Power receiving device

Abstract

To provide a power receiving device capable of improving power receiving efficiency.SOLUTION: A power receiving device 1 is roughly composed by including: a plurality of antenna groups each including at least one antenna that receives a microwave 81 and having different directivity; a communication unit 4 that transmits a beacon signal 12 for each of the plurality of antenna groups; a switching unit 3 that selects and switches a receiving antenna group that receives the microwave 81 from the plurality of antenna groups; and a control unit 7 that searches for the receiving antenna group in which a power value obtained by converting the microwave 81 transmitted from a power transmission device 8 on the basis of transmission of the beacon signal 12 for each of the plurality of antenna groups is equal to or greater than a threshold value 70, retransmits the beacon signal 12 corresponding to the searched receiving antenna group, receives the microwave 81 transmitted toward the receiving antenna group, and charges a charging body 6 that is a charging target.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power receiving device. [Background technology]

[0002] 2. Description of the Related Art As a conventional technique, a wireless power transmitting and receiving system including a power transmitting device that outputs microwaves and a power receiving device that converts the received microwaves into electric power for charging is known (see, for example, Patent Document 1).

[0003] The power transmitting device of this wireless power transmitting and receiving system can adjust the phase of microwaves based on the beacon signal output by the power receiving device, and direct the microwaves toward the power receiving device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 059453 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional wireless power transmitting and receiving systems, the orientation of the antenna of the power receiving device relative to the power transmitting device affects power receiving efficiency, so there is a limit to how much power receiving efficiency can be improved by simply orienting the microwave directionality toward the power receiving device.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a power receiving device capable of improving power receiving efficiency. [Means for solving the problem]

[0007] One aspect of the present invention provides a power receiving device comprising: a plurality of antenna groups, each having a different directivity, each of which is composed of at least one antenna that receives a power transmission signal transmitted from a power transmitting device for contactless power supply; a transmitting unit that transmits a beacon signal for each of the plurality of antenna groups to the power transmitting device; a switching unit that selects and switches a receiving antenna group from the plurality of antenna groups to receive the power transmission signal; and a control unit that controls the transmitting unit and the switching unit to search for a receiving antenna group having a power value obtained by converting the power transmission signal transmitted from the power transmitting device based on the transmission of the beacon signal for each of the plurality of antenna groups and which is equal to or greater than a predetermined threshold value, retransmits a beacon signal corresponding to the searched receiving antenna group, receives the power transmission signal transmitted toward the receiving antenna group, and charges an object to be charged. Effect of the Invention

[0008] According to the present invention, it is possible to improve the power receiving efficiency. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1(a) is a diagram showing an example of a power receiving device according to a first embodiment, and FIG. 1(b) is a side view showing an example of an antenna. [Diagram 2] FIG. 2 is an example of a block diagram of a power transmission system according to the first embodiment. [Diagram 3] FIG. 3 shows an example of a timing chart when searching for a receiving antenna group from all antenna groups in the power receiving device according to the first embodiment. [Figure 4] FIG. 4 shows an example of a timing chart when the power receiving device according to the first embodiment starts searching for receiving antenna groups from the antenna group with the largest power value during previous charging. [Diagram 5] FIG. 5(a) is a diagram showing an example of a power receiving device according to the second embodiment, and FIG. 5(b) is a diagram showing an example of a plurality of antennas constituting an antenna group. [Figure 6] FIG. 6 is an example of a block diagram of a power transmission system according to the third embodiment. [Figure 7] 7(a) and 7(b) are diagrams showing an example of opposing antenna groups according to the fourth embodiment, and FIG. 7(c) is a diagram showing an example in which the antenna groups are not opposing each other. [Figure 8] 8(a) and 8(b) are diagrams showing an example of a combination group of a plurality of power receiving devices according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Summary of the embodiment) The power receiving device of the embodiment is generally configured to include a plurality of antenna groups, each having a different directivity, which are composed of at least one antenna that receives a power transmission signal transmitted from a power transmitting device for contactless power supply, a transmitting unit that transmits a beacon signal for each of the plurality of antenna groups to the power transmitting device, a switching unit that selects and switches a receiving antenna group from the plurality of antenna groups to receive the power transmission signal, and a control unit that controls the transmitting unit and the switching unit, searches for a receiving antenna group having a power value obtained by converting the power transmission signal transmitted from the power transmitting device based on the transmission of the beacon signal for each of the plurality of antenna groups and having a power value equal to or greater than a predetermined threshold value, re-transmits a beacon signal corresponding to the searched receiving antenna group, receives the power transmission signal transmitted toward the receiving antenna group, and charges an object to be charged.

[0011] Since the power receiving device searches for a receiving antenna group from an antenna group with different directivities, the effect of the orientation of the receiving antenna group of the power receiving device with respect to the power transmitting device can be suppressed and the power receiving efficiency can be improved compared to the case where at least one antenna with the same directivity is used. Note that the power receiving efficiency is the ratio of the power when the transmitted power transmission signal is converted without loss to the actually converted power.

[0012] [First embodiment] (Overview of power receiving device 1) FIG. 1(a) is a diagram showing an example of a power receiving device according to the first embodiment, and FIG. 1(b) is a side view showing an example of an antenna. FIG. 2 is an example of a block diagram of a power transmitting system according to the first embodiment. In each diagram according to the embodiments described below, the ratio and shape between figures may differ from the actual ratio and shape. Furthermore, "A to B" indicating a numerical range is used to mean A or more and B or less.

[0013] The power transmission system 9 is configured so that the power receiving device 1 receives a power transmission signal transmitted from the power transmitting device 8, thereby charging the device without the user being aware of it. The power receiving device 1 has an antenna group arranged in a housing 10. The housing 10 is, for example, a housing for an electronic device such as a smartphone, a tablet terminal, a personal computer, a drone, a remote controller, a mobile battery, or an electronic key, but is not limited to these. The power receiving device 1 may be configured to be connected to these electronic devices via a harness, for example.

[0014] Specifically, as shown in Fig. 1(a) to Fig. 2, the power receiving device 1 is generally configured to include a plurality of antenna groups each having different directivities, each of which is composed of at least one antenna that receives a power transmission signal transmitted from the power transmitting device 8 for contactless power supply, a communication unit 4 as a transmission unit that transmits a beacon signal 12 to the power transmitting device 8 for each of the plurality of antenna groups, a switching unit 3 that selects and switches a receiving antenna group that receives the power transmission signal from the plurality of antenna groups, and a control unit 7 that controls the communication unit 4 and the switching unit 3, searches for a receiving antenna group whose power value obtained by converting the power transmission signal transmitted from the power transmitting device 8 based on the transmission of the beacon signal 12 for each of the plurality of antenna groups is equal to or greater than a predetermined threshold value 70, retransmits the beacon signal 12 corresponding to the searched receiving antenna group, receives the power transmission signal transmitted toward the receiving antenna group, and charges the charging body 6 that is the charging target. As an example, the power receiving device 1 further includes a conversion unit 5 as shown in Fig. 2. When searching for a receiving antenna group, if there is an antenna group to be switched to after the antenna group whose obtained power value is equal to or greater than the threshold value 70, the power receiving device 1 determines that antenna group as the receiving antenna group and does not need to switch to another antenna group.

[0015] The antenna groups in this embodiment are a first antenna group 2a and a second antenna group 2b. The first antenna group 2a and the second antenna group 2b are each composed of one patch antenna 21, but are not limited to this, and each may be composed of multiple patch antennas 21.

[0016] Moreover, the power transmitting device 8 of the present embodiment transmits power using, as an example, microwaves 81 as a power transmission signal. Note that the power transmitting device 8 is not limited to a power transmission method using microwaves 81, and may use a power transmission method such as a laser method using laser light.

[0017] As an example, as shown in FIG. 2, the power transmission device 8 is roughly configured to include a transmitting antenna 80, a transmitting communication unit 82, a phase adjustment unit 83, a transmitting conversion unit 84, a power supply unit 85, and a transmitting control unit 86.

[0018] The transmitting antenna 80 is an antenna used for transmitting microwaves 81 to the power receiving device 1 and for receiving beacon signals 12 transmitted from the power receiving device 1. The transmitting communication unit 82 transmits the microwaves 81 and receives the beacon signals 12 via the transmitting antenna 80. The phase adjustment unit 83 adjusts the phase of the microwaves 81 based on the reception of the beacon signal 12 so that the microwaves 81 head in the direction from which the beacon signal 12 was transmitted. The transmitting conversion unit 84 converts power from a power supply unit 85 into microwaves 81. The power supply unit 85 supplies power for conversion into microwaves 81. This power supply unit 85 may be configured to use power supplied from an external power supply, or may be configured as a storage battery.

[0019] The microwaves 81 have a frequency of, for example, 900 MHz to 60 GHz, but are not limited to this.

[0020] The transmission side control unit 86 is, for example, a microcomputer including a CPU (Central Processing Unit) that performs calculations and processing on acquired data according to a stored program, a RAM (Random Access Memory) that is a semiconductor memory, and a ROM (Read Only Memory), etc. The transmission side control unit 86 is configured to control the transmission side communication unit 82, the phase adjustment unit 83, the transmission side conversion unit 84, and the power supply unit 85.

[0021] (Configuration of the first antenna group 2a and the second antenna group 2b) 1(b), the first antenna 22 and the second antenna 23 of this embodiment include a substrate 20 and a patch antenna 21. The first antenna 22 and the second antenna 23 are used for both transmitting a beacon signal 12 and receiving a microwave 81. Since the first antenna 22 and the second antenna 23 have the same configuration, the first antenna 22 will be described below.

[0022] The substrate 20 is, for example, a rigid substrate. The patch antenna 21 is, for example, formed on the surface 20a of the substrate 20 as a thin film of a conductive metal such as copper. The patch antenna 21 has, for example, a rectangular shape. Note that the patch antenna 21 is, for example, formed by plating a thin film of a conductive metal with gold or nickel. The directivity of the patch antenna 21 is mainly in the normal direction of the surface 21a.

[0023] 1(a), the first antenna group 2a is arranged on a front surface 100 of the housing 10. The second antenna group 2b is arranged on a back surface 101 opposite to the front surface 100. The receiving antenna groups are searched for, for example, in the order from the first antenna group 2a on the front surface 100 which is likely to be on top when the power receiving device 1 is placed, to the second antenna group 2b on the back surface 101.

[0024] In this embodiment, the patch antennas 21 of the first antenna group 2a and the second antenna group 2b have the same shape and are arranged opposite each other, but this is not limited to this and they may have different shapes or be arranged offset from each other.

[0025] The first antenna group 2a and the second antenna group 2b are connected to a switching unit 3. One of the first antenna group 2a and the second antenna group 2b becomes a receiving antenna group by switching by the switching unit 3. For example, when the first antenna group 2a is connected to the communication unit 4 via the switching unit 3, the first antenna group 2a becomes a receiving antenna group. Also, for example, when the second antenna group 2b is connected to the communication unit 4 via the switching unit 3, the second antenna group 2b becomes a receiving antenna group.

[0026] The directivity of the patch antenna 21 is in the normal direction of the front surface 21a. Because of the substrate 20, the patch antenna 21 receives microwaves 81 from the rear surface 21b side at a much lower efficiency than the microwaves 81 from the front surface 21a side, or the patch antenna 21 cannot receive microwaves.

[0027] Therefore, the first antenna group 2a and the second antenna group 2b are arranged opposite each other to have different directivities, and are configured so that either antenna group can receive microwaves 81 directed toward the front surface 20a of the substrate 20, rather than microwaves 81 directed toward the back surface 20b of the substrate 20.

[0028] (Configuration of Switching Unit 3) The switching unit 3 is configured to switch between a group of antennas that receive microwaves 81 and a group of antennas that transmit beacon signals 12 .

[0029] (Configuration of communication unit 4) The communication unit 4 is configured to transmit the beacon signal 12 using at least one antenna of the antenna group. The antennas in this embodiment are the first antenna 22 of the first antenna group 2a and the second antenna 23 of the second antenna group 2b. Therefore, the communication unit 4 transmits the beacon signal 12 using the first antenna 22 and the second antenna 23.

[0030] The communication unit 4 is configured to receive microwaves 81 and transmit beacon signals 12 under the control of the control unit 7. As a modified example, the power receiving device 1 may have a mode in which, during reception, the conversion unit 5 is directly connected to the switching unit 3 without going through the communication unit 4, and charges the charging unit 6. In this mode, for example, when the power for operating the communication unit 4 and the control unit 7 is not sufficiently stored in the charging unit 6, the received microwaves 81 are directly rectified by a rectifier circuit in the conversion unit 5 to charge the charging unit 6 for recovery.

[0031] (Configuration of conversion unit 5) The conversion unit 5 has a rectifier circuit and converts the microwaves 81 received by the first antenna group 2a and the second antenna group 2b into a direct current. The conversion unit 5 is arranged, for example, after the switching unit 3, but is not limited to this, and may be arranged between the first antenna group 2a and the switching unit 3, and between the second antenna group 2b and the switching unit 3. Furthermore, as described above, the conversion unit 5 may be directly connected to the switching unit 3. The conversion unit 5 is arranged, for example, on the rear surface 20b of the substrate 20, but is not limited to this.

[0032] When the switching unit 3 and the conversion unit 5 are arranged on the substrate 20, the power receiving device 1 has the first antenna group 2a, the second antenna group 2b, the switching unit 3 and the conversion unit 5 close to each other, so that the decrease in power receiving efficiency can be suppressed compared to when they are far apart.

[0033] Furthermore, when multiple antenna groups are located close to each other and the rectifier circuit of the conversion unit 5 can be placed after the switching unit 3, the power receiving device 1 can have a smaller number of components and reduce manufacturing costs compared to a case in which this configuration is not adopted.

[0034] (Configuration of charging body 6) The charging unit 6 is, for example, a secondary battery such as a lithium ion battery, a nickel-metal hydride battery, or a nickel-cadmium battery. The charging unit 6 in this embodiment is, for example, a lithium ion battery, but is not limited to this. The charging unit 6 is charged by microwaves 81 transmitted from a power transmitting device 8.

[0035] (Configuration of control unit 7) The control unit 7 is, for example, a microcomputer including a CPU, a RAM, a ROM, etc. The control unit 7 has a threshold value 70, power value information 71, and antenna information 72.

[0036] This threshold value 70 is compared with a power value obtained by converting the received microwaves 81. This power value may be, for example, an average power value for a predetermined period, or an integrated value for a predetermined period. For example, when the power value is an average value, the threshold value 70 is set to a value greater than the average power consumption of the power receiving device 1 for the predetermined period. For example, when the power value is an integrated value, the threshold value 70 is set to a value greater than the integrated value of the power consumption of the power receiving device 1 for the predetermined period. In other words, the threshold value 70 is set based on whether or not the power value is greater than the power consumption and the charging body 6 can be charged.

[0037] The control unit 7 is also configured to store power values ​​obtained from microwaves 81 received by a plurality of antenna groups, and when searching for a receiving antenna group, transmit a beacon signal 12 from the antenna group with the largest power value during previous charging. When searching for a receiving antenna group, for example, the power receiving device 1 searches for a receiving antenna group with high power receiving efficiency in order to start charging. The control unit 7 stores a history of power values ​​for each antenna group as power value information 71.

[0038] When transmitting beacon signal 12 to charge charging body 6, control unit 7 transmits beacon signal 12 from the antenna group that obtained a large power value during previous charging based on power value information 71. Then, when the power value obtained from microwaves 81 received by that antenna group is equal to or greater than threshold value 70, control unit 7 ends the search and determines that antenna group as the receiving antenna group.

[0039] As a modified example, when searching for a receiving antenna group, the control unit 7 may be configured to transmit the beacon signal 12 from the previous receiving antenna group based on the power value information 71. As another modified example, the control unit 7 may store the power value at the time of the previous search as the power value information 71, and start the search from the antenna group with the highest power receiving efficiency based on this power value information 71. As yet another modified example, the control unit 7 may refer to the frequency of the antenna groups that have been determined as receiving antenna groups based on the power value information 71, and transmit the beacon signal 12 in the order of the antenna groups with the highest frequency.

[0040] The control unit 7 has antenna information 72 related to the first antenna group 2a and the second antenna group 2b. The antenna information 72 includes, for example, information on the order of the antenna groups that transmit the beacon signal 12 as an initial value.

[0041] Fig. 3 shows an example of a timing chart when searching for a receiving antenna group from all antenna groups. Fig. 4 shows an example of a timing chart when starting to search for a receiving antenna group from the antenna group with the largest power value during previous charging. First, an example of an operation of the power receiving device 1 to search for a receiving antenna group from all antenna groups that are the initial settings will be described below with reference to the timing chart of Fig. 3.

[0042] (operation) In order to search for a receiving antenna group, the control unit 7 of the power receiving device 1 controls the switching unit 3 and the communication unit 4, and issues an instruction to transmit a beacon signal 12 from the first antenna group 2a (Step 1). The switching unit 3 connects the first antenna group 2a to the communication unit 4.

[0043] The first antenna group 2a transmits a beacon signal 12 (Step 2).

[0044] When the power transmitting device 8 receives the beacon signal 12 (Step 3), the power transmitting device 8 adjusts the phase so that the directivity of the microwaves 81 increases in the direction of the beacon signal 12, and transmits the microwaves 81 (Step 4).

[0045] The first antenna group 2a receives the microwaves 81 transmitted from the power transmitting device 8 (Step 5). The conversion unit 5 acquires the microwaves 81 received by the first antenna group 2a via the communication unit 4 and converts them into power. The control unit 7 stores the power value of the converted power as power value information 71 (Step 6).

[0046] The control unit 7 controls the switching unit 3 and the communication unit 4 to instruct the second antenna group 2b to transmit the beacon signal 12 (Step 7). The switching unit 3 switches the connection from the first antenna group 2a to the second antenna group 2b, and connects the second antenna group 2b to the communication unit 4.

[0047] The second antenna group 2b transmits the beacon signal 12 (Step 8).

[0048] When the power transmitting device 8 receives the beacon signal 12 (Step 9), the power transmitting device 8 adjusts the phase so that the directivity of the microwaves 81 increases in the direction of the beacon signal 12, and transmits the microwaves 81 (Step 10).

[0049] The second antenna group 2b receives the microwaves 81 transmitted from the power transmitting device 8 (Step 11). The conversion unit 5 acquires the microwaves 81 received by the second antenna group 2b via the communication unit 4 and converts them into power. The control unit 7 stores the power value of the converted power as power value information 71 (Step 12).

[0050] The control unit 7 compares the stored power value of the first antenna group 2a and the power value of the second antenna group 2b with a threshold value 70 based on the power value information 71. For example, when the power value of the first antenna group 2a is equal to or greater than the threshold value 70, the control unit 7 determines the first antenna group 2a as the receiving antenna group (Step 13). Note that when both are equal to or greater than the threshold value 70, the control unit 7 determines the antenna group with the larger obtained power value as the receiving antenna group.

[0051] The control unit 7, having determined that the first antenna group 2a is the receiving antenna group, again controls the switching unit 3 and the communication unit 4 to instruct the first antenna group 2a to transmit the beacon signal 12 (Step 14). The switching unit 3 connects the first antenna group 2a to the communication unit 4.

[0052] The first antenna group 2a transmits the beacon signal 12 (Step 15).

[0053] When the power transmitting device 8 receives the beacon signal 12 (Step 16), the power transmitting device 8 adjusts the phase so that the directivity of the microwaves 81 increases in the direction of the beacon signal 12, and transmits the microwaves 81 (Step 17).

[0054] The first antenna group 2a receives the microwaves 81 transmitted from the power transmitting device 8 (Step 18). When the conversion unit 5 acquires the microwaves 81 received by the first antenna group 2a via the communication unit 4, the conversion unit 5 converts the microwaves 81 into power and charges the charging body 6.

[0055] Next, an example of the operation when the power receiving device 1 transmits the beacon signal 12 from the antenna group having the largest power value during the previous charging will be described with reference to the timing chart of Fig. 4. This antenna group is, for example, the second antenna group 2b.

[0056] The control unit 7 of the power receiving device 1 issues an instruction to transmit the beacon signal 12 from the second antenna group 2b selected as the antenna group with the largest power value during the previous charging based on the power value information 71 (Step 20). Note that if the switching unit 3 is not connected to the second antenna group 2b, the control unit 7 connects the switching unit 3 to the second antenna group 2b.

[0057] The second antenna group 2b transmits a beacon signal 12 (Step 21).

[0058] When the power transmitting device 8 receives the beacon signal 12 (Step 22), the power transmitting device 8 adjusts the phase so that the directivity of the microwaves 81 increases in the direction of the beacon signal 12, and transmits the microwaves 81 (Step 23).

[0059] The second antenna group 2b receives the microwaves 81 transmitted from the power transmitting device 8 (Step 24). The conversion unit 5 acquires the microwaves 81 received by the second antenna group 2b via the communication unit 4 and converts them into power. The control unit 7 stores the power value of the converted power as power value information 71 (Step 25).

[0060] If the power value of the second antenna group 2b is equal to or greater than the threshold value 70, the control unit 7 determines the second antenna group 2b as the receiving antenna group (Step 26).

[0061] The control unit 7, having determined that the second antenna group 2b is the receiving antenna group, again controls the switching unit 3 and the communication unit 4 to issue an instruction to transmit the beacon signal 12 from the second antenna group 2b (Step 27).

[0062] The second antenna group 2b transmits the beacon signal 12 (Step 28).

[0063] When the power transmitting device 8 receives the beacon signal 12 (Step 29), the power transmitting device 8 adjusts the phase so that the directivity of the microwaves 81 increases in the direction of the beacon signal 12, and transmits the microwaves 81 (Step 30).

[0064] The second antenna group 2b receives the microwaves 81 transmitted from the power transmitting device 8 (Step 31). When the conversion unit 5 acquires the microwaves 81 received by the first antenna group 2a via the communication unit 4, the conversion unit 5 converts the microwaves 81 into power and charges the charging body 6.

[0065] The communication unit 4 may be configured to transmit the beacon signal 12 including information indicating that the beacon signal is for searching for a receiving antenna group. In this case, when the power transmitting device 8 receives the beacon signal 12 for searching, the power transmitting device 8 is configured to recognize that the beacon signal is not for charging but for searching for a receiving antenna group, and transmits the microwaves 81 for a period shorter than that of the microwaves 81 for charging.

[0066] When the beacon signal 12 is a test beacon signal, the microwave 81 is transmitted in about 1 ms, for example, whereas it is transmitted in 10 to 80 ms as a response to a normal beacon signal 12. Therefore, the power consumption of the power transmitting device 8 is suppressed.

[0067] (Effects of the First Embodiment) The power receiving device 1 according to the present embodiment can improve the power receiving efficiency. Specifically, the power receiving device 1 determines the receiving antenna group with the best power receiving efficiency from the first antenna group 2a and the second antenna group 2b, each of which has a different directivity, and therefore can suppress the influence of the orientation of the receiving antenna group of the power receiving device 1 with respect to the power transmitting device 8 and improve the power receiving efficiency, compared to the case of using at least one antenna having the same directivity.

[0068] The power receiving device 1 switches between antenna groups to receive microwaves 81 with the most advantageous antenna group, and therefore, compared to a case where no switching is performed, the decrease in power receiving efficiency can be suppressed even if the relative positions of the power receiving device 1 and the power transmitting device 8 change.

[0069] In the power receiving device 1, the first antenna group 2a and the second antenna group 2b are arranged on the housing 10 with the back surface 21b, which has a lower power receiving efficiency than the front surface 21a, facing each other. Therefore, compared to a case in which this configuration is not adopted, the power receiving device 1 can receive microwaves 81 from the front surface 21a, which has a higher power receiving efficiency, thereby improving the power receiving efficiency.

[0070] Since the power receiving device 1 can determine the advantages and disadvantages of the antenna group to be used without relying on the judgment of the power transmitting device 8, compared to a case in which this configuration is not adopted, the power transmitting device 8 does not need to memorize the arrangement of the antenna group of the power receiving device 1, etc., and a variety of power receiving devices 1 can be used, thereby increasing the scalability of the power transmission system 9.

[0071] Since the power receiving device 1 uses the thin and highly efficient patch antenna 21, it is possible to obtain a higher power receiving efficiency than when other antennas are used.

[0072] When searching for a receiving antenna group, the power receiving device 1 ends the search if the power converted from the microwaves 81 received by the antenna group that transmitted the beacon signal 12 is equal to or greater than the threshold value 70, thereby reducing time and power consumption compared to determining the receiving antenna group after performing an exhaustive search.

[0073] Since the power receiving device 1 starts searching from an advantageous antenna group that had a high power value during previous charging, the search time is shortened compared to a case where this configuration is not adopted. In particular, when there is no change in the relative position between the power receiving device 1 and the power transmitting device 8, the power receiving device 1 shortens the time required to search the receiving antenna group and suppresses power consumption, thereby shortening the time required for charging.

[0074] [Second embodiment] The second embodiment differs from the other embodiments in that the antenna group is made up of a plurality of antennas.

[0075] Fig. 5(a) is a diagram showing an example of a power receiving device according to the second embodiment, and Fig. 5(b) is a diagram showing an example of a plurality of antennas constituting an antenna group. In the following embodiments, parts having the same functions and configurations as those in the first embodiment are given the same reference numerals as those in the first embodiment, and the description thereof will be omitted.

[0076] The housing 10 of this embodiment is configured as a hexahedron as shown in Fig. 5(a). The housing 10 has a first surface 10a to a sixth surface 10f. The first surface 10a and the second surface 10b, the third surface 10c and the fourth surface 10d, and the fifth surface 10e and the sixth surface 10f face each other.

[0077] The first surface 10a to the sixth surface 10f are provided with the first antenna group 2a to the sixth antenna group 2f. The first antenna group 2a and the second antenna group 2b, the third antenna group 2c and the fourth antenna group 2d, and the fifth antenna group 2e and the sixth antenna group 2f face each other. Therefore, the first antenna group 2a to the sixth antenna group 2f each have a different directivity.

[0078] 5(b), the first to sixth antenna groups 2a to 2f respectively include a first to ninth antennas 210 to 218. The first to ninth antennas 210 to 218 are configured as patch antennas, but are not limited to this.

[0079] The communication unit 4 is configured to transmit the beacon signal 12 using at least one antenna of the antenna group. Since the first antenna group 2a to the sixth antenna group 2f of this embodiment each have the first antenna 210 to the ninth antenna 218, at least one of the first antenna 210 to the ninth antenna 218 is used to transmit the beacon signal 12. As an example, the beacon signal 12 is transmitted from the fifth antenna 214 located at the center of the nine antennas. That is, as an example, the beacon signal 12 is transmitted from the fifth antenna 214 of the first antenna group 2a to the sixth antenna group 2f.

[0080] When transmitting a beacon signal 12, the switching unit 3 connects the fifth antenna 214 of the target antenna group to the communication unit 4, and when receiving microwaves 81, the switching unit 3 connects the first antenna 210 to the ninth antenna 218 of the target antenna group to the communication unit 4.

[0081] Although the housing 10 is a hexahedron, the present invention is not limited to this and may be another polyhedron. Furthermore, the antenna groups are not limited to a configuration having the same number of antennas and may each have a different number of antennas.

[0082] Here, when searching for receiving antenna groups, if there is an antenna group whose power value is equal to or greater than a predetermined threshold value 70, the control unit 7 is configured to select the antenna group whose power value is equal to or greater than the predetermined threshold value 70 as the receiving antenna group without searching all of the multiple antenna groups.

[0083] For example, the control unit 7 transmits beacon signals 12 in the order of the first antenna group 2a to the sixth antenna group 2f, and when the fourth antenna group 2d receives microwaves 81 that are greater than or equal to the threshold value 70, the control unit 7 designates the fourth antenna group 2d as the receiving antenna group without transmitting the beacon signal 12 from the fifth antenna group 2e.

[0084] As a modified example, the control unit 7 may determine, as the receiving antenna group, the antenna group that has obtained the highest power value among the power values ​​obtained by converting the microwaves 81 received by all the antenna groups.

[0085] (Effects of the second embodiment) The power receiving device 1 of this embodiment is equipped with a group of multiple antennas each having a different directivity, so that it can efficiently receive microwaves 81 even if the position relative to the power transmitting device 8 changes, thereby improving power receiving efficiency, compared to a case in which this configuration is not adopted.

[0086] The power receiving device 1 determines the antenna group whose power value is first equal to or greater than the threshold value 70 as the receiving antenna group even if there are many antenna groups, thereby reducing time and power consumption compared to a brute-force search.

[0087] Since the power receiving device 1 searches for the receiving antenna group in order starting from the opposing antenna group, it can search for the receiving antenna group more efficiently than when this configuration is not adopted.

[0088] Since the power receiving device 1 uses one or more antennas for both transmitting the beacon signal 12 and receiving the microwaves 81, there is no need to use an antenna for outputting the beacon signal 12 or all of the antennas for multiple purposes, which is more efficient than when this configuration is not adopted.

[0089] [Third embodiment] The third embodiment differs from the other embodiments in that the determined receiving antenna group is reviewed.

[0090] FIG. 6 is an example of a block diagram of a power transmission system according to the third embodiment.

[0091] The control unit 7 of this embodiment is configured to search for another receiving antenna group when a predetermined condition for reviewing the receiving antenna group is satisfied after determining the receiving antenna group. The control unit 7 has condition information 73 relating to this condition, as shown in FIG. 6.

[0092] Examples of the predetermined conditions include when the power consumption of the power receiving device 1 becomes greater than the power value obtained from the received microwaves 81, when the power value decreases at a predetermined rate compared to the power value when the receiving antenna group was determined, when the microwaves 81 from the power transmitting device 8 can no longer be received, when the power transmitting device 8 requests that the beacon signal 12 be retransmitted, when the control unit 7 is configured to periodically review the receiving antenna group, and when a user operation instructs review of the receiving antenna group.

[0093] When the power consumption of the power receiving device 1 becomes greater than the power value obtained from the received microwaves 81, as an example, the power consumption and the average power value for a predetermined period are compared, but this is not limited to this.

[0094] When the power value decreases at a predetermined rate compared to the power value when the receiving antenna group was determined, as an example, the determination is made based on the amount of change in the obtained power value or its absolute value, but is not limited to this.

[0095] When microwaves 81 from power transmitting device 8 cannot be received, the determination is made based on the length of time for which reception has been disabled, but is not limited to this.

[0096] (Effects of the third embodiment) In the power receiving device 1 of this embodiment, after the receiving antenna group is determined, the receiving antenna group is reviewed based on the condition information 73. Therefore, compared to the case where the determined receiving antenna group is continued to be used, the decrease in the power receiving efficiency can be suppressed even if there is a change in the situation, such as a change in the relative positions of the power transmitting device 8 and the power receiving device 1.

[0097] [Fourth embodiment] The fourth embodiment differs from the other embodiments in that a search for a receiving antenna group is performed from an opposing antenna group.

[0098] Figures 7(a) and 7(b) are diagrams showing an example of opposing antenna groups according to the fourth embodiment, and Figure 7(c) is a diagram showing an example in which the antenna groups are not opposing each other. In Figures 7(a) to 7(c), the normal line 200b is shown by a dotted line, which has been moved to show the angle θ.

[0099] The control unit 7 of this embodiment has three or more antenna groups as the multiple antenna groups, and is configured to transmit the beacon signal 12 in order from the combination of antenna groups when there is a combination of antenna groups in which the smaller angle between the normals indicating the directivity of the antenna groups is greater than 90° and less than 180°. Note that Fig. 7(a) to Fig. 7(c) show two of the three or more antenna groups.

[0100] Specifically, as shown in FIG. 7(a), if the smaller angle between the normal 200a of the first antenna group 2a and the normal 200b of the second antenna group 2b is defined as angle θ, when the back surfaces 21b of the first antenna group 2a and the second antenna group 2b are arranged facing each other, the angle θ becomes 180°.

[0101] Furthermore, as shown in FIG. 7(b), if the smaller angle between the normal 200a of the first antenna group 2a and the normal 200b of the second antenna group 2b is defined as angle θ, the angle between the rear surfaces 21b of the patch antennas 21 becomes an acute angle, and angle θ is greater than 90° and less than 180°.

[0102] As such, the first antenna group 2a and the second antenna group 2b shown in Figures 7(a) and 7(b) are opposed to each other, and when no other antenna groups are opposed to each other, the beacon signal 12 is first transmitted from the first antenna group 2a and the second antenna group 2b.

[0103] 7(c), the angle θ between the normal 200a of the first antenna group 2a and the normal 200b of the second antenna group 2b is less than 90°. Therefore, the first antenna group 2a and the second antenna group 2b are not considered to be facing each other.

[0104] The control unit 7 has information about this opposing antenna group as antenna information 72. When an opposing antenna group exists, the control unit 7 first outputs a beacon signal 12 from this antenna group to search for a receiving antenna group.

[0105] (Effects of the Fourth Embodiment) The power receiving device 1 of this embodiment searches for a power receiving antenna from the opposing antenna groups, so that when the power receiving efficiency of one antenna group is low, the power receiving efficiency of the other antenna group is likely to be high, compared to when this configuration is not adopted, and the time required to determine the receiving antenna group can be shortened.

[0106] [Fifth embodiment] The fifth embodiment differs from the other embodiments in that a plurality of antenna groups are further divided into a plurality of antenna subgroups and a search for a receiving antenna group is performed.

[0107] Fig. 8(a) and Fig. 8(b) are diagrams showing an example of a plurality of combination groups of a power receiving device according to the fifth embodiment. Fig. 8(a) shows a beacon signal 12 being transmitted for each of three combination groups. Fig. 8(b) shows a beacon signal 12 being transmitted for each of antenna groups included in one combination group determined to be advantageous. Fig. 8(a) and Fig. 8(b) show the antenna groups transmitting the beacon signal 12 with diagonal lines.

[0108] In this embodiment, the multiple antenna groups are divided into multiple combination groups of antenna groups. The control unit 7 then transmits a beacon signal 12 for each of the multiple combination groups to search for a combination group with a large power value from the multiple combination groups, and then transmits a beacon signal 12 for each of the antenna groups included in the searched combination group to search for a receiving antenna group.

[0109] As shown in Fig. 8(a) and Fig. 8(b), the power receiving device 1 has a first housing 13 to a third housing 15. The first housing 13 to the third housing 15 have a cylindrical shape, for example. The first housing 13 to the third housing 15 have a plurality of antenna groups arranged in a row on their side surfaces, but are not limited to this.

[0110] The first housing 13 has the first antenna group 2a to the sixth antenna group 2f. As an example, the first combination group 201 is made up of the first antenna group 2a to the sixth antenna group 2f.

[0111] The second housing 14 has the seventh antenna group 2g to the twelfth antenna group 2l. As an example, the second combination group 202 is made up of the seventh antenna group 2g to the twelfth antenna group 2l.

[0112] The third housing 15 has a thirteenth antenna group 2m to an eighteenth antenna group 2r. As an example, the second combination group 202 is made up of the thirteenth antenna group 2m to the eighteenth antenna group 2r.

[0113] The control unit 7 stores information about the antenna groups constituting the first combination group 201 to the third combination group 203 as antenna information 72.

[0114] Searching for receiving antenna groups takes time and consumes a lot of power if it is performed in order from the first antenna group 2a to the 18th antenna group 2r. Therefore, the power receiving device 1 divides antenna groups into combination groups, and first transmits a beacon signal 12 for each combination group to search for a combination group with a large power value. Furthermore, the power receiving device 1 transmits a beacon signal 12 for each antenna group constituting a combination group with a large power value, and determines the antenna group with the large power value as a receiving antenna group. Note that the search for receiving antenna groups may be configured to further divide multiple antenna groups into multiple layers, and transmit a beacon signal 12 for each combination group for each layer to search for receiving antennas.

[0115] 8(a), the control unit 7 causes the beacon signal 12 to be transmitted from the first antenna group 2a of the first combination group 201, the seventh antenna group 2g of the second combination group 202, and the thirteenth antenna group 2m of the third combination group 203. The transmission of the beacon signal 12 is performed in the order of the first combination group 201 to the third combination group 203, for example.

[0116] As an example, as shown in Figure 8 (b), if the power value of the power converted from the microwaves 81 received by the first combination group 201 among the first combination group 201 to the third combination group 203 is greater than or equal to the threshold value 70 and is the largest, the control unit 7 searches for a receiving antenna group from the antenna group of the first combination group 201.

[0117] Because the first antenna group 2a has already received microwaves 81, the control unit 7 transmits beacon signals 12 from the second antenna group 2b to the sixth antenna group 2f constituting the first combination group 201 in order, stores the transmitted beacon signals 12 as power value information 71, and compares the transmitted power value with the threshold value 70. The control unit 7 then starts charging the charging body 6 with the antenna group that has the largest power value equal to or greater than the threshold value 70 as the receiving antenna group.

[0118] (Effects of the Fifth Embodiment) The power receiving device 1 of this embodiment divides multiple antenna groups into multiple combination groups, searches for a combination group that includes a candidate receiving antenna group, and searches for a receiving antenna group from the searched combination group, thereby reducing the time required for search and reducing power consumption compared to searching for receiving antenna groups in a brute force manner.

[0119] According to at least one of the power receiving devices 1 of the embodiments described above, it is possible to improve the power receiving efficiency.

[0120] The power receiving device 1 according to the above-described embodiment and modified examples may be partially realized by a program executed by a computer, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like, depending on the application.

[0121] Although some embodiments and modifications of the present invention have been described above, these embodiments and modifications are merely examples and do not limit the invention according to the claims. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the present invention. In addition, not all combinations of features described in these embodiments and modifications are necessarily essential to the means for solving the problems of the invention. Furthermore, these embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0122] 1...power receiving device, 2a to 2r...first antenna group to eighteenth antenna group, 3...switching unit, 4...communication unit, 5...conversion unit, 6...charger, 7...control unit, 8...power transmitting device, 9...power transmitting system, 10...casing, 10a to 10f...first surface to sixth surface, 12...beacon signal, 13 to 15...first housing 1 to third housing, 20...substrate, 20a...front surface, 20b...rear surface, 21...patch antenna, 21a...front surface, 21b...rear surface, 22...first antenna , 23... second antenna, 70... threshold value, 71... power value information, 72... antenna information, 73... condition information, 80... transmitting antenna, 81... microwave, 82... transmitting communication unit, 83... phase adjustment unit, 84... transmitting conversion unit, 85... power supply unit, 86... transmitting control unit, 100... front surface, 101... back surface, 200a, 200b... normal, 201-203... first combination group to third combination group, 210-218... first antenna to ninth antenna

Claims

1. a plurality of antenna groups each having a different directivity, the antenna groups including at least one antenna for receiving a power transmission signal transmitted from a power transmitting device for contactless power supply; a transmission unit that transmits a beacon signal to the power transmitting device for each of the plurality of antenna groups; a switching unit that selects and switches a receiving antenna group that receives the power transmission signal from the plurality of antenna groups; a control unit that controls the transmitting unit and the switching unit, searches for the receiving antenna group in which the power value obtained by converting the power transmission signal transmitted from the power transmitting device based on the transmission of the beacon signal for each of the plurality of antenna groups is equal to or greater than a predetermined threshold value, retransmits the beacon signal corresponding to the searched receiving antenna group, and receives the power transmission signal transmitted toward the receiving antenna group to charge an object to be charged; A power receiving device comprising:

2. When searching for the receiving antenna group, if there is an antenna group whose power value is equal to or greater than the predetermined threshold, the control unit does not search all of the plurality of antenna groups, but sets the antenna group whose power value is equal to or greater than the predetermined threshold as the receiving antenna group. The power receiving device according to claim 1 .

3. The control unit stores the power value obtained from the power transmission signal received by the plurality of antenna groups, and when searching for the receiving antenna group, transmits the beacon signal from the antenna group having the largest power value during a previous charging. The power receiving device according to claim 2 .

4. the control unit has three or more antenna groups as the plurality of antenna groups, and when there is a combination of antenna groups in which the smaller angle between normals indicating the directivities of the antenna groups is greater than 90° and less than 180°, transmits the beacon signal in order from this combination of antenna groups. The power receiving device according to claim 1 .

5. After determining the receiving antenna group, the control unit searches for another receiving antenna group when a predetermined condition for reviewing the receiving antenna group is satisfied. The power receiving device according to claim 1 .

6. The plurality of antenna groups are divided into a plurality of combination groups combining the antenna groups, The control unit transmits the beacon signal for each of the plurality of combination groups to search for a combination group having a large power value from the plurality of combination groups, and further transmits the beacon signal for each antenna group included in the searched combination group to search for the receiving antenna group. The power receiving device according to claim 1 .

7. the transmitting unit transmits the beacon signal including information indicating that the beacon signal is a signal for searching the group of receiving antennas. The power receiving device according to claim 1 .

8. The transmitter transmits the beacon signal using the at least one antenna of an antenna group. The power receiving device according to claim 1 .

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