Patent Publication Number: US-2022231348-A1

Title: Universal-battery-outer-shape wirelessly chargeable battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of priority to International Patent Application No. PCT/JP2020/030602, filed Aug. 11, 2020, and to Japanese Patent Application No. 2019-188230, filed Oct. 11, 2019, the entire contents of each are incorporated herein by reference. 
    
    
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a wirelessly chargeable battery including a secondary battery and a wireless charging circuit connected to the secondary battery. 
     Background Art 
     In Japanese Patent No. 5798407, a contactless chargeable secondary battery including a secondary battery and a wireless power transmission circuit that are housed in an outer casing is suggested. Specifically, the contactless chargeable secondary battery includes a power reception circuit that includes an alkaline secondary battery, a power receiving coil, and a resonant capacitor connected in parallel to the power receiving coil and receives AC power through a magnetic field from a power transmission device; a rectifier circuit that rectifies the AC power received at the power reception circuit; a circuit limiting circuit that limits a charging current flowing from the rectifier circuit to the alkaline secondary battery; and an outer casing of a cylindrical shape including a positive terminal and a negative terminal that are connected to the alkaline secondary battery. The configuration in which the power receiving coil is provided along an inner circumferential surface of the outer casing is described. 
     SUMMARY 
     The contactless chargeable secondary battery described in Japanese Patent No. 5798407 is assumed to include a casing of a tubular shape and be an alkaline secondary battery interchangeable with a dry battery. Such a contactless chargeable secondary battery is assumed to be chargeable in a state in which the contactless chargeable secondary battery is placed close to a charging device dedicated to charging the contactless chargeable secondary battery. Thus, under the circumstance in which an external magnetic field having a size exceeding a predetermined value is applied, the received power might be too large, and induced voltage and induced current might be unable to satisfy the practicality or versatility. 
     Furthermore, the contactless chargeable secondary battery disclosed in Japanese Patent No. 5798407 is assumed to be charged as a contactless chargeable secondary battery single unit, and it is difficult to wirelessly charge the contactless chargeable secondary battery in a state in which the contactless chargeable secondary battery is attached to an electronic device. In the state in which the contactless chargeable secondary battery is attached to an electronic device, the distance, positional displacement, tilt, and the like between the power receiving coil and a power transmitting coil may vary depending on the attached state. Thus, the size of the external magnetic field viewed from the power receiving coil significantly varies depending on the attached state. In the case where the external magnetic field is small, an insufficient amount of power is received. In the case where the external magnetic field is too large, the received voltage and received power may become too large, and an electrically connected circuit or electronic component may break down or wiring may be disconnected. Therefore, it is difficult to wirelessly charge the contactless chargeable secondary battery in the state in which the contactless chargeable secondary battery is attached to an electronic device. 
     Thus, the present disclosure provides a universal-outer-shape wirelessly chargeable battery that is capable of being used as a power source component achieving practicality, versatility, and security by enabling both charging of a secondary battery and voltage output or only voltage output in the case where the size of an external electromagnetic field or an external magnetic field is within a predetermined range and causing a circuit connected to a power receiving coil and a power reception protecting circuit that protects an electronic component to operate and interrupting (rejecting) power reception in the case where the size of the external electromagnetic field or the external magnetic field exceeds the predetermined range. 
     A universal-outer-shape wirelessly chargeable battery according to an example of the present disclosure includes a secondary battery; a wireless charging circuit that is connected to the secondary battery; a housing body that has an outer shape equivalent to an outer shape of a universal battery and accommodates the secondary battery and the wireless charging circuit; and a positive terminal and a negative terminal that are electrically connected to the secondary battery and are provided at positions corresponding to positions of a positive terminal and a negative terminal, respectively, of the universal battery. The wireless charging circuit includes a power receiving coil that receives an electromagnetic field or a magnetic field having a predetermined size caused by power transmission from an outside, a rectifier circuit that rectifies a received voltage received at the power receiving coil, a first voltage conversion circuit that converts a voltage output from the rectifier circuit to generate a charging voltage, a charging control circuit that receives a voltage output from the first voltage conversion circuit and controls charging of the secondary battery, a second voltage conversion circuit that converts a voltage of the secondary battery into an output voltage to be output from the universal battery, and a power reception protecting circuit that protects the first voltage conversion circuit in a case where the received voltage exceeds a predetermined voltage range. The universal-outer-shape wirelessly chargeable battery is able to be attached to an electronic device that uses the universal battery, and wireless charging using an electromagnetic field caused by power transmission from the outside is able to be performed using the wireless charging circuit. 
     According to the present disclosure, a universal-outer-shape wirelessly chargeable battery that may be used as a power source component achieving practicality, versatility, and security can be obtained, in which both charging of a secondary battery and voltage output or only voltage output can be performed in the case where the size of an external electromagnetic field or an external magnetic field is within a predetermined range and a circuit connected to a power receiving coil and a power reception protecting circuit that protects an electronic component operates and power reception is interrupted (rejected) in the case where the size of the external electromagnetic field or the external magnetic field exceeds the predetermined range. Furthermore, according to the present disclosure, a universal-battery-outer-shape wirelessly chargeable battery that is able to be wirelessly charged in a single unit state or a state being mounted at a device is obtained. Furthermore, a device or an electronic circuit at which a universal-battery-outer-shape wirelessly chargeable battery according to the present disclosure is mounted is able to receive electric power from the outside through an electromagnetic field or a magnetic field caused by power transmission from the outside. Thus, there is no need to configure a wireless charging circuit in the device or the electronic circuit. Furthermore, according to the present disclosure, the secondary battery and the wireless charging circuit can be connected by a short wiring. Thus, power loss in the wiring can be reduced, and a malfunction caused by an external magnetic field can be prevented. Accordingly, downsizing and lightening, thinning, and increasing of efficiency of a device and an electronic circuit at which the universal-battery-outer-shape wirelessly chargeable battery is mounted can be achieved. 
     Furthermore, a device or an electronic circuit at which a universal-battery-outer-shape wirelessly chargeable battery according to the present disclosure is mounted can be used as a device or an electronic circuit including a secondary battery and a wireless charging function. Thus, downsizing and lightening and increasing of efficiency of the device or the electronic circuit can be achieved. 
     Furthermore, a secondary battery is able to be repeatedly charged and discharged, and battery replacement is not required, unlike a primary battery. Therefore, labor saving in maintenance can be achieved, and there is no need to dispose of primary batteries. Thus, an environmentally friendly and ecological device or electronic circuit can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external perspective view of a universal-battery-outer-shape wirelessly chargeable battery according to a first embodiment; 
         FIG. 2  is an exploded perspective view of the universal-battery-outer-shape wirelessly chargeable battery; 
         FIG. 3  is an exploded perspective view of a universal-battery-outer-shape wirelessly chargeable battery according to the first embodiment; 
         FIGS. 4A and 4B  are diagrams each illustrating the positional relationship between a power transmission plate and the universal-battery-outer-shape wirelessly chargeable battery; 
         FIG. 5A  is an exploded perspective view of a state in which the universal-battery-outer-shape wirelessly chargeable battery is attached to an electronic device, and  FIG. 5B  is an external perspective view illustrating a state in which the universal-battery-outer-shape wirelessly chargeable battery attached to the electronic device is charged; 
         FIG. 6  is a circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery and other elements; 
         FIG. 7  is another circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery and other elements; 
         FIGS. 8A, 8B, 8C, and 8D  are circuit diagrams illustrating specific examples of a power reception protecting circuit; 
         FIG. 9  is another circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery and other elements; 
         FIGS. 10A and 10B  are diagrams for explaining an operation of an interruption circuit in  FIG. 9  at the time of normal power reception; 
         FIGS. 11A and 11B  are diagrams for explaining an operation of the interruption circuit performed when a received voltage exceeds a specified value; 
         FIGS. 12A and 12B  are diagrams illustrating examples of the configuration of a received voltage detecting circuit illustrated in  FIG. 9 ; 
         FIG. 13  is a circuit diagram illustrating a specific example of a protection circuit  56 ; 
         FIG. 14  is a plan view illustrating a state in which a universal-battery-outer-shape wirelessly chargeable battery according to a second embodiment is developed; 
         FIG. 15  is a bottom view illustrating a state in which the universal-battery-outer-shape wirelessly chargeable battery is developed; 
         FIG. 16  is a bottom view of the universal-battery-outer-shape wirelessly chargeable battery; 
         FIG. 17  is a diagram illustrating a configuration of an interruption circuit of a universal-battery-outer-shape wirelessly chargeable battery according to a third embodiment; 
         FIG. 18  is a diagram illustrating another configuration of the interruption circuit of the universal-battery-outer-shape wirelessly chargeable battery according to the third embodiment; 
         FIG. 19  is a circuit diagram of part of a universal-battery-outer-shape wirelessly chargeable battery and a power transmission device according to a fourth embodiment; 
         FIG. 20  is a circuit diagram of part of another universal-battery-outer-shape wirelessly chargeable battery and a power transmission device according to the fourth embodiment; 
         FIG. 21  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery according to a fifth embodiment; 
         FIG. 22  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery according to the fifth embodiment; 
         FIG. 23  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery according to a sixth embodiment; and 
         FIG. 24  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery according to a seventh embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a plurality of embodiments of the present disclosure will be described by taking some specific examples with reference to drawings. In each of the drawings, the same signs are assigned to the same parts. For convenience of explanation of embodiments, taking into consideration an easier explanation and understanding of key points, a plurality of embodiments will be described separately. However, configurations described in different embodiments may be partially replaced or combined with each other. In a second embodiment and subsequent embodiments, description of items common to those in the first embodiment will be omitted, and only differences will be described. In particular, similar operational advantages owing to similar configurations will not be mentioned in each embodiment. 
     First Embodiment 
       FIG. 1  is an external perspective view of a universal-battery-outer-shape wirelessly chargeable battery  101 A according to a first embodiment.  FIG. 2  is an exploded perspective view illustrating an internal configuration of the universal-battery-outer-shape wirelessly chargeable battery  101 A. 
     The universal-battery-outer-shape wirelessly chargeable battery  101 A includes a secondary battery  1 , a wireless charging circuit connected to the secondary battery  1 , a housing body that has an outer shape equivalent to the outer shape of a universal battery and accommodates the secondary battery  1  and the wireless charging circuit, and a positive terminal  711  and a negative terminal  72  that are electrically connected to the secondary battery  1  and are provided at positions corresponding to the positions of a positive terminal and a negative terminal, respectively, of the universal battery. A positive electrode  71  is electrically connected to the positive terminal  711 . In  FIG. 1 , a second outer casing member  22  is covered with a first outer casing member  21 . The first outer casing member  21  and the second outer casing member  22  configure a “housing body” according to the present disclosure. 
     The second outer casing member  22  has openings  2212 , and light guide members  590  are provided inside the openings  2212 . 
     The first outer casing member  21  includes a wall  211 , two walls  212 , a wall  213 , and a wall  214 . 
     The wall  211  has a shape extending in an X direction and a Y direction that are orthogonal to each other. The wall  211  is a rectangular flat plate shape in a plan view. The wall  211  is long in the X direction and short in the Y direction. 
     The two walls  212  each have a shape extending in a direction orthogonal to the flat plate surface of the wall  211 . The two walls  212  each have a shape extending along a side along the X direction of the wall  211 . The two walls  212  are arranged on corresponding two sides of the wall  211 . 
     The wall  213  and the wall  214  each have a shape extending in a direction orthogonal to the flat plate surface of the wall  211 . The wall  213  and the wall  214  each have a shape extending along an end side along the Y direction of the wall  211 . The wall  213  is arranged on one end of the wall  211  in the Y direction, and the wall  214  is arranged on the other end of the wall  211  in the Y direction. The wall  213  and the wall  214  are connected to the two walls  212 . 
     The second outer casing member  22  includes a wall  221 , a wall  223 , and a wall  224 . 
     The wall  221  has a shape including a flat plate part and an arc-shaped part. The arc-shaped part has a shape in which a surface curves at a predetermined curvature radius, and the cross-section shape of the arc-shaped part (in  FIG. 1  and other figures, the cross-section on a YZ plane) is a hemispherical shape. The flat plate part is connected to sides of the arc-shaped part so as to extend in the Z direction. Thus, the cross-section of the wall  221  is U-shaped. The wall  221  is long in the X direction and short in the Y direction. 
     The wall  223  is arranged on one end of the wall  221  in the X direction. The wall  223  has a flat plate shape parallel to the YZ plane. The wall  223  is arranged on the one end of the wall  221  in the X direction and is connected to the wall  221 . The wall  224  has a flat plate shape parallel to the YZ plane. The wall  224  is arranged on the other end of the wall  221  in the X direction and is connected to the wall  221 . 
     With this arrangement, the second outer casing member  22  has a space  220  surrounded by the wall  221 , the wall  223 , and the wall  224 . That is, the second outer casing member  22  has substantially a semi-tubular shape, and the space  220  has substantially a semi-cylindrical shape in which a semi-cylinder and a substantial cuboid are connected. 
     As described above, the first outer casing member  21  and the second outer casing member  22  have different shapes, and the outer shape of the first outer casing member  21  and the outer shape of the second outer casing member  22  are different. 
     The first outer casing member  21  is engaged with the second outer casing member  22  so that a cylindrical outer casing is formed. Thus, a space  210  of the first outer casing member  21  is connected to the space  220  of the second outer casing member  22 , so that an inner space of the outer casing is formed. The inner space of the outer casing has a shape in which the semi-cylinder and the substantial cuboid are connected and integrated with each other. 
     With this arrangement, part of the cylindrical outer casing in the circumferential direction forms a flat surface composed of the wall  211  of the first outer casing member  21 , and the other part of the cylindrical outer casing in the circumferential direction forms a curved surface composed of the wall  221  of the second outer casing member  22 . Thus, a user is able to easily distinguish between the first outer casing member  21  and the second outer casing member  22  and easily understand the orientation of the universal-battery-outer-shape wirelessly chargeable battery  101 A. 
     The engagement mentioned above is implemented by causing engagement protrusions  2121  formed at the walls  212  of the first outer casing member  21  to be engaged in engagement grooves  2211  formed at the wall  221  of the second outer casing member  22 . Thus, the first outer casing member  21  and the second outer casing member  22  configure a detachably engaged shape. 
     For example, the outer shape of the outer casing is substantially the same as the shape of an AA dry battery and has substantially the same size. The dimensions of the outer shape are merely an example, and the outer shape of the outer casing may have substantially the same shape as other types of dry batteries. 
     A power receiving coil member  30 , a magnetic sheet  40 , a circuit substrate  550 , the secondary battery  1 , the positive electrode  71 , the negative terminal  72 , a substrate fixing member  500 , and the light guide member  590  are arranged in the inner space of the outer casing. The magnetic sheet  40  corresponds to a “magnetic layer” according to the present disclosure. 
     The power receiving coil member  30  has a flat film shape having a main surface. The power receiving coil member  30  includes a power receiving coil  31  and a base member  32 . The base member  32  has a flat film shape having a main surface and has insulating characteristics. For example, the power receiving coil member  30  is arranged in contact with the wall  211  of the first outer casing member  21 . 
     The power receiving coil  31  is implemented by a linear conductor of a winding shape. The power receiving coil  31  has a coil opening having a predetermined area at the center of the winding shape. The power receiving coil  31  is arranged at the base member  32 . A face at which the winding shape of the power receiving coil  31  is formed is parallel to the main surface of the base member  32 . 
     The power receiving coil member  30  is arranged next to the first outer casing member  21 . When the power receiving coil member  30  is arranged close to the first outer casing member  21 , the main surface of the power receiving coil member  30  is substantially parallel to the wall  211  of the first outer casing member  21 . With this arrangement, as described later, when a power transmitting coil is arranged on the first outer casing member  21  side, the power receiving coil  31  and the power transmitting coil (a power transmitting coil  900  described later) face each other. 
     As described above, the power receiving coil  31  is located closer to the outer surface of the housing body than the secondary battery  1  is, and the magnetic sheet  40  is provided between the power receiving coil  31  and the secondary battery  1 . With this arrangement, the power receiving coil  31  and the power transmitting coil  900  are made to face each other. Thus, with this arrangement, the universal-battery-outer-shape wirelessly chargeable battery  101 A is able to receive power at high efficiency. 
     Desirably, the area of the main surface of the base member  32  is substantially the same as the area of a face of the wall  211  of the first outer casing member  21  closer to the space  210 , and the power receiving coil  31  is arranged substantially along the four sides of the main surface of the base member  32  and close to the four sides. That is, the flat surface area of the power receiving coil member  30  is substantially the same as the flat surface area (are of a flat surface) of the wall  211  of the first outer casing member  21 . With the use of the power receiving coil  31  and the base member  32  having the arrangement described above, a higher power receiving efficiency can be achieved than the case where the power receiving coil  31  and the base member  32  having smaller sizes are used. For example, the outer shape of the power receiving coil  31  may be equal to or more than half the area of the wall  211  of the first outer casing member  21 . The outer shape of the power receiving coil  31  may be adjusted appropriately according to the specifications of the universal-battery-outer-shape wirelessly chargeable battery  101 A. However, for example, assuming that the universal-battery-outer-shape wirelessly chargeable battery  101 A has the shape of an AA dry battery, a predetermined power receiving performance can be achieved in the case where the outer shape of the power receiving coil  31  is equal to or more than half the area of the wall  211  of the first outer casing member  21 . 
     The magnetic sheet  40  has a flat film shape having a main surface. The magnetic sheet  40  is arranged next to the power receiving coil member  30 . The magnetic sheet  40  is arranged opposite the wall  211  of the first outer casing member  21  relative to the power receiving coil member  30 . The magnetic sheet  40  is arranged in contact with the power receiving coil member  30 . Desirably, the area (area of the main surface) of the magnetic sheet  40  is equal to or more than the flat surface area of the power receiving coil  31 . With the arrangement of the magnetic sheet  40  described above, a closed magnetic path can be formed in the case where a power transmitting coil is arranged relative to the power receiving coil member  30 , as described above. Thus, with this structure, the universal-battery-outer-shape wirelessly chargeable battery  101 A is able to receive power with a higher efficiency. 
     The circuit substrate  550  has a flat plate shape. The circuit substrate  550  is implemented by forming a conductor pattern on a substrate made of an insulating material (for example, an insulating resin). Various circuit elements that implement a circuit of a power receiving system, which will be described later, are mounted on the circuit substrate  550 . 
     The circuit substrate  550  is arranged next to the magnetic sheet  40  with the substrate fixing member  500  interposed therebetween. The circuit substrate  550  is arranged opposite the power receiving coil member  30  relative to the magnetic sheet  40 . The circuit substrate  550  is arranged in such a manner that the flat plate surface of the circuit substrate  550  is substantially in parallel to the wall  211  of the first outer casing member  21 . For example, the circuit substrate  550  is fixed to the second outer casing member  22  by the substrate fixing member  500 . 
     The secondary battery  1  has a cylindrical shape. The secondary battery  1  is, for example, a lithium-ion battery. However, the secondary battery  1  is not necessarily a lithium-ion battery and may be other types of secondary batteries. Furthermore, as described later, the shape of the secondary battery  1  is not necessarily a cylindrical shape and may be any shape fitting in the second outer casing member  22 . 
     The secondary battery  1  is arranged next to the circuit substrate  550 . The secondary battery  1  is arranged opposite the magnetic sheet  40  relative to the circuit substrate  550 . The secondary battery  1  is arranged in such a manner that the direction in which the cylindrical shape extends is parallel to the longitudinal direction of the second outer casing member  22  (X direction in  FIG. 2  and other figures). The secondary battery  1  arranged in this state is housed in the space  220  of the second outer casing member  22 . 
     A wiring  600  is provided at the secondary battery  1 . The wiring  600  is connected to the circuit substrate  550 . 
     Each of the positive electrode  71  and the negative terminal  72  is a flat-plate conductor. The positive electrode  71  is attached to the wall  223  of the second outer casing member  22 . A wiring  701  is connected to the positive electrode  71 . The wiring  701  is connected to the circuit substrate  550 . 
     The negative terminal  72  is connected to the wall  224  of the second outer casing member  22 . The negative terminal  72  is exposed to the outside of the wall  224  of the second outer casing member  22 . A wiring  702  is connected to the negative terminal  72 . The wiring  702  is connected to the circuit substrate  550 . 
     The positive terminal  711  has a shape having a protrusion. The positive terminal  711  is in contact with the positive electrode  71 . The protruding part of the positive terminal  711  is exposed to the outside of the wall  223 . 
     The protruding part of the positive terminal  711  is positive when the universal-battery-outer-shape wirelessly chargeable battery  101 A is used as a chargeable battery. Furthermore, the negative terminal  72  described above is negative in the case where the universal-battery-outer-shape wirelessly chargeable battery  101 A is used as a chargeable battery. 
     The light guide member  590  is in contact with the openings  2212  formed in the wall  221  of the second outer casing member  22 . The light guide member  590  guides light emitted from a light-emitting element (for example, a light-emitting diode (LED)) mounted on the circuit substrate  550 . The light guided by the light guide member  590  is output through the openings  2212  to the outside. 
       FIG. 3  is an exploded perspective view of a universal-battery-outer-shape wirelessly chargeable battery  101 B according to the first embodiment. The universal-battery-outer-shape wireless rechargeable battery  101 B is different from the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 2  in the shapes of the secondary battery  1  and the substrate fixing member  500  that are built inside the universal-battery-outer-shape wirelessly chargeable battery  101 B. The universal-battery-outer-shape wirelessly chargeable battery  101 B is also different from the universal-battery-outer-shape wirelessly chargeable battery  101 A in that the universal-battery-outer-shape wirelessly chargeable battery  101 B includes a secondary battery cushion member  510 . The outer shape of the secondary battery  1  provided in the universal-battery-outer-shape wirelessly chargeable battery  101 B is a cuboid shape. The secondary battery cushion member  510  is provided between the secondary battery  1  and the inner bottom surface of the second outer casing member  22 . The secondary battery  1  is held at the second outer casing member  22  with the secondary battery cushion member  510  interposed therebetween. Thus, the impact received by the secondary battery  1  when the universal-battery-outer-shape wirelessly chargeable battery  101 B receives acceleration or vibrations, is moderated. 
     The substrate fixing member  500  has a frame shape, and the circuit substrate  550  is housed in the inner space of the substrate fixing member  500 . The substrate fixing member  500  also has a function for holding a peripheral part of the upper surface of the secondary battery  1  in such a manner that the impact is absorbed. The secondary battery cushion member  510  mainly holds the central part of the bottom surface of the secondary battery  1  in such a manner that the impact is absorbed. Thus, the impact received by the secondary battery  1  can be reduced more effectively by using the secondary battery cushion member  510  and the substrate fixing member  500 . The secondary battery cushion member  510  and the substrate fixing member  500  correspond to a “cushion layer” according to the present disclosure. 
     As described above, the universal-battery-outer-shape wirelessly chargeable battery  101 A and the universal-battery-outer-shape wirelessly chargeable battery  101 B are different in the shape of outer casings. Thus, a user is able to easily recognize the orientation of the universal-battery-outer-shape wirelessly chargeable battery  101 A by appearance and feel. 
     Furthermore, with the configuration described above, the magnetic sheet  40  is arranged between the power receiving coil member  30  and the circuit substrate  550 . Thus, leakage of a coupling magnetic field or a coupling electromagnetic field between the power transmitting coil  900  and the power receiving coil  31  of the power receiving coil member  30  toward the circuit substrate  550  and the secondary battery  1  is negligible. Therefore, magnetic flux is interlinked with the conductor part of the circuit substrate  550  and the housing of the secondary battery  1 , and generation of an eddy current can be reduced. Thus, loss such as heat generation caused by an eddy current can be reduced. 
       FIGS. 4A and 4B  are diagrams each illustrating the positional relationship between a power transmission plate  901  and the universal-battery-outer-shape wirelessly chargeable battery  101 A. A power transmission device includes the power transmitting coil  900  and the power transmission plate  901 . The power transmitting coil  900  includes a linear conductor pattern having a winding shape. The power transmitting coil  900  is formed on the power transmission plate  901 . The power transmitting coil  900  is arranged in such a manner that an opening face of the winding shape is substantially parallel to a surface of the power transmission plate  901 . 
     In the case where power is supplied to the universal-battery-outer-shape wirelessly chargeable battery  101 A as a single unit, the universal-battery-outer-shape wirelessly chargeable battery  101 A is arranged close on the power transmission plate  901  as illustrated in  FIG. 4A . Alternatively, the universal-battery-outer-shape wirelessly chargeable battery  101 A is placed on the power transmission plate  901  as illustrated in  FIG. 4B . In the example of  FIG. 4B , two universal-battery-outer-shape wirelessly chargeable batteries  101 A are placed at the same time. In each of  FIGS. 4A and 4B , when the power transmission plate  901  is viewed in plan, a coil opening of the power receiving coil  31  of the universal-battery-outer-shape wireless rechargeable battery  101 A and a coil opening of the power transmitting coil  900  on the power transmission plate  901  overlap. 
       FIG. 5A  is an exploded perspective view of a state in which the universal-battery-outer-shape wirelessly chargeable battery  101 A is attached to an electronic device.  FIG. 5B  is an external perspective view illustrating a state in which the universal-battery-outer-shape wirelessly chargeable battery  101 A attached to the electronic device is charged. As illustrated in  FIG. 5B , an electronic device  80  is arranged on the surface of the power transmission plate  901  in such a manner that the bottom face of the electronic device  80  is in contact with the surface of the power transmission plate  901 . 
     The electronic device  80  includes a battery holder  800 . The battery holder  800  is implemented by a recessed part provided at a wall  830  of the casing of the electronic device  80 . The battery holder  800  includes a bottom wall  810 , a side wall  820 , a side wall  821 , a side wall  822 , and a lid  832 . 
     The universal-battery-outer-shape wirelessly chargeable battery  101 A is housed in the battery holder  800 . In this embodiment, three universal-battery-outer-shape wirelessly chargeable batteries  101 A are housed in the battery holder  800 . 
     When the universal-battery-outer-shape wirelessly chargeable batteries  101 A are housed in the battery holder  800 , which has the configuration described above, in such a manner that the walls  221  are close to the bottom wall  810 , the walls  221  of the universal-battery-outer-shape wirelessly chargeable batteries  101 A are parallel to the bottom wall  810  and the side wall  820  of the battery holder  800 . That is, the universal-battery-outer-shape wirelessly chargeable batteries  101 A are housed in the battery holder  800  without any gap. 
     As described above, when the universal-battery-outer-shape wirelessly chargeable batteries  101 A are housed in the battery holder  800 , the positive terminals  711  of the universal-battery-outer-shape wirelessly chargeable batteries  101 A are made in contact with positive terminal electrodes  841  of the electronic device  80 , and the negative terminals  72  of the universal-battery-outer-shape wirelessly chargeable batteries  101 A are made in contact with negative terminal electrodes  842  of the electronic device  80 . 
     Furthermore, with the configuration described above, the universal-battery-outer-shape wirelessly chargeable batteries  101 A are housed in the battery holder  800  of the electronic device  80  in such a manner that the power receiving coil members  30  are close to the outside of the electronic device  80 . Thus, the universal-battery-outer-shape wirelessly chargeable batteries  101 A that are attached to the electronic device  80  are able to receive power supply from the power transmission device. 
       FIG. 6  is a circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery  101 A and other elements. In  FIG. 6 , a circuit of a power transmission device  90  is also illustrated. 
     The universal-battery-outer-shape wirelessly chargeable battery  101 A includes the secondary battery  1  and a wireless charging circuit  50  that is connected to the secondary battery  1 . The wireless charging circuit  50  includes the power receiving coil  31  that receives a power transmission magnetic field or a power transmission electromagnetic field, a power reception protecting circuit  58 , a rectifier circuit  52 , a DC-DC converter  54  that converts a rectification and smoothing output voltage output from the rectifier circuit  52  to generate a charging voltage, a charging control circuit  55  that receives the voltage output from the DC-DC converter  54  and performs charging control for the secondary battery  1 , a protection circuit  56  that protects the secondary battery  1 , and a voltage regulator  57  that converts the current of the secondary battery  1  into an output voltage of a universal battery. 
     The power receiving coil  31  is expressed by an inductor  31 L and an equivalent resistor  31 R. A resonant capacitor  51  is connected to the power receiving coil  31 , and the resonant capacitor  51  and the power receiving coil  31  configure a resonant circuit. The power reception protecting circuit  58  restricts output to the rectifier circuit  52  in the case where the received voltage exceeds a predetermined voltage range. The rectifier circuit  52  includes a smoothing capacitor C 3 . The rectifier circuit  52  rectifies the current input from the power reception protecting circuit  58 , and outputs the rectified current to the DC-DC converter  54 . The DC-DC converter  54  corresponds to a “first voltage conversion circuit” according to the present disclosure. 
     A capacitor  532  is connected to output of the DC-DC converter  54 . For example, the voltage regulator  57  is an LDO (Low Dropout regulator) and is a linear regulator including a MOS-FET and an operational amplifier. The voltage regulator  57  stabilizes the voltage of the secondary battery  1  and outputs the stabilized voltage to the positive terminal  711  and the negative terminal  72 . The voltage regulator  57  corresponds to a “second voltage conversion circuit” according to the present disclosure. 
     The power transmission device  90  includes a power transmission control circuit  91 , the power transmitting coil  900 , and a resonant capacitor  92 . The power transmitting coil  900  is expressed by an inductor  900 L and an equivalent resistor  900 R. The power transmitting coil  900  and the resonant capacitor  92  configure a resonant circuit resonating in a power transmission frequency band. For example, the resonant circuit resonates in a frequency band of 6.78 MHz or 13.56 MHz. These frequency bands are ISM (industrial, scientific and medical) bands and are advantageous in design regarding EMC (electromagnetic compatibility). Coupling between the resonance on the power transmission device side and the resonant circuit including the power receiving coil  31  and the resonant capacitor  51  on the universal-battery-outer-shape wirelessly chargeable battery  101 A side causes magnetic field resonance. 
     The resonant circuit including the power receiving coil  31  and the resonant capacitor  51  resonates in a frequency band of an electromagnetic field or a magnetic field received from the power transmission device  90 , for example, a frequency band of 6.78 MHz or 13.56 MHz. The power receiving coil  31  outputs received power to the rectifier circuit  52 . The power reception protecting circuit  58  rectifies an AC received voltage into a DC voltage, and stops power reception at the DC-DC converter  54  in the case where the received voltage exceeds a predetermined voltage range. The DC-DC converter  54  performs voltage conversion and outputs the converted voltage to the charging control circuit  55 . The capacitor  532  smooths the voltage output from the DC-DC converter  54 . The charging control circuit  55  charges the secondary battery  1  using a received DC voltage that has been rectified and converted from AC voltage. The voltage regulator  57  converts the voltage output from the secondary battery  1  and outputs the converted voltage to between the positive terminal  711  and the negative terminal  72 . 
     The protection circuit  56  performs overcurrent protection at the time of charging and discharging the secondary battery  1  and overvoltage input protection to the secondary battery  1 . The protection circuit  56  also performs overheat protection in accordance with the resistance of an NTC thermistor. For example, in the case where a charging/discharging current to the secondary battery  1  exceeds a specified value, the protection circuit  56  restricts the current. Furthermore, in the case where the voltage of the secondary battery  1  exceeds a predetermined value, the protection circuit  56  restricts a charging current. Moreover, in the case where the temperature of the secondary battery  1  or the ambient temperature is outside a predetermined value range, the protection circuit  56  reduces charging or discharging. 
       FIG. 7  is another circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery  101 A and other elements. The order of connection between the power reception protecting circuit  58  and the rectifier circuit  52  of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 7  is opposite the order of connection between the power reception protecting circuit  58  and the rectifier circuit  52  of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . Furthermore, the resonant capacitor  51 , which configures a resonant circuit, together with the power receiving coil  31 , is connected in parallel to the power receiving coil  31 . The other features of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 7  are similar to those of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . 
       FIGS. 8A, 8B, 8C, and 8D  are circuit diagrams illustrating specific examples of the power reception protecting circuit  58  illustrated in  FIGS. 6 and 7 . In  FIGS. 8A, 8B, 8C, and 8D , the power reception protecting circuit  58  and the rectifier circuit  52  are illustrated so that connection between the rectifier circuit  52  and the power reception protecting circuit  58  is clarified. 
     In the example illustrated in  FIG. 8A , a diode D 1  and a capacitor C 3  configure a rectification and smoothing circuit. When the received voltage exceeds the Zener voltage of Zener diodes ZD 1  and ZD 2 , both ends of a connection circuit including the Zener diodes ZD 1  and ZD 2  are electrically connected, and the received voltage is restricted to the Zener voltage. This circuit configuration is used as the power reception protecting circuit  58  illustrated in  FIG. 6 . 
     In the example illustrated in  FIG. 8B , the diode D 1  and the capacitor C 3  configure a rectification and smoothing circuit. When the divided voltage of resistors R 1  and R 2  exceeds the Zener voltage of a Zener diode ZD, the Zener diode ZD is electrically connected, and the received voltage is restricted by a series circuit including the Zener diode and the resistors. This circuit configuration is used as the power reception protecting circuit  58  illustrated in  FIG. 7 . 
     In the example illustrated in  FIG. 8C , the diode D 1  and the capacitor C 3  configure a rectification and smoothing circuit. When the rectification and smoothing voltage exceeds the Zener voltage of the Zener diode ZD, an FET Q is electrically connected, and the received voltage is restricted by a series circuit including the FET Q and a resistor. This circuit configuration is used as the power reception protecting circuit  58  illustrated in  FIG. 7 . 
     In the example illustrated in  FIG. 8D , the diode D 1  and the capacitor C 3  configure a rectification and smoothing circuit. When the rectification and smoothing voltage exceeds the Zener voltage of the Zener diode ZD, the Zener diode ZD is electrically connected, and the received voltage is restricted to the Zener voltage. This circuit configuration is used as the power reception protecting circuit  58  illustrated in  FIG. 7 . 
     As described above, the power reception protecting circuit  58  protects the DC-DC converter  54  (first voltage conversion circuit) in the case where the received voltage exceeds a predetermined voltage range. 
       FIG. 9  is another circuit diagram of the universal-battery-outer-shape wirelessly chargeable battery  101 A and other elements. Schematically, the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 9  includes an interruption circuit  58 C as a derived example of the power reception protecting circuit  58  of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . 
     The universal-battery-outer-shape wirelessly chargeable battery  101 A includes the secondary battery  1  and the wireless charging circuit  50  that is connected to the secondary battery  1 . The wireless charging circuit  50  includes the power receiving coil  31  that receives a power transmission magnetic field or a power transmission electromagnetic field, the rectifier circuit  52  that rectifies an induced current of the power receiving coil  31 , the interruption circuit  58 C that stops power reception at the rectifier circuit  52  in the case where the received voltage exceeds a predetermined voltage range, a resistor dividing circuit  58 R, a received voltage detecting circuit  58 D, the DC-DC converter  54  that converts the voltage output from the rectifier circuit  52  to generate a charging voltage, the charging control circuit  55  that receives the voltage output from the DC-DC converter  54  and performs charging control for the secondary battery  1 , the protection circuit  56  that protects the secondary battery  1 , and the voltage regulator  57  that converts the current of the secondary battery  1  into an output voltage of a universal battery. The interruption circuit  58 C, the received voltage detecting circuit  58 D, and the resistor dividing circuit  58 R configure a power reception protecting circuit. Features other than this configuration feature of the power reception protecting circuit are similar to those of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . 
     When the received voltage detecting circuit  58 D detects that the voltage output from the resistor dividing circuit  58 R exceeds a predetermined value, the received voltage detecting circuit  58 D outputs a detection signal to the interruption circuit  58 C. When receiving the detection signal from the received voltage detecting circuit  58 D, the interruption circuit  58 C stops power reception at the rectifier circuit  52 . 
       FIGS. 10A and 10B  are diagrams for explaining an operation of the interruption circuit  58 C at the time of normal power reception. At the time of normal power reception, an FET Q 2  of the interruption circuit  58 C is turned off. 
     As illustrated in  FIG. 10A , when a first end of the power receiving coil  31  near the capacitor  51  becomes positive, current flows through a path in the order of the power receiving coil  31 , the capacitor  51 , the diode D 1 , and the capacitor C 3 . In this case, a voltage obtained by adding the voltage charged in the resonant capacitor  51  to the voltage induced by the power receiving coil  31  is charged into the capacitor C 3 . That is, this voltage is supplied to the rectifier circuit  52 . 
     As illustrated in  FIG. 10B , when a second end of the power receiving coil  31  is positive, current flows from the power receiving coil  31 , through a body diode of the FET Q 2 , to the capacitor  51 . Thus, the capacitor  51  is charged. 
     At the time of normal power reception, the state illustrated in  FIG. 10A  and the state illustrated in  FIG. 10B  are repeated alternately, and the received voltage is output to the rectifier circuit  52 . 
       FIGS. 11A and 11B  are diagrams for explaining an operation of the interruption circuit  58 C in the case where the received voltage exceeds a specified value. The FET Q 2  is turned on in accordance with the detection signal output from the received voltage detecting circuit  58 D illustrated in  FIG. 9 . 
     When the voltage is induced by the power receiving coil  31  and the first end of the power receiving coil  31  becomes positive, as illustrated in  FIG. 11A , current flows through a path in the order of the power receiving coil  31 , the resonant capacitor  51 , and the FET Q 2 . As illustrated in  FIG. 11B , in the case where the second end of the power receiving coil  31  is positive, current flows from the power receiving coil  31 , through the body diode of the FET Q 2 , to the capacitor  51 . In the case where the received voltage exceeds a specified value, the state illustrated in  FIG. 11A  and the state illustrated in  FIG. 11B  are repeated alternately. That is, the received voltage is not output to the rectifier circuit  52 . 
     Accordingly, even when the power receiving coil  31  receives an electromagnetic field or a magnetic field larger than a specified value, interruption of power reception at the rectifier circuit  52  enables interruption of electric power, and influence such as heat generation caused by reception of large power in the rectifier circuit  52  and circuits provided downstream of the rectifier circuit  52  can be reduced. 
       FIGS. 12A and 12B  are diagrams illustrating examples of the configuration of the received voltage detecting circuit  58 D illustrated in  FIG. 9 . 
     In the example illustrated in  FIG. 12A , the received voltage detecting circuit  58 D includes comparators  25 A and  25 B and a controller  25 C. The comparator  25 A compares a received voltage Va with a threshold voltage Va 1 . When Va is more than Va 1 , the comparator  25 A outputs an H level signal (H: high potential). When Va is less than or equal to Va 1 , the comparator  25 A outputs an L level signal (L: low potential). The comparator  25 B compares the received voltage Va with a threshold voltage Va 2 . When Va is more than Va 2 , the comparator  25 B outputs an H level signal. When Va is less than or equal to Va 2 , the comparator  25 B outputs an L level signal (L). 
     The controller  25 C outputs a gate signal to the FET Q 2  in accordance with signals output from the comparators  25 A and  25 B. Specifically, when both the signals output from the comparators  25 A and  25 B represent L, that is, when Va is less than Va 1 , the controller  25 C turns off the FET Q 2 . When the signal output from the comparator  25 A represents H and the signal output from the comparator  25 B represents L, that is, when the relationship Va 1 &lt;Va&lt;Va 2  is obtained, the controller  25 C outputs a pulse signal to the gate of the FET Q 2  and turns on and off the FET Q 2 . When both the signals output from the comparators  25 A and  25 B represent H, that is, when Va 2  is less than Va, the controller  25 C turns on the FET Q 2 . 
     The interruption circuit  58 C in  FIG. 12B  includes a resistor R 1  and the FET Q 2 . The received voltage detecting circuit  58 D includes a series circuit including a resistor R 2  and a Zener diode Dz 1 . A connection point A between the resistor R 2  and the Zener diode Dz 1  is connected to the gate of the FET Q 2 . 
     With this configuration, in the case where the received voltage Va is less than the Zener voltage of the Zener diode Dz 1 , the potential of the connection point A represents L (low potential), and the FET Q 2  is turned off. Thus, the potential of the connection point between the resistor R 1  and the FET Q 2  becomes H (high potential), and no current flows to the resistor RE When the received voltage Va increases and exceeds the Zener voltage, the potential of the connection point A becomes H (high potential), and the FET Q 2  is turned on. Thus, the potential of the connection point between the resistor R 1  and the FET Q 2  becomes L (low potential), and current flows to the resistor RE The Zener voltage is set to protect the voltage input to the gate of the FET Q 2 . 
     When the received voltage Va exceeds the Zener voltage and the FET Q 2  is turned on, a power reception interruption state is entered. Thus, charging of the capacitor C 3  stops, and the received voltage Va drops. When the received voltage Va decreases to be lower than the Zener voltage, the potential of the connection point A becomes L, and the FET Q 2  is turned off again. Then, when the received voltage Va exceeds the Zener voltage again, the FET Q 2  is turned on. By repeating the states described above, received voltage is suppressed from becoming excessive. 
     When the received voltage Va is higher than a specified value (equal to or more than the threshold voltage Va 2 ), the FET Q 2  is turned on, and a power reception interruption state is entered. Then, the interruption circuit  58 C maintains the interruption state until the received voltage Va decreases to be lower than the Zener voltage, and power reception thus stops. 
       FIG. 13  is a circuit diagram illustrating a specific example of the protection circuit  56 . The protection circuit  56  includes a protection IC that detects the voltage across the secondary battery  1  and FETs Q 61  and Q 62 . The protection IC controls the gate voltage of the FETs Q 61  and Q 62  to interrupt a charging current path to the secondary battery  1  when the voltage applied to the secondary battery  1  exceeds a predetermined voltage. 
     Second Embodiment 
     In a second embodiment, an example of a universal-battery-outer-shape wirelessly chargeable battery applied to a coin-type battery is illustrated. 
       FIG. 14  is a plan view of a state in which a universal-battery-outer-shape wirelessly chargeable battery  102  according to the second embodiment is developed, and  FIG. 15  is a bottom view of the state in which the universal-battery-outer-shape wirelessly chargeable battery  102  is developed.  FIG. 16  is a bottom view of the universal-battery-outer-shape wirelessly chargeable battery  102 . 
     A substrate includes a first section  3 A, a second section  3 B, and a bent section BS. The first section  3 A is a main section of a circuit. The power receiving coil  31  is formed in the second section  3 B. The secondary battery  1  is a coin-shaped secondary battery. An electrode  14  is in contact with the negative pole of the secondary battery  1  and is electrically connected, and electrodes  12  and  13  are in contact with the positive pole of the secondary battery  1  and is electrically connected. 
     The power receiving coil  31  is magnetically or electromagnetically coupled to the power transmitting coil  900  of the power transmission device  90 . The power receiving coil  31  receives high-frequency power, rectifies and smooths the received high-frequency power, and charges the secondary battery arranged inside. The voltage of the secondary battery can be directly extracted to the outside. Thus, the universal-battery-outer-shape wirelessly chargeable battery  102  may be used as a coin-type battery that is chargeable and dischargeable. 
     An assembling procedure of the universal-battery-outer-shape wirelessly chargeable battery  102  is as described below. 
     (1) As illustrated in  FIG. 14 , by arranging the first section  3 A at the center and folding a protruding section  1 P 4  to 180 degrees onto the top face of the first section  3 A, the protruding section  1 P 4  is made in contact with the first section  3 A. Then, the secondary battery  1  is arranged in such a manner that the positive pole of the secondary battery  1  is in contact with the electrode  14 . 
     (2) A protruding section  1 P 3  is folded to about 180 degrees to be in contact with the negative pole on the top face of the secondary battery  1 . 
     (3) A magnetic sheet  4  of a disc shape that is one size larger than the secondary battery  1  is placed on the top face of the protruding section  1 P 3  on the secondary battery  1  in such a manner that the magnetic sheet  4  covers the secondary battery  1 . 
     (4) The bent section BS is folded to 180 degrees, and the power receiving coil  31  is arranged on the top face of the disc-shape magnetic sheet  4 . 
     (5) A protruding section  1 P 2  is folded upwards to 90 degrees, and the electrode  12  is arranged along a side face of the secondary battery  1 . Thus, the electrode  12  is exposed on the side face of the universal-battery-outer-shape wirelessly chargeable battery  102  and operates as an external connection electrode of a positive pole for a device in which the universal-battery-outer-shape wirelessly chargeable battery  102  is to be inserted. 
     (6) A protruding section  1 P 1  is folded to 180 degrees towards the first section  3 A. Thus, the electrode  11  is exposed below the universal-battery-outer-shape wirelessly chargeable battery  102  and operate as an external connection electrode of a negative pole for a device in which the universal-battery-outer-shape wirelessly chargeable battery  102  is to be inserted. 
     (7) With the electrodes  11  and  12  exposed, the entire universal-battery-outer-shape wirelessly chargeable battery  102  is sealed with resin, and the outer shape of the universal-battery-outer-shape wirelessly chargeable battery  102  thus has the shape of a coin battery. 
     In accordance with the assembling procedure described above, the universal-battery-outer-shape wirelessly chargeable battery  102  used as a chargeable and dischargeable coin-shape battery, as illustrated in  FIG. 16 . 
     Third Embodiment 
     In a third embodiment, an example of a circuit that performs, under the control of a rectifier element, interruption of power reception is described. 
       FIGS. 17 and 18  are diagrams each illustrating a configuration of an interruption circuit of a universal-battery-outer-shape wirelessly chargeable battery according to the third embodiment. In  FIG. 17 , FETs Q 2  and Q 31  configure a synchronous rectifier circuit. The received voltage detecting circuit  58 D controls a synchronous rectifying operation by controlling the FETs Q 2  and Q 31 . That is, to interrupt power reception, the FET Q 2  is turned on and the FET Q 31  is turned off. 
     In  FIG. 18 , an FET Q 32  and a diode D 12  configure a rectifier circuit. The received voltage detecting circuit  58 D controls a rectifying operation by controlling the FET Q 32 . That is, to interrupt power reception, the FET Q 32  is turned off. 
     Fourth Embodiment 
     In a fourth embodiment, an example of the configuration of a power reception protecting circuit that includes a bridge rectifier circuit is described. 
       FIGS. 19 and 20  are circuit diagrams each illustrating part of a universal-battery-outer-shape wirelessly chargeable battery and a power transmission device according to the fourth embodiment. 
     In  FIG. 19 , the power transmission device includes a transmission-side resonant circuit  111  and a power transmission circuit  122 A. In the power transmission circuit  122 A, a series circuit including FETs Q 11  and Q 12  and a series circuit including FETs Q 13  and Q 14  are connected in parallel. By turning on and off the FETs Q 11  and Q 14  and the FETs Q 12  and Q 13  alternately, a DC voltage from a DC power source is converted into an AC voltage and the AC voltage is supplied to the transmission-side resonant circuit  111 . 
     In  FIG. 19 , a series circuit including an FET Q 51  and a diode D 31  and a series circuit including an FET Q 52  and a diode D 32  are connected in parallel to configure a rectifier circuit. The FETs Q 51  and Q 52  are switching-controlled by the received voltage detecting circuit  58 D ( FIG. 9 ). 
     In  FIG. 20 , a diode bridge rectifier circuit including diodes D 31 , D 32 , D 33 , and D 34  and FETs Q 51  and Q 52  is provided. The example illustrated in  FIG. 20  is different from the example illustrated in  FIG. 19  in the directions of the drains and sources of the FETs Q 51  and Q 52 . 
     In both  FIGS. 19 and 20 , the FETs Q 51  and Q 52  are turned off in the case where power reception is interrupted, and rectification by the diodes D 31 , D 32 , D 33 , and D 34  is blocked. 
     Fifth Embodiment 
     In a fifth embodiment, a circuit configuration of a universal-battery-outer-shape wirelessly chargeable battery that is different from the example of the circuit configuration illustrated in  FIG. 6  is described. 
       FIG. 21  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery  105 A according to the fifth embodiment. The universal-battery-outer-shape wirelessly chargeable battery  105 A includes the DC-DC converter  54 , the charging control circuit  55 , the secondary battery  1 , and the protection circuit  56 . The protection circuit  56  protects against overvoltage input to the secondary battery  1  and protects against overcurrent discharge from the secondary battery  1 . A temperature sensor may be connected to the protection circuit  56  so that overheat protection can be performed. The other configuration features are similar to those in the example illustrated in  FIG. 6 . However, in the example illustrated in  FIG. 21 , the voltage regulator  57  is not provided. An output unit of the secondary battery  1  may be connected to the positive terminal  711  and the negative terminal  72 , as illustrated in  FIG. 21 . 
       FIG. 22  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery  105 B according to the fifth embodiment. The universal-battery-outer-shape wirelessly chargeable battery  105 B includes the DC-DC converter  54 , the charging control circuit  55 , the secondary battery  1 , the protection circuit  56 , and the voltage regulator  57 . The other configuration features are similar to those in the example illustrated in  FIG. 6 . The voltage regulator  57  may be directly connected to the secondary battery  1 , as illustrated in  FIG. 22 . 
     Sixth Embodiment 
     In a sixth embodiment, a circuit configuration of a universal-battery-outer-shape wirelessly chargeable battery that includes a transmission circuit is described. 
       FIG. 23  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery  106  according to the sixth embodiment. The universal-battery-outer-shape wirelessly chargeable battery  106  includes the power receiving coil  31 , the rectifier circuit  52 , the DC-DC converter  54 , the charging control circuit  55 , the secondary battery  1 , the voltage regulator  57 , a transmission control circuit  53 , and a transmission circuit  59 . 
     The transmission control circuit  53  detects whether or not the voltage output from the rectifier circuit  52  exceeds a specified value and detects whether or not the voltage of the secondary battery  1  has reached a specified value. The transmission circuit  59  changes the size of the load of the power receiving coil  31 . For example, the transmission circuit  59  performs 2-level ASK (amplitude-shift keying) by changing the load on the power reception side in accordance with backscatter modulation similar to a passive RFID tag. Alternatively, the transmission circuit  59  changes resonant conditions of a resonant circuit including the power receiving coil  31  and the resonant capacitor  51 , and transmits a signal according to the change. For example, the composite capacitance of the resonant capacitor  51  and the transmission circuit  59  is changed, so that the resonant frequency of the resonant circuit is displaced. Thus, the impedance of the resonant circuit viewed from the power transmission device is changed. Accordingly, the power transmission device receives a communication signal. The transmission circuit  59  corresponds to a “signal transmission circuit” according to the present disclosure. The other configuration features are the same as those of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . 
     In the case where the voltage output from the rectifier circuit  52  exceeds the specified value, the transmission control circuit  53  causes the transmission circuit  59  to perform load modulation or displaces the resonant frequency of the resonant circuit, and thus transmits a code (communication signal) representing a state in which excessive power is received. Furthermore, when the voltage charging the secondary battery  1  has reached the specified value, by causing the transmission circuit  59  to perform load modulation or displacing the resonant frequency of the resonant circuit, the transmission control circuit  53  transmits a code (communication signal) representing a fully charged state. The power transmission device stops power transmission or controls transmission power, in accordance with the received code. 
     Seventh Embodiment 
     In a seventh embodiment, a circuit configuration of a universal-battery-outer-shape wirelessly chargeable battery that includes a reception circuit is described. 
       FIG. 24  is a circuit diagram of a universal-battery-outer-shape wirelessly chargeable battery  107  according to the seventh embodiment. The universal-battery-outer-shape wireless rechargeable battery  107  includes the power receiving coil  31 , the rectifier circuit  52 , the DC-DC converter  54 , the charging control circuit  55 , the secondary battery  1 , a DC-DC converter  63 , a reception circuit  60 , an antenna  61 , and an output voltage setting circuit  62 . The other configuration features are the same as those of the universal-battery-outer-shape wirelessly chargeable battery  101 A illustrated in  FIG. 6 . 
     The reception circuit  60  receives a wireless signal from the outside. The output voltage setting circuit  62  controls the DC-DC converter  63  in accordance with a signal received at the reception circuit  60 , and determines the voltage to be output from the universal-battery-outer-shape wirelessly chargeable battery  107 . That is, the universal-battery-outer-shape wirelessly chargeable battery  107  operates as a universal-battery-outer-shape wirelessly chargeable battery that outputs a voltage corresponding to a control signal supplied from the outside. 
     Other Embodiments 
     In each of the embodiments described above, an example in which a lithium-ion battery is used as the secondary battery  1  has been described. However, the secondary battery  1  may be an electrical double layer capacitor. Alternatively, the secondary battery  1  may be a solid-state battery. 
     Materials described below are examples of a positive electrode active material, a negative electrode active material, and a solid electrolyte of the above-mentioned solid-state battery. 
     &lt;Positive Electrode Active Material&gt; 
     For example, at least one kind selected from a group consisting of a lithium-containing phosphate compound having a NASICON-type structure, a lithium-containing phosphate compound having an olivine-type structure, a lithium-containing layered oxide, a lithium-containing compound having a spinel-type structure, and the like. 
     &lt;Negative Electrode Active Material&gt; 
     And, for example, at least one kind selected from a group consisting of an oxide containing at least a type of element selected from a group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo, a graphite-lithium compound, a lithium alloy, a lithium-containing phosphate compound having a NASICON-type structure, a lithium-containing phosphate compound having an olivine-type structure, a lithium-containing oxide having a spinel-type structure, and the like. 
     &lt;Solid Electrolyte&gt; 
     For example, a lithium-containing phosphate compound having a NASICON structure, an oxide having a perovskite structure, an oxide having a garnet-type structure or a structure similar to the garnet-type structure, and the like may be used. The lithium-containing phosphate compound having a NASICON structure may be Li x M y (PO 4 ) 3  (1≤x≤2, 1≤y≤2, M represents at least one kind selected from a group consisting of Ti, Ge, Al, Ga, and Zr). The lithium-containing phosphate compound having a NASICON structure may be, for example, Li 1.2 Al 0.2 Ti 1.8 (PO 4 ) 3 . The oxide having a perovskite structure may be, for example, La 0.55 Li 0.35 TiO 3 . The oxide having a garnet-type structure or a structure similar to the garnet-type structure may be, for example, Li 7 La 3 Zr 2 O 12 . 
     The embodiments described above should be considered by way of example in all respects, but not limiting. Modifications and changes may be made in an appropriate manner by those skilled in the art. The scope of the present disclosure is defined by the claims, but not by the embodiments described above, and is intended to encompass changes from the embodiments within the meaning and scope equivalent to the claims.