Wireless power reception device

Abstract

This wireless power reception device comprises: an annular heat conduction member that extends in one peripheral direction; a first magnetic sheet that extends along the outer periphery of the heat conduction member and that contacts the heat conduction member; a second magnetic sheet that covers one opening of the heat conduction member; a third magnetic sheet that covers another opening of the heat conduction member; a power reception coil that is wound around the outer periphery of the first magnetic sheet; a power reception circuit board that is provided inward of the heat conduction member, that is electrically connected to the power reception coil, that uses a resonant capacitor and a rectification smoothing circuit to rectify a resonance current induced in the power reception coil and convert the resonance current into direct current, and that supplies electric power to a load; and a heat-generating electronic component that is mounted to the power reception circuit board and that contacts the heat conduction member.

Description

Wireless Power Receiver

[0001] The present disclosure relates to a wireless power receiving device.

[0002] Wireless power transfer technology, which wirelessly supplies power to electronic devices from an external power transmitter, is one charging technology for secondary batteries installed in small electronic devices. By using wireless power transfer technology, electronic devices do not need to have charging terminals, so there is no problem with corrosion or deterioration of metal terminals (charging terminals) and waterproofing can be improved.

[0003] As wireless power supply technology, Patent Document 1 describes a power supply receiving device and a portable device, and Patent Document 2 describes a contactless power supply device and a contactless power transmission device.

[0004] JP 2015-15860 A International Publication No. 2017 / 145266

[0005] It is preferable that small electronic devices using wireless power supply technology use a sealed housing to ensure waterproofing.

[0006] Furthermore, the electronic device is equipped with a power conversion circuit to charge the secondary battery with the power obtained by the power receiving coil, and the semiconductor device (IC) that constitutes the power conversion circuit generates heat.

[0007] In this way, when an electronic device employs a sealed structure and the semiconductor elements that make up the power conversion circuit generate heat, the temperature rises significantly locally on the surface of the housing of the electronic device (near the power conversion circuit).

[0008] Furthermore, in electronic devices, magnetic flux interlinks with the wireless power receiving circuit or secondary battery, causing the wireless power receiving circuit or secondary battery to heat up or be subject to electromagnetic interference, and the power receiving efficiency of the electronic device decreases due to reduced magnetic coupling with the power transmitting coil.

[0009] The present disclosure has been made in view of the above, and aims to suppress a local temperature rise on the surface of a housing, suppress electromagnetic interference, and increase power receiving efficiency.

[0010] A wireless power receiving device according to one aspect of the present disclosure includes: an annular heat conduction member extending circumferentially in one direction; a first magnetic sheet extending along the outer periphery of the heat conduction member and in thermal contact with the heat conduction member; a second magnetic sheet covering an opening on one side of the heat conduction member; a third magnetic sheet covering a side opening on the opposite side to the one direction of the heat conduction member; a receiving coil wound around the outer periphery of the first magnetic sheet; a receiving circuit board provided inside the heat conduction member and electrically connected to the receiving coil, rectifying a resonant current induced in the receiving coil and converting it to direct current to supply power to a load; and a heat-generating electronic component mounted on the receiving circuit board and in thermal contact with the heat conduction member. The thermal conduction member conducts heat generated from the heat-generating electronic components to the first magnetic sheet, and the first magnetic sheet has a length in one direction that is longer than the distance between the main surface of the second magnetic sheet on one side and the main surface of the third magnetic sheet on the opposite side to the one direction, forms a magnetic path by the main magnetic flux that has greater magnetic coupling with the magnetic flux generated from the external power transmission coil than the magnetic path formed in the second magnetic sheet or the third magnetic sheet, and radiates heat from the heat-generating electronic components.

[0011] According to the present invention, it is possible to suppress the temperature rise of heat-generating components mounted on the power receiving circuit, as well as to suppress local temperature rise on the surface of the housing, and it is also possible to suppress heat generation due to eddy currents in the wireless power receiving circuit and secondary battery, thereby suppressing electromagnetic interference and improving power receiving efficiency.

[0012] FIG. 1 is a diagram illustrating the principle of wireless power transmission and reception. FIG. 2 is a diagram illustrating a circuit block configuration of a wireless power receiving device according to an embodiment. FIG. 3 is a diagram illustrating the external appearance of a wireless power receiving device according to an embodiment. FIG. 4 is a diagram illustrating the external appearance of a wireless power receiving device according to an embodiment. FIG. 5 is a diagram illustrating the internal structure of a wireless power receiving device. FIG. 6 is a diagram illustrating the internal structure of a wireless power receiving device. FIG. 7 is a diagram illustrating the internal structure of a wireless power receiving device. FIG. 8 is a diagram illustrating an example of a first magnetic sheet. FIG. 9 is a diagram illustrating an example of a second magnetic sheet. FIG. 10 is a diagram illustrating an example of a third magnetic sheet. FIG. 11 is a diagram illustrating a first example of magnetic flux linking a wireless power receiving device. FIG. 12 is a diagram illustrating a second example of magnetic flux linking a wireless power receiving device.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description of matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0014] <Embodiments> (Principles of Wireless Power Transmission and Reception) Prior to describing wireless power receiving devices according to embodiments, the principles of wireless power transmission and reception will be described.

[0015] 1 is a diagram illustrating the principle of wireless power transmission and reception. A wireless power transmitting and receiving device 1 includes a wireless power transmitting device 2 and a wireless power receiving device 3.

[0016] The wireless power transmitter 2 includes a DC power supply 11, a transistor 12, a transistor 13, a power transmitting resonant circuit 14, and a control circuit 15. Each of the transistors 12 and 13 has a parasitic capacitance and a parasitic diode. The power transmitting resonant circuit 14 includes a power transmitting coil 16 and a resonant capacitor 17.

[0017] The wireless power receiver 3 includes a power receiver resonant circuit 21, a transistor 22, a transistor 23, a smoothing capacitor 24, a load 25, and a control circuit 26. The transistor 22 and the transistor 23 each have a parasitic capacitance and a parasitic diode. The power receiver resonant circuit 21 includes a power receiver coil 27 and a resonant capacitor 28.

[0018] The drain of the transistor 12 is electrically connected to the high potential side end of the DC power supply 11. The source of the transistor 12 is electrically connected to the drain of the transistor 13. The source of the transistor 13 is electrically connected to the low potential side end of the DC power supply 11. One end of the resonant capacitor 17 is electrically connected to the drain of the transistor 12. The other end of the resonant capacitor 17 is electrically connected to one end of the transmitting coil 16. The other end of the transmitting coil 16 is electrically connected to the source of the transistor 12 and the drain of the transistor 13.

[0019] One end of the receiving coil 27 is electrically connected to one end of the resonant capacitor 28. The other end of the resonant capacitor 28 is electrically connected to the drain of the transistor 22. The source of the transistor 22 is electrically connected to the other end of the receiving coil 27 and the drain of the transistor 23. One end of the smoothing capacitor 24 is electrically connected to the drain of the transistor 22. The other end of the smoothing capacitor 24 is electrically connected to the source of the transistor 23. One end of the load 25 is electrically connected to one end of the smoothing capacitor 24. The other end of the load 25 is electrically connected to the other end of the smoothing capacitor 24.

[0020] The power transmitting resonant circuit 14 and the power receiving resonant circuit 21 are electromagnetically coupled.

[0021] [Operation] The control circuit 15 alternately turns on and off the transistor 12 and the transistor 13 at a predetermined switching frequency, thereby applying a rectangular wave (pulse-shaped) voltage to the power transmitting resonant circuit 14, causing the power transmitting resonant circuit 14 to resonate and causing a resonant current to flow through the power transmitting resonant circuit 14.

[0022] When the power transmitting resonant circuit 14 resonates, the power transmitting resonant circuit 14 and the power receiving resonant circuit 21 resonate with each other. That is, the power receiving resonant circuit 21 resonates. As a result, a resonant current flows through the power receiving resonant circuit 21.

[0023] The frequency of the magnetic field generated by the power transmitting resonant circuit 14 is, for example, 6.78 MHz or 13.56 MHz in the ISM (Industrial, Scientific and Medical) band, but the present disclosure is not limited to this.

[0024] The control circuit 26 alternately turns on and off the transistors 22 and 23 depending on the direction of the current flowing through the power receiving coil 27. As a result, the resonant current of the power receiving resonant circuit 21 is rectified in synchronization with the direction of the current. The smoothing capacitor 24 smoothes the rectified current. The voltage smoothed by the smoothing capacitor 24 is applied to the load 25.

[0025] (Circuit Block Configuration of Wireless Power Receiver) FIG. 2 is a diagram showing the circuit block configuration of a wireless power receiver according to the embodiment.

[0026] The wireless power receiver 50 includes a wireless power receiver circuit 51 and a load circuit 52. The wireless power receiver circuit 51 includes a power receiver resonant circuit 61, a resonance adjustment circuit 62, a rectifying and smoothing circuit 63, a voltage conversion circuit 64, and a charge control circuit 65. The power receiver resonant circuit 61 includes a power receiver coil 71 and a resonant capacitor 72. The load circuit 52 includes a charging circuit 81, a secondary battery 82, and a function circuit 83.

[0027] The resonance adjustment circuit 62 adjusts the resonance of the power receiving resonance circuit 61. For example, the resonance adjustment circuit 62 corresponds to the transistor 22, the transistor 23, and the control circuit 26 in FIG.

[0028] The rectifying and smoothing circuit 63 rectifies and smoothes the resonant current of the power receiving resonant circuit 61. For example, the rectifying and smoothing circuit 63 corresponds to the smoothing capacitor 24 in Fig. 1. The rectifying and smoothing circuit 63 may include a diode in addition to the smoothing capacitor 24.

[0029] The voltage conversion circuit 64 is exemplified by a switching regulator that increases or decreases the voltage after being rectified and smoothed by the rectifying and smoothing circuit 63 .

[0030] The charge control circuit 65 controls the charge circuit 81 to cause the charge circuit 81 to charge the secondary battery 82 .

[0031] The functional circuit 83 operates by receiving power from the secondary battery 82. For example, if the wireless power receiving device 50 is a hearing aid, the functional circuit 83 may be a circuit that amplifies and outputs an audio signal.

[0032] (Housing of Wireless Power Receiver) In the embodiment, an example in which the wireless power receiver of the present disclosure is applied to a hearing aid will be described, but the present disclosure is not limited thereto. The wireless power receiver of the present disclosure can be applied to various electronic devices.

[0033] 3 and 4 are diagrams showing the external appearance of a wireless power receiving device according to an embodiment. The components that implement the wireless power receiving device 50 are housed in a housing 100. In the following, to easily explain the shape of the wireless power receiving device 50, the X-axis, Y-axis, and Z-axis directions will be used, but the X-axis, Y-axis, and Z-axis simply refer to three axes that are perpendicular to each other.

[0034] The Z-axis direction corresponds to an example of "one direction" in the present disclosure.

[0035] The housing 100 has a surface 101, a surface 102, a surface 103, a surface 104, a surface 105, and a surface 106. The housing 100 has a shape that matches the shape of the human auricle.

[0036] Surfaces 101 and 102 are parallel to the X-Y plane and are separated by a predetermined distance in the Z-axis direction. Surfaces 101 and 102 are parallel and face each other. Surface 103 is connected to the end edges of surfaces 101 and 102 on the tip side along the Y axis. Surface 104 is connected to the end edges of surfaces 101 and 102 on the base side along the Y axis. Surface 105 is connected to the end edges of surfaces 101 and 102 on the tip side along the X axis. Surface 106 is connected to the end edges of surfaces 101 and 102 on the base side along the X axis. Each of surfaces 103, 104, 105, and 106 is perpendicular to the X-Y plane.

[0037] Here, the length in the Y-axis direction on the X-axis tip side of surfaces 101 and 102 is longer than the length in the Y-axis direction on the X-axis base end side of surfaces 101 and 102. That is, in surfaces 101 and 102, region 110 on the side adjacent to surface 105 is wider than region 120 on the side adjacent to surface 106.

[0038] The components that realize the wireless power receiving device 50 are housed inside the housing 100. The housing 100 is exemplified as being made of resin, but the present disclosure is not limited thereto. The housing 100 is exemplified as being sealed and housing the components that realize the wireless power receiving device 50, but the present disclosure is not limited thereto.

[0039] (Internal Structure of Wireless Power Receiver) Figures 5, 6, and 7 are diagrams showing the internal structure of the wireless power receiver. Figure 5 is a diagram of the wireless power receiver 50 viewed in the direction opposite to the Z-axis direction, with surface 101 of the housing 100 (see Figures 3 and 4) removed. Figure 6 is a cross-sectional view taken along line A-B in Figure 5. Figure 7 is an enlarged view of region 301 in Figure 6.

[0040] The housing 100 contains a thermal conductive member 201, a receiving circuit board 202, a first magnetic sheet 203, a second magnetic sheet 204, a third magnetic sheet 205, a receiving coil 206, a secondary battery 207, and a functional circuit board 208.

[0041] The power receiving coil 206 corresponds to the power receiving coil 71 in Fig. 2. The secondary battery 207 corresponds to the secondary battery 82 in Fig. 2.

[0042] The heat conducting member 201 may be made of a metal, but the present disclosure is not limited thereto. The heat conducting member 201 may be made of copper (Cu), but the present disclosure is not limited thereto. The metal may be an alloy.

[0043] One end 201a and the other end 201b of the heat conduction member 201 in the circumferential direction of the Z axis are located opposite to the surface 106. The heat conduction member 201 extends clockwise in the circumferential direction of the Z axis along the surfaces 103, 105, and 104, forming a ring. However, a gap 401 is provided between the one end 201a and the other end 201b. In other words, the heat conduction member 201 is C-shaped when viewed from the Z axis direction. A circulating current is prevented from flowing through the heat conduction member 201 in the circumferential direction of the Z axis.

[0044] The wireless power receiving device 50 can suppress a circulating current from flowing in the circumferential direction of the Z axis through the heat conducting member 201 by providing the gap 401 between the one end 201a and the other end 201b of the heat conducting member 201. This enables the wireless power receiving device 50 to suppress loss and increase power receiving efficiency.

[0045] The heat conducting member 201 has a protrusion 201c on the inner periphery of the portion facing the surface 103.

[0046] First magnetic sheet 203 extends in the circumferential direction of the Z-axis along the outer periphery of heat conduction member 201 and is annular. In other words, first magnetic sheet 203 is O-shaped when viewed from the Z-axis direction. First magnetic sheet 203 is in thermal contact with heat conduction member 201. For example, first magnetic sheet 203 is in close contact with heat conduction member 201. This allows heat from heat conduction member 201 to be dissipated to the housing 100 side via first magnetic sheet 203.

[0047] Examples of the first magnetic sheet 203 include ferrite sintered bodies and fine soft magnetic metals solidified with resin, but the present disclosure is not limited thereto. Generally, the relative permeability of ferrite sintered bodies is high (e.g., approximately 200), while that of fine soft magnetic metals solidified with resin is low (e.g., approximately 50). In terms of cost, ferrite is expensive, while that of fine soft magnetic metals solidified with resin is inexpensive. In terms of flexibility (ease of bending, ease of processing), that of fine soft magnetic metals solidified with resin is high, while that of ferrite sintered bodies is low.

[0048] 8 is a diagram showing an example of the first magnetic sheet 203. As shown in FIG. 8, the first magnetic sheet 203 is exemplified as a strip-shaped sheet. The strip-shaped first magnetic sheet 203 is exemplified as being wrapped (e.g., attached) around the outer periphery of the heat conduction member 201 along the circumferential direction of the Z axis.

[0049] 5 and 6 again, the power receiving coil 206 is wound around the outer periphery of the first magnetic sheet 203. Both ends of the power receiving coil 206 are electrically connected to the power receiving circuit board 202 via wiring 261.

[0050] The power receiving circuit board 202 includes a resonant capacitor 72 (see FIG. 2), a resonance adjustment circuit 62 (see FIG. 2), a rectifying and smoothing circuit 63 (see FIG. 2), a voltage conversion circuit 64 (see FIG. 2), a charge control circuit 65 (see FIG. 2), and a charging circuit 81 (see FIG. 2). The power receiving circuit board 202 converts the resonant current of the power receiving resonant circuit (power receiving coil 206 and resonant capacitor 72) into direct current, and supplies the power to a load (secondary battery 207).

[0051] The wireless power receiving device 50 can be used repeatedly without battery replacement because the power receiving circuit board 202 includes a charging circuit 81 that charges the secondary battery 207 .

[0052] The power receiving circuit board 202 is provided inside the heat conducting member 201, in a position facing the surface 103. The power receiving circuit board 202 is disposed so that its first main surface (the main surface on the tip side of the Y axis, the main surface facing upward in FIG. 5 ) faces the heat conducting member 201. In other words, the power receiving circuit board 202 is disposed so that its first main surface is perpendicular to the XY plane and parallel to the Z axis.

[0053] The wireless power receiving device 50 can have a larger internal space than when the first main surface of the power receiving circuit board 202 is arranged parallel to the X-Y plane and perpendicular to the Z axis because the first main surface of the power receiving circuit board 202 is arranged perpendicular to the X-Y plane and parallel to the Z axis. Alternatively, the wireless power receiving device 50 can be made smaller than when the first main surface of the power receiving circuit board 202 is arranged parallel to the X-Y plane and perpendicular to the Z axis because the first main surface of the power receiving circuit board 202 is arranged perpendicular to the X-Y plane and parallel to the Z axis.

[0054] Heat-generating electronic components 251, 252, and 253 are mounted on a first main surface of the power receiving circuit board 202. Each of the heat-generating electronic components 251, 252, and 253 is exemplified by a semiconductor device, but the present disclosure is not limited thereto.

[0055] The heat-generating electronic component 251 is the electronic component that generates the largest amount of heat among the components of the wireless power receiving device 50. An example of the heat-generating electronic component 251 is a semiconductor device in which a voltage conversion circuit 64 (e.g., a switching regulator) is formed, but the present disclosure is not limited to this.

[0056] The resonance adjustment circuit 62 (see FIG. 2), the rectifying and smoothing circuit 63 (see FIG. 2), the charge control circuit 65 (see FIG. 2), and the charge circuit 81 (see FIG. 2) are each formed in the electronic component 252 or the electronic component 253.

[0057] The heat-generating electronic component 251 is in thermal contact with the protrusion 201c of the heat-conducting member 201. For example, a first main surface (the main surface on the tip side of the Y-axis, the main surface facing upward in FIG. 5 ) of the heat-generating electronic component 251 is in close contact with the protrusion 201c of the heat-conducting member 201.

[0058] In the wireless power receiving device 50, the first main surface of the receiving circuit board 202 is arranged perpendicular to the X-Y plane and parallel to the Z axis, which makes it easier to bring the heat-generating electronic component 251 into contact with the heat-conducting member 201 compared to when the first main surface of the receiving circuit board 202 is arranged parallel to the X-Y plane and perpendicular to the Z axis.

[0059] Heat-generating electronic component 251 is in thermal contact with protrusion 201c of heat conduction member 201, and thus heat from heat-generating electronic component 251 is conducted to heat conduction member 201. The heat conducted to heat conduction member 201 is diffused throughout heat conduction member 201. The heat diffused throughout heat conduction member 201 is conducted throughout first magnetic sheet 203.

[0060] The wireless power receiving device 50 can suppress local temperature increases on the surface of the housing 100 by diffusing the heat from the heat-generating electronic component 251 throughout the heat conduction member 201 and then to surfaces 103, 104, 105 and 106 of the housing 100 via the first magnetic sheet 203.

[0061] The secondary battery 207 is provided inside the heat conducting member 201 and in a position facing the surface 105 .

[0062] The wireless power receiving device 50 can be made smaller by providing the secondary battery 207 inside the heat conducting member 201 .

[0063] The secondary battery 207 is exemplified by a coin battery or a button battery.

[0064] The wireless power receiving device 50 has a button-type or coin-type secondary battery 207, which allows the electronic device to be miniaturized, making it suitable for a hearing aid.

[0065] The secondary battery 207 is electrically connected to the power receiving circuit board 202 via a wiring 262. The secondary battery 207 is charged via the wiring 262 when the power receiving circuit board 202 is receiving power.

[0066] The functional circuit board 208 includes a functional circuit 83 (see FIG. 2 ). When the wireless power receiving device of the present disclosure is applied to a hearing aid, the functional circuit board 208 is exemplified as a board that amplifies and outputs an audio signal, but the present disclosure is not limited thereto.

[0067] The functional circuit board 208 is provided inside the heat conduction member 201, at a location facing the surface 104. The functional circuit board 208 is provided so that its first main surface (the main surface on the base end side of the Y axis, the main surface facing downward in FIG. 5 ) faces the heat conduction member 201. In other words, the first main surface of the functional circuit board 208 is disposed perpendicular to the XY plane and parallel to the Z axis.

[0068] The wireless power receiving device 50 can have a larger internal space because the first main surface of the functional circuit board 208 is arranged perpendicular to the X-Y plane and parallel to the Z-axis, compared to a case in which the first main surface of the functional circuit board 208 is arranged parallel to the X-Y plane and perpendicular to the Z-axis. Alternatively, the wireless power receiving device 50 can be made smaller because the first main surface of the functional circuit board 208 is arranged perpendicular to the X-Y plane and parallel to the Z-axis, compared to a case in which the first main surface of the functional circuit board 208 is arranged parallel to the X-Y plane and perpendicular to the Z-axis.

[0069] The functional circuit board 208 is electrically connected to the power receiving circuit board 202 via the wiring 263. The functional circuit board 208 receives power from the secondary battery 207 via the wiring 263, the power receiving circuit board 202, and the wiring 262, and operates accordingly.

[0070] Second magnetic sheet 204 is disposed at a first opening (the opening on the tip side of the Z axis, the opening on the side facing surface 101) of heat conduction member 201, and covers the first opening of heat conduction member 201. Third magnetic sheet 205 is disposed at a second opening (the opening on the base end side of the Z axis, the opening on the side facing surface 102) of heat conduction member 201, and covers the second opening of heat conduction member 201.

[0071] Fig. 9 is a diagram showing an example of the second magnetic sheet, and Fig. 10 is a diagram showing an example of the third magnetic sheet.

[0072] For example, the relative magnetic permeability of first magnetic sheet 203 is greater than the relative magnetic permeability of second magnetic sheet 204 and third magnetic sheet 205. For example, first magnetic sheet 203 may be a sintered ferrite body, and second magnetic sheet 204 and third magnetic sheet 205 may be made of fine soft magnetic metal solidified with resin.

[0073] As will be described later, first magnetic sheet 203 forms magnetic coupling with power transmission coil 501 (described later) or power transmission coil 521 (described later), while second magnetic sheet 204 and third magnetic sheet 205 form an electromagnetic seal. Therefore, first magnetic seal 203 preferably has a high relative permeability to increase magnetic coupling and improve power receiving efficiency, while second magnetic sheet 204 and third magnetic sheet 205 do not necessarily need to have a high relative permeability.

[0074] As explained above, ferrite sintered bodies are expensive, while those made of fine soft magnetic metals solidified with resin are inexpensive.

[0075] Therefore, for example, the first magnetic sheet 203 may be a sintered ferrite body, and the second magnetic sheet 204 and the third magnetic sheet 205 may be made of fine soft magnetic metal solidified with resin.

[0076] By making the first magnetic sheet 203 a sintered ferrite body, the wireless power receiving device 50 can increase the magnetic coupling with the power transmitting coil 501 or the power transmitting coil 521, thereby improving the power receiving efficiency. Furthermore, by making the second magnetic sheet 204 and the third magnetic sheet 205 out of fine soft magnetic metal particles solidified with resin, the wireless power receiving device 50 can reduce costs.

[0077] 7 , the tip end of first magnetic sheet 203 in the Z axis direction is located closer to the tip end of second magnetic sheet 204 than the tip end of the first main surface of second magnetic sheet 204. The base end of first magnetic sheet 203 in the Z axis direction is located closer to the base end of third magnetic sheet 205 than the base end of the first main surface of third magnetic sheet 205. In other words, width d2 of first magnetic sheet 203 in the Z axis direction is longer than distance d1 between the first main surface of second magnetic sheet 204 and the first main surface of third magnetic sheet 205.

[0078] This enables the wireless power receiving device 50 to prevent magnetic flux from the power transmitting coil 501 or the power transmitting coil 521 from entering the interior of the wireless power receiving device 50 through the gap between the first magnetic sheet 203 and the second magnetic sheet 204 and the gap between the first magnetic sheet 203 and the third magnetic sheet 205. Therefore, the wireless power receiving device 50 prevents magnetic flux from interlinking with the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208, thereby preventing heat generation in the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208 and preventing the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208 from being subjected to electromagnetic interference.

[0079] 11 is a diagram illustrating a first example of magnetic flux linking the wireless power receiving device. In Fig. 11, the power transmitting coil 501 has an annular shape along the circumferential direction of the Z axis, and faces the surfaces 106, 103, 105, and 104 (see Fig. 3, etc.).

[0080] For example, as indicated by arrow 511, the magnetic flux travels counterclockwise on the X-Z plane from the end of first magnetic sheet 203 on the tip side in the Z axis, surrounding power receiving coil 206 and power transmitting coil 501, and reaches the end of first magnetic sheet 203 on the base side in the Z axis. Furthermore, as indicated by arrow 512, the magnetic flux travels clockwise on the X-Z plane from the end of first magnetic sheet 203 on the tip side in the Z axis, surrounding power receiving coil 206 and power transmitting coil 501, and reaches the end of first magnetic sheet 203 on the base side in the Z axis.

[0081] In this way, the first magnetic sheet 203 can form a magnetic path that allows magnetic flux to efficiently interlink with the power receiving coil 206 .

[0082] This allows the wireless power receiving device 50 to improve power receiving efficiency.

[0083] Furthermore, first magnetic sheet 203 can suppress magnetic flux interlinking with heat conducting member 201 , and can suppress the generation of eddy currents in heat conducting member 201 .

[0084] This allows the wireless power receiving device 50 to reduce loss and improve power receiving efficiency.

[0085] 12 is a diagram showing a second example of magnetic flux linking the wireless power receiving device. In Fig. 12, the power transmitting coil 521 is parallel to the XY plane and faces the surface 102 (see Fig. 3, etc.).

[0086] For example, as indicated by arrow 531, the magnetic flux travels counterclockwise from third magnetic sheet 205 on the X-Z plane, passes inside power transmission coil 521, and reaches third magnetic sheet 205. Furthermore, for example, as indicated by arrow 532, the magnetic flux travels clockwise from third magnetic sheet 205 on the X-Z plane, passes inside power transmission coil 521, and reaches third magnetic sheet 205.

[0087] In this way, the third magnetic sheet 205 can prevent magnetic flux from interlinking with the power receiving circuit board 202 , the secondary battery 207 , and the functional circuit board 208 .

[0088] This allows the wireless power receiving device 50 to prevent the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208 from being subjected to electromagnetic interference.

[0089] 12 , a magnetic flux may be generated that extends from the first magnetic sheet 203, surrounds the power receiving coil 206, passes through the inside of the power transmitting coil 521, and reaches the first magnetic sheet 203. Therefore, the wireless power receiving device 50 can be charged from the power transmitting coil 521.

[0090] (Effects) [1] Heat-generating electronic component 251 is in thermal contact with protrusion 201c of heat conduction member 201, so that heat from heat-generating electronic component 251 is conducted to heat conduction member 201. The heat conducted to heat conduction member 201 is diffused throughout heat conduction member 201. The heat diffused throughout heat conduction member 201 is conducted throughout first magnetic sheet 203.

[0091] The wireless power receiving device 50 can suppress local temperature increases on the surface of the housing 100 by diffusing the heat from the heat-generating electronic component 251 throughout the heat conduction member 201 and then to surfaces 103, 104, 105 and 106 of the housing 100 via the first magnetic sheet 203.

[0092] [2] The end of first magnetic sheet 203 on the tip side in the Z axis direction is located further toward the tip side in the Z axis than the first main surface on the tip side in the Z axis of second magnetic sheet 204. The end of first magnetic sheet 203 on the base side in the Z axis direction is located further toward the base side in the Z axis than the first main surface on the base side in the Z axis of third magnetic sheet 205. In other words, width d2 of first magnetic sheet 203 in the Z axis direction is longer than distance d1 between the first main surface of second magnetic sheet 204 and the first main surface of third magnetic sheet 205.

[0093] This enables the wireless power receiving device 50 to prevent magnetic flux from the power transmitting coil 501 or the power transmitting coil 521 from entering the interior of the wireless power receiving device 50 through the gap between the first magnetic sheet 203 and the second magnetic sheet 204 and the gap between the first magnetic sheet 203 and the third magnetic sheet 205. Therefore, the wireless power receiving device 50 prevents magnetic flux from interlinking with the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208, thereby preventing heat generation in the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208 and preventing the power receiving circuit board 202, the secondary battery 207, and the functional circuit board 208 from being subjected to electromagnetic interference.

[0094] [3] Because the first main surface of the power receiving circuit board 202 is arranged perpendicular to the X-Y plane and parallel to the Z axis, the wireless power receiving device 50 can have a larger internal space than when the first main surface of the power receiving circuit board 202 is arranged parallel to the X-Y plane and perpendicular to the Z axis. Alternatively, because the first main surface of the power receiving circuit board 202 is arranged perpendicular to the X-Y plane and parallel to the Z axis, the wireless power receiving device 50 can be made smaller than when the first main surface of the power receiving circuit board 202 is arranged parallel to the X-Y plane and perpendicular to the Z axis.

[0095] [4] For example, the first magnetic sheet 203 may be a sintered ferrite body, and the second magnetic sheet 204 and the third magnetic sheet 205 may be made of fine soft magnetic metal solidified with resin.

[0096] By making the first magnetic sheet 203 a sintered ferrite body, the wireless power receiving device 50 can increase the magnetic coupling with the power transmitting coil 501 or the power transmitting coil 521, thereby improving the power receiving efficiency. Furthermore, by making the second magnetic sheet 204 and the third magnetic sheet 205 out of fine soft magnetic metal particles solidified with resin, the wireless power receiving device 50 can reduce costs.

[0097] [5] The wireless power receiving device 50 can suppress electromagnetic interference by setting the frequency of the magnetic field generated by the power transmitting coil to 6.78 MHz or 13.56 MHz in the ISM band.

[0098] [6] The wireless power receiving device 50 can be made smaller by providing the secondary battery 207 inside the heat conducting member 201.

[0099] [7] In the wireless power receiving device 50, the secondary battery 207 has a button or coin shape, which allows the electronic device to be miniaturized, making it suitable for use in a hearing aid.

[0100] [8] The wireless power receiving device 50 can be used repeatedly without battery replacement because the power receiving circuit board 202 includes a charging circuit that charges the secondary battery 207.

[0101] [9] In the wireless power receiving device 50, the gap 401 is provided between the one end 201a and the other end 201b of the heat conducting member 201, thereby preventing a circulating current from flowing in the circumferential direction of the Z axis through the heat conducting member 201. This allows the wireless power receiving device 50 to reduce loss and improve power receiving efficiency.

[0102] <Configuration Example of the Present Disclosure> The present disclosure may also have the following configuration.

[0103] (1) A power receiving device comprising: an annular heat conducting member extending in one circumferential direction; a first magnetic sheet extending along the outer periphery of the heat conducting member and in thermal contact with the heat conducting member; a second magnetic sheet covering an opening on the one side of the heat conducting member; a third magnetic sheet covering an opening on the opposite side of the heat conducting member; a power receiving coil wound around the outer periphery of the first magnetic sheet; a power receiving circuit board provided inside the heat conducting member, electrically connected to the power receiving coil, rectifying a resonant current induced in the power receiving coil and converting it to direct current to supply power to a load; and a heat-generating electronic component mounted on the power receiving circuit board and in thermal contact with the heat conducting member, wherein the heat conducting member conducts heat generated from the heat-generating electronic component to the first magnetic sheet, and the first magnetic sheet a length in the one direction is longer than the distance between the main surface of the second magnetic sheet on the one direction side and the main surface of the third magnetic sheet on the opposite side to the one direction, a magnetic path is formed by a main magnetic flux that has greater magnetic coupling with a magnetic flux generated from an external power transmission coil than a magnetic path formed in the second magnetic sheet or the third magnetic sheet, and the wireless power receiving device radiates heat from the heat-generating electronic component.

[0104] (2) The wireless power receiving device according to (1) above, wherein the power receiving circuit board has a main surface disposed parallel to the one direction.

[0105] (3) The wireless power receiving device according to (1) or (2) above, wherein the relative magnetic permeability of the first magnetic sheet is greater than the relative magnetic permeability of the second magnetic sheet or the third magnetic sheet.

[0106] (4) The wireless power receiving device according to any one of (1) to (3) above, wherein the frequency of the magnetic field generated by the power transmitting coil is 6.78 MHz or 13.56 MHz in the ISM (Industrial, Scientific and Medical) band.

[0107] (5) The wireless power receiving device according to any one of (1) to (4) above, further including a secondary battery provided inside the heat conducting member.

[0108] (6) The wireless power receiving device according to (5) above, wherein the secondary battery is a coin battery or a button battery.

[0109] (7) The wireless power receiving device according to (5) or (6) above, wherein the power receiving circuit board includes a charging circuit that charges the secondary battery.

[0110] (8) The wireless power receiving device according to any one of (1) to (7) above, wherein the heat conducting member is made of copper, and a gap is provided between one end in the circumferential direction and the other end in the circumferential direction.

[0111] The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the present invention, and equivalents thereof are also included in the present invention.

[0112] REFERENCE SIGNS LIST 1 Wireless power transmitting and receiving device 2 Wireless power transmitting device 3, 50 Wireless power receiving device 11 DC power supply 12, 13, 22, 23 Transistor 14 Power transmitting resonant circuit 16, 501, 521 Power transmitting coil 17, 28, 72 Resonant capacitor 15, 26 Control circuit 21, 61 Power receiving resonant circuit 24 Smoothing capacitor 25 Load 27, 71 Power receiving coil 51 Wireless power receiving circuit 52 Load circuit 62 Resonance adjustment circuit 63 Rectification smoothing circuit 64 Voltage conversion circuit 65 Charging control circuit 81 Charging circuit 82 Secondary battery 83 Functional circuit 100 Housing 101, 102, 103, 104, 105, 106 Surface 201 Heat conducting member 201c Protrusion 202 Power receiving circuit board 203 First magnetic sheet 204 Second magnetic sheet 205 Third magnetic sheet 206 Power receiving coil 207 Secondary battery 208 Functional circuit board

Claims

1. An annular heat conductive member extending in a circumferential direction in one direction, A first magnetic sheet extending along the outer circumference of the heat conductive member and in thermal contact with the heat conductive member, A second magnetic sheet covering the opening on the one-way side of the heat conductive member, A third magnetic sheet covers the opening on the side of the heat conductive member opposite to the one direction, A receiving coil wound around the outer circumference of the first magnetic sheet, A power receiving circuit board is provided inside the heat conductive member, electrically connected to the power receiving coil, rectifies the resonant current induced in the power receiving coil, converts it to DC, and supplies power to the load. A heat-generating electronic component mounted on the power receiving circuit board and in thermal contact with the heat conductive member, Equipped with, The aforementioned heat conductive member is The heat generated from the heat-generating electronic component is conducted to the first magnetic sheet. The first magnetic sheet is The length in one direction is longer than the distance between the main surface of the second magnetic sheet on the side in that direction and the main surface of the third magnetic sheet on the side opposite to that direction, and a magnetic path is formed by a main magnetic flux that has greater magnetic coupling to the magnetic flux generated from an external power transmission coil than the magnetic path formed in the second magnetic sheet or the third magnetic sheet, and the heat of the heat-generating electronic component is radiated thermally. Wireless power receiving device.

2. A wireless power receiving device according to claim 1, The power receiving circuit board has a main surface that is arranged parallel to the aforementioned one direction. Wireless power receiving device.

3. A wireless power receiving device according to claim 1, The relative permeability of the first magnetic sheet is greater than the relative permeability of the second magnetic sheet or the third magnetic sheet. Wireless power receiving device.

4. A wireless power receiving device according to claim 1, The frequency of the magnetic field generated from the transmission coil is 6.78 MHz or 13.56 MHz in the ISM (Industrial, Scientific and Medical) band. Wireless power receiving device.

5. A wireless power receiving device according to claim 1, The heat conductive member further includes a secondary battery provided inside the heat conductive member, Wireless power receiving device.

6. A wireless power receiving device according to claim 5, The aforementioned secondary battery is a coin-type battery or a button-type battery. Wireless power receiving device.

7. A wireless power receiving device according to claim 5, The power receiving circuit board includes a charging circuit for charging the secondary battery. Wireless power receiving device.

8. A wireless power receiving device according to claim 1, The heat conductive member is made of copper, and a gap is provided between one end in the circumferential direction and the other end in the circumferential direction. Wireless power receiving device.