mounted on a metal cover 3g in which an opening 3g1 is formed. In this modification, the first conductor is a bent metal cover 3g having an inclined surface 3g1, and as shown in FIG. 10B, the loop antenna 11g is provided on the inclined surface 3g1 of the metal cover 3g. . The magnetic flux from the reader / writer 120 collected by the second magnetic sheet 22g is sent to the loop antenna 11g via the second magnetic sheet 22g and the first magnetic sheet 21g.

  As a result of intensive studies in order to achieve the above-described object of the present invention, the present inventor has found that the second magnetic sheet is formed when the opening 3g1 is formed in the metal cover 3g serving as the first conductor. It was found that when the metal cover 3 is shielded at 22, the NFC communication characteristics utilizing the magnetic shielding effect of the metal plate 3 are greatly improved. For this reason, in this embodiment, the second magnetic body 22 is provided so as to shield the metal cover 3 in which the opening 3g1 is formed. In the modification shown in FIG. 10B, the first magnetic sheet 21g and the second magnetic sheet 22g are integrally formed. However, the first magnetic sheet 21g and the second magnetic sheet 22g are integrally formed. It is good also as a structure stuck after shape | molding separately.

Next, Example 1 of the antenna device according to one embodiment of the present invention, Comparative Example 1 as an example of a conventional antenna device corresponding to Example 1, and the antenna device according to one embodiment of the present invention Example 2 in the case where the metal plate has an opening and Comparative Example 2 that is an example of a conventional antenna device corresponding to Example 2 will be described in comparison. In addition, this invention is not limited to a present Example.

  Here, a reader / writer 120 that is opposed to each of Example 1 of the antenna device 1 (see FIG. 3) according to an embodiment of the present invention and a comparative example of the conventional antenna device 1h shown in FIG. The coupling coefficient when moving in the direction was determined by simulation.

That is, in Example 1, using the antenna device 1 according to one embodiment of the present invention shown in FIG. 3, the metal plate 3 and the reader / writer 120 (see FIG. 1) are opposed to each other, so that the metal plate 3 and the loop antenna. 11 was evaluated for communication characteristics when the relative positional relationship with the No. 11 was changed. In the first comparative example, the metal plate 3h and the reader / writer 120 (see FIG. 1) are opposed to each other using the antenna device 1h including the normal magnetic sheet 20h to which the second magnetic sheet is not added as shown in FIG. by, it was evaluated for the communication characteristics when changing the relative positional relationship between the metal plate 3h and the loop antenna 11 h.

  Further, in Example 2 and Comparative Example 2, the performance difference was evaluated when there was a metal cover with an opening on the top of the loop antenna 11. That is, in Example 2, when the first conductor is the metal cover 3g (see FIGS. 10A and 10B) and the opening 3g1 is formed in the metal cover 3g, the metal plate 3g Communication characteristics when the relative positional relationship between the metal plate 3g and the loop antenna 11 was changed while facing the reader / writer 120 (see FIG. 1) were evaluated. On the other hand, in the comparative example 2, the metal plate and the reader / writer are opposed to each other by using an antenna device including a normal magnetic sheet to which the second magnetic sheet is not added to the antenna device of the second embodiment. The communication characteristics when the relative positional relationship with the loop antenna was changed were evaluated.

  Specific evaluation conditions were as follows. That is, the antenna 121 of the reader / writer 120 is a two-turn coil having an outer diameter defined in the xy axis direction of 70 mm. Moreover, the metal plate 3 was made of stainless steel having dimensions defined in the xyz axis direction of 50 mm × 100 mm × 0.3 mm. The antenna coil 12 of the loop antenna 11 is a coil having a structure in which the outer shape defined in the xy-axis direction is 30 mm × 10 mm. Furthermore, the distance from the surface of the metal plate 3 defined by the z-axis direction to the surface of the antenna coil 12 was 4 mm. The distance between the reader / writer 120 and the antenna coil 12 was 45 mm.

  In Example 2 and Comparative Example 2, a metal plate having the same dimensions and material as in Example 1 and Comparative Example 1 was formed with an opening of 20 mm × 20 mm at a position 10 mm from the tip. The coupling coefficient when the opposing reader / writer was moved in a predetermined direction was obtained by simulation. In Example 1 and Example 2, the reader / writer was moved in the Y-axis direction shown in FIG. 3, and in Comparative Example 1 and Comparative Example 2, the reader / writer was moved in the X-axis direction shown in FIG.

  FIG. 12 shows a graph of changes in coupling coefficient according to Example 1 and Comparative Example 1, and FIG. 13 shows a graph of changes in coupling coefficient according to Example 2 and Comparative Example 2.

  When the change in the coupling coefficient between Example 1 and Comparative Example 1 is seen, as shown in FIG. 12, it can be seen that compared with Conventional Example 1, Example 1 has a somewhat improved communication characteristic of about 5%. . Therefore, by adding the second magnetic sheet 22 and deploying the magnetic sheet 20 from the center portion 12a of the loop antenna 11 toward the opposite end portion of the outer edge portion 3a of the metal plate 3, the NFC communication characteristics are obtained. It can be seen that there is a slight improvement.

  On the other hand, when the change of the coupling coefficient of Example 2 and Comparative Example 2 is seen, as shown in FIG. 13, compared with Conventional Example 2, Example 2 has significantly improved the communication characteristics of about 2.7 times. I understand that. For this reason, by adding the second magnetic sheet and deploying the magnetic sheet from the center of the loop antenna toward the opposite end of the outer edge of the metal plate, the NFC communication characteristics are greatly improved. I understand that.

  This may be because the magnetic flux received from the reader / writer is likely to leak from the opening of the metal cover when the antenna device performs near-field non-contact communication with the reader / writer. That is, since the second magnetic sheet is provided on the upstream side of the flow of magnetic flux from the reader / writer, the magnetic flux that leaks from the opening of the metal cover is reliably collected by the second magnetic sheet. Then, by guiding the magnetic flux collected by the second magnetic sheet to the center portion of the loop antenna via the first magnetic sheet, a large electromotive force is generated in the antenna coil and communication characteristics can be further improved. Can be considered as the reason.

  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 Outer edge part, 3a2 Opposite edge part, 3g Metal cover, 3g1 opening part, 11 Loop antenna, 11a One side part, 11b The other side part, 12 antenna coil, 12a center part, 12b center line, 13 communication processing part, 14 terminal part, 20 magnetic sheet, 21 first magnetic sheet, 22 second magnetic sheet, 22b1 hole part, 22c1 notch, 30 electronic equipment 32 Housing, 120 Reader / writer (external device), 121 Antenna, 122 Control board

Claims (7)

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 around any of the outer edge portions of the first conductor and around which an antenna coil inductively coupled to the external device;
Is formed of a magnetic material, and a magnetic sheet provided so as to expand toward the center of the loop antenna at opposite ends facing the said loop antenna of said outer edge,
The first conductor is a metal cover covering the housing;
An antenna device in which an opening is formed in any part of the metal cover . The loop antenna is divided into one side and the other side via a longitudinal center line,
The magnetic sheet includes a first magnetic sheet extending from the central portion of the loop antenna to end portions in the width direction of the one side portion and the other side portion, and from the central portion of the loop antenna. A second magnetic sheet developed toward the opposite end,
One end of the first magnetic sheet is disposed above the one side as viewed from the external device, and a portion other than the one end is disposed below the other side as viewed from the external device. The antenna device according to claim 1 , provided as described above. The antenna device according to claim 2 , wherein the second magnetic sheet has a configuration in which at least one of a hole and a notch is formed. The antenna device according to claim 3 , wherein the hole is formed in a portion facing the opening and has an outer diameter smaller than that of the opening. The antenna device according to claim 2, wherein the first magnetic sheet and the second magnetic sheet are integrally molded. The antenna device according to any one of claims 2 to 4 , wherein the first magnetic sheet and the second magnetic sheet are separately molded and connected. An electronic device in which the antenna device according to any one of claims 1 to 6 is incorporated and can communicate with an external device via an electromagnetic field signal.

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