WO2024071097A1

WO2024071097A1 - Power transmission system

Info

Publication number: WO2024071097A1
Application number: PCT/JP2023/034883
Authority: WO
Inventors: 順一小俣; 信貴清水
Original assignee: ミネベアミツミ株式会社; 順一小俣; 信貴清水
Priority date: 2022-09-26
Filing date: 2023-09-26
Publication date: 2024-04-04
Also published as: JP2024047209A

Abstract

Provided is a power transmission system with which it is not necessary to, for example, replace the batteries in an electronic lock, which is low cost, for which maintenance is not required, and with which an electronic lock can be sufficiently driven. The power transmission system comprises a microwave contactless power supplying device: that is disposed so as to be divided between a door provided with an electronic lock, and the inside/outside of a partition unit provided with the door; and that supplies power to the electronic lock by propagating microwaves in a contactless manner from the partition unit toward the door.

Description

Power Transmission System

The present invention relates to a power transmission system.

The hotel lock system disclosed in Patent Document 1, which uses NFC or other technologies to lock and unlock in a contactless manner, requires a power source to drive the NFC lead, latch bolt, and deadbolt. This power source uses a battery. This battery needs to be replaced periodically.

Battery replacement is carried out simultaneously in all hotel guest rooms. This means that battery replacement is required in several hundred rooms, and carrying out battery replacement takes time (and costs money). Also, if there are guests staying in rooms for consecutive nights, the battery replacement cannot be carried out and must be carried out on another day.

Estimate how often the batteries in a battery-powered hotel lock need to be changed. The operating power consumption of a hotel lock is approximately 2 mW. The hotel lock is powered by four AA batteries. Therefore, if we calculate that each battery has a capacity of 3,000 mAh, four AA batteries can be used for 3,000 mAh x 1.5 V x 4 = 18,000 mWh. The operating time is 18,000 mWh / 2 mW = 9,000 hours. Converting this to a year, it is 9,000 hours / 24 hours / 365 days = 1 year, meaning that the batteries need to be changed once a year.

Patent No. 4295571

If battery replacement is eliminated, the hotel management company will not need to do this work. This will reduce maintenance costs. One way to eliminate batteries from hotel locks is to use wirelessly powered hotel locks. Examples of wirelessly powered hotel locks include the following:

(1) Proximity power supply (electric field method or magnetic field method)
If the proximity power supply device is installed near the door, power supply construction is required. Since there is no power wiring, the construction costs are high. If the power supply device has a built-in battery, there are problems such as long charging time and the need for regular maintenance (every few months). In addition, construction costs are also incurred.

(2) Photovoltaic power generation Solar cell devices that can generate electricity using indoor lights have also been developed. However, the amount of electricity generated by the solar cell devices is insufficient for the operating power consumption (2 mW) of hotel locks. The amount of electricity generated by indoor lights is less than 1 mW, which is problematic.

(3) Piezoelectric device The movement of the doorknob when opening and closing the door can be converted into electricity using a piezoelectric device. However, the amount of electricity generated by the piezoelectric device is insufficient for the operating power consumption (2 mW) of the hotel lock. With a realistic number of door openings, there is a problem that the power shortage cannot be resolved.

When using the wireless power supply method, i.e., the contactless power supply system, there are issues such as the need to incur additional construction costs for power wiring and the need for maintenance. There is also the issue of not being able to obtain enough power to operate the hotel lock.

The object of the present invention is to solve the above problems and to provide a power transmission system that does not require battery replacement for electronic locks, is low-cost, requires no maintenance, and can adequately power electronic locks.

The power transmission system according to the present invention includes a microwave contactless power supply device that is arranged separately on the door on which the electronic lock is installed and inside and outside the compartment in which the door is installed, and transmits microwaves in a contactless manner from the compartment side to the door side to supply power to the electronic lock.

The present invention eliminates the need to replace batteries in electronic locks, making it low-cost and maintenance-free, and allowing the electronic lock to function satisfactorily.

FIG. 1 is a block diagram showing a power transmission system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a power transmission system according to a modified example of the embodiment of the present invention.

The following describes in detail the embodiments of the present invention with reference to the drawings.

<Power transmission system 100>
Fig. 1 is a block diagram showing a power transmission system 100 according to an embodiment of the present invention. As shown in Fig. 1, the power transmission system 100 is a system that performs power transmission by microwave power transmission.

In the embodiment of the present invention described below, an example is given in which the power transmission system 100 is applied to a hotel lock system. However, systems to which the power transmission system 100 can be applied are not limited to hotel lock systems. Other examples of systems to which the power transmission system 100 can be applied include door lock systems for homes, including apartment complexes, stores, offices, factories, etc.

The power transmission system 100 includes a card switch system 10 and an electronic lock system 20.

The card switch system 10 includes a power source 11 and a card switch 12. The card switch system 10 supplies power to the card switch 12 and switches the card switch 12 on or off.

The power source 11 supplies power to the card switch 12 via the power grid.

The card switch 12 supplies power from the power source 11 to the compartment when a contactless IC card used to unlock or lock the door is inserted into the partition wall adjacent to the door that forms the entrance to the compartment. The card switch 12 also cuts off the supply of power from the power source 11 to the compartment when the contactless IC card is removed. The card switch 12 is connected to the power source 11 by a power line.

The electronic lock system 20 includes an electronic lock 21 installed on the door. The electronic lock system 20 is a system that unlocks or locks the door using power supplied to the electronic lock 21 installed on the door.

In the power transmission system 100 applied to a hotel lock system, the compartment having an entrance that is unlocked or locked by a door is a hotel guest room, the interior of the compartment is the interior of the guest room, the exterior of the compartment is the hotel corridor space, the structure having multiple compartments is a hotel building, and the electronic lock 21 is a hotel lock.

The electronic lock 21 is called a keyless lock, and as the name suggests, it is a lock that does not require a key. The electronic lock 21 is a lock that incorporates a mechanism that uses electrical power to lock and unlock the door. Here, the electronic lock 21 is different from an electric lock that is powered using electrical wiring. The electronic lock 21 does not require electrical wiring that runs through a power grid from a power source. Furthermore, the electronic lock 21 is not a typical lock that uses a battery, but rather a lock that locks and unlocks the door using power supplied by microwave power transmission.

<Microwave contactless power supply device 1>
The microwave contactless power supply device 1 is arranged separately between a door where an electronic lock 21 is provided and a partition where the door is also provided. The microwave contactless power supply device 1 transmits microwaves in a contactless state from the partition side to the door side to supply power to the electronic lock 21. The microwave contactless power supply device 1 has a power transmitter 13 and a power receiver 22.

<Power transmitter 13>
The power transmitter 13 includes an MCU (Micro Controller Unit) 14, a reader/writer unit 16, a first wireless communication antenna 17, a WLAN (Wireless LAN) 18, and a second wireless communication antenna 19. The MCU 14 includes a CPU, a storage unit, and a communication port, and controls power transmission from the power transmitter 13. The WLAN 18 enables the power transmitter 13 to wirelessly communicate with an external system 30 mounted on a notebook PC or the like.

The power transmitter 13 transmits microwaves supplied from the power source 11 to the power receiver 22. The power transmitter 13 is mounted on the card switch system 10. The power transmitter 13 is installed in a partition wall adjacent to the door that forms an entrance/exit within the compartment.

The power transmitter 13 is disposed in a power transmission network from the power source 11 to the card switch 12. In detail, the power transmitter 13 is electrically connected to the power source 11 using a power transmission line without passing through the card switch 12 so that the card switch 12 does not switch on or off the electricity in the power transmission network from the power source 11 to the card switch 12.

The power transmitter 13 transmits microwave power from the reader/writer unit 16 to the first wireless communication antenna 17 via a power transmission and communication line. The power transmitter 13 transmits microwave wireless power to the power receiver 22 using the first wireless communication antenna 17 without using a wire such as a power transmission line.

The power transmitter 13 connects the reader/writer unit 16 and the first wireless communication antenna 17 via a power transmission and communication line.

The power transmitter 13 can communicate with the external system 30 using the WLAN 18. The power transmitter 13 connects the WLAN 18 to a second wireless communication antenna 19 via a communication line. The second wireless communication antenna 19 is connected to an external wireless antenna 31 of the external system 30 via a wireless line, allowing wireless communication between the power transmitter 13 and the external system 30.

<Power receiver 22>
The power receiver 22 is built in an electronic lock 21 provided in a door handle that a user uses to open and close the door. The power receiver 22 is mounted in an electronic lock system 20 together with the electronic lock 21. The power receiver 22 has a power receiving antenna 23, a rectifier circuit 24, a capacitor (capacitance) 25 connected to a ground terminal GND, an RFID tag unit 26, and a third wireless communication antenna 27.

The receiver 22 receives the microwaves transmitted from the first wireless communication antenna 17 of the transmitter 13 via the receiving antenna 23.

The receiver 22 charges the power transmitted from the transmitter 13 to a capacitor 25 connected to a ground terminal GND through a receiving antenna 23 and a rectifier circuit 24 connected via a power transmission line, and uses the power as the power source for the electronic lock 21.

The receiver 22 can wirelessly communicate with the reader/writer unit 16 of the transmitter 13 using the RFID tag unit 26. The receiver 22 connects the RFID tag unit 26 to a third wireless communication antenna 27 via a communication line. The electronic lock 21 can exchange information with an external system 30 and can be controlled from the external system 30 via wireless communication between the RFID tag unit 26 and the reader/writer unit 16 using the first wireless communication antenna 17 and the third wireless communication antenna 27.

Here, the UHF band is used as the wireless communication method between the RFID tag unit 26 and the reader/writer unit 16. For example, backscatter communication is used as the wireless communication method between the RFID tag unit 26 and the reader/writer unit 16. Backscatter communication is a communication method used by a passive tag of the RFID tag unit 26 of the RFID. The passive tag of the RFID tag unit 26 operates by converting the transmission power of the reader/writer unit 16 to DC and using it as power supply. A response to the reader/writer unit 16 is generated by modulating the transmission wave of the reader/writer unit 16 by changing the internal impedance. However, this is not limited to this. Other wireless communication methods may be used.

<Actions and Effects of Microwave Contactless Power Supply Device 1>
The microwave contactless power supply device 1 transmits power by microwave power transmission. Microwave power transmission enables a relatively long transmission distance. Although increasing the transmission distance inevitably increases propagation loss, which limits the improvement of power efficiency, it also has the advantage of increasing the degree of freedom in the distance between the power transmitting and receiving devices.

For example, assuming a frequency of 920 MHz, a speed of light of 300 Mm/s, a transmission power of 250 mW, a first wireless communication antenna gain of 3 dBi, a receiving antenna gain of 6 dBi, and a rectenna power conversion efficiency of 20%, the distance between the transmitter 13 and receiver 22 capable of transmitting 2.0 mW of operating power consumption of the electronic lock 21 is approximately 37 cm, as calculated by the above formula (1).

The card switch 12 installed on the partition (wall) is installed at a relatively short distance from the electronic lock 21. In other words, when the contactless IC card used to unlock the partition is removed, the power supply within the partition is cut off and the interior lights are turned off. For this reason, the card switch 12 is necessarily installed near the doorknob. The power supply 11 for this card switch 12 is equipped with a power transmitter 13 that is powered by the power supply 11 regardless of whether the card switch 12 is locked or unlocked. This makes it possible to constantly supply power via microwave power transmission.

The microwave contactless power supply device 1 is made up of a power transmitter 13 incorporated in the card switch system 10 and a power receiver 22 incorporated in the electronic lock system 20. The power transmitter 13 is provided inside a partition in a compartment having an entrance that is opened and closed by a door, and the power receiver 22 is built into an electronic lock 21 provided in the door handle of the door. Even if the compartment and the electronic lock 21 are separated by a certain distance, the electronic lock 21 is supplied with power by microwave power transmission. This makes it possible to realize a stable power supply to the electronic lock 21 by taking advantage of the freedom of positioning the power transmitter 13 and the power receiver 22 that constitute the microwave contactless power supply device 1 at a desired distance.

The receiver 22 also has an RFID tag section (UHF band RFID tag) 26, which is connected to the electronic lock 21 and provides an interface, allowing communication between the card switch system 10 and the electronic lock system 20.

The following functions can be realized by communication between the card switch system 10 and the electronic lock system 20.

Firstly, it will be possible to supply power to the electronic lock 21, which is the hotel lock, without contact. This will eliminate the need for maintenance such as battery replacement for the battery-powered electronic lock, which is the hotel lock, that previously had to be performed about once a year by the hotel management company.

Secondly, the power efficiency of microwave power transmission decreases as the transmission distance increases due to propagation loss. By installing the power transmitter 13 in the card switch 12 or in the bulkhead, it becomes possible to supply the power required to operate the electronic lock 21, which is the hotel lock, using a relatively small amount of transmission power.

　Considering that the card switch system 10 can communicate with the external system 30, the following functions can also be realized:

Thirdly, the power transmitter 13 is equipped with a UHF band (920 MHz) reader/writer section (RFID Reader/Writer (R/W)) 16. In contrast, the power receiver 22 mounted on the electronic lock 21 is equipped with an RFID tag section (UHF band RFID Tag) 26. This allows the power transmitter 13 to communicate with the power receiver 22 of the electronic lock 21. In this case, information on the status of the electronic lock 21 (unlocked status information and locked status information) can be notified to an external system 30 such as another hotel management system.

Fourthly, it is possible to realize unlocking in an emergency. In other words, an unlock command can be sent directly from the external system 30 to the electronic lock 21 via the card switch system 10.

Fifth, it is possible to reuse and manage the same contactless IC card. In other words, the contactless IC card information recorded in the electronic lock 21 can be updated remotely from the external system 30.

Sixth, the locked/unlocked state of the electronic lock 21 can be monitored. That is, the power transmitter 13 uses a UHF band (920 MHz) reader/writer section (RFID Reader/Writer (R/W)) 16. It is also possible to obtain information on the electronic lock 21 (unlocked state information and locked state information) from an RFID tag section (UHF band RFID Tag) 26 mounted on the power receiver 22. The obtained information on the electronic lock 21 is transmitted from the electronic lock system 20 to the external system 30 via the WLAN 18 mounted on the power transmitter 13 of the card switch system 10. In the case of a battery-powered hotel lock system, which is the conventional technology, the external system 30 cannot obtain information on the battery-powered electronic lock that is the hotel lock.

<Modification>
Fig. 2 is a block diagram showing a power transmission system 100 according to a modified example of the embodiment of the present invention. As shown in Fig. 2, the power transmission system 100 may include a solar cell power supply device 40 that photoelectrically converts light on the outside side of the entrance and supplies power to the electronic lock 21 together with the microwave contactless power supply device 1.

The solar cell power supply device 40 alone does not have enough power supply capacity to lock and unlock the electronic lock 21. However, by combining the solar cell power supply device 40 with the microwave contactless power supply device 1 in the power transmission system 100, it is possible to increase the transmission distance. If the solar cell power supply device 40 generates 0.4 mW due to indoor lighting, of the 2.0 mW of operating power consumption of the electronic lock 21, the solar cell power supply device 40 can generate 0.4 mW, so the power required by the microwave contactless power supply device 1 is 2.0 mW - 0.4 mW = 1.6 mW. Replacing the 2.0 mW in equation (1) with this 1.6 mW results in a transmission distance of 41 cm. In other words, the transmission distance of 37 cm with only the microwave non-contact power supply device 1 can be improved by 11% (41 cm/37 cm = 1.11, an improvement of 0.11) to 41 cm with the combination of the microwave non-contact power supply device 1 and the solar cell power supply device 40.

<Additional Notes>
The power transmission system 100 includes a microwave contactless power supply device 1 which is arranged separately between a door on which an electronic lock 21 is installed and inside and outside the compartment in which the door is installed, and which supplies power to the electronic lock 21 by transmitting microwaves in a contactless manner from the compartment side to the door side.

With this configuration, when the power transmission system 100 is used, no additional construction costs for power wiring are required, and no maintenance is required. In addition, sufficient power is obtained to operate the electronic lock 21, which is a hotel lock. Therefore, there is no need to replace the battery of the electronic lock 21, and the electronic lock 21 can be operated sufficiently at low cost and without maintenance.

The microwave contactless power supply device 1 has a power transmitter 13 that transmits microwaves, and a power receiver 22 that receives the microwaves transmitted from the power transmitter 13. The power transmitter 13 is installed in a partition wall that is adjacent to the door and forms the entrance/exit of the partition. The power receiver 22 is built into the electronic lock 21.

The power efficiency of microwave power transmission decreases as the transmission distance increases due to propagation loss. With this configuration, the power transmitter 13 is installed in a partition that is adjacent to the door and forms an entrance/exit. Meanwhile, the power receiver 22 is built into the electronic lock 21 installed on the door. As a result, the transmission distance between the power transmitter 13 and the power receiver 22 is close, and the power efficiency of microwave power transmission does not decrease. This allows power to be supplied to the electronic lock 21 using a relatively small amount of transmission power.

The partition is provided with a card switch 12 that supplies power from the power source 11 to the room when a contactless IC card used to lock or unlock the door is inserted, and cuts off the power supply from the power source 11 to the room when the contactless IC card is removed. The power transmitter 13 is located in the power transmission network from the power source 11 to the card switch 12.

With this configuration, power can be supplied from the power source 11 to the power transmitter 13 using the power transmission network from the power source 11 to the existing card switch 12.

The power transmitter 13 is electrically connected to the power source 11 without passing through the card switch 12 so that the card switch 12 does not switch on or off the electricity in the power transmission network from the power source 11 to the card switch 12.

With this configuration, the card switch 12 does not switch on or off the electricity to the power transmitter 13, and power can be constantly supplied from the power source 11 to the power transmitter 13.

The power transmitter 13 has a reader/writer unit 16. The power receiver 22 has an RFID tag unit 26 that can wirelessly communicate with the reader/writer unit 16.

With this configuration, information and status of the electronic lock 21 can be transmitted to the power transmitter 13.

The power transmitter 13 can communicate with the external system 30. The electronic lock 21 can exchange information with the external system 30 and can be controlled by the external system 30 via wireless communication between the RFID tag unit 26 and the reader/writer unit 16.

With this configuration, information such as the locked/unlocked state of the electronic lock 21 can be transmitted from the power transmitter 13 to the external system 30 via wireless communication between the RFID tag unit 26 and the reader/writer unit 16. In addition, control such as updating the contactless IC card information recorded in the electronic lock 21 and unlocking the electronic lock 21 in an emergency can be executed from the external system 30 via wireless communication between the RFID tag unit 26 and the reader/writer unit 16.

The power transmission system 100 is equipped with a solar cell power supply device 40 that photoelectrically converts the light from the outside of the entrance and supplies power to the electronic lock 21 together with the microwave contactless power supply device 1.

With this configuration, the transmission distance of the solar cell power supply device 40 is added to the transmission distance of the microwave non-contact power supply device 1, increasing the transmission distance of the power transmission system 100 and improving the transmission performance of the power transmission system 100.

＜Other＞
In the above embodiment, the card switch system 10 is configured to have the power source 11. However, this is not limited to this. For example, the power source 11 may be configured to be a system that does not have the card switch 12. Also, in the above embodiment, the electronic lock 21 is configured to be locked and unlocked by a non-contact IC card. However, this is not limited to this. The electronic lock 21 may be of a number button lock type or the like. Also, each of the

antennas

17, 19, 23, and 27 may be configured as a shared antenna to the extent that they can be shared.

The power transmitter 13 may be installed not only inside the partition but also outside the partition (such as in a hallway space in a hotel). When the power transmitter 13 is installed outside the partition, for example, the power transmitter 13 may be built into an existing intercom that is connected to a power grid from a power source.

In addition, the above embodiments are merely examples of concrete ways of implementing the present invention, and the technical scope of the present invention should not be interpreted in a limiting manner based on them. In other words, the present invention can be implemented in various forms without departing from its main features.

The entire disclosures of the specification, drawings and abstract contained in the Japanese application for Patent Application No. 2022-152709, filed on September 26, 2022, are incorporated herein by reference.

REFERENCE SIGNS LIST 1 Microwave contactless power supply device 10 Card switch system 11 Power supply 12 Card switch 13 Power transmitter 14 MCU
16 Reader/writer unit 17 First wireless communication antenna 18 WLAN
Reference Signs List 19 Second wireless communication antenna 20 Electronic lock system 21 Electronic lock 22 Power receiver 23 Power receiving antenna 24 Rectifier circuit 25 Capacitor 26 RFID tag unit 27 Third wireless communication antenna 30 External system 31 External wireless antenna 40 Solar cell power supply device

Claims

A microwave contactless power supply device is provided, which is arranged separately on a door on which an electronic lock is provided and inside and outside a partition in which the door is provided, and supplies power to the electronic lock by transmitting microwaves in a contactless manner from the partition side to the door side.
Power transmission system.
The microwave contactless power supply device includes a power transmitter that transmits microwaves and a power receiver that receives the microwaves transmitted from the power transmitter,
The power transmitter is installed in a partition wall portion adjacent to the door and constituting an entrance/exit of the partition portion,
The power receiver is built into the electronic lock.
The power transfer system of claim 1 .
a card switch is provided in the partition wall, which supplies power from a power source to the compartment when a contactless IC card used to lock or unlock the door is inserted, and cuts off the supply of power from the power source to the compartment when the contactless IC card is removed;
The power transmitter is disposed in a power transmission network from the power source to the card switch.
The power transfer system of claim 2 .
The power transmitter is electrically connected to the power source without passing through the card switch so that the card switch does not switch on or off the electricity in the power transmission network from the power source to the card switch.
The power transfer system of claim 3 .
The power transmitter has a reader/writer unit,
The power receiver has an RFID tag unit capable of wireless communication with the reader/writer unit.
The power transfer system of claim 2 .
The power transmitter is capable of communicating with an external system;
The electronic lock is capable of exchanging information with the external system and being controlled by the external system through wireless communication between the RFID tag unit and the reader/writer unit.
The power transfer system of claim 5 .
A solar cell power supply device is provided which photoelectrically converts light from the outside of the entrance and supplies power to the electronic lock together with the microwave contactless power supply device.
The power transfer system of claim 1 .