KR20150077678A - Wireless power transmitting method and wireless power transmitter performing the same - Google Patents

Abstract

A wireless power transmitting method is performed in a wireless power transmitter which supplies wireless power to at least one receiver by using an in-band communication method. The wireless power transmitting method includes a step (a) of receiving device information and state information from the at least one receiver by being changed into a communication mode at a specific point; and a step (b) of transmitting wireless power to the at least one receiver by being changed into a wireless power transmission mode. Therefore, the wireless power transmitter performs a transmitting and receiving process with high bandwidth in a communication mode and improves a data transmission speed, and shorts communication time. At the same time, it increases wireless power transmission time and improves the wireless charge efficiency of a wireless power transmitting system.

Description

TECHNICAL FIELD [0001] The present invention relates to a wireless power transmission method and a wireless power transmitter for performing the wireless power transmission method.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless power transmission technology, and more particularly, to a wireless power transmission technology for supplying wireless power by distinguishing a communication mode from a wireless power transmission mode on the basis of a quality factor in a wireless power transmitter will be.

Wireless power transmission is a technology that transmits signals through electromagnetic radiation other than light or infrared rays. Wireless power transmission is one of the most desirable technologies for electric appliance users in pursuit of freedom from electric wires.

More specifically, the wireless power transmission is a method of transmitting power without a contact between a power source and an electronic device, and it is a method of conducting electric power, inductive coupling, resonant magnetic coupling and RF-based wireless power), and a method using an optical system and an ultrasound system is also being studied.

Particularly, in the self-resonance induction system, a kind of energy tunnel is formed when an electromagnetic field of a certain frequency is formed on a power source side and a receiver known by the same frequency is placed in an electromagnetic field, and energy is transmitted by using this energy tunnel .

Electronic devices that provide a wireless power transmission service using a self-resonance induction method receive monitoring information on charging and power receiving states of charging devices through wireless communication for more efficient wireless power transmission.

The wireless communication method includes an in-band communication method using a wireless power transmission frequency as a carrier wave and an out-band communication method using an existing peripheral communication method such as Bluetooth, ZigBee, WiFi, LTE, Communication method.

The charger including the communication module is easy to use the out-of-band communication method through the built-in communication module, but it is effective that the charger that does not include the separate communication module uses the intra-lending communication.

Korean Patent No. 1171938 (registered on Aug. 1, 2012) is related to a multi-node wireless power transmission system using a self-resonance induction method and a charging method thereof. The transmitter analyzes the distance from the transmitter to each receiver through magnetic field communication , An efficient charging of an entire multi-node wireless power transmission system can be achieved by controlling some receivers to be used as repeaters or by blocking the power receiving function of some receivers.

Korean Registered Patent No. 1110325 (registered on Jan. 19, 2012) is a wireless charging system using resonance and magnetic field communication. It monitors the charging environment information of a plurality of terminals requiring charging, and based on the information, So that it can be charged at a very low rate.

These prior arts use an in-band communication method that uses a wireless power transmission frequency band as a carrier frequency, but use an antenna having a high quality index for wireless power transmission, Lt; / RTI >

Korea registered patent No. 1171938 (registered on August 1, 2012) Korean Registered Patent No. 1110325 (registered on January 19, 2012)

An aspect of the present invention is to provide a wireless power transmission technology capable of enhancing wireless communication efficiency of a wireless power transmitter.

The present invention provides a wireless power transmission technology capable of enhancing wireless charging efficiency of a wireless power transmission system.

In embodiments, the wireless power transmission method is performed in a wireless power transmitter that provides wireless power to at least one receiver using an in-band communication scheme. The wireless power transmission method includes the steps of: (a) switching to a communication mode at a specific time point to receive device information or status information from the at least one receiver; And (b) switching to a wireless power transmission mode to transmit wireless power to the at least one receiver.

Here, the communication mode may vary the inductance and the capacitor in the resonant antenna to raise the quality factor to a specific value or more, and in the radio power transmission mode, the quality index of the resonant antenna may be lowered to a specific value or more.

In one embodiment, step (a) may further comprise transmitting a join request signal to at least one receiver present in the communication zone.

In one embodiment, the step (a) may further include, upon receiving the device information, determining whether the at least one receiver is a wireless power transmission object based on the device information.

In one embodiment, the step (b) may further include the step of performing impedance matching according to the resonance frequency information included in the device information.

In one embodiment, the step (b) may increase the size of the inductor and decrease the capacitor by an increased ratio of the inductor, if the resonant antenna corresponds to a series resonance.

In one embodiment, the step (a) may lower the quality index of the resonant antenna and maintain the resonant frequency to continuously transmit the wireless power.

In one embodiment, the wireless power transmission method may repeat the above-mentioned steps (a) and (b) periodically.

In embodiments, a wireless power transmitter that provides wireless power to at least one receiver using an in-band communication scheme includes: (a) a controller for selecting a communication mode or a wireless power transmission mode; (b) a wireless communication unit for receiving device information or status information from the at least one receiver in the communication mode; And (c) a resonant antenna that transmits radio power to the at least one receiver in the wireless power transfer mode.

In one embodiment, the resonant antenna may vary the inductor and the capacitor to increase the quality factor to a specific value or higher in the communication mode, and lower the quality index to a certain value or less in the wireless power transmission mode .

In one embodiment, if the resonant antenna corresponds to a series resonance, the size of the inductor may be increased, and the capacitor may be decreased by an increased ratio of the inductor to increase the quality index.

In one embodiment, the resonant antenna can lower the quality index in the communication mode and maintain the resonant frequency to continuously transmit wireless power.

The disclosed technique may have the following effects. It is to be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, as it is not meant to imply that a particular embodiment should include all of the following effects or only the following effects.

The wireless power transmission technology according to an embodiment of the present invention can divide the wireless power transmission mode into the communication mode and the wireless power transmission mode based on the quality index and perform the wireless communication in the communication mode.

The wireless power transmission technology according to an embodiment of the present invention improves the data transmission speed and communication time by transmitting and receiving through the high bandwidth in the communication mode and increases the wireless power transmission time to increase the wireless charging efficiency .

1 is a block diagram schematically showing the overall configuration of a wireless power transmission system according to an embodiment of the present invention.
2 is a block diagram showing the configuration of a transmitter and a receiver shown in FIG.
3 is a graph showing a quality index for the resonant antenna of the transmitter in FIG.
4 is a circuit diagram of a resonance antenna capable of adjusting the quality index in the transmitter shown in FIG.
5 is a flow chart illustrating a wireless power transmission method performed in the wireless power transmitter of FIG.

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas.

Meanwhile, the meaning of the terms described in the present invention should be understood as follows.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include "or" have "are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present invention.

1 is a block diagram schematically showing the overall configuration of a wireless power transmission system according to an embodiment of the present invention.

1, a wireless power transmission system 100 is a system for transmitting wireless power within a magnetic field region and includes a wireless power transmitter 110 (e.g., a wireless power transmitter, hereinafter referred to as a transmitter) And a plurality of wireless power receivers 120 (e.g., wireless charging devices, hereinafter referred to as "receivers"). The transmitter 110 wirelessly supplies power through a self-resonant induction method, and the receiver 120 receives power wirelessly from the transmitter 110 by being spaced apart from the transmitter 110 by a certain distance. Here, the self-resonance induction method corresponds to a wireless power transmission method in which the efficiency of wireless transmission of energy is maximized by resonance between a transmitting antenna and a receiving antenna, as described above. Transmitter 110 and receiver 120 may establish a resonant frequency to establish a resonant frequency and transmit or receive wireless power over the formed channel.

Transmitter 110 corresponds to a device that supplies power to a plurality of receivers 120 within a magnetic field region and manages the wireless power transmission system.

More specifically, the transmitter 110 receives power from the outside, converts the power into radio power to be transmitted by radio, and transmits the radio power to the receiver 120 through grounding resonance induction. In addition, the transmitter 110 receives device information or status information from the plurality of receivers 120 to the receiver 120, and monitors the status of the transmitter 110. Transmitter 110 provides a communication mode and a wireless power transmission mode based on the quality index of the antenna.

Here, the communication mode is suitable for wireless communication between the transmitter and the receiver through a low quality index, and the wireless power transmission mode is suitable for wireless power transmission through a high quality index. The quality factor corresponds to the amount of resonance sharpness.

Meanwhile, the transmitter 110 may receive the device information or status information of the receiver 120 through the wireless communication of the receiver 120. Here, the wireless communication may correspond to the magnetic field communication capable of bidirectional data communication using the induction of the magnetic field between the local devices. In particular, it may correspond to an in-band magnetic field communication in which a frequency such as a wireless power transmission is used for wireless communication in a magnetic field region in order to increase the efficiency of frequency use.

In addition, the device information of the receiver 120 includes identification information of the receiver 120, position, resonance frequency information, etc., and the state information includes the position of the receiver 120, the state of charge, The size of the received wireless power).

In one embodiment, the transmitter 110 may determine whether to charge the plurality of receivers 120, the charging order, and so on, based on the received status information.

More specifically, the transmitter 110 may recognize and authenticate the receiver 120 in advance in an area where communication is possible for managing a plurality of receivers 120, exchange data necessary for the wireless power transmission, Preparatory procedures must be preceded. The transmitter 110 sets a virtual space divided into a charging area and a communication area based on the distance between the transmitter 110 and the receiver 120. The transmitter 110 sets a virtual space divided into a charging area and a communication area, And supplies actual wireless power to the receiver 120 located in the charging area, which is a region where wireless power transmission is possible. Here, the charging area corresponds to an area where actual wireless power transmission is possible within the magnetic field area, and may vary depending on the size of the application, the required power, and the operating frequency. The communication area corresponds to an area for managing the receiver 120 in the magnetic field area, and may be wider than the charging area.

In one embodiment, the transmitter 110 may provide wireless power to a plurality of receivers 120 via a time division based scheduling technique.

In one embodiment, the transmitter 110 may be implemented as a fixed or mobile type. For example, when the transmitter 110 is implemented as a fixed type, it may be installed in a room such as a ceiling or a table in a room, or in an implant type such as a bus stop or a subway station outside, Or may be installed inside the same moving body. In another example, if the transmitter 110 is implemented in a mobile manner, the transmitter 110 itself may be implemented as a separate mobile device, or may be implemented as part of another digital device, such as a lid of a notebook computer.

The receiver 120 receives the radio power transmitted from the transmitter 110 through self-resonance induction, supplies the received power to the load, monitors the state of the receiver 120, and transmits the radio power to the transmitter 110 through the wireless communication. Here, the state of the receiver 120, i.e., the state information, may include a received strength intensity for the wireless power received from the transmitter 110.

In one embodiment, the receiver 120 may include any digital device having a battery, such as various mobile terminals, a digital camera, a notebook computer, etc., and may be located in a location that is not easily accessible, such as underground, Electronic devices such as sensors and instruments.

2 is a block diagram showing the configuration of the transmitter 110 and the receiver 120 shown in FIG.

Referring to FIG. 2, the transmitter 110 includes a first resonant antenna 210, a power conversion unit 220, a wireless communication unit 230, and a control unit 240.

The first resonant antenna 210 transmits radio power generated by a power conversion unit 220 to be described later through a self resonance induction method and transmits and receives data between the transmitter 110 and the receiver 120.

In one embodiment, the first resonant antenna may be implemented in the form of an inductor and a capacitor connected in series or in parallel.

For example, the first resonant antenna may include a variable inductor and a variable capacitor, and the magnitude of the inductor and the capacitor may be changed, that is, impedance matching may be performed under the control of a control unit described later. The first resonant antenna can perform magnetic coupling by matching the frequency of the transmitter with the resonant frequency of the receiver through impedance matching.

The specific configuration will be described later with reference to Fig.

In one embodiment, the first resonant antenna can vary the inductance and the capacitor in a communication mode to raise the quality index above a certain value, and in a wireless power transfer mode, the quality index can be lowered below a certain value.

That is, in the case of the communication mode, the first resonant antenna can increase the quality index to widen the frequency bandwidth and improve the data transmission rate using the high bandwidth. Alternatively, in the case of the wireless power transmission mode, the first resonant antenna can lower the quality index to narrow the frequency bandwidth, while enhancing the wireless power transmission efficiency.

In one embodiment, if the first resonant antenna corresponds to a series resonance (an inductor and a capacitor are connected in series), the size of the inductor is increased and the size of the capacitor is decreased by an increased ratio of the inductor, . This allows the resonant frequency to remain constant and to control only the quality index.

In another embodiment, if the first resonant antenna corresponds to a parallel resonance, the size of the inductor as opposed to the series resonance may be reduced, and the size of the capacitor may be increased by a reduced ratio of the inductor to increase the quality index have.

In one embodiment, the first resonant antenna can lower the quality index in the communication mode and maintain the resonant frequency to continuously transmit wireless power.

The power conversion unit 220 receives power from an external power supply source and converts the AC power into AC power having a resonance frequency band between the transmitter 110 and the receiver 120.

In one embodiment, the power conversion unit 220 may further include a power amplifier for amplifying and outputting the converted wireless power, and may increase the efficiency of the wireless power transmission through a change in the intensity of the wireless power.

The wireless communication unit 230 performs magnetic field communication with the receiver 120 using a magnetic field communication protocol.

In one embodiment, the wireless communication unit 230 converts the received state information of the receiver 120 into a signal of a type available in the transmitter 110 in the form of a magnetic field signal, For example, a merge request signal) into a magnetic field signal.

More specifically, the wireless communication unit 230 supports bi-directional communication and generates information to be transmitted from the transmitter 110 as a magnetic field communication protocol packet. The generated packet can be converted to an analog signal via a digital accessory control (MAC) layer and a digital signal processor (DSP), and then amplified through an amplifier. The amplified signal generates an amplified current through the first resonant antenna 210 and the current is transmitted to the receiver 120 by generating an induced current in the second resonant antenna 250 of the receiver 120 .

The control unit 240 controls the first resonant antenna 210, the power conversion unit 220, and the wireless communication unit 230, and controls the data flow between the components. In addition, the control unit 240 may control (or select) the state of the transmitter to switch between the communication mode and the power transmission mode.

In one embodiment, the control unit 240 may transmit a join request signal to at least one receiver 120 in the communication zone via the wireless communication unit 230.

Here, the confluence request signal may correspond to a signal requesting the receiver 120 to transmit the device information of the receiver 120 to the transmitter 110 for inclusion in the wireless power transmission system 100.

In one embodiment, the control unit 240, upon receiving the device information of the receiver 120, may determine whether at least one receiver 120 is a wireless power transmission object based on the device information.

That is, the control unit 240 performs authentication for the wireless power transmission target, and more specifically, the control unit 240 determines whether or not the wireless power transmission target is the charging target based on the identification number, the resonance frequency, Can be determined.

For example, when the resonant frequency of the receiver 120 does not correspond to the frequency range of the transmitter 110, the controller 240 can determine the receiver 120 as a non-charging object. For example, if the charging rate of the receiver 120 is below a predetermined criterion (90% or less) based on the charging state, the controller 240 can determine the receiver 120 to be charged.

The receiver 120 includes a second resonant antenna 250, a power management unit 260, a wireless communication unit 270, and a control unit 280.

The second resonant antenna 250 receives the radio power supplied from the transmitter 110. In addition, the second resonant antenna 250 may be used for wireless communication between the transmitter 110 and the receiver 120. For example, the second resonant antenna may be implemented in the same manner as the first resonant antenna described above.

The power management unit 260 converts the received radio power into available power in the load and supplies the converted power. Here, the load may correspond to the battery of the receiver 120 or the like.

In one embodiment, the power management unit 260 monitors the status of the receiver 120. [ Here, the state information of the receiver 120 may include the state of charge and the intensity of the received power (the magnitude of the wireless power received from the transmitter 110).

The wireless communication unit 270 may transmit the status information of the receiver 120 via the magnetic field communication protocol or may receive the merging request information from the transmitter 110. [ The wireless communication unit 270 may convert the status information into a magnetic field signal or convert the received merging request information into a signal of a format usable in the receiver 120. [ The wireless communication unit 270 transforms the magnetic field signal transmitted through the second antenna into a waveform having a scale that can be recognized by the amplifier, removes noise through a filter, and digitizes the signal through an analog-to-digital converter . The wireless communication unit 230 can convert and restore the digitized signal into a packet data format through a media access control layer (MAC layer) and a digital signal processing (DSP).

The control unit 280 can control the second resonant antenna 250, the power management unit 260, and the wireless communication unit 270, respectively, and controls the data flow between the components.

3 is a graph showing a quality index for the resonant antenna of the transmitter in FIG.

Referring to FIG. 3, the X axis and the Y axis represent the frequency and the transmitter output, respectively.

The top graph shows the frequency characteristics of the antenna with high quality index for wireless power transmission and the other graph shows the frequency characteristics of the antenna suitable for wireless communication because the frequency band is relatively wide.

Here, the quality index (Q) is expressed by the following formula (1) upon series resonance of the antenna.

Here, w0 is a resonance frequency, L is an inductor component of the transmitter, R is a resistance component, and C is a capacitor component.

The quality index is expressed as Equation (2) below at the parallel resonance of the antenna.

Therefore, the quality index can be increased or decreased in proportion to the size of the inductor in series resonance.

4 is a circuit diagram of a resonance antenna capable of adjusting the quality index in the transmitter shown in FIG.

Referring to FIG. 4, the first resonant antenna 210 includes a plurality of inductors and a plurality of capacitors connected in series.

The first inductor L1 and the second inductors L2 to nn are connected in series by a switch and the first capacitor C1 and the second to nth capacitors Cn to Cn are connected in series. And are connected in parallel by switches. Here, the first to n < th > inductors may have the same or different capacitances, and similarly, the first to n < th > capacitors may have the same or different capacitances. However, for the sake of impedance matching, .

FIG. 4 is merely an example of the present invention, and the present invention is not limited thereto. For example, the first resonant antenna 210 may be implemented as a plurality of inductors or a plurality of capacitors, unlike FIG. 4, and may also be implemented as a series resonant or parallel resonant and combinations thereof Will be apparent to those skilled in the art.

The first resonant antenna 210 may be implemented by only a first inductor and a first capacitor by turning on only the first and eleventh switches in a normal state.

Meanwhile, when the controller 240 selects the wireless power transmission mode, the first resonant antenna 210 turns off the eleventh switch, turns on the twenty-first, twenty-second, and twenty-third switches, And a second capacitor and a second inductor. That is, as the size of the inductor increases from L1 to L1 + L2, the quality index can be increased.

Likewise, the first resonant antenna 210 may be implemented as first through n-th inductors by turning off the twenty-first switch and turning on the n1, n2, and n3 switches. Therefore, the quality index can be higher than before.

On the other hand, when the communication mode is selected in the control unit 240, the first resonant antenna 210 turns on only the first and eleventh switches and turns off the other switches so that the quality index is low, .

Similarly, the first resonant antenna 210 can increase or decrease the quality index using the second to n-th capacitors.

In one embodiment, if the first resonant antenna corresponds to a series resonance, the control unit 240 may increase the size of the inductor and increase the quality index by reducing the capacitor by an increased ratio of the inductor.

For example, the first resonant antenna 210 may be formed of a first inductor and a first capacitor, and the second inductor and the second capacitor of the same capacity may be connected to each other to maintain the resonance frequency, .

The first resonant antenna 210 is smaller than the power magnitude in the wireless power transmission mode, but can transmit the wireless power to the receiver 120 through the maintained known frequency.

When using the time division based scheduling scheme, the transmitter 110 may periodically repeat switching between the communication mode and the wireless power transmission mode.

More specifically, the transmitter 110 may switch to the communication mode for one second to receive the status information of the receiver 120 or the like, or may transmit the join request information, and may switch to the wireless power transmission mode for 59 seconds, Lt; / RTI > to the receiver 120. < RTI ID = 0.0 > The transmitter 110 may repeatedly perform this in a cycle of one minute.

In one embodiment, the transmitter 110 may sequentially supply the wireless power to the plurality of receivers 120 through a time-division-based scheduling technique.

For example, the transmitter 110 divides the power transmission interval into three equal parts, changes the resonance frequency matched to the first receiver in the first section, to the second receiver in the second section, and to the third receiver in the third section Wireless power can be supplied.

5 is a flow chart illustrating a wireless power transmission method performed in the wireless power transmitter of FIG.

Referring to FIG. 5, a method for measuring the distance between wireless power transceivers 120 is performed in a wireless power transmission system 100.

The receiver 120 measures the RSSI of the received radio power from the transmitter 110 (S510).

The receiver 120 transmits the measured strength of received strength to the transmitter 110 via the wireless communication unit 230 and the transmitter 110 receives the measured strength of received strength through the wireless communication unit 230 at step S520.

In one embodiment, the transmitter 110 may measure the input impedance. Here, the input impedance corresponds to the impedance of the equivalent circuit viewed from the transmitter 110 side, and the transmitter 110 can calculate the input impedance by measuring the voltage and current of the node connected to the external power supply source.

The transmitter 110 calculates the distance between the transmitter 110 and the receiver 120 based on the state information of the transmitter 110 and the received intensity of the received signal (S530).

Here, the state information of the transmitter 110 may include at least one of the size of the wireless power to be supplied, the position information of the transmitter 110, and the input impedance information that can be changed by the receiver 120, as described above .

The control unit 240 of the transmitter 110 determines that the receiver 120 is located at a short distance from the transmitter 110 so that the change of the impedance of the receiver 120 The distance to the transmitter 110 and the receiver 120 can be calculated based on the distance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

100: Wireless power transmission system
110: Transmitter
120: receiver
210: first resonant antenna
220:
230:
240:
250: second resonant antenna
260:
270:
280:

Claims (12)

A wireless power transmission method performed in a wireless power transmitter that provides wireless power to at least one receiver using an in-band communication scheme,
(a) receiving device information or status information from the at least one receiver by switching to a communication mode at a particular time; And
(b) switching to a wireless power transmission mode to transmit wireless power to the at least one receiver.
The method according to claim 1,
In the communication mode, an inductor and a capacitor in a resonant antenna are varied to increase a quality factor to a specific value or more,
Wherein the wireless power transmission mode lowers the quality index of the resonant antenna to a specific value or higher.
The method of claim 1, wherein step (a)
And transmitting a join request signal to at least one receiver present in the communication zone.
4. The method of claim 3, wherein step (a)
And upon receiving the device information, determining whether the at least one receiver is a wireless power transmission subject based on the device information.
5. The method of claim 4, wherein step (b)
And performing impedance matching according to the resonance frequency information included in the device information.
2. The method of claim 1, wherein step (b)
And increasing the quality index by increasing the size of the inductor and decreasing the capacitor by an increased ratio of the inductor when the resonant antenna corresponds to a series resonance.
The method of claim 1, wherein step (a)
The quality index of the resonant antenna is lowered, and the resonant frequency is maintained to continuously transmit the radio power.
The method according to claim 1,
Wherein the steps (a) and (b) are repeated periodically.
1. A wireless power transmitter for providing wireless power to at least one receiver using an in-band communication scheme,
(a) a control unit for selecting a communication mode or a wireless power transmission mode;
(b) a wireless communication unit for receiving device information or status information from the at least one receiver in the communication mode; And
(c) a resonant antenna for transmitting wireless power to the at least one receiver in the wireless power transfer mode.
The antenna according to claim 9, wherein the resonant antenna
In the communication mode, the inductor and the capacitor are varied to increase the quality factor to a specific value or more,
And in the wireless power transfer mode, lowering the quality index to a certain value or less.
The antenna according to claim 9, wherein the resonant antenna
To increase the size of the inductor and to reduce the capacitor by an increased ratio of the inductor to increase the quality index if it is a series resonance.
The antenna according to claim 9, wherein the resonant antenna
Wherein the quality index is lowered in the communication mode, and the wireless power is continuously transmitted while maintaining the resonance frequency.

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