Charger and wireless power supply system

Abstract

To provide a charger and wireless power supply system that miniaturize energy storage devices. [Solution] In the wireless power supply system S, the charger 20 includes a power receiving unit 22 that receives power from a power transmission device 10 by wireless power supply using radio waves, a storage battery 23 that is charged by the power received by the power receiving unit, and a power transmission unit 24 that transmits the power stored in the storage battery 23 to the electrical equipment to be charged by wireless power supply. If the power transmitted from the power transmission device 10 is not received, the power transmission of the power stored in the storage battery 23 to the electrical equipment to be charged is prohibited.

Description

Technical Field

[0001] The present invention relates to a charger and a wireless power supply system.

Background Art

[0002] Patent Document 1 discloses a charger used for charging an electrical device inside a vehicle compartment of a vehicle such as an automobile. The charger of Patent Document 1 includes a power receiving unit that receives power sent from a power transmission device by radio wave-based wireless power supply, a storage battery that is charged by receiving the power received by the power receiving unit, and a power transmission unit that transmits the power stored in the storage battery to the electrical device to be charged.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A charger having a storage battery charged by radio wave-based wireless power supply includes a power receiving unit that receives power sent from a power transmission device by radio wave-based wireless power supply. The power receiving unit has a power receiving antenna and a power receiving conversion unit that converts the power transmission signal received by the power receiving antenna into direct current power. Therefore, a charger including a power receiving unit is likely to be larger than a charger having a storage battery charged by wire.

Means for Solving the Problems

[0005] [Aspect 1] A charger comprising: a power receiving unit that receives power from a power transmission device by radio wave wireless power transmission; a storage battery that is charged by the power received by the power receiving unit; and a power transmission unit that transmits the power stored in the storage battery to an electrical device to be charged, wherein the charger is configured to prohibit the transmission of power stored in the storage battery to the electrical device when it is not receiving power transmitted from the power transmission device.

[0006] [Aspect 2] A charger according to Appendix 1, comprising a power receiving control unit for controlling the power receiving unit and a power transmission control unit for controlling the power transmitting unit, wherein the power receiving unit comprises a power receiving antenna and a power receiving conversion unit for converting the power received by the power receiving antenna into DC power, the power receiving control unit transmits a receiving signal to the power transmission control unit indicating whether or not the power receiving antenna is receiving power, and the power transmission control unit transmits the power stored in the battery to the electrical equipment based on the receiving signal.

[0007] [Aspect 3] The charger according to Appendix 2, wherein the power receiving control unit transmits the receiving signal to the power transmission control unit, indicating that the power receiving antenna is receiving power, while the DC current converted by the power receiving conversion unit is output from the power receiving conversion unit to the power receiving control unit.

[0008] According to the configurations of embodiments 1 to 3 described above, charging of electrical equipment by the charger is not performed when power is not being received from the power transmission device, and is only performed when power is being received from the power transmission device. Therefore, when charging electrical equipment by the charger, the rate at which the remaining charge of the storage battery decreases is slowed down, or the remaining charge hardly decreases at all. As a result, even when a storage battery with a small capacity is used, the rapid decrease in the remaining charge of the storage battery can be suppressed. Therefore, it is possible to miniaturize the charger by using a small, low-capacity storage battery.

[0009] [Aspect 4] A wireless power supply system comprising a charger according to any one of aspects 1 to 3 and the power transmission device. [Effects of the Invention]

[0010] According to the present invention, energy storage devices can be miniaturized. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing a wireless power transfer system. [Figure 2] Figure 2 is a perspective view showing the charger and how to use it. [Figure 3] Figure 3 is a block diagram of the wireless power transfer system. [Figure 4] Figure 4 is a schematic cross-sectional view of the charger. [Figure 5] Figure 5 is a flowchart showing the execution procedure for the operation control of the power receiving unit. [Figure 6] Figure 6 is a flowchart showing the execution procedure for the operation control of the power transmission unit. [Modes for carrying out the invention]

[0012] The following describes one embodiment of the present invention. <Overview of Wireless Power Transfer System> As shown in Figure 1, the wireless power supply system S comprises a power transmission device 10 and a charger 20. The power transmission device 10 supplies power to the charger 20 using radio wave wireless power transmission. The charger 20 is charged by the power sent from the power transmission device 10. In other words, radio waves for power supply are transmitted and received between the power transmission antenna 11 of the power transmission device 10 and the power receiving antenna 21 of the charger 20. The radio waves for power supply are, for example, microwaves.

[0013] The charger 20 transmits a beacon signal containing location information to the power transmission device 10 at predetermined time intervals. The power transmission device 10 receives the beacon signal from the charger 20 if the charger 20 is within its power transmission range AR. Upon receiving the beacon signal from the charger 20, the power transmission device 10 determines the location of the charger 20 based on the beacon signal. The power transmission device 10 wirelessly supplies power to the charger 20 by transmitting radio waves (hereinafter sometimes referred to as power transmission signals) towards the determined location. The power transmission signal corresponds to the power sent from the power transmission device 10.

[0014] The power transmission device 10 is installed in a structure that has a space inside which a user enters and uses. Examples of such structures include a dwelling with a room as the space, and a vehicle with a passenger compartment as the space. The power transmission device 10 is installed, for example, in a wall (e.g., a ceiling wall) that partitions the room and passenger compartment, which are the spaces. The power transmission range AR of the power transmission device 10 is set to include one or more of the spaces. The charger 20 is located inside the space. The number of chargers 20 in the wireless power supply system S is not particularly limited and may be one or two or more.

[0015] As shown in Figure 2, the charger 20 is a portable charger that supplies power to the electrical device 100 to be charged in a contactless manner. Examples of the electrical device 100 to be charged include mobile devices such as smartphones and tablet terminals, and wearable devices such as smartwatches, smart glasses, and wireless earphones.

[0016] The details of the power transmission device 10 and the charger 20 will be described below with reference to Figure 3. <Power transmission equipment> The power transmission antenna 11 is used for various communications with the charger 20. The power transmission antenna 11 is used for transmitting power transmission signals and receiving beacon signals.

[0017] As the control unit 12, for example, a micro control unit is used. The control unit 12 includes a processor and a storage unit. The storage unit includes a ROM (Read Only Memory) and a RAM (Random Access Memory). The control unit 12 executes various controls related to communication with the charger 20. The control unit 12 controls the power transmission antenna 11 to receive the beacon signal transmitted by the charger 20. The control unit 12 converts the power supplied from a power supply device (not shown) into a power transmission signal, and transmits this power transmission signal using the power transmission antenna 11.

[0018] <Charger> The charger 20 includes a power receiving unit 22, a storage battery 23, a power transmission unit 24, and a control unit 25. The power receiving unit 22 constitutes a part that receives the power sent from the power transmission device 10 by wireless power supply using a radio wave method. The power receiving unit 22 has a power receiving antenna 21 and a power receiving conversion unit 26.

[0019] The power receiving antenna 21 is used for various communications with the power transmission device 10. Specifically, the power receiving antenna 21 is used for receiving the power transmission signal transmitted from the power transmission device 10 and transmitting the beacon signal to the power transmission device 10.

[0020] The power receiving conversion unit 26 constitutes a part that converts the power transmission signal received by the power receiving antenna 21 into direct current power. The power receiving conversion unit 26 is, for example, a rectifier circuit. Further, the power receiving conversion unit 26 may have a rectifier circuit and a transformer circuit. In the charger 20 of the present embodiment, the storage battery 23 is charged by supplying the direct current power converted by the power receiving conversion unit 26 to the storage battery 23.

[0021] The storage battery 23 is, for example, a secondary battery capable of repeated charging and discharging. Examples of the secondary battery include a lithium ion secondary battery and a nickel hydrogen secondary battery. Further, the storage battery 23 is not limited to a secondary battery, and may be, for example, a capacitor.

[0022] The power transmission unit 24 is the part that transmits power stored in the battery 23 to the electrical equipment 100 by electromagnetic induction wireless power transfer. Wireless power transfer by the power transmission unit 24 is performed in accordance with a standard called Qi, for example. Qi is an international standard established by the Wireless Power Consortium (WPC). Wireless power transfer by the power transmission unit 24 may also conform to other standards, such as those set by the Power Matters Alliance (PMA).

[0023] The power transmission unit 24 includes a power transmission conversion unit 27 and a power transmission coil 28. The power transmission conversion unit 27 has an inverter circuit. The power transmission conversion unit 27 constitutes the part that converts DC power supplied from the storage battery 23 into AC power. The power transmission coil 28 is made up of wound conductors. In the charger 20 of this embodiment, the AC power converted by the power transmission conversion unit 27 is supplied to the power transmission coil 28.

[0024] In the charger 20 of this embodiment, the DC power supplied from the storage battery 23 is converted to AC power by the power transmission conversion unit 27. This AC power is then sent to the power transmission coil 28. As a result, the power transmission coil 28 generates magnetic flux for electromagnetic induction wireless power transmission.

[0025] The control unit 25 includes a power receiving control unit 25A that controls the power receiving unit 22 and a power transmission control unit 25B that controls the power transmission unit 24. For example, a microcontroller unit is used as the power receiving control unit 25A. The power receiving control unit 25A includes a processor and a memory unit. For example, a microcontroller unit is used as the power transmission control unit 25B. The power transmission control unit 25B includes a processor and a memory unit. The memory units of the power receiving control unit 25A and the power transmission control unit 25B each include ROM and RAM.

[0026] The power receiving control unit 25A controls the power receiving antenna 21 to transmit a beacon signal to the power transmitting device 10. The power receiving control unit 25A supplies the DC current converted by the power receiving conversion unit 26 to the storage battery 23. The power receiving control unit 25A also transmits a reception signal to the power transmitting control unit 25B, which is information regarding whether or not the power receiving antenna 21 is receiving a power transmission signal. For example, while the DC current converted by the power receiving conversion unit 26 is output from the power receiving conversion unit 26 to the power receiving control unit 25A, the power receiving control unit 25A transmits a reception signal indicating that the power receiving antenna 21 is receiving a power transmission signal. The communication method for the reception signal is not particularly limited. For example, the communication method for the reception signal is serial communication.

[0027] The power transmission control unit 25B controls the power transmission conversion unit 27 to convert the DC power supplied from the battery 23 into AC power. Based on the received signal, the power transmission control unit 25B supplies the AC power converted by the power transmission conversion unit 27 to the power transmission coil 28.

[0028] <Charger layout> As shown in Figure 2, the charger 20 comprises a housing 30. The power receiving unit 22, the storage battery 23, the power transmitting unit 24, and the control unit 25 are housed inside the housing 30. An example of the layout of the charger 20 will be described with reference to Figure 4.

[0029] As shown in Figure 4, the housing 30 comprises a charging side wall 30a and a power receiving side wall 30b arranged opposite each other with a gap between them, and a peripheral wall 30c connecting the edges of the charging side wall 30a and the power receiving side wall 30b. The shape of the housing 30 is, for example, a rectangular parallelepiped. In the drawing, as an example, the case in which the housing 30 is a flattened rectangular parallelepiped having two main faces is shown. In this case, the charging side wall 30a and the power receiving side wall 30b constitute, for example, two rectangular main faces that have the largest area among the six faces that make up the rectangular parallelepiped.

[0030] Here, we define the axis extending parallel to the longer sides of the charging side wall 30a and the receiving side wall 30b as the "x-axis," and the axis extending parallel to the shorter sides as the "y-axis." We also define the axis extending perpendicular to both the "x-axis" and the "y-axis" as the "z-axis." Therefore, it can be said that the charging side wall 30a and the receiving side wall 30b are parallel to the x-axis and y-axis, and are spaced apart in the z-axis direction.

[0031] An intermediate chassis 31 is positioned inside the housing 30 so as to face the power receiving side wall 30b. The intermediate chassis 31 is a flat plate-shaped member parallel to the power receiving side wall 30b. A power receiving board 32 is positioned between the power receiving side wall 30b and the intermediate chassis 31, supported by the intermediate chassis 31.

[0032] Multiple power receiving antennas 21 are mounted on the first surface 32a of the power receiving board 32, which is located on the side facing the power receiving side wall 30b. Multiple power receiving conversion units 26 are mounted on the second surface 32b of the power receiving board 32, which is located on the opposite side of the first surface 32a. The number of power receiving conversion units 26 is the same as the number of power receiving antennas 21, with one power receiving conversion unit 26 provided for each of the multiple power receiving antennas 21. The power receiving conversion units 26 are connected to the corresponding power receiving antennas 21. More specifically, at least a portion of the power receiving conversion units 26 are positioned in a location that overlaps with the corresponding power receiving antenna 21 in the z-axis direction, that is, in the region where the power receiving antenna 21 is vertically projected. The power receiving conversion units 26 are connected to the power receiving antennas 21 via a connection part (not shown) that penetrates the power receiving board 32.

[0033] Furthermore, a power receiving control unit 25A is mounted on the side of the power receiving board 32 opposite to the power receiving side wall 30b. The power receiving control unit 25A is connected to each power receiving conversion unit 26 via wiring (not shown) provided on the power receiving board 32.

[0034] Furthermore, within the housing 30, the power transmission coil 28 and the power transmission board 33 are arranged facing the charging side wall 30a. The power transmission board 33 is supported by the charging side wall 30a and is positioned next to the power transmission coil 28 in the x-axis direction.

[0035] The power transmission board 33 is equipped with a power transmission conversion unit 27 and a power transmission control unit 25B. The power transmission conversion unit 27 is connected to the power transmission control unit 25B and the power transmission coil 28 via a connection part (not shown). The power transmission control unit 25B is also connected to the power receiving control unit 25A via a signal wiring 34. The signal wiring 34 is used to transmit received signals from the power receiving control unit 25A to the power transmission control unit 25B.

[0036] Within the housing 30, a storage battery 23 is positioned between the intermediate chassis 31 and the power transmission coil 28, and between the intermediate chassis 31 and the power transmission board 33. The storage battery 23 is also located between the power receiving board 32 and the power transmission board 33, and between the power receiving board 32 and the power transmission coil 28. The storage battery 23 is connected to the power receiving control unit 25A and the power transmission conversion unit 27 via a connection part (not shown).

[0037] The battery 23 is, for example, flattened and has two main surfaces parallel to the charging side wall 30a and the receiving side wall 30b. The thickness A2 of the battery 23 is thinner than the thickness A1 of the housing 30. The thickness A1 of the housing 30 is, for example, 5 mm or more and 50 mm or less. In this case, the thickness A2 of the battery 23 is less than 50 mm. In one example, the battery 23 is thinner than the power transmission coil 28. In this embodiment, thickness refers to the dimension in the z-axis direction.

[0038] <Power reception from the power transmission device to the charger> As shown in Figure 1, the charger 20 controls the receiving antenna 21 to transmit a beacon signal. The power transmission device 10 receives the beacon signal transmitted by the charger 20 using the power transmission antenna 11. Upon receiving the beacon signal, the power transmission device 10 controls the power transmission antenna 11 to transmit a power transmission signal to the charger 20. A portion of the power stored in the battery 23 is used to transmit the beacon signal.

[0039] The charger 20 receives a power transmission signal through the operation control of the power receiving antenna 21. Then, the power receiving conversion unit 26 of the charger 20 converts this power transmission signal into DC power, and this DC power is supplied to the storage battery 23. The storage battery 23 is then charged by the supplied DC power.

[0040] Figure 5 shows the execution procedure for the operation control of the power receiving unit 22 of the charger 20. The series of processes shown in the flowchart of Figure 5 are executed by the power receiving control unit 25A of the charger 20 as processes at predetermined cycles.

[0041] As shown in Figure 5, if the remaining charge (SOC) of the battery 23 is less than the full charge threshold (for example, a value equivalent to a full charge [100%]) (step S11: NO), the power receiving control unit 25A permits power receiving by the power receiving unit 22 (step S12). Here, power receiving means that DC power converted from the received power transmission signal is supplied to the battery 23, that is, the battery 23 is charged. On the other hand, if the remaining charge (SOC) is equal to or greater than the full charge threshold (step S11: YES), the power receiving control unit 25A prohibits (stops) power receiving by the power receiving unit 22 (step S13).

[0042] <Power transmission from charger to electrical equipment> As shown in Figure 2, when charging the electrical device 100 using the charger 20, the electrical device 100 is placed on the charging side wall 30a of the housing 30. This allows the electrical device 100 to be charged by electromagnetic induction wireless power transfer. The power transmission coil 28 of the charger 20 generates magnetic flux when energized. The charger 20 is configured such that when the electrical device 100 is placed on the charging side wall 30a, the magnetic flux generated by the power transmission coil 28 links with the power receiving coil of the electrical device 100. This magnetic flux links with the power receiving coil of the electrical device 100, generating an induced electromotive force in the power receiving coil of the electrical device 100. The electrical device 100 is charged using this induced electromotive force.

[0043] Although Figure 2 shows the charger 20 and the electrical device 100 separated, it is desirable to bring the charging side wall 30a of the charger 20 into contact with the electrical device 100 when actually charging it. This improves the efficiency of power transmission from the power transmission coil 28 to the electrical device 100.

[0044] Figure 6 shows the execution procedure for the operation control of the power transmission unit 24 of the charger 20. The series of processes shown in the flowchart of Figure 6 are executed by the power transmission control unit 25B of the charger 20 as processes at predetermined intervals, triggered when the electrical equipment 100 is placed on the charging side wall 30a of the housing 30. The series of processes shown in the flowchart of Figure 6 are executed in parallel with the series of processes shown in the flowchart of Figure 5.

[0045] As shown in Figure 6, if the receiving antenna 21 is receiving a power transmission signal (step S21: YES) and the remaining charge (SOC) of the storage battery 23 exceeds a preset low-charge threshold (step S22: YES), the power transmission control unit 25B permits power transmission from the storage battery 23 to the electrical equipment 100 (step S23). In this case, the power from the storage battery 23 is transmitted to the electrical equipment 100, thereby charging the electrical equipment 100. Note that in step S22, if the receiving antenna 21 is receiving a power transmission signal, it means that the received signal has been input to the power transmission control unit 25B, and if the receiving antenna 21 is not receiving a power transmission signal, it means that the received signal has not been input to the power transmission control unit 25B.

[0046] On the other hand, if the receiving antenna 21 does not receive a power transmission signal (step S21: NO), the power transmission control unit 25B prohibits power transmission from the storage battery 23 to the electrical equipment 100 (step S24). In this case, since power from the storage battery 23 is not transmitted to the electrical equipment 100, charging of the electrical equipment 100 is not performed.

[0047] Furthermore, if the receiving antenna 21 is receiving a power transmission signal (step S21: YES) and the remaining charge (SOC) of the battery 23 is below the low charge threshold (step S22: NO), the power transmission control unit 25B prohibits power transmission from the battery 23 to the electrical equipment 100 (step S24). In this case as well, since power from the battery 23 is not transmitted to the electrical equipment 100, charging of the electrical equipment 100 is not performed. Note that in order to maintain the function of transmitting a beacon signal even when the remaining charge (SOC) of the battery 23 is below the low charge threshold, the low charge threshold is set to a value that leaves enough power to transmit a beacon signal.

[0048] [Effect] The operation of this embodiment will be described below. When the electrical device 100 is placed in a designated position on the charger 20, the power stored in the battery 23 is supplied to the electrical device 100, causing the remaining charge (SOC) of the battery 23 to decrease. When the remaining charge (SOC) falls below a low level threshold, the charger 20 stops charging the electrical device 100.

[0049] In this embodiment, the charger 20 prohibits power transmission from the battery 23 to the electrical equipment 100 if the receiving antenna 21 is not receiving a power transmission signal. In other words, the receiving antenna 21 receiving a power transmission signal is a condition for transmitting power from the battery 23 to the electrical equipment 100.

[0050] In this case, when the electrical equipment 100 is placed in a predetermined position on the charger 20 and the receiving antenna 21 is receiving a power transmission signal, the charging of the storage battery 23 based on the received power transmission signal and the charging of the electrical equipment 100 using the power of the storage battery 23 are performed simultaneously. As a result, the rate at which the remaining charge (SOC) of the storage battery 23 decreases during the charging of the electrical equipment 100 is slowed down, or the remaining charge (SOC) hardly decreases at all.

[0051] On the other hand, when the receiving antenna 21 is not receiving a power transmission signal, even if the electrical equipment 100 is placed in a designated position on the charger 20, the charger 20 will not charge the electrical equipment 100. Therefore, of the charging of the storage battery 23 and the power transmission from the storage battery 23 to the electrical equipment 100, only the power transmission from the storage battery 23 to the electrical equipment 100 takes place, and the remaining charge (SOC) of the storage battery 23 does not decrease at a rapid rate.

[0052] Thus, the charger 20 of this embodiment is less prone to a decrease in the remaining charge (SOC) of the battery 23, and can maintain a state where the remaining charge (SOC) exceeds the low-charge threshold for a longer period. As a result, even when a battery 23 with a small capacity is used, it is possible to suppress the early decrease of the remaining charge (SOC) of the battery 23 below the low-charge threshold. Therefore, it is possible to miniaturize the charger 20 by using a small, low-capacity battery 23.

[0053] In addition, situations in which the receiving antenna 21 does not receive a power transmission signal include, for example, when the power transmission device 10 is not transmitting a power transmission signal, when the charger 20 is outside the power transmission range AR of the power transmission device 10, or when the power transmission signal does not reach the charger 20 which is within the power transmission range AR due to an obstruction between the power transmission device 10 and the charger 20.

[0054] [effect] The effects of this embodiment will be described below. (1) The charger 20 includes a power receiving unit 22 that receives power from the power transmission device 10 by wireless power transmission using radio waves, a storage battery 23 that is charged by the power received by the power receiving unit 22, and a power transmission unit 24 that transmits the power stored in the storage battery 23 to the electrical equipment 100 to be charged. The charger 20 prohibits transmitting the power stored in the storage battery 23 to the electrical equipment 100 when it has not received power transmitted from the power transmission device 10.

[0055] According to the above configuration, charging of the electrical device 100 by the charger 20 is not performed when the receiving antenna 21 is not receiving a power transmission signal, and is only performed when the receiving antenna 21 is receiving a power transmission signal. Therefore, when charging the electrical device 100 by the charger 20, the rate at which the remaining charge SOC of the storage battery 23 decreases is slowed down, or the remaining charge SOC hardly decreases at all. As a result, even when a storage battery 23 with a small capacity is used, it is possible to suppress the storage battery 23's remaining charge SOC from decreasing to below the low-charge threshold prematurely. Therefore, it is possible to miniaturize the charger 20 by using a small, low-capacity storage battery 23.

[0056] Furthermore, with the above configuration, the state in which the electrical equipment 100 can be charged and the state in which it cannot be charged are switched based on whether or not the receiving antenna 21 is receiving power transmitted from the power transmission device 10, so that the user's judgment and operation are not required for the switch. In contrast, the charger of Patent Document 1 is configured so that the state in which the electrical equipment can be charged and the state in which it cannot be charged are switched by the user through the operation of a physical switch, in order to suppress the unnecessary decrease in the remaining charge of the power storage unit. In this case, unless the user judges for themselves whether or not it is necessary to put the electrical equipment in a state where it cannot be charged and operates the physical switch, the effect of suppressing the unnecessary decrease in the remaining charge of the power storage unit cannot be obtained. (2) The power transmission unit 24 includes a power transmission coil 28 that generates magnetic flux for electromagnetic induction wireless power transmission. The storage battery 23 is positioned between the power receiving board 32 on which the components constituting the power receiving unit 22 are mounted and the power transmission board 33 on which the components constituting the power transmission unit 24 are mounted, and between the power receiving board 32 and the power transmission coil 28. With the above configuration, electromagnetic interference (e.g., high-frequency constant deviation) caused by the proximity or contact between the power receiving board 32 and the power transmission board 33, or between the power receiving board 32 and the power transmission coil 28 can be suppressed.

[0057] (3) The charger 20 comprises a flattened housing 30 having two main surfaces. The power transmission unit 24 comprises a power transmission coil 28 that generates magnetic flux for electromagnetic induction wireless power transmission. Within the housing 30, the power transmission coil 28 and the power transmission board 33 are arranged adjacent to each other in the direction along the main surface of the housing 30. Among the components arranged within the housing 30, the power transmission coil 28 is a component with a large dimension in the thickness direction. Therefore, reducing the overlap in the thickness direction between the power transmission coil 28 and other components greatly contributes to making the charger 20 thinner.

[0058] (4) The power receiving unit 22 includes a power receiving antenna 21 and a power receiving conversion unit 26 that converts the power transmission signal received by the power receiving antenna 21 into DC power. The power receiving antenna 21 is mounted on the first surface 32a of the power receiving board 32. The rectifier circuit is mounted on the second surface 32b of the power receiving board 32, and at least a part of the power receiving conversion unit 26 is located in the region where the power receiving antenna 21 is vertically projected. The power receiving conversion unit 26 is connected to the power receiving antenna 21 via a connection part that penetrates the power receiving board 32. With the above configuration, the electrical path between the power receiving antenna 21 and the power receiving conversion unit 26 can be reduced. As a result, the transmission loss between the power receiving antenna 21 and the power receiving conversion unit 26 is reduced, and the antenna gain is improved.

[0059] [Example of changes] The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0060] The received signal may also be a signal indicating that the receiving antenna 21 is not receiving a power transmission signal. In this case, the receiving control unit 25A transmits the received signal to the transmitting control unit 25B based on the fact that, for example, the DC current converted by the receiving conversion unit 26 is not being input to the receiving control unit 25A.

[0061] The received signal may be transmitted from the power receiving conversion unit 26. In this case, the signal wiring 34 is wired to connect the power receiving conversion unit 26 and the power transmission control unit 25B. In this case, the power receiving conversion unit 26 transmits a received signal indicating that the power receiving antenna 21 is receiving the power transmission signal, for example, while the power transmission signal is input to the power receiving conversion unit 26.

[0062] The control unit 25 may be configured to perform a determination process to determine whether or not the receiving antenna 21 is receiving a power transmission signal. For example, if the strength of the power transmission signal received by the receiving antenna 21 is equal to or greater than a preset reference strength, it is determined that the receiving antenna 21 is receiving a power transmission signal. The above determination process may be performed by the receiving control unit 25A or by the transmitting control unit 25B. The reference value may be set to a value corresponding to an intensity that is substantially incapable of charging the storage battery 23. Alternatively, the reference value may be set to a value that is capable of charging the storage battery 23, but where the charging speed of the storage battery 23 is less than or equal to a reference speed.

[0063] The charger 20 may include a display device that indicates whether or not the receiving antenna 21 is receiving a power transmission signal. One example of a display device includes a light-emitting part such as a light-emitting diode, and indicates whether or not the power transmission signal is being received based on the light emitted by the light-emitting part. It is also preferable that the display device is configured to operate based on the input of a reception signal indicating that the receiving antenna 21 is receiving a power transmission signal. In this case, if the reception signal is input to the display device through the signal wiring 34, there is no need to add a separate configuration for controlling the display device.

[0064] Regarding the power transmission unit 24, instead of a configuration that transmits power to the electrical equipment 100 by wireless power supply, a configuration that transmits power to the electrical equipment 100 by wired power supply using a charging cord may be adopted. In this case, the power transmission unit 24 has, for example, a connection terminal for connecting a charging cord, a connection circuit that connects the connection terminal to the storage battery 23 (or power receiving conversion unit 26), etc. The charging cord can be, for example, a USB standard (Type-A, Type-B, Type-C) cord. Furthermore, the power transmission unit 24 may have both a configuration for transmitting power to the electrical equipment 100 by wireless power supply and a configuration for transmitting power to the electrical equipment 100 by wired power supply using a charging cord.

[0065] The charger 20 may be equipped with a magnet for securing the charger 20 to the electrical equipment 100. Within the housing 30, the magnet is arranged, for example, to surround the outer circumference of the power transmission coil 28.

[0066] The charger 20 may be a stationary charger fixed to a specific location within the power transmission range AR of the power transmission device 10. [Note] Next, the technical concepts that can be understood from the above embodiments and modified examples are described below.

[0067] (Note 1) The storage battery is the charger which is positioned between a power receiving board on which the components constituting the power receiving unit are mounted and a power transmitting board on which the components constituting the power transmitting unit are mounted. (Note 2) The power transmission unit is equipped with a power transmission coil that generates magnetic flux for electromagnetic induction wireless power transmission, and the storage battery is the charger which is positioned between the power receiving board on which the components constituting the power receiving unit are mounted and the power transmission coil.

[0068] (Note 3) The charger comprises a flattened housing having two main surfaces, the power transmission unit comprises a power transmission coil that generates magnetic flux for electromagnetic induction wireless power transmission, and within the housing, the power transmission coil and the power transmission board on which the components constituting the power transmission unit are mounted are arranged adjacent to each other in a direction along the main surface of the housing.

[0069] (Note 4) The charger comprises a power receiving antenna and a power receiving conversion unit that converts the power received by the power receiving antenna into DC power, wherein the power receiving antenna is mounted on a first surface of a power receiving board, and the power receiving conversion unit is mounted on a second surface of the power receiving board opposite to the first surface, and at least a portion of the power receiving conversion unit is positioned to overlap with the power receiving antenna in the thickness direction of the power receiving board. [Explanation of Symbols]

[0070] S... Wireless power supply system 10... Power transmission equipment 20…Charger 21... Receiving antenna 22... Power receiving section 23… Storage battery 24... Power transmission section 25A... Power receiving control unit 25B... Power transmission control unit 26... Power receiving conversion unit 34... Signal wiring 100… Electrical equipment

Claims

1. A power receiving unit that receives power from a power transmission device via radio wave wireless power transfer, The power receiving unit receives power and charges a storage battery, The system includes a power transmission unit that transmits the power stored in the aforementioned battery to the electrical equipment to be charged, A charger configured to prohibit the transmission of power stored in the battery to the electrical equipment if it has not received power transmitted from the power transmission device.

2. A power receiving control unit that controls the power receiving unit, The system comprises a power transmission control unit that controls the power transmission unit, The power receiving unit comprises a power receiving antenna and a power receiving conversion unit that converts the power received by the power receiving antenna into DC power. The power receiving control unit transmits a receiving signal to the power transmission control unit indicating whether or not the power receiving antenna is receiving power. The charger according to claim 1, wherein the power transmission control unit transmits power stored in the storage battery to the electrical equipment based on the received signal.

3. The charger according to claim 2, wherein the power receiving control unit transmits the receiving signal to the power transmission control unit, indicating that the power receiving antenna is receiving power, while the DC current converted by the power receiving conversion unit is output from the power receiving conversion unit to the power receiving control unit.

4. A charger according to any one of claims 1 to 3, A wireless power supply system comprising the aforementioned power transmission device.

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