JP2014225817A - Antenna, antenna device and communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna, an antenna device and a communication apparatus capable of easily performing satisfactory communication even when no metal body is disposed nearby or the antenna is disposed in a metal body.SOLUTION: The antenna includes: a core 11 having a plane; a coil-wound portion (rejoin B) wound with a coil on the plane; and plural non-coil wound portions (rejoin A, C) wound with no coil on the plane. The coil-wound portion (rejoin B) is positioned between the plural non-coil wound portions (rejoin A, C) in a first direction on the plane. Each of the plural non-coil wound portions (rejoin A, C) is inclined in an identical direction with respect to the axis of the coil.

Description

  The present invention relates to an antenna, an antenna device, and a communication device that perform communication with a wireless communication medium such as an IC card or IC tag such as an RF-ID or NFC.

  Conventionally, when an antenna is mounted in a metal casing, the metal body cancels out the magnetic flux generated by the antenna. Therefore, the magnetic field generated by the antenna does not reach the outside of the metal body, and the communication characteristics of the antenna can be maintained. It was difficult.

  Therefore, a technique has been proposed in which a through hole and a slot for connecting the end of the metal body and the through hole are provided in the metal body, and a loop antenna disposed so as to overlap the metal body is arranged around the through hole. (For example, refer to Patent Document 1). As a result, communication can be performed using a metal body.

Japanese Patent No. 5177314

  However, in the technique described in (Patent Document 1), it is necessary to open a through-hole of about the opening area of the antenna in the metal body, which is contrary to the improvement in communication characteristics as the opening area of the antenna is larger. It was difficult to make the through hole small. Furthermore, a slot for connecting the end portion of the metal body and the through hole is indispensable, and the freedom of arrangement of the antenna is limited by the slot. Furthermore, good communication characteristics cannot be obtained with a single antenna unless a metal body is used.

  Therefore, the present invention has good communication characteristics even if the metal body is not disposed nearby, and even if the antenna is disposed in the metal body, only a simple hole is provided in the metal body. An object of the present invention is to provide an antenna, an antenna device, and an electronic device that can easily perform good communication with the outside.

  The present invention includes a core having a surface, a coil winding portion in which a coil is wound on the surface, and a plurality of coil non-winding portions in which the coil is not wound out of the surface. The coil winding part is sandwiched between the plurality of coil non-winding parts in the first direction on the surface, and each of the plurality of coil non-winding parts is the same on the basis of the axis of the coil. The antenna is characterized by being inclined in the direction.

  According to the present invention, even if the metal body is not disposed nearby, the metal body has good communication characteristics, and even if the antenna is disposed in the metal body, only the simple hole is provided in the metal body. Good communication can be easily performed with the outside. Furthermore, even if a hole is covered with a metal body, communication can be performed and the area of the hole can be reduced.

1 is an exploded perspective view of a mobile terminal equipped with an antenna according to Embodiment 1 of the present invention. The perspective view of the antenna in Embodiment 1 of this invention 1 is an exploded perspective view of an antenna according to Embodiment 1 of the present invention. The perspective view of the core in Embodiment 1 of this invention 1 is an exploded perspective view of a mobile terminal equipped with an antenna according to Embodiment 1 of the present invention. 1 is an exploded perspective view of a mobile terminal equipped with an antenna according to Embodiment 1 of the present invention. The figure which shows an example of the conventional antenna The figure which shows the magnetic field which the antenna in Embodiment 1 of this invention generates The figure which shows the magnetic field which the antenna of FIG. 7 generates The figure which shows the magnetic field which the antenna in Embodiment 1 of this invention generates The figure which shows the magnetic field which the antenna of FIG. 7 generates The figure which shows the communication possible distance when the antennas in Embodiment 1 of this invention and the antenna of FIG. The figure which shows the communicable distance when the antennas are facing each other at an angle of 45 degrees in the antenna according to Embodiment 1 of the present invention and the antenna of FIG. The figure which shows the relationship between the size of the core of the antenna in Embodiment 1 of this invention, and the induced voltage of an antenna The figure which shows arrangement | positioning with the antenna of Embodiment 1 of this invention in an electronic device, the conventional antenna, and the antenna of another frequency band The perspective view of the antenna of this Embodiment The perspective view of the antenna of this Embodiment 1 is an exploded perspective view of a mobile terminal including a metal body on which an antenna according to Embodiment 1 of the present invention is mounted. 1 is an exploded perspective view of a mobile terminal including a metal body on which an antenna according to Embodiment 1 of the present invention is mounted. The figure which shows the relationship between a back cover, a slot, and an antenna in Embodiment 1 of this invention. The figure which shows the relationship between the magnetic flux which the antenna in Embodiment 1 of this invention generate | occur | produces, a back cover, and a slot. The figure which shows the electric current which flows into the back cover (metal body) in Embodiment 1 of this invention. Top view of an antenna provided with an inductance adjustment mechanism in Embodiment 1 of the present invention The figure explaining the parameter which determines the inductance of the antenna in Embodiment 1 of this invention The figure which shows a mode that the inductance in Embodiment 1 of this invention changed the inductance with the inductance adjustment mechanism. The disassembled perspective view of the portable terminal in which the antenna in Embodiment 2 of this invention is mounted. The perspective view of the antenna in Embodiment 2 of this invention The exploded perspective view of the antenna in Embodiment 2 of this invention The perspective view of the core in Embodiment 1 of this invention The figure which shows the electric current which flows into the metal plate by the antenna of Embodiment 2 of this invention The figure which shows the electric current which flows into the metal plate with the conventional antenna The figure which shows the magnetic field which the antenna of Embodiment 2 of this invention and the conventional antenna form The figure which shows the electric current in the case with a cap in the antenna of Embodiment 2 of this invention. The figure which shows the magnetic field in the case of with and without a cap in the antenna of Embodiment 2 of this invention. The figure which shows the connection of the cap and back cover in the antenna of Embodiment 2 of this invention

  The present invention includes a core having a surface, a coil winding portion in which a coil is wound on the surface, and a plurality of coil non-winding portions in which the coil is not wound out of the surface, The coil winding portion is sandwiched between the plurality of coil non-winding portions in a first direction on the surface, and each of the plurality of coil non-winding portions is in the same direction with respect to the axis of the coil The antenna is characterized in that it has good communication characteristics even if the metal body is not placed nearby, and even if the antenna is placed in the metal body, only a simple hole is made in the metal. Good communication can be easily performed with the outside of the metal body simply by being provided on the body.

(Embodiment 1)
FIG. 1 is an exploded perspective view of a mobile terminal on which an antenna according to Embodiment 1 of the present invention is mounted. The mobile terminal 1 includes a display panel 2, a back cover 3, a battery 4 that is housed between the display panel 2 and the back cover 3, a camera 5, an electronic circuit board 6, and the like. As shown in FIG. 1, the display panel 2 may be a touch panel type and may not have an operation button. However, the display panel 2 may or may not be a touch panel type, and may have a separate operation button. good. The display panel 2 is a liquid crystal panel and includes a panel cover 2a. On the back cover 3, the antenna 8 according to the first embodiment of the present invention is mounted by sticking with an adhesive tape or fixing with a screw. At this time, the back cover 3 may be a non-metallic body such as a resin or a metallic body. The back cover 3 in FIG. 1 is a resin. In FIG. 1, the antenna 8 is arranged so as not to overlap the camera 5. Although the antenna 8 may be disposed so as to overlap the battery 4, the entire mobile terminal 1 can be thinned by being disposed so as to overlap the thinner electronic circuit board 6. In the first embodiment, the antenna 8 is arranged on the flat portion of the back cover 3, but it can be arranged along the curved surface of the back cover 3. Moreover, it is preferable that the longitudinal direction of the back cover 3 and the axial direction (longitudinal direction) of the coil of the antenna 8 are substantially the same direction as shown in FIG. Thereby, the communication direction of the antenna 8 becomes a direction convenient for the user.

  External connection terminals 8 a and 8 b for forming an antenna device by connecting to the electronic circuit board 6 are provided on the surface of the antenna 8 facing the electronic circuit board 6. The connection between the electronic circuit board 6 and the antenna 8 may be contact with a pin, connector connection, or soldering of a conductive wire. In the first embodiment, the electronic circuit board 6 includes antenna input / output pins 7a and 7b. As generally known, the antenna input / output pins 7a and 7b are connected to an antenna control unit 9 on an electronic circuit board 6 on which a matching circuit, a control IC, and the like are arranged. The antenna input / output pins 7a and 7b are connected to coil portions having both ends of the external connection terminals 8a and 8b provided on the antenna 8, thereby forming an antenna device. In the space formed between the back cover 3 and the display panel 2, components such as an antenna for other frequencies, a speaker, and an RF module are arranged in addition to the IC for RF-ID and the matching circuit.

  FIG. 2 is a perspective view of the antenna according to Embodiment 1 of the present invention. FIG. 3 is an exploded perspective view of the antenna according to Embodiment 1 of the present invention. Furthermore, FIG. 4 is a perspective view of the core in Embodiment 1 of the present invention.

  As shown in FIG. 2, the antenna 8 according to the first embodiment of the present invention includes a thin plate-like core 11 having a surface, and a coil winding portion (region B) around which the coil is wound. And a plurality of non-coiled portions (regions A and C) in which the coil is not wound on the surface, and the coil-wound portion is a plurality of non-coiled portions in the axial direction of the coil on the surface. The width of the surface in the axial direction of the coil (first direction) is greater than or equal to the width of the coil winding direction (second direction). More preferably, the core 11 has a plate shape having a substantially rectangular surface as a front surface or a back surface, and the coil is wound so that the short direction of the surface intersects the axial direction of the coil. More preferably, the axial direction of the coil is substantially the same as the longitudinal direction of the surface of the core 11 (within ± 10 degrees). That the core 11 is plate-shaped means that the thickness of the core 11 is very small compared to the vertical and horizontal widths of the surface of the core 11 and is 10% or less, preferably 5% or less of the width of the surface. Indicates that there is.

  In addition, in the axial direction of the coil, the overall length of the plurality of coil non-winding portions (regions A and C) is preferably equal to or greater than the length of the coil winding portion (region B). That is, in the axial direction of the coil, the total length obtained by adding the lengths of the regions A and C is not less than the length of the region B, and the length of the core 11 is not less than twice the length of the region B. Become. More preferably, the length of each of the plurality of coil non-winding portions (regions A and C) is substantially the same as the length of the coil winding portion (region B). That is, the length of the core 11 is about three times the length of the region B in the axial direction of the coil.

  More specifically, the antenna pattern is formed on a core 11 made of a magnetic material such as ferrite, amorphous, silicon steel, permalloy, or soft magnetic material, and disposed around the core 11 and mainly made of resin. And a flexible substrate 12 on which a coil pattern (conductive wire) and the like are formed. In the first embodiment, the core 11 is made of ferrite, and in the first embodiment, the size is 40 × 10 × 0.3 mm, and due to variation in the firing dimensions, 39.5 to 40.5 mm × 9.7 to It may be about 10.3 mm × 0.27 to 0.33 mm. The shape of the core 11 is a parallelepiped, particularly a rectangular parallelepiped plate, and the two large surfaces are preferably rectangular but may be square. The coil pattern referred to here is a coil pattern that generates magnetic lines of force for communicating with a wireless communication medium such as an IC card or IC tag (not shown) and has an arrow S as a coil axis. The coil pattern is usually formed by a copper foil formed between two resin layers of the flexible substrate 12 such as a polyimide film and a coverlay or a resist. The coil axis S is a coil pattern wound about the coil axis S and is substantially perpendicular to the coil pattern of the flexible substrate 12. The conductive wire is not limited to a conductor pattern, and a metal wire or the like may be wound around the core 11, or a conductor film may be formed on the core 11. The external connection terminals 8 a and 8 b are located outside the core 11.

  As for the shape of the core 11, the longitudinal direction is the same direction as the coil axis S as shown in FIG. 2, and the short direction is the same direction as the winding direction of the coil pattern. The core 11 can have the effect of forming a large antenna even with a small coil pattern by making the width in the longitudinal direction at least twice as large as the width in the short direction, preferably 3 times or more. . Details will be described later.

  As shown in FIG. 3, the flexible substrate 12 has a shape divided into two with the core 11 interposed therebetween. In the first embodiment, for convenience, the side having the external connection terminals 8a and 8b among the two flexible substrates 12 divided into two is the lower flexible substrate 12a, and the other side is the upper flexible substrate 12b. As will be described in detail later, the lower flexible substrate 12a and the upper flexible substrate 12b are joined by solder. In the first embodiment, the flexible substrate 12 is joined at two sides substantially parallel to the coil axis S. Further, “lower side” and “upper side” are given for convenience in order to facilitate understanding in FIG. 3, and when the antenna 8 is mounted on a device, it may be upside down.

  In order to fix the core 11 between the lower flexible substrate 12a and the upper flexible substrate 12b, double-sided adhesive tapes 31 and 32 as adhesive layers are used in the first embodiment. That is, the double-sided adhesive tape 32 is affixed between the core 11 and the lower flexible substrate 12a, and the double-sided adhesive tape 31 is affixed between the core 11 and the upper flexible substrate 12b. Furthermore, a double-sided adhesive tape 33 for attaching the antenna 8 to the back cover of FIG. 1 is provided.

  Further, since the core 11 is inevitably exposed from the flexible substrate 12, the entire core 11 is firmly protected from both sides by the protective tapes 34 and 35 as shown in FIG. That is, the core 11 has a protective member separately from the flexible substrate 12 because the characteristics are easily changed due to breakage or the like. Moreover, in this Embodiment 1, the core 11 consists of a ferrite sintered body, and in order to have a softness | flexibility, it is grind | pulverized into the several small piece beforehand. In order to maintain these small pieces in a sheet shape, protective tapes 34 and 35 are provided. This also allows the antenna 8 to be affixed and disposed along the curved surface, even if the part affixed to the back cover 3 has a curved surface. Further, by crushing into small pieces, it becomes difficult to break further, and characteristic deterioration due to breakage can be prevented.

  About the fixing method of the core 11 to the flexible substrate 12, as shown in this Embodiment 1, it does not necessarily need to stick the double-sided adhesive tape on both surfaces of the core 11. FIG.

  With reference to FIG. 3 again, the first embodiment will be described. As described above, the lower flexible substrate 12a and the upper flexible substrate 12b constituting the flexible substrate 12 are joined to each other by soldering at two sides of the flexible substrate 12 substantially parallel to the coil axis S. Thereby, a coil pattern is formed by the lower flexible substrate 12a and the upper flexible substrate 12b.

  Next, the size of the core 11 and the flexible substrate 12 which is one characteristic of the antenna 8 of the first embodiment will be described. As described above, the core 11 has a shape extending longer in the longitudinal direction as the width in the longitudinal direction is four times the width in the shorter direction. And the flexible substrate 12 is located in the approximate center (area | region B of FIG. 2) of the longitudinal direction of the core 11. As shown in FIG. Magnetic flux is most efficiently generated when the flexible substrate 12 is substantially in the center in the longitudinal direction of the core 11, but may be arranged at another position depending on the application. The width in the same direction of the flexible substrate 12 is smaller than the width in the longitudinal direction of the core 11, and preferably less than half the width in the longitudinal direction of the core 11. In the first embodiment, the width of the flexible substrate 12 in the longitudinal direction of the core 11 is 20 mm. In FIG. 2, the width of the core 11 in the longitudinal direction is about region A: region B: region C = 1: 2: 1. On the other hand, the width of the flexible substrate 12 in the same direction is larger than the width of the core 11 in the short direction, and the length necessary for joining the lower flexible substrate 12a and the upper flexible substrate 12b with solder or the like. That's big.

  By adopting such a shape, it is possible to achieve both reduction in size and improvement in characteristics of the antenna 8. That is, the region B where the flexible substrate 12 is provided is thicker than the regions A and C where the flexible substrate 12 is not provided. That is, by making the region B as small as possible, the antenna 8 can be reduced in thickness and size. Although there is a possibility that the characteristics of the antenna 8 are deteriorated by reducing the area B, it is possible to obtain sufficient performance even if the area B is reduced by increasing the size of the core 11. Furthermore, even if the size of the region B is constant and the number of windings is constant, the characteristics can be changed by changing the lengths of the regions A and C. That is, the characteristics can be improved by setting at least one of the regions A and C longer.

  Next, the arrangement and shape of the antenna 8 in the mobile terminal 1 different from those in FIG. 1 will be described. FIG. 5 is an exploded perspective view of the mobile terminal on which the antenna according to Embodiment 1 of the present invention is mounted. FIG. 6 is an exploded perspective view of the mobile terminal on which the antenna according to Embodiment 1 of the present invention is mounted. However, the antenna 8 of FIGS. 5 and 6 is basically the same as the antenna 8 of FIG. 1 and is almost the same, although there are some differences in characteristics and effects.

  5 differs from FIG. 1 in that a part of the core 11 of the antenna 8 (a portion corresponding to the region A or the region C in FIG. 2) overlaps the battery 4. As described above, even when the antenna 8 is arranged at the approximate center of the back cover 3, high-quality communication can be performed. That is, in view of the communication characteristics of the antenna 8, there is no problem even if it is disposed at any location on the back cover 3. However, by disposing at the end, various parts (particularly parts containing metal) in the casing located around the antenna 8 are reduced, and the antenna 8 is not easily affected by them. As shown in FIG. Further, the thickness of the core 11 may not be uniform. It is possible to make the portion overlapping with the battery 4 thin, or to make the portion overlapping with other parts thin. You may change the thickness of the core 11 so that it may arrange | position easily within a housing | casing. Note that even if the antenna 8 is arranged in the center, oblique communication is possible. However, since the shape of the mobile terminal 1 is difficult to perform communication in an oblique direction, the end arrangement is preferable. 6 includes a through hole in a part of the core 11 (a portion corresponding to the region A or the region C in FIG. 2). The through hole overlaps with the through hole provided in the back cover 3, and the camera 5 is inserted into the through hole. That is, the core 11 is disposed so as to surround the camera 5. Thereby, the adverse effect of the camera (metal body) can be reduced. This is because the magnetic flux hardly reaches the camera because the magnetic flux passes through the core 11.

  Next, the reason why the antenna 8 of the present invention has good characteristics will be described. In order to make the explanation easy to understand, it is compared with the conventional antenna of FIG.

  FIG. 7 is a diagram illustrating an example of a conventional antenna. FIG. 8 is a diagram showing a magnetic field generated by the antenna according to Embodiment 1 of the present invention. FIG. 9 is a diagram illustrating a magnetic field generated by the antenna of FIG. FIG. 10 is a diagram showing a magnetic field generated by the antenna according to Embodiment 1 of the present invention. FIG. 11 is a diagram illustrating a magnetic field generated by the antenna of FIG. FIG. 12 is a diagram illustrating a communicable distance when the antennas of the antenna according to Embodiment 1 of the present invention and the antenna of FIG. 7 face each other in parallel. FIG. 13 is a diagram showing a communicable distance when the antennas of the antenna according to Embodiment 1 of the present invention and the antenna of FIG. 7 face each other at an angle of 45 degrees. 8 to 13, the antenna 8 and the antenna 108 are placed on the metal body 103, and the metal body 103 is for considering the influence of the metal body in the mobile terminal 1.

  One of the differences between the antenna 8 of the present invention shown in FIG. 2 and the conventional antenna 108 shown in FIG. 7 is the difference in the sizes of the areas A and C. The conventional antenna 108 of FIG. 7 has almost no region A and region C, but the antenna 8 of the present invention has the region A and region C and protrudes from the flexible substrate 12. Since the region A and the region C function in the same manner as the opening of the coil, they serve as an entrance and an exit for the generated magnetic flux. That is, in FIG. 8, the magnetic flux enters the core 11 with the region A as a large entrance, passes through the space sandwiched between the flexible substrates 12, and the magnetic flux exits the core 11 with the region C as a large exit. .

  In the conventional antenna 108, the area of the flexible substrate is 12.5 mm × 46 mm with respect to the core size 12 mm × 42 mm × 0.3 mm. On the other hand, in the antenna 8 of the present invention, the area of the flexible substrate 12 is 20 mm × 16 mm with respect to the size of the core 11 of 40 mm × 10 mm × 0.3 mm. Thus, the antenna 8 of the present invention is smaller in both the core and the flexible substrate (that is, the size of the coil). That is, when an antenna having the same size as the conventional one is formed in the size of the embodiment of the present invention, it is obvious that the antenna 8 of the present invention deteriorates characteristics such as the size of the communicable area and the communication distance.

  However, the area of the Z direction (vertical direction) component of FIG. 8 becomes large among the magnetic fluxes (magnetic fluxes used for communication) generated by the antenna 8 of the present invention. On the other hand, in the conventional antenna 108 of FIG. 9, since the opening area is small, the magnetic flux concentrates in the small opening, and the area of the Z direction component of the magnetic flux used for communication is reduced. Thus, even if the conventional antenna (general antenna) has an opening area in the axial direction of the coil, it is difficult to have an opening area other than in the axial direction of the coil. As a result, the communicable area is biased, and if the area deviates even a little, communication becomes difficult immediately. The region where communication is difficult means that among the magnetic fluxes generated by one antenna, both the magnetic flux from one antenna to the other antenna and the magnetic flux from the other antenna to the one antenna penetrate the other antenna. This is a case where the magnetic flux generated by one antenna is canceled. Since the conventional antenna 108 has a small opening area of the coil, it easily falls into a situation where magnetic fluxes cancel each other. On the other hand, since the antenna 8 of the present invention has a large coil opening area, the bidirectional magnetic flux hardly penetrates the counterpart antenna. As described above, in the conventional antenna 108 and other antennas, generally, the entrance and exit of the magnetic flux are directed in the axial direction of the coil. Therefore, the main communication direction is basically the axial direction of the coil, and communication in other directions becomes difficult. On the other hand, in the antenna 8, the core 11 has a plate shape, and two large surfaces face the Z direction in FIG. 8 and do not face the axial direction of the coil of the antenna 8. And since the surface which forms the entrance and exit of magnetic flux is formed in directions (Z direction) other than the axial direction of a coil, favorable communication can be performed also in directions (Z direction) other than the axial direction of a coil. Of course, since communication is possible also in the axial direction of the coil, the communicable region can be expanded three-dimensionally from the axial direction of the coil to the direction in which the surface of the core 11 faces.

  Similar to FIGS. 10 and 11, it can be seen that the portable antenna 8 of FIG. 10 has a wide range of magnetic flux in the Z45 direction. This is because since the area of the region C is large, the same effect as that of the large opening area of the antenna 8 can be obtained. On the other hand, in the conventional antenna 108 of FIG. 11, since the opening area is small, the magnetic flux concentrates in the small opening, and the area of the Z45 direction component of the magnetic flux used for communication becomes small. As a result, the communicable area is biased, and if the area deviates even a little, communication becomes difficult immediately.

  These results are shown in FIGS.

  Under the conditions of FIGS. 12A and 12B, experimental results as shown in FIGS. 12C and 12D were obtained. That is, FIG. 12A is a diagram of a case in which communication is performed while the antenna to be communicated faces the antenna 8 or the antenna 108 in parallel, and the positional relationship is coordinates (0, 0). . The communication distance referred to here is the distance from the surface of the antenna that is the communication partner to the surface of the antenna 8. FIG. 12B is a view of FIG. 12A as viewed from above. FIG.12 (c) is a figure which shows the communicable distance of the antenna 8 of this invention according to a coordinate. FIG. 12D is a diagram showing the communicable distance of the conventional antenna 108 by coordinates. The coordinate (0, 0) is the short side (the upper side of FIGS. 12B and 13B) of the end of the metal body 103 in the arrangement of the metal body 103 and the antennas 8 and 108 in FIGS. This means that the center point of (side) coincides with the center point of the communication partner card (80 mm × 50 mm). In FIG. 13, the short side of the end of the metal body 103 means the short side of the surface on which the antennas 8 and 108 are placed.

  As shown in FIG. 12 (c), the antenna 8 of the present invention has less deviation in communication distance due to coordinates, and can stably communicate over a wide range. Further, in most areas, the communication distance has increased. On the other hand, in the conventional antenna 108, there is a considerable variation in the communication distance, and communication is particularly difficult at a position where Y = 0 mm. In addition, since there is an area where communication is difficult in the middle of the communication area, it is particularly difficult to perform communication stably.

  Further, under the conditions shown in FIGS. 13A and 13B, experimental results as shown in FIGS. 13C and 13D were obtained. That is, FIG. 13 (a) is a diagram seen from the side where the antenna to be communicated communicates with the antenna 8 or the antenna 108 at an angle of 45 degrees, and the positional relationship is expressed by coordinates (0, 0). It is. Moreover, FIG.13 (b) is the figure which looked at Fig.13 (a) from the top. FIG.13 (c) is a figure which shows the communicable distance of the antenna 8 of this invention according to a coordinate. FIG. 13D is a diagram illustrating the communicable distance of the conventional antenna 108 by coordinates.

  As shown in FIG. 13C, the antenna 8 of the present invention has a small communication distance due to coordinates and can stably communicate over a wide range. On the other hand, in the conventional antenna 108, there is a considerable variation in the communication distance, and communication is particularly difficult at a position where Y = 15 mm. Of course, communication in the axial direction of the coil is possible satisfactorily.

  From these results, compared with the conventional antenna 108 of FIG. 7, the antenna 8 of the present invention is stable in a wide range regardless of whether the communicating antennas face each other in parallel or obliquely. Can communicate. This is because the area where the magnetic field spreads has increased because the areas of the area A and the area C in FIG. 2 have increased. That is, when the antenna 8 communicates with the other antenna, a magnetic flux from the antenna 8 side toward the other antenna side and a magnetic flux from the other antenna side toward the antenna 8 side are generated. If the magnetic fluxes in both directions penetrate through the other antennas, the magnetic fluxes in the respective directions cancel each other, and communication cannot be performed. When the opening area of the coil is narrow as in the conventional antenna 108, the magnetic flux concentrates on the narrow opening area, so that the area where the magnetic flux in one direction spreads is small. As a result, both bidirectional magnetic fluxes tend to penetrate through an antenna of a card-sized area (about 80 mm × about 50 mm) (the direction other than the axial direction of the coil is also the communication direction, and the bidirectional magnetic flux Because there is nearby). On the other hand, in the antenna 8 of the present invention, since the area in which the magnetic flux in one direction spreads is large, it is difficult for both bidirectional magnetic fluxes to penetrate through the antenna having a large card area. In other words, communication can hardly be difficult because most of the card-sized antenna can be penetrated with a magnetic flux in one direction. Furthermore, it can be seen that the area of the flexible substrate 12 is considerably smaller in the antenna 8 of the present invention than in the conventional antenna 108, while the core 11 is kept to the same size. Furthermore, since the thick portion (region B) of the antenna 8 is reduced and the thin portions (regions A and C) are used, thickness and size can be reduced as compared with the conventional antenna 108. Nevertheless, the antenna 8 of the present invention can maintain a communication distance equal to or greater than that and can stably communicate over a wide range.

  Furthermore, as a feature of the present invention, communication characteristics can be improved as a communication direction even in a direction different from the axial direction of the coil constituting the flexible substrate 12. That is, when FIG. 8 is seen, the axial direction of the coil of the antenna 8 is the left-right direction, and communication in the left-right direction is also possible. For example, with a general antenna, only the coil axis direction is likely to be the main communication direction. However, the antenna 8 of the present invention has a plate-like core 11, and two large surfaces provided in the core 11 are directed to the back cover 3, but the other is the main communication direction. Facing. And by providing the area A and the area C facing downward in a sufficient area, the wide area in the Z direction in FIG. 8 can be used as the communication direction even though it is not in the axial direction of the coil.

  Next, the size of the core 11 will be described. FIG. 14 is a diagram showing the relationship between the antenna core size and the antenna induced voltage in Embodiment 1 of the present invention.

  In FIG. 14, the width of the core 11 is 10 mm, the length of the coil (in the longitudinal direction of the core 11) is 20 mm, and the coil is arranged in the longitudinal center of the core 11, and the width in the longitudinal direction of the core 11 is changed. ing. In the situation as shown in FIG. 12A, the maximum voltage induced in each of the cases where the size of the communication partner antenna is large, medium, and small is measured. The size of each antenna is 70 mm × 40 mm for the antenna (large), 45 mm × 30 mm for the antenna (medium), and 25 mm × 20 mm for the antenna (small). The values on the vertical axis in FIG. 14 are normalized and plotted with each induced voltage when the length of the core 11 is 20 mm.

  When the length of the core 11 is 30 to 40 mm (1.5 to 2 times the length of the coil), the maximum induced voltage values of the antenna (large), the antenna (medium), and the antenna (small) are 11 is 20% or more larger than 20 mm, and the antenna 8 can stably and satisfactorily communicate with a communication partner having antennas of various sizes. When the length of the core 11 is 40 to 70 mm (2 to 3.5 times the length of the coil), the maximum induction voltage of the antenna (large) and the antenna (medium) is maintained high, and the antenna The (small) maximum induced voltage can be made better than when the core length is 20 mm. When the length of the core 11 exceeds 120 mm, the maximum induced voltage only decreases regardless of the size of the communication partner antenna. Accordingly, the length of the core 11 is preferably 120 mm or less at the longest.

  Furthermore, the antenna 8 of the present invention is advantageous over the conventional antenna 108 when mounted in an electronic device that performs communication in a plurality of frequency bands.

  FIG. 15 is a diagram showing the arrangement of the antenna according to the first embodiment of the present invention and the conventional antenna and antennas of other frequency bands in the electronic device. A region D indicates a recommended mounting position of the antenna of the present invention, a region E indicates a recommended mounting position of the conventional antenna, and a region F indicates an antenna position for a frequency band such as GPS, Bluetooth (registered trademark), WLAN, or the like. Indicates.

  Generally, an antenna for a frequency band such as GPS, Bluetooth (registered trademark), WLAN, or the like is disposed at an end of the casing of the electronic device. This is to suppress the influence of other parts such as a metal body in the housing. And since the antenna for normal telephones etc. are arrange | positioned at the lower end part of the battery 4 side, it arrange | positions in the position near the upper end part on the side away from the battery 4. In addition, for antennas for frequency bands such as GPS, Bluetooth (registered trademark), and WLAN, magnetic materials such as magnetic sheets and cores provided in most antennas for NFC frequency bands are the source of adverse effects. That is, when an antenna for a frequency band such as GPS, Bluetooth (registered trademark), WLAN or the like operates, an eddy current is generated in the magnetic body of the antenna for the NFC frequency band, which interferes with communication of other antennas. Therefore, it is preferable to dispose the antenna for the NFC frequency band and the antenna for the frequency band such as GPS, Bluetooth (registered trademark), WLAN, etc. separately. However, considering the ease of use for the user, the communication direction becomes inconvenient unless the longitudinal direction of the mobile terminal 1 and the axial direction of the coil of the antenna 108 are the same. As a result, the conventional antenna 108 in FIG. 7 has the left-right direction in FIG. 15 as the longitudinal direction and the axial direction of the coil is the short direction, so both ends of the antenna 108 in the longitudinal direction extend to the vicinity of the end of the back cover 3. It is difficult to dispose from the end portion of the back cover 3 on the center side of the back cover 3. Even if a planar loop antenna is used, the opening area must be increased to ensure communication characteristics, and the antenna extends to the vicinity of the end of the back cover 3.

  However, in the antenna of the present invention, the longitudinal direction of the antenna 8 and the longitudinal direction of the back cover 3 are substantially the same even if the longitudinal direction of the back cover 3 and the axial direction of the coil of the antenna 8 are the same. It can be arranged away from the end of the cover 3.

  Next, the antenna 8 of the present invention having a shape different from that shown in FIG. 2 will be introduced. FIG. 16 is a perspective view of the antenna of the present embodiment, and the ratio of the lengths of region A and region C is greatly different. As described above, the region A and the region C may have different lengths and different areas. In the case of FIG. 16, the opening of the coil pattern of the antenna 8 is in the same state as being wide on the region A side and narrowing on the region C side. Therefore, in the vicinity of the area A, the area where the magnetic flux in the Z direction and the Z45 degree direction in FIGS. 8 and 10 is increased, and communication can be performed in a wide range.

  FIG. 17 is a perspective view of the antenna according to the present embodiment, and the shape of the core 11 is not rectangular. That is, the width of the coil pattern of the core 11 in the winding direction (direction perpendicular to the coil axis direction) increases from the region B side toward the outside. Therefore, compared with the rectangular core having the same width as the region B, the areas of the region A and the region C are increased. As a result, the communicable distance can be increased by increasing the influence of the core 11 without increasing the area of the flexible substrate 12.

  Next, an antenna device including the antenna 8 and the metal body described so far will be described. Here, in particular, for example, a case where the back cover 3 is a metal body will be described. That is, it is a case where it is desired to generate a magnetic field through the metal body as viewed from the antenna 8, and the metal body is not limited to the back cover 3. At this time, the antenna device includes an antenna 8 and a back cover (metal body), and a slot 41 is provided in the back cover 3, and a coil winding portion (region B) and a coil non-winding portion (regions A and C). At least a part of which faces the slot 41. Preferably, the length of the slot 41 is not less than the length of the antenna 8 in the axial direction of the coil of the antenna 8. In the coil winding direction, the length of the slot 41 is equal to or shorter than the length of the antenna.

  When the metal body is positioned near the antenna 8, an eddy current that cancels the magnetic flux of the antenna 8 flows through the metal body. Since the magnetic flux generated by the antenna 8 is weakened by the eddy current flowing in the metal body, it becomes quite difficult for the antenna 8 to communicate with the communication partner on the back side across the metal body. However, with the antenna 8 of the present invention, communication is possible by simply inserting one slot in the metal body. The principle of communication will be described later.

  FIG. 18 is an exploded perspective view of a mobile terminal including a metal body on which the antenna according to Embodiment 1 of the present invention is mounted. Here, the back cover 3 is a metal body. FIG. 19 is an exploded perspective view of a mobile terminal including a metal body on which the antenna according to Embodiment 1 of the present invention is mounted. A difference between FIG. 19 and FIG. 18 is that a slot 41 provided in the back cover 3 is connected to a camera through hole. The core 11 is also shaped to surround the camera.

  Unlike FIG. 1, a slot 41 is formed in the back cover 3 of FIG. The slot 41 faces the antenna 8, and the antenna 8 is located on or without contact with the slot 41. That is, the arrangement relationship is such that the antenna 8 can be seen through the slot 41 when the mobile terminal 1 is viewed from the outside of the back cover 3. The longitudinal direction of the slot 41, the coil axis direction of the antenna 8, and the longitudinal direction of the core 11 are parallel. However, it is preferable that all three directions are parallel to each other, but a good effect can be obtained even if they are deviated by about ± 30 degrees.

  In the first embodiment of the present invention, the slot 41 has a length of 40 mm and a width of 4 mm. The antenna 8 has a length of 40 mm and a width of 10 mm. The slot 41 has the same length as that of the antenna 8, but is not limited thereto. Basically, the slot 41 is preferably longer and longer than the antenna 8. This is because the longer the length of the slot 41, the larger the loop of eddy current flowing in the back cover 3, and the larger the magnetic field is formed. Since the slot 41 is longer than the core 11, the magnetic field that the core 11 originally forms becomes larger. At least a portion longer than the flexible substrate 12 (region B), and the region A and region C of the core 11 overlap at least a part of the slot 41. Further, the width of the slot 41 is smaller than the width of the core 11. Originally, the larger the width of the slot 41, the better. However, since the slot 41 is smaller than the width of the core 11, the slot 41 can be reduced in size, and an eddy current flows through the back cover 3 well. Further, since the slot 41 does not need to be connected to the end of the back cover 3, it can be freely arranged at any position on the back cover 3.

  Next, the reason why the antenna 8 can be communicated by providing the slot 41 even if the back cover 3 is a metal body will be described. Note that the metal body is not limited to the back cover 3 and may be any metal body mounted on the portable terminal 1 or the like, and will be described using the back cover 3 as an example.

  FIG. 20 is a diagram showing the relationship among the back cover, the slot, and the antenna according to Embodiment 1 of the present invention. 20A is a top view, and FIG. 20B is a cross-sectional view taken along a line XX in FIG. 20A. FIG. 21 is a diagram showing the relationship between the magnetic flux generated by the antenna, the back cover, and the slot according to Embodiment 1 of the present invention. 21A is a top view, FIG. 21B is a cross-sectional view taken along a line YY in FIG. 21A, and FIG. 21C is a cross-sectional view taken along a line ZZ in FIG. 21A. . FIG. 22 is a diagram showing a current flowing through the back cover (metal body) according to the first embodiment of the present invention.

  As can be seen from FIG. 20A, the slot 41 overlaps a part of each of the non-winding portion and the winding portion of the core 11 of the antenna 8. Here, “overlapping” may be either contact or non-contact. However, at least the back cover 3 (metal body) and the antenna 8 are insulated. That is, all of the area A, the area B, and the area C in FIG. Both the area A and the area C do not necessarily overlap, but at least the area B overlaps. As shown in FIG. 20B, the antenna 8 partially overlaps the back cover 3, and the slot 41 and other portions overlap. However, it is not necessary that the center line of the slot 41 and the center line of the antenna 8 in the left-right direction in FIG. 20B overlap, but preferably, the right side part and the left side part of the antenna 8 overlap the back cover 3 respectively. The center portion sandwiched between the right part and the left part of the antenna 8 preferably overlaps the slot 41.

  In such an arrangement, when the antenna 8 is operated, first, a current flows through the antenna pattern as shown in FIG. FIG. 21A shows a case where the flow is from left to right. As a result, as shown in FIG. 21 (b), an eddy current opposite to the current of the antenna 8, that is, a current flowing from right to left flows on the surface of the back cover 3 facing the antenna 8. . This eddy current flowing in the back cover 3 also flows through the slot 41 on the surface opposite to the surface facing the antenna 8. The direction of the current flowing on the opposite surface is opposite to the direction of the current flowing on the surface facing the antenna 8 (from right to left), and is from left to right. As a result, as can be seen from FIG. 22, the direction of the current flowing in the opposite surface and the direction of the current flowing in the antenna pattern of the antenna 8 are the same direction. The current flowing in the opposite surface forms a loop around each end of the slot 41 along the short direction. That is, as shown in FIG. 21A, the current forms a clockwise loop and a counterclockwise loop. As a result, a magnetic field as shown in FIG. 21 (c) is formed. That is, in the current, one of the clockwise loop and the counterclockwise loop is the magnetic field entrance, and the other is the exit. This is always the same as the direction of the magnetic field generated by the antenna 8. As a result, the magnetic field generated by the back cover 3, which is a metal body, does not interfere with the magnetic field of the antenna 8, so that the magnetic flux of the antenna 8 reaches the opposite side of the metal body. At this time, the antenna 8 of the present invention is not used like an antenna by exciting the back cover 3 which is a metal body, but the antenna 8 communicates to the last. Accordingly, the communication characteristics are better when the metal body is not present nearby, but even if the metal body is present nearby, good communication can be performed by forming only one slot.

  As a result, only by forming the slot 41, even if a metal body such as the back cover 3 is close or surrounded by the metal body, communication can be performed as in the case where the metal body is not close.

  Furthermore, when a magnetic material such as the core 11 is inserted into the slot 41, the communication characteristics of the antenna 8 are further improved. At this time, the magnetic material should not be inserted into the portion that overlaps the flexible substrate 12, and the magnetic material is inserted into the portion that overlaps the region A and region C of the core 11. Moreover, although the magnetic material inserted into the slot 41 is the same material as the magnetic material of the core 11, the communication characteristics can be further improved, but another material may be used.

  The shape of the slot 41 is not limited to a rectangle, and may be any shape such as a polygon, a circle, an ellipse, and a curve. Preferably, the longitudinal direction of the slot 41 is substantially the same as the longitudinal direction of the core 11 of the antenna 8.

  Next, a method for adjusting the inductance (L value) of the coil pattern of the antenna 8 will be described. That is, the antenna 8 described so far has a shape in which an inductance adjusting mechanism is added.

  FIG. 23 is a top view of an antenna including the inductance adjusting mechanism according to Embodiment 1 of the present invention. FIG. 24 is a diagram for explaining parameters for determining the inductance of the antenna according to the first embodiment of the present invention. FIG. 25 is a diagram illustrating a state in which the inductance of the antenna according to Embodiment 1 of the present invention is changed by the inductance adjustment mechanism.

  The conductive wire constituting the coil in the flexible substrate 12 of the antenna 8 is branched into two at both ends thereof. The branching into two is that branching conductors 51 and 52 are added to the conductors 151 and 152 as compared with the antenna 8 shown in FIG. Since the branch conductors 51 and 52 are connected to the conductors 151 and 152 at both ends thereof (by the branch points 55 and 56 and the trimming points 53 and 54), the number of turns of the coil of the antenna 8 is not changed. In order to adjust the inductance, the trimming points 53 and 54 are trimmed as necessary. The trimming referred to here means that the conducting wire is disconnected at the trimming point by punching or laser processing. Therefore, the trimming points 53 and 54 are preferably located outside the core 11. Thereby, it is possible to prevent the core 11 from being damaged during trimming.

  The trimming point is located on the conductors 151 and 152 located outside the conductors 151 and 152 and the branch conductors 51 and 52. Therefore, in FIG. 23, the trimming points 53 and 54 are located in the conducting wires 151 and 152 that are not the branch conducting wires 51 and 52. This is because the inductance is changed by changing the axial length of the coil by disconnecting the conductive wires 151 and 152. That is, when trimming is not performed at the trimming point, the inductance is the same as that of the coil in which the branch conductors 51 and 52 are not present.

  24, the magnetic permeability of the magnetic core is μ, the cross-sectional area of the coil is S, the number of turns of the coil is N, the length of the coil is l, and the inductance L of the coil is L = (μ × S × N × N) / l. It can be seen that the smaller the coil length l is, the larger the coil inductance L is. That is, by trimming at least one of the trimming points 53 and 54, the length of the coil is shortened, so that the inductance can be increased. The branch conducting wires 51 and 52 are preferably at least one turn around the core 11, and are preferably wound around the core 11 more than once as shown in FIG. 23. Moreover, the branch conducting wire 51 and the branch conducting wire 52 are wound around the same circumference, so that the characteristics of the antenna 8 can be stabilized evenly. However, the number of turns of the branch conductor 51 and the branch conductor 52 may be different. In FIG. 23, the branch conductors 51 and 52 and the conductors 151 and 152 are closely adjacent to each other, and the central conductors where the branch conductors 51 and 52 do not exist are sparsely adjacent to each other. By doing in this way, a winding part can be reduced in size. On the other hand, since all of the central conductor, the branch conductors 51 and 52, and the conductors 151 and 152 are adjacent to each other with the same width, the antenna 8 that is easy to manufacture can be obtained.

  In FIG. 25, a free space (a metal body is not close to the antenna 8), a back cover 3 (a metal body) in which a 40 mm × 4 mm slot is formed, and a 40 mm × 1 mm slot are formed. The inductance of the antenna 8 is compared with the case where the rear cover 3 (metal body) is close. Although the inductance changes for each of the three patterns, the rate of change of the inductance that changes when the trimming points 53 and 54 are disconnected is about 4.6 to 5%. Note that the rate of change when only one of the trimming points 53 and 54 is disconnected is about 2.3 to 2.5%, which is half. At this time, not only the back cover 3 but also other metal plates 203 are close to the antenna 8. That is, it can be seen that the antenna 8 of the present invention can adjust the inductance even in a situation surrounded by the metal body by providing the slot 41 and can communicate.

(Embodiment 2)
In the second embodiment, the shape of the antenna 80 is slightly different from that of the antenna 8 described in the first embodiment. However, the basic configuration and operation principle are the same, and the slot 41 in the first embodiment is a round hole 42 by changing the shape of the antenna 8 to the antenna 80. Therefore, what is attached with the same number represents that the same thing is shown fundamentally.

  FIG. 26 is an exploded perspective view of a mobile terminal on which the antenna according to Embodiment 2 of the present invention is mounted. FIG. 27 is a perspective view of an antenna according to Embodiment 2 of the present invention. FIG. 28 is an exploded perspective view of the antenna according to the second embodiment of the present invention. FIG. 29 is a perspective view of the core in the first embodiment of the present invention.

  In the antenna 80 according to the second embodiment, the coil 11 is wound so that the core 11 having at least the first surface and the second surface that is the back surface thereof, and the conductors pass on the first surface and the second surface. Among the coil winding portions (region B), the two non-coiled portions (region A, region C) where the coil is not wound out of the first surface and the second surface. The coil winding portion is sandwiched between a plurality of coil non-winding portions in the axial direction of the coil, and each of the plurality of coil non-winding portions is inclined in the same direction with respect to the coil axis. In addition, it is good also as a coil winding part being divided | segmented into two or more, and the space | interval between them being a coil non-winding part.

  That is, as a change from the first embodiment, as shown in FIG. 27, the antenna 80 has an area of the coil non-winding portion (regions A and C) larger than the area of the coil winding portion (region B). . Of course, the area of the coil non-winding portion (regions A and C) does not necessarily need to be larger than the area of the coil winding portion (region B). Communication characteristics can be obtained. Further, since the areas A to C are not arranged in a straight line, the entire antenna 80 has a C shape or a U shape. That is, one end side of the region A and the region C is connected by the region B, and the other end side of the region A and the region C faces each other with a certain distance therebetween. With reference to the coil axis of the coil winding portion, the region A and the region C are inclined and bent (bent) toward the left side of FIG. That is, the longitudinal direction of the region A and the region C is the winding direction of the coil of the antenna 80 (the direction perpendicular to the winding axis of the coil), and the core 11 in the region A and the region C is the coil winding part (region). It protrudes from the width of B). In FIG. 27, the core 11 in the region A and the region C extends only to the left and has a C shape, but may extend to both the left and right to have an H shape. The region A may be on the right side and the region B on the left side, for example. However, in this case, it is desirable that at least a part of factors that determine characteristics such as the size, thickness, and shape of the region A and the region B are different. The core 11 in the region A and the core 11 in the region C face each other at a certain distance outside the winding direction of the coil winding portion in the region B. The core 11 in the region A and the core 11 in the region C are parallel and the distance between them is constant, but is not limited thereto. In FIG. 27, the fixed distance between the core 11 in the region A and the core 11 in the region C is about the length in the axial direction of the coil. The core 11 in the region A and the core 11 in the region C are never connected.

  As shown in FIG. 26, other parts such as the camera 5 mounted on the mobile terminal 1 can be arranged in the area surrounded by the areas A, B, and C. That is, compared to the antenna 8 of the first embodiment, the structure is easy to coexist with other components even in a miniaturized portable terminal.

  When the metal body is not present nearby, similarly to the first embodiment, the area A or the area C can be an entrance or exit of the magnetic flux, and the antenna 80 capable of stable communication over a wide range can be obtained. The same effect as in the first embodiment can be obtained.

  The shape of the core 11 in the region A and the region C may be any shape. In FIG. 27, the outer shape of the core 11 is curved so that the outer shape of the core 11 approaches a circle in accordance with the circular hole 42 of FIG. 26, but is not limited thereto. Further, the cores 11 in the region A and the region C may be formed thinner than the core 11 in the region B, and can be reduced in size.

  Further, as shown in FIG. 26, the hole 42 is circular and is larger than the antenna 80, and the entire antenna 80 is exposed from the hole 42. That is, the antenna 80 does not overlap the back cover 3. The antenna 80 may be enlarged so that the antenna 80 and the back cover 3 overlap. However, when the size of the antenna 80 is considered to be constant, the antenna 80 is smaller than the hole 42 as shown in FIG. It's better to do it. The hole 42 may be provided with a cap 43 that covers the antenna 80. At this time, when the cap 43 is a metal body, a frame 44 is provided around the cap 43 by an insulator such as a resin. The frame 44 has a function of forming a gap between the back cover 3 (metal body) and the cap 43.

  As shown in FIG. 28, the structure of the antenna 80 is basically the same as that of the antenna 8 of FIG. 3 and 28, the double-sided tape 33 is attached to the lower flexible board 12a and attached to other components (for example, the back cover 3 and the electronic circuit board 6). The tape 33 may be attached. However, in that case, it is only necessary that the external connection terminals 8 a and 8 b provided on the lower flexible substrate 12 a are not covered with the double-sided tape 33.

  Further, since the core 11 is protected by the protective tapes 34 and 35 having the same shape, there is no problem even if the cores 11 in the regions A and C are exposed from the flexible substrate 12. The region A and the region C do not have to have the same shape and the same size, but the region A and the region C that protrude from the coil are always necessary.

  Next, the magnetic field formed by the antenna 80 when the metal body (back cover 3) is present nearby will be described. FIG. 30 is a diagram showing a current flowing through the metal plate by the antenna according to the second embodiment of the present invention. FIG. 31 is a diagram illustrating a current flowing through a metal plate by a conventional antenna. FIG. 32 is a diagram showing a magnetic field formed by the antenna according to the second embodiment of the present invention and the conventional antenna. FIG. 32A shows the case of the antenna according to the second embodiment of the present invention, and FIG. 32B shows the case of the conventional antenna. 31 and 32, the sizes of the holes formed in the back cover 3 (metal body) are the same. Further, as a conventional antenna, an annular loop antenna is used.

  Although the principle is the same as the principle of FIG. 21, as can be seen from FIG. 30, when a current flowing from the bottom to the top as shown in the figure flows through the coil of the antenna 80, the direction of the magnetic flux in the region B is from right to left. It becomes. As a result, the non-winding portion (for example, the region C) of the right core 11 in the drawing serves as an entrance for the magnetic flux, and the non-winding portion (for example, the region A) of the left core 11 in the drawing is used. It becomes the exit of magnetic flux. As a result, a large magnetic field as shown in FIG. At this time, an eddy current is generated on the inner side surface (surface on the antenna 80 side) of the back cover 3 so as to cancel the magnetic field generated by the antenna 80. The point in the present invention is that the eddy current flowing through the back cover 3 exists on one plane in the clockwise eddy current and the counterclockwise eddy current. Therefore, eddy currents in the respective directions cannot form a loop-shaped current path on one plane, and each eddy current travels between the front surface (outer surface) and the back surface (inner surface) of the back cover 3. As a result, the direction of current differs between the front surface (outer surface) and the back surface (inner surface). Since the eddy current flowing on the back surface (inner side surface) has the action of canceling out the magnetic flux of the antenna 80, the eddy current flowing on the front surface (outer side surface) flows in a direction that supports the magnetic flux of the antenna 80.

  As a result, as in Embodiment 1, the communication characteristics of the antenna 80 are better when not surrounded by the metal body, but even if surrounded by the metal body, a magnetic flux in the same direction as the magnetic flux of the antenna 80 is formed on the metal body. Eddy current flows and communication can be sufficiently performed.

  On the other hand, the conventional antenna shown in FIG. 31 does not become the present invention. That is, when a counterclockwise current flows through the loop antenna, a clockwise current flows around the hole 42 on the inner surface of the back cover 3 so as to cancel it. Since this current does not move between the outer surface and the inner surface of the back cover 3, a clockwise current also flows on the outer surface of the back cover 3. As a result, the back cover 3 only weakens the magnetic field generated by the loop antenna, and the communication characteristics of the loop antenna are lowered.

  As can be seen from these results, as shown in FIG. 32, the antenna 80 of the present embodiment forms a larger magnetic field than the conventional antenna. In particular, the antenna 80 is clearly better at the magnetic field strength at a point 30 mm above the center of the hole 42. The common conditions in FIG. 31 are an input to the antenna of 100 mV, a housing size of 60 mm × 120 mm × 8 mm, a housing plate thickness of 1 mm, and a housing made of magnesium. The diameter of the hole 42 is 30 mm, and the outer diameter of the antenna 80 is 28 mm.

  In addition, in the antenna 80 of FIG. 27, the area A and the area C are opposed substantially in parallel to the antenna 8 of the first embodiment. Therefore, the center of the antenna 80 is not located above the coil winding part (region B), but is located above the region surrounded by the regions A and C. As a result, the magnetic field generated by the antenna 80 becomes easier to move above the area surrounded by the area A and the area C than above the coil winding portion of the antenna 80. Therefore, the place where the magnetic field generated by the antenna 80 is the strongest, that is, the place where the communication partner can communicate most easily is above the area surrounded by the area A and the area C rather than above the coil winding portion of the antenna 80. Become the side. As described above, in the second embodiment, the location where communication is easy in the upper part of the antenna 80 is determined based on the shape, size, thickness, and coil axis of the coil non-winding portion (region A and region C). It can be changed freely by adjusting the tilt, etc.

  On the other hand, the center of antenna 8 in the first embodiment is located on the coil, and the place where the magnetic field generated by antenna 8 is the strongest is substantially above the coil.

  As can be seen from the drawing of FIG. 15, in the first embodiment, the center of the antenna 8 is positioned around the center in the width direction (short direction) of the mobile terminal 1. By doing in this way, if the user aligns the center of the portable terminal 1 in the width direction with the communication partner, it becomes easier to communicate, which is convenient. On the other hand, if the most communicable part is shifted from the center in the width direction of the mobile terminal 1, the user needs to check every time where the mobile terminal 1 must be aligned with the communication partner. . Therefore, in the first embodiment, it is preferable that the coil portion is always arranged near the center in the width direction of the mobile terminal 1, and the degree of freedom with respect to the arrangement of the antenna 8 is limited. In particular, the camera 5 is often placed at the center in the width direction of the mobile terminal 1 and thus overlaps.

  On the other hand, in the case of the antenna 80, the position of the strongest magnetic field can be adjusted by adjusting the size and shape of the core 11. In addition, the shape of the core 11 of the antenna 80 is not limited to the C shape, and the angle of the region A and the region C with respect to the coil may be adjusted to other than 90 degrees. Can be adjusted to the right or left side. That is, if the strongest part of the magnetic field is to be separated from the coil winding part, the coil axis of the coil winding part and the core 11 of the coil non-winding part are substantially perpendicular (about ± 10 degrees or less), and the coil is not wound. The core 11 may be formed larger so that the longitudinal direction of the part is longer. If it is desired to bring the strongest part of the magnetic field closer to the coil winding part, there is no need to make the core of the coil non-winding part small, and the angle of inclination between the coil axis of the coil winding part and the core 11 of the coil non-winding part. Should be close to parallel.

  Next, the case where the cap 43 is attached to the antenna 80 will be described. The cap 43 may be a resin (non-conductor) or a metal body (conductor). In the case of a non-conductor, it can be used without changing the principle described above. That is, the cap 43 has little influence on the magnetic field. The case where the cap 43 is a conductor such as a metal body will now be described.

  FIG. 33 is a diagram showing a current in the case where there is a cap in the antenna according to the second embodiment of the present invention. FIG. 34 is a diagram showing a magnetic field in the case of the antenna according to the second embodiment of the present invention with and without a cap. FIG. 34 (a) shows the case without a cap, and FIG. 34 (b) shows the case with a cap. FIG. 35 is a diagram showing the connection between the cap and the back cover in the antenna according to the second embodiment of the present invention.

  Referring to FIG. 33, it can be seen that current flows also on the outer surface (front surface) of the cap 43 in the same direction as the eddy current flowing on the outer surface (front surface) of the back cover 3. This is because, like the back cover 3, an eddy current that cancels the magnetic flux of the antenna 80 flows on the inner surface (back surface) of the cap 43, and the eddy current travels between the inner surface and the outer surface of the cap 43. That is, as a result, an eddy current that generates a magnetic flux in the same direction as the magnetic flux of the antenna 80 flows on the outer surface of the cap. As shown in FIG. 34, the communication characteristic of the antenna 80 is larger when the metal cap 43 of FIG. 34 (a) is not present than when the metal cap 43 of FIG. 34 (b) is present. The difference is a slight difference. In FIG. 34, the antenna is 100 mV, the housing size is 60 mm × 120 mm × 8 mm, and the housing thickness is 1 mm. The cap 43 is a circle having an outer diameter of 26 mm and a cylindrical shape having a height of 10 mm.

  Moreover, when connecting the back cover 3 and the cap 43, metals will contact. That is, eddy currents flowing through the back cover 3 and the cap 43 flow so as to go back and forth through the contact portion 45. In the case of connection at one point, any part may be used for connection. However, when connecting at a plurality of points, the performance deteriorates if the region X and the region Y in FIG. 35 are connected simultaneously. This is because, in the region X and the region Y, the eddy current flowing through the back cover 3 and the cap 43 goes back and forth between the front surface and the back surface. Therefore, if the back cover 3 and the cap 43 are connected in the region X and the region Y, it is difficult to pass current between the front surface and the back surface. For this reason, when the connection portion 45 is provided, the connection portion 45 is less affected by the connection, and the communication characteristics of the antenna 80 can be maintained.

  As described above, the antennas 8 and 80 according to the present invention have good characteristics as an antenna even if the metal is not present nearby, and even if the metal is present nearby, only small processing is performed on the metal. Good characteristics as an antenna can be obtained. In processing to metal, the antennas 8 and 80 face one surface of the metal, and an eddy current that interferes with the antennas 8 and 80 flows on the one surface. It is necessary to extend to. The other surface is a communication surface. One surface does not necessarily face the antennas 8 and 80, but has a surface on the antennas 8 and 80 side. Furthermore, the metal does not need to be plate-shaped, and it is sufficient if it has the other surface opposite to the surface on the antenna side. In addition, these surfaces are not perpendicular to the axial direction of the coils of the antennas 8 and 80, and are preferably parallel to each other.

  According to the present invention, an antenna having a small size and a stable inductance value can be maintained, and the communication characteristics of the antenna can be maintained. In addition, the present invention can also be applied to uses such as storage shelves that enable automatic product management and book management, medicine management other than display shelves, dangerous goods management, and valuables management systems.

DESCRIPTION OF SYMBOLS 1 Mobile terminal 2 Display panel 3 Back cover 4 Battery 5 Camera 6 Electronic circuit board 7a, 7b Antenna input / output pin 8, 80 Antenna 8a, 8b External connection terminal 9 Antenna control part 11 Core 12 Flexible board 12a Lower flexible board 12b Upper flexible board 41 Slot 51, 52 Branch conductor 53, 54 Trimming point 55, 56 Branch point

Claims (6)

A core with a surface;
A coil winding portion in which a coil is wound on the surface;
Among the surfaces, a plurality of coil non-winding portions where the coil is not wound,
The coil winding part is sandwiched between the plurality of coil non-winding parts in the first direction on the surface,
Each of the plurality of coil non-winding portions is inclined in the same direction with respect to the axis of the coil. The antenna according to claim 1, wherein a longitudinal direction of each of the plurality of coil non-winding portions is substantially perpendicular to an axis of the coil. 3. The antenna according to claim 1, wherein a length in a longitudinal direction of each of the plurality of coil non-winding portions is equal to or longer than an axial length of the coil. The antenna according to any one of claims 1 to 3,
A metal body insulated from the antenna;
A through hole provided in the metal body,
At least a part of each of the coil winding part and the plurality of coil non-winding parts of the antenna overlaps with the through hole. The antenna device according to claim 4, wherein a part of the through hole is covered with a metal cap without contacting the through hole. An antenna device according to any one of claims 4 and 5,
And a camera,
The communication apparatus is characterized in that the camera is disposed in a region sandwiched between the coil non-winding portions.