Antenna device and IC card equipped with the same

Abstract

To further increase a communication distance in an antenna device having a metal plate and a coil pattern.SOLUTION: An antenna device 1 includes a metal plate 40 having a first through hole 43 and a first slit 44 connected to the first through hole 43 and narrower than the first through hole 43, a first coil pattern 110 whose opening 110a overlaps with the first through hole 43 and that winds around along the first through hole 43, and a second coil pattern 120 connected to the first coil pattern 110 and winding around along the outer edge 48 of the metal plate 40. The tip 44A of the first slit 44 does not reach the outer edge 48 of the metal plate 40, and the first through hole 43 and the first slit 44 have a closed shape.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an antenna device and an IC card including the same.

Background Art

[0002] Patent Document 1 discloses an antenna device including a lower metal housing provided with a plurality of slit patterns and a planar coil antenna overlapping the plurality of slit patterns.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the antenna device described in Patent Document 1, since most of the coil opening of the planar coil antenna is covered by the lower metal housing, there is a problem that the communication distance is short.

[0005] In the present disclosure, a technique for further expanding the communication distance in an antenna device including a metal plate and a coil pattern will be described.

Means for Solving the Problems

[0006] An antenna device according to an embodiment of the present disclosure includes a metal plate having a first through hole and a first slit connected to the first through hole and narrower than the first through hole, a first coil having an opening overlapping the first through hole and surrounding along the first through hole, and a coil including a second coil connected to the first coil and surrounding along an outer edge of the metal plate. The tip of the first slit does not reach the outer edge of the metal plate, and the first through hole and the first slit have a closed shape.

Effects of the Invention

[0007] According to the present disclosure, in an antenna device including a metal plate and a coil, a technique for further expanding the communication distance is provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Best Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic perspective view showing the appearance of an IC card 3 including an antenna device according to an embodiment of the present disclosure.

[0011] As shown in FIG. 1, the IC card 3 according to the present embodiment is a plate-like body having the Y direction as the longitudinal direction, the X direction as the short-side direction, and the Z direction as the thickness direction, and has an upper surface 3a and a back surface 3b that constitute the XY plane. An IC module described later is built in the IC card 3, and the terminal electrode E of the IC module is exposed on the upper surface 3a of the IC card 3.

[0012] FIGS. 2 and 3 are a schematic exploded perspective view and a schematic cross-sectional view for explaining the structure of the IC card 3 including the antenna device 1 according to the present embodiment, respectively.

[0013] The IC card 3 shown in FIGS. 2 and 3 has a structure in which a plastic plate 10, a film-like base material 20, a coil including a first coil pattern 110 and a second coil pattern 120 supported by the base material 20, a magnetic body 30, a metal plate 40, and a protective sheet 50 are laminated in this order from the back surface 3b side to the upper surface 3a side. The antenna device 1 according to the present embodiment is composed of the first coil pattern 110, the second coil pattern 120, and the metal plate 40. The plastic plate 10, the base material 20, and the first coil pattern 110 and the second coil pattern 120 supported by the base material 20 are adhered via an adhesive layer 61. The base material 20 and the magnetic body 30 are adhered via an adhesive layer 62. The magnetic body 30 and the metal plate 40 are adhered via an adhesive layer 63. The metal plate 40 and the protective sheet 50 are adhered via an adhesive layer 64. Examples of the materials for the adhesive layers 61 to 64 include acrylic double-sided tape, thermosetting resin, and thermoplastic resin.

[0014] The plastic plate 10 is made of a resin material that does not obstruct magnetic flux. The outer surface of the plastic plate 10 constitutes the back surface 3b of the IC card 3.

[0015] The base material 20 is a film made of an insulating resin material, and conductor patterns are formed on both its one surface 21 and the other surface 22. The conductor pattern provided on the surface 21 of the base material 20 includes a first coil pattern 110 and a second coil pattern 120. Examples of the conductive material constituting the conductor pattern include copper, aluminum, or alloys thereof. Examples of the insulating resin material constituting the base material 20 include PET (polyethylene terephthalate) and PI (polyimide). In the example shown in FIG. 3, the surface 21 of the base material 20 faces the plastic plate 10 side, and the surface 22 of the base material 20 faces the magnetic body 30 and the metal plate 40 side, but the front and back of the base material 20 may be reversed.

[0016] The magnetic body 30 is made of a high magnetic permeability material. The magnetic body 30 may be a sheet-like member or may be applied to the surface 22 of the base material 20. When the magnetic body 30 is a sheet-like member, the magnetic body 30 and the base material 20 are adhered to each other via an adhesive layer 62 as shown in FIG. 3. When the magnetic body 30 is applied to the surface 22 of the base material 20, the magnetic body 30 and the base material 20 are in direct contact without an adhesive layer. The magnetic body 30 is provided with a second through hole 31.

[0017] The metal plate 40 is made of a metal material such as stainless steel or titanium. On one surface 41 side of the metal plate 40, the plastic plate 10, the base material 20, the first coil pattern 110 and the second coil pattern 120 formed on its surface, and the magnetic body 30 are arranged. On the other surface 42 side of the metal plate 40, the protective sheet 50 and the IC module 70 are arranged. In the metal plate 40, a first through hole 43 is provided at a position overlapping the second through hole 31 of the magnetic body 30. The entire first through hole 43 may overlap the second through hole 31. In this way, the IC card 3 is a card in which the metal plate 40 is used as a part of the main body.

[0018] The protective sheet 50 is made of a material such as resin, and its outer surface constitutes the upper surface 3a of the IC card 3. In the protective sheet 50, a third through hole 51 is provided at a position overlapping the first through hole 43 of the metal plate 40. The entire first through hole 43 may overlap the third through hole 51. The IC module 70 is arranged inside the third through hole 51. A part of the IC module 70 overlaps the metal plate 40, and the remaining part of the IC module 70 overlaps the first through hole 43 of the metal plate 40. Thereby, the IC module 70 and the first coil pattern 110 face each other through the first through hole 43. The surfaces 41 and 42 of the metal plate 40 may be flat. For example, among the surface 42 of the metal plate 40, the region overlapping the IC module 70 and the region not overlapping the IC module 70 constitute the same plane. That is, there is no step or the like provided between the region of the surface 42 of the metal plate 40 that overlaps the IC module 70 and the region that does not overlap the IC module 70. Therefore, complicated processing is not required in the production of the metal plate 40.

[0019] FIG. 4 is a schematic plan view for explaining the shape of the metal plate 40.

[0020] As shown in FIG. 4, the metal plate 40 is provided with a first through hole 43 and a first slit 44 connected thereto. The first through hole 43 and the first slit 44 constitute a spatial region where the metal plate 40 does not exist. The first through hole 43 is substantially rectangular and has a first edge 431 and a fourth edge 434 extending in the X direction, and a second edge 432 and a third edge 433 extending in the Y direction. The width of the first through hole 43 in the X direction, that is, the distance between the second edge 432 and the third edge 433 in the X direction is W1. The width of the through hole 43 in the Y direction, that is, the distance between the first edge 431 and the fourth edge 434 in the Y direction is W2. In the example shown in FIG. 4, the width W2 is larger than the width W1. That is, the planar shape of the first through hole 43 is substantially rectangular.

[0021] The first slit 44 extends in the +Y direction from the first edge 431 of the first through hole 43. The width of the first slit 44 in the X direction is W3, and the length of the first slit 44 in the Y direction is L1. The width W3 of the first slit 44 is narrower than the width W1 of the first through hole 43 and smaller than the length L1 of the first slit 44. The tip 44A of the first slit 44 in the +Y direction does not reach the outer edge 48 of the metal plate 40, whereby the first through hole 43 and the first slit 44 have a closed shape in plan view. That is, a part of the outer edge 48 of the metal plate 40 is not divided by a slit or the like, and a metal member constituting the metal plate 40 exists over the entire circumference of the outer edge 48.

[0022] The width W3 of the first slit 44 may be smaller than the distance L2 in the Y direction between the tip 44A of the first slit 44 and the outer edge 48 of the metal plate 40. According to this, since the distance L2 is sufficiently ensured, it becomes possible to suppress a decrease in mechanical strength between the tip 44A of the first slit 44 and the outer edge 48 of the metal plate 40. Further, the width W3 of the first slit 44 may be smaller than the thickness T of the metal plate 40 (see FIG. 3). According to this, since the volume of the metal plate 40 between the tip 44A of the first slit 44 and the outer edge 48 of the metal plate 40 is sufficiently ensured, it becomes possible to suppress a decrease in mechanical strength between the tip 44A of the first slit 44 and the outer edge 48 of the metal plate 40.

[0023] In FIG. 4, the position of the second through-hole 31 provided in the magnetic body 30 is shown by a broken line. The second through-hole 31 is substantially rectangular, with a width in the X direction of W4 and a width in the Y direction of W5. In the example shown in FIG. 4, the width W4 of the second through-hole 31 is larger than the width W1 of the first through-hole 43, and the width W5 of the second through-hole 31 is larger than the width W2 of the first through-hole 43. That is, the area of the second through-hole 31 is larger than the area of the first through-hole 43. In the example shown in FIG. 4, the whole of the first through-hole 43 and a part of the first slit 44 overlap with the second through-hole 31. The remaining part of the first slit 44 does not overlap with the second through-hole 31.

[0024] FIG. 5 is a schematic plan view of a conductor pattern formed on one surface 21 of the base material 20.

[0025] In the example shown in FIG. 5, a first coil pattern 110, a second coil pattern 120, and capacitor patterns 131 and 133 are provided on one surface 21 of a base material 20. In FIG. 5, the position of a second through hole 31 provided in a magnetic body 30 is indicated by a dashed line. The first coil pattern 110 is disposed at a position overlapping with the second through hole 31 of the magnetic body 30. In the example shown in FIG. 5, the number of turns of the first coil pattern 110 is approximately 9 turns. The width of the first coil pattern 110 in the X direction is W6, and the width of the first coil pattern 110 in the Y direction is W7. The width W6 is smaller than the width W4, and the width W7 is smaller than the width W5. In the example shown in FIG. 5, the entire first coil pattern 110 overlaps with the second through hole 31 of the magnetic body 30.

[0026] The second coil pattern 120 is a pattern that winds around approximately 3 turns along the outer edge of the base material 20, and the first coil pattern 110 and the capacitor patterns 131 and 133 are disposed within an opening 120a surrounded by the second coil pattern 120. The outer shape of the base material 20 and the outer shape of the metal plate 40 are substantially the same. Therefore, when the base material 20 and the metal plate 40 are overlapped, in a plan view, the second coil pattern 120 winds along the outer edge 48 of the metal plate 40.

[0027] The capacitor pattern 131 is a pattern branched in the X direction from the innermost turn of the second coil pattern 120. In the example shown in FIG. 5, seven capacitor patterns 131 are branched from the innermost turn of the second coil pattern 120, but the number of the capacitor patterns 131 is not particularly limited. Further, a plurality of capacitor patterns 133 are branched from one capacitor pattern 131. The capacitor patterns 133 all extend in the Y direction. In the example shown in FIG. 5, twelve capacitor patterns 133 are branched from one capacitor pattern 131, but the number of the capacitor patterns 133 is not particularly limited.

[0028] FIG. 6 is a schematic plan view of the conductor pattern formed on the other surface 22 of the base material 20, showing the state seen through the base material 20 from the side of one surface 21.

[0029] As shown in FIG. 6, capacitor patterns 132, 134 and connection patterns 141, 142 are arranged on the other surface 22 of the base material 20. The planar positions of the capacitor patterns 132, 134 respectively coincide with the capacitor patterns 131, 133. That is, the capacitor patterns 131, 132 face each other through the base material 20, and the capacitor patterns 133, 134 face each other through the base material 20. Thereby, the capacitor C is constituted by the capacitor patterns 131, 133 provided on one surface 21 of the base material 20, the capacitor patterns 132, 134 provided on the other surface 22 of the base material 20, and the base material 20 positioned therebetween. The capacitance of the capacitor C having such a pattern shape can be finely adjusted by removing some of the capacitor patterns 133 by trimming.

[0030] As shown in FIGS. 5 and 6, the outer peripheral ends of the second coil pattern 120 are connected to the capacitor patterns 132, 134 via via conductors 151 provided penetrating the base material 20. Also, a part of the second turn (the second turn counted from the innermost turn) among the turns constituting the second coil pattern 120 is divided. One and the other ends of the divided part are respectively connected to via conductors 152, 153 provided penetrating the base material 20. The via conductor 152 is connected to one end of the connection pattern 141, and the via conductor 153 is connected to one end of the connection pattern 142. The other ends of the connection patterns 141, 142 are respectively connected to via conductors 154, 155 provided penetrating the base material 20. The via conductors 154, 155 are respectively connected to the inner peripheral end and the outer peripheral end of the first coil pattern 110.

[0031] With such a configuration, the first coil pattern 110 and the second coil pattern 120 are connected in series, and as shown in FIG. 7, the capacitor C is connected in series to the first and second coil patterns 110, 120. A resonance circuit composed of the first and second coil patterns 110, 120 and the capacitor C forms a closed circuit that is not connected to an external circuit. The capacitor C plays a role of enhancing communication characteristics by adjusting the resonance frequency. By setting the resonance frequency of this closed circuit to a frequency band of 13.56 MHz or near 13.56 MHz, near-field wireless communication (NFC) becomes possible. Alternatively, as shown in FIG. 8, the capacitor C may be connected in parallel to the first and second coil patterns 110, 120. In this case, by designing such that the line length of the first coil pattern 110 is longer than the line length of the second coil pattern 120, it is possible to obtain the same resonance characteristics as when the capacitor C is connected in series to the first and second coil patterns 110, 120.

[0032] FIG. 9 is a schematic plan view showing a state in which the base material 20, the magnetic body 30, and the metal plate 40 are stacked.

[0033] As shown in FIG. 9, when the base material 20, the magnetic body 30, and the metal plate 40 are stacked, the first coil pattern 110 provided on the base material 20, the second through-hole 31 of the magnetic body 30, and the first through-hole 43 of the metal plate 40 overlap in the Z direction. The opening 110a surrounded by the first coil pattern 110 also overlaps with the second through-hole 31 and the first through-hole 43. The width of the opening 110a in the X direction is W8, and the width of the opening 110a in the Y direction is W9. The width W8 is smaller than the widths W1, W4 (see FIGS. 4 and 5), and the width W9 is smaller than the widths W2, W5 (see FIGS. 4 and 5). That is, the area of the opening 110a is smaller than the areas of the through-holes 31, 43. The opening 110a of the first coil pattern 110 may entirely overlap with the through-holes 31, 43. According to this, it is possible to prevent the interference between the magnetic flux passing through the opening 110a of the first coil pattern 110 and the magnetic body 30 and the metal plate 40.

[0034] The width W6 (see Fig. 5) of the first coil pattern 110 in the X direction is larger than the width W1 (see Fig. 4) of the first through hole 43 of the metal plate 40 in the X direction. The width W7 (see Fig. 5) of the first coil pattern 110 in the Y direction is larger than the width W2 (see Fig. 4) of the first through hole 43 of the metal plate 40 in the Y direction. Thus, when the base material 20 and the metal plate 40 are overlapped, the edges 431 to 434 of the first through hole 43 overlap with the winding region of the first coil pattern 110. The winding region of the first coil pattern 110 is a region located between the inner peripheral edge 111 and the outer peripheral edge 112 of the first coil pattern 110. As a result, there are a portion of the first coil pattern 110 that overlaps with the metal plate 40 and a portion that overlaps with the first through hole 43 without overlapping with the metal plate 40. The outer peripheral edge 112 of the first coil pattern 110 is located between the edge of the second through hole 31 of the magnetic body 30 and the edge of the first through hole 43 of the metal plate 40. Also, the winding region of the second coil pattern 120 is a region located between the inner peripheral edge 121 and the outer peripheral edge 122 of the second coil pattern 120.

[0035] In the example shown in Fig. 9, the edges 431 to 434 of the first through hole 43 are located outside the center in the radial direction of the winding region of the first coil pattern 110. According to this, since the overlapping area of the winding region of the first coil pattern 110 and the metal plate 40 is reduced, it becomes possible to pass more magnetic flux through the first through hole 43. Also, since the magnetic flux density above and below the winding region of the first coil pattern 110 is lower than that in the vicinity of the opening 110a and the outer peripheral edge 112, by arranging the edges 431 to 434 of the first through hole 43 in this region, it becomes possible to suppress the deterioration of the antenna characteristics due to the demagnetizing field.

[0036] The positional relationship between the edges 431 to 434 of the first through-hole 43 and the winding region of the first coil pattern 110 may be constant over the entire circumference. However, as in the example shown in FIG. 9, the position where the edge 431 (see FIG. 4) of the first through-hole 43 overlaps with the winding region may be inside in the radial direction compared to the positions where the edges 432 and 433 (see FIG. 4) of the first through-hole 43 overlap with the winding region. According to this, it becomes possible to arrange the portion where the first through-hole 43 and the first slit 44 are connected in a region with a lower magnetic flux density.

[0037] The connection pattern 141 that connects the inner peripheral end of the first coil pattern 110 and the second coil pattern 120 may have a portion that overlaps with the first slit 44 in a plan view seen from the Z direction. According to this, it becomes possible to reduce the loss of the connection pattern 141 caused by the overlap with the metal plate 40.

[0038] FIG. 10 is a schematic perspective view of the IC module 70 seen from the back side.

[0039] As shown in FIG. 10, the IC module 70 includes a module substrate 71, an IC chip 72 mounted or incorporated in the module substrate 71, and a coupling coil 73. The IC chip 72 is protected by being covered with a dome-shaped protective resin 74. The protective resin 74 is made of an insulating member. When the IC module 70 is arranged on the surface 42 of the metal plate 40, as shown in FIG. 3, the coupling coil 73 and the adhesive layer 64 are adhered via a hot melt tape 75. In this state, a part of the protective resin 74 may be arranged in the first through-hole 43 of the metal plate 40. On the back side of the module substrate 71, the terminal electrode E shown in FIG. 1 is provided. The IC module 70 having such a configuration is arranged on the other surface 42 side of the metal plate 40. As described above, a part of the protective resin 74 may be arranged in the first through-hole 43 of the metal plate 40, but the module substrate 71 itself is not arranged in the first through-hole 43 of the metal plate 40. Thereby, the size of the first through-hole 43 of the metal plate 40 can be made smaller than the size of the module substrate 71.

[0040] When the IC module 70 is disposed on the other surface 42 side of the metal plate 40, the coupling coil 73 and the first coil pattern 110 provided on the base material 20 are electromagnetically coupled through the first through hole 43 of the metal plate 40. The planar position of the winding region of the coupling coil 73 may substantially coincide with the planar position of the winding region of the first coil pattern 110. In this case, the edges 431 to 434 of the first through hole 43 of the metal plate 40 overlap the winding region of the coupling coil 73. Since the first coil pattern 110 is connected in series to the second coil pattern 120, when a current flows through the first coil pattern 110, a current also flows through the second coil pattern 120, and a magnetic field is generated from the second coil pattern 120. Thereby, as shown in FIG. 11, when the back surface 3b of the IC card 3 faces the card reader 6, communication can be performed between the card reader 6 and the IC chip 72.

[0041] In the present embodiment, the number of turns of the first coil pattern 110 is about 9 turns, and the number of turns of the second coil pattern 120 is about 3 turns. The first coil pattern 110 has a larger number of turns than the second coil pattern 120. Thereby, the coupling between the first coil pattern 110 and the coupling coil 73 of the IC module 70 is enhanced. On the other hand, for the second coil pattern 120, since the number of turns is smaller than that of the first coil pattern 110 and the pattern width is larger than the pattern width of the first coil pattern 110, the resistance value of the second coil pattern 120 is reduced.

[0042] FIG. 12 is a schematic diagram for explaining the current flowing through the metal plate 40 when communication is performed between the card reader 6 and the IC chip 72.

[0043] The dashed arrows shown in FIG. 12 indicate the directions of the currents flowing through the first coil pattern 110 and the coupling coil 73. When currents flow through the first coil pattern 110 and the coupling coil 73, eddy currents are generated in the metal plate 40 by the magnetic fluxes thus produced. The solid arrows shown in FIG. 12 indicate the directions of the eddy currents generated in the metal plate 40. Here, if the first slit 44 is not provided in the metal plate 40 and only the first through-hole 43 is provided, the eddy currents circulate largely around the first through-hole 43, and most of the signal components are cancelled out. However, in the present embodiment, since not only the first through-hole 43 but also the first slit 44 connected thereto is provided, the eddy currents cannot simply circulate around the first through-hole 43 and detour through the first slit 44. As a result, even though the first through-hole 43 and the first slit 44 are in a closed shape, the signal components cancelled out by the eddy currents are reduced, and correct communication becomes possible.

[0044] In the example shown in FIG. 9, the tip 44A of the first slit 44 is located outside the outer peripheral edge 122 of the second coil pattern 120 in a plan view seen from the Z direction. According to this, since the eddy currents detour more greatly, it becomes possible to further expand the communication distance.

[0045] As described above, the antenna device 1 according to the present embodiment includes the metal plate 40 having the first through-hole 43 and the first slit 44 connected thereto, and since the opening 110a overlaps the first through-hole 43 and the first coil pattern 110 is arranged so as to circulate along the first through-hole 43, it becomes possible to couple the IC module 70 arranged on the other surface 42 of the metal plate 40 and the first coil pattern 110 arranged on one surface 41 of the metal plate 40. Moreover, since the first slit 44 does not reach the outer edge 48 of the metal plate 40, when the antenna device 1 is applied to the IC card 3, the aesthetics of the card are enhanced and it becomes possible to prevent the intrusion of foreign matters such as moisture through the first slit 44.

[0046] FIG. 13 is a schematic plan view for explaining the shape of the metal plate 40 according to the modified example.

[0047] The metal plates 40 shown in FIG. 13 are all different from the metal plate 40 shown in FIG. 4 in that they are each provided with a second slit 45, a third slit 46, and a fourth slit 47 that communicate with the first through hole 43. The second slit 45 extends in a direction opposite to the extending direction of the first slit 44, that is, in the -Y direction. The third slit 46 extends in the +X direction perpendicular to the Y direction, which is the extending direction of the first slit 44. The fourth slit 47 extends in a direction opposite to the extending direction of the third slit 46, that is, in the -X direction. The tips of the second, third, and fourth slits 45 to 47 do not reach the outer edge 48 of the metal plate 40. That is, the first through hole 43 and the first to fourth slits 44 to 47 have a closed shape in plan view.

[0048] As in the example shown in FIG. 13, by providing a plurality of slits connected to the first through hole 43 and extending them in different directions from each other, the eddy current can detour more greatly, so that the communication distance can be further expanded.

[0049] As described above, the embodiments of the present disclosure have been described. However, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present disclosure, and it goes without saying that those are also included in the scope of the present disclosure.

[0050] For example, the conductor patterns provided on the surfaces 21 and 22 of the base material 20 may be provided on the surfaces 21 and 22 of the base material 20 via other material layers containing resin therebetween. Further, the coil may be formed by winding a conducting wire.

[0051] Further, the first coil pattern 110 and the second coil pattern 120 constituting the coil are not limited to the pattern shapes shown in FIG. 5. For example, each turn of the second coil pattern 120 may protrude toward the opening 120a, and the first coil pattern 110 may be a pattern in which the protruding portion is wound in a direction opposite to that of the second coil pattern 120. In this case, the first coil pattern 110 and the second coil pattern 120 can be formed only on one surface of the base material 20.

[0052] The technology according to the present disclosure includes, but is not limited to, the following configuration examples.

[0053] An antenna device according to an embodiment of the present disclosure includes a metal plate having a first through hole and a first slit that is connected to the first through hole and is narrower than the first through hole, a first coil whose opening overlaps the first through hole and that circulates along the first through hole, and a coil including a second coil that is connected to the first coil and circulates along the outer edge of the metal plate. The tip of the first slit does not reach the outer edge of the metal plate, and the first through hole and the first slit have a closed shape. According to this, eddy currents generated in the metal plate can bypass the first slit.

[0054] In the antenna device described above, the area of the first through hole may be larger than the area of the opening, and the entire opening may overlap the first through hole. According to this, it is possible to suppress the interference between the magnetic flux passing through the opening and the metal plate.

[0055] In the antenna device described above, the width of the first slit may be smaller than the distance between the tip of the first slit and the outer edge of the metal plate. According to this, it is possible to ensure the mechanical strength of the metal plate.

[0056] In the antenna device described above, the width of the first slit may be smaller than the thickness of the metal plate. According to this, it is possible to ensure the mechanical strength of the metal plate.

[0057] In the above-described antenna device, the metal plate is connected to the first through-hole and further has second, third, and fourth slits that are narrower than the first through-hole. The second slit extends in a direction opposite to the extending direction of the first slit, the third slit extends in a direction orthogonal to the extending direction of the first slit, the fourth slit extends in a direction opposite to the extending direction of the third slit, and the tips of the second, third, and fourth slits do not reach the outer edge of the metal plate. The first through-hole and the first, second, third, and fourth slits may have a closed shape. According to this, it is possible to make the eddy current generated in the metal plate detour more greatly.

[0058] In the above-described antenna device, the tip of the first slit may be located outside the outer peripheral edge of the second coil in a plan view. According to this, it is possible to make the eddy current generated in the metal plate detour more greatly.

[0059] In the above-described antenna device, the edge of the first through-hole may be located outside the center in the radial direction of the winding region of the first coil. According to this, it is possible to reduce the overlapping area between the first coil and the metal plate. In this case, the edge of the first through-hole has a first edge connected to the first slit and second and third edges extending in a direction orthogonal to the extending direction of the first edge. The position where the first edge overlaps the winding region may be inside in the radial direction compared to the position where the second and third edges overlap the winding region. According to this, it is possible to arrange the portion where the first through-hole and the first slit are connected in a region with a lower magnetic flux density.

[0060] In the above-described antenna device, the connection pattern connecting the inner peripheral end of the first coil and the second coil may have a portion overlapping the first slit in a plan view. According to this, it is possible to reduce the loss of the connection pattern.

[0061] In the above antenna device, the pattern width of the second coil may be larger than the pattern width of the first coil, and the number of turns of the second coil may be less than the number of turns of the first coil. According to this, the magnetic flux density generated by the first coil can be increased, and the resistance value of the second coil can be reduced.

[0062] The above antenna device further includes a magnetic body having a second through hole overlapping the first through hole. The area of the second through hole is larger than the area of the first through hole, and the outer peripheral edge of the first coil may be located between the edge of the second through hole and the edge of the first through hole. According to this, it is possible to arrange the edge of the first through hole of the metal plate in a region with a low magnetic flux density while eliminating the overlap between the first coil and the magnetic body.

[0063] An IC card according to an embodiment of the present disclosure includes any of the above antenna devices and an IC module overlapping the first coil through the first through hole. According to this, it is possible to provide an IC card including a metal plate.

[0064] In the above IC card, the first coil is disposed on one surface side of the metal plate, the IC module is disposed on the other surface side of the metal plate, the IC module has a module substrate, an IC chip mounted on the module, and a protective resin covering the IC chip, and at least a part of the protective resin may be located in the first through hole. According to this, it is possible to couple the IC module and the first coil without disposing the module substrate in the first through hole of the metal plate.

Description of Reference Numerals

[0065] 1 Antenna device 3 IC card 3a Upper surface of the IC card 3b Back surface of the IC card 6 Card reader 10 Plastic plate 20 Base material 21, 22 Surfaces of the base material 22 Surface 30 Magnet 31 Second through-hole 40 Metal plate 41, 42 Surfaces of the metal plate 43 First through-hole 44 First slit 44A Tip of the first slit 45 Second slit 46 Third slit 47 Fourth slit 48 Outer edge of the metal plate 50 Protection sheet 51 Third through-hole 61 - 64 Adhesive layer 70 IC module 71 Module substrate 72 IC chip 73 Coupling coil 74 Protection resin 75 Hot melt tape 110 First coil pattern 110a Opening of the first coil pattern 111 Inner peripheral edge of the first coil pattern 112 Outer peripheral edge of the first coil pattern 120 Second coil pattern 120a Opening of the second coil pattern 121 Inner peripheral edge of the second coil pattern 122 Outer peripheral edge of the second coil pattern 131 - 134 Capacitor pattern 141, 142 Connection pattern 151 - 155 Via conductor 431 - 434 Edges of the first through-hole C Capacitor E Terminal electrode

Claims

1. A metal plate having a first through hole and a first slit connected to the first through hole and narrower than the first through hole, A coil including a first coil whose opening overlaps the first through hole and circulates along the first through hole, and a second coil connected to the first coil and circulating along the outer edge of the metal plate, Comprising, The tip of the first slit does not reach the outer edge of the metal plate, and the first through hole and the first slit have a closed shape, An antenna device.

2. The area of the first through hole is larger than the area of the opening, The entire opening overlaps the first through hole, The antenna device according to claim 1.

3. The width of the first slit is smaller than the distance between the tip of the first slit and the outer edge of the metal plate, The antenna device according to claim 1.

4. The width of the first slit is smaller than the thickness of the metal plate, The antenna device according to claim 1.

5. The metal plate further has second, third, and fourth slits connected to the first through hole and narrower than the first through hole, The second slit extends in a direction opposite to the extending direction of the first slit, The third slit extends in a direction orthogonal to the extending direction of the first slit, The fourth slit extends in a direction opposite to the extending direction of the third slit, The tips of the second, third, and fourth slits do not reach the outer edge of the metal plate, and the first through hole and the first, second, third, and fourth slits have a closed shape, The antenna device according to claim 1.

6. The tip of the first slit is located outside the outer peripheral edge of the second coil in a plan view, The antenna device according to claim 1.

7. The edge of the first through hole is located outside the center in the radial direction of the winding region of the first coil, The antenna device according to claim 1.

8. The edge has a first edge connected to the first slit, and second and third edges extending in a direction orthogonal to the extending direction of the first edge, The position where the first edge overlaps the winding region is radially inner than the position where the second and third edges overlap the winding region, The antenna device according to claim 7.

9. The connection pattern that connects the inner peripheral end of the first coil and the second coil has a portion that overlaps with the first slit in a plan view. The antenna device according to claim 1.

10. The pattern width of the second coil is larger than the pattern width of the first coil. The number of turns of the second coil is less than the number of turns of the first coil. The antenna device according to claim 1.

11. The antenna device further includes a magnetic body having a second through hole that overlaps with the first through hole. The area of the second through hole is larger than the area of the first through hole. The outer peripheral edge of the first coil is located between the edge of the second through hole and the edge of the first through hole. The antenna device according to claim 1.

12. The antenna device according to any one of claims 1 to 11, and an IC module that overlaps with the first coil through the first through hole. An IC card comprising the same.

13. The first coil is disposed on one surface side of the metal plate. The IC module is disposed on the other surface side of the metal plate. The IC module includes a module substrate, an IC chip mounted on the module, and a protective resin that covers the IC chip. At least a part of the protective resin is located in the first through hole. The IC card according to claim 12.

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