Single antenna-based wireless charging and near-field communication control apparatus and user terminal therefor

Disclosed are a single antenna-based wireless charging and near field communication control apparatus and a user terminal therefor. A single antenna-based wireless charging and near field communication control apparatus according to one embodiment comprises: a switch control unit for detecting a resonance frequency from an input signal of a rectifier in a power receiver and determining whether the detected resonance frequency is a first frequency for wireless charging using a single antenna or a second frequency for near field communication using a single antenna, to generate a control signal; and a switch which is turned on/off for wireless charging or near field communication according to the received control signal from the switch control unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of International Application No. PCT/KR2016/012418, filed on Nov. 1, 2016, which claims the benefit under 35 USC 119(a) and 365(b) of Korean Patent Application No. 10-2015-0160684, filed on Nov. 16, 2015 and of Korean Patent Application No. 10-2015-0174283, filed on Dec. 8, 2015 in the Korean Intellectual Property Office.

TECHNICAL FIELD

The present invention relates to a technology for wireless charging and short-range wireless communication.

BACKGROUND ART

A short-range communication module that performs a communication by forming a magnetic field in a frequency band of several to tens of MHz is used in a radio frequency identification (hereinafter, referred to as an RFID) module, a near field communication (hereinafter, referred to as an NFC) module, and the like. In particular, various applications using the NFC method are used in portable terminals, such as smart phones, and are gaining popularity as an auxiliary payment device.

Meanwhile, there is a method of wireless charging using magnetic resonance. As a representative magnetic resonance wireless power transfer standard, the Alliance for Wireless Power (hereinafter, referred to as A4WP) method uses an industrial, scientific, and medical (ISM) frequency band of 6.78 MHz, which corresponds to half of an ISM frequency band (13.56 MHz) of an NFC module. In order to receive A4WP power, an additional A4WP antenna is needed, and a resonator configured with the A4WP antenna is set to resonate at a frequency of 6.78 MHz. In comparison, the NFC module performs communication at a 13.56 MHz ISM frequency band, and needs to be provided with an NFC antenna for wireless communication and a resonator that generates a resonance at a frequency of 13.56 MHz.

Technical Problem

The present invention is directed to providing a single antenna-based wireless charging and near-field communication control apparatus, capable of performing wireless charging and short-range communication by using a single antenna, and a user terminal therefor.

Technical Solution

One aspect of the present invention provides an apparatus for controlling wireless charging and short-range communication on the basis of a single antenna, the apparatus including: a switch controller configured to detect a resonance frequency from a rectifier input signal of a power receiving unit, determine whether the detected resonance frequency is a first frequency for performing wireless charging using a single antenna or a second frequency for performing short-range communication using the single antenna, and generate a control signal; and a switch configured to be turned on or off according to the control signal received from the switch controller in order to perform wireless charging or short-range communication.

The switch controller may be configured to: confirm a wireless chargeable state when the detected resonance frequency is the first frequency and generate a driving signal of a high level to turn the switch on, to block power from being supplied to a short-range communication module, and protect the short-range communication module; and confirm a short-range communicable state when the detected resonance frequency is the second frequency and generate a driving signal of a low level to turn the switch off in order to operate the short-range communication module.

The power receiving unit may transmit or receive a wireless power signal to or from a power transmitting unit using an Alliance for Wireless Power (A4WP) method. The short-range communication may be a near field communication (NFC) or radio frequency identification (RFID) communication. The first frequency for wireless charging may be 6.78 MHz, and the second frequency for short-range communication may be 13.56 MHz.

The switch may have a source connected to a ground voltage, a drain connected to a short-range communication module, and a gate to which a driving voltage is input from the switch controller. The switch may include: a first switch having a source connected to a first ground voltage, a drain connected to a short-range communication module, and a gate to which a first driving voltage is input from the switch controller; and a second switch having a source connected to a second ground voltage, a drain connected to the short-range communication module, and a gate to which a second driving voltage is input from the switch controller, wherein the short-range communication module receives differential input signals and the switch controller receives differential input signals.

Another aspect of the present invention provides a user terminal including: a resonator including a single antenna for wireless power signal reception and short-range communication; a power receiving unit configured to receive a wireless power signal using a first frequency signal that is resonated by the resonator; a short-range communication module configured to perform wireless communication using a second frequency signal that is resonated by the resonator; a switch controller configured to detect a resonance frequency from a rectifier input signal of the power receiving unit, determine whether the detected resonance frequency is a first frequency or a second frequency, and generate a control signal; and a switch configured to be turned on or off according to the control signal received from the switch controller to perform wireless charging or short-range communication.

The resonator may include an antenna and a third capacitor connected in series and further includes a first capacitor and a second capacitor to form a resonance tank, wherein the first capacitor may be connected in series to the second capacitor and may be connected in parallel to the antenna, and the second capacitor may be connected in series to the first capacitor and may be connected in parallel to the antenna, and a connection node between the first capacitor and the antenna may be provided with a ground voltage, a connection node between the second capacitor and the first capacitor may be connected to an input of the power receiving unit, and a connection node between the third capacitor and the switch may be connected to an input of the short-range communication module.

The switch controller may be configured to: confirm a wireless chargeable state when the detected resonance frequency is the first frequency and generate a driving signal of a high level to turn the switch on, to block power from being supplied to the short-range communication module and protect the short-range communication module; and confirm a short-range communicable state when the detected resonance frequency is the second frequency and generate a driving signal of a low level to turn the switch off in order to operate the short-range communication module.

Advantageous Effects

According to the present invention, wireless charging and a short-range wireless communication can be performed using a single antenna, rather than using separate antennas for wireless charging and short-range wireless communication. In addition, when a great amount of power is supplied from a power transmitting unit for wireless charging to a power receiving unit, power is blocked from being excessively supplied to a short-range communication module that is configured to transmit and receive lower power, thereby preventing the short-range communication module from being broken due to excessive power and protecting the short-range communication module.

MODES OF THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the embodiments, the detailed description of related known functions or constructions will be omitted herein to avoid making the subject matter of the present invention unclear. In addition, terms which will be described below are defined in consideration of functions in the embodiments of the present invention and may vary with an intention of a user, an operator, or a custom. Accordingly, the definition of the terms should be determined based on overall contents of the specification.

The present invention is a control technology for implementing a power receiving unit (hereinafter, referred to as a PRU) that receives power from a power transmitting unit (hereinafter, referred to as a PTU) for wireless charging and a short-range communication module that performs a short-range wireless communication by using a single antenna. In this case, when power is supplied from the PTU for wireless charging, a power signal is prevented from being supplied to the short-range communication module, thereby protecting the short-range communication module.

The short-range communication module according to an embodiment may refer to all types of communication modules that transmit and receive a wireless signal in a magnetic field, for example, a near field communication (hereinafter, referred to as an NFC) module or radio frequency identification (hereinafter, referred to as an RFID) module. The short-range communication module performs a short-range wireless communication in a frequency band of several to tens of MHz, and an NFC module, for example, may transmit or receive a wireless signal at a frequency band of 13.56 MHz.

The PTU and PRU according to the embodiment use the Alliance for Wireless Power (hereinafter, referred to as an A4WP) method. According to the A4WP method, an A4WP PTU supplies a power signal to an A4WP PRU through a magnetic resonance at a frequency band of 6.78 MHz. However, the wireless charging method is not limited to the A4WP method. For example, a Qi method owned by the Wireless Power Consortium (WPC) and a Power Matters Alliance (PMA) method that are used in low-frequency bands are available. In addition, when wireless charging, even that which does not conform to the A4WP method, is performed at a frequency band different from that at which short-range wireless communication is performed, for example, when wireless charging is performed at a frequency of 4 MHz, an NFC module of a frequency band of 13.56 MHz and other short-range communication modules in frequency bands around 13.56 MHz may be protected.

Hereinafter, for convenience sake, an NFC module, an A4WP PTU, and an A4WP PRU are taken as examples of the short communication module, the power transmitting unit, and the power receiving unit respectively in the following description, but the present invention is not limited thereto.

FIG. 1is a circuit diagram illustrating a resonator according to an embodiment of the present invention.

Referring toFIG. 1, a resonator10includes an antenna100and a third capacitor Cc103connected in series and further includes a first capacitor Ca101and a second capacitor Cb102to form a resonance tank. The first capacitor Ca101is connected in series to the second capacitor Cb102and is connected in parallel to the antenna100. The second capacitor Cb102is connected in series to the first capacitor Ca101and is connected in parallel to the antenna100.

The antenna100is a single antenna which supports both an A4WP wireless charging mode and a short-range communication mode. For example, the A4WP PRU may receive a wireless power signal from the A4WP PTU through magnetic resonance of the resonator10including the antenna100. In addition, the NFC module may perform a wireless communication with an opposing NFC module in a magnetic field of the resonator10including the antenna100.

A switch SW107has a source connected to a ground voltage108, a drain connected to the third capacitor Cc103, and a gate to which a driving voltage Vdrv is input. The switch SW107is turned on when the driving voltage Vdrv is a predetermined threshold voltage or higher, and is turned off when the driving voltage Vdrv is less than or equal to the predetermined threshold voltage.

Node (A)104inFIG. 1is used as an input of the NFC module, Node (B)105inFIG. 1is used as an input of the A4WP PRU, and Node (C)106inFIG. 1is provided with a ground voltage. When the driving voltage Vdrv is set to be less than to the threshold voltage of the switch SW107in the above configuration, an equivalent circuit is formed as shown inFIG. 2.

FIG. 2is a circuit diagram illustrating operation of the NFC module when the switch is turned off according to the embodiment of the present invention.

Referring toFIGS. 1 and 2, a rectifier121is connected to an output of the resonator10and receives an input voltage IN_A4WP200in the form of an alternating current (AC) and outputs an output voltage VRECT_A4WP in the form of a direct current (DC). The rectifier121includes at least one diode, for example, diodes D1121-1and D2121-2, as shown inFIG. 2. A rectifier capacitor CRECT123smooths the rectifier output voltage VRECT_A4WP. The rectifier output voltage VRECT_A4WP allows a constant voltage to be supplied to a load through a power converter125. The power converter125may be a DC-to-DC converter, a low drop-out regulator (LDO), or the like.

FIG. 2illustrates a state in which the NFC module14operates in response to the switch SW107being turned off. Since a level of a voltage IN_NFC210input to the NFC module14is controlled to be 5 V or lower by the NFC module14, the input voltage IN_A4WP200of the A4WP is 5 V or lower. In general, an A4WP PRU12is set to be operated by a rectifier output voltage VRECT_A4WP of 5 V or higher. Since a terminal having a charging battery is supplied with the rectifier output voltage VRECT_A4WP, and in most cases, the battery voltage is 3 V or higher, the output voltage VRECT_A4WP needs to be sufficiently greater than at least the battery voltage. Referring toFIG. 2, the input voltage IN_A4WP200of the A4WP is 5 V or lower, and thus the A4WP PRU12does not perform a normal operation. Accordingly, almost no current is introduced to the input voltage IN_A4WP200of the A4WP. When the inductance of the antenna100is L, the resonance frequency of the resonator10is determined as shown in Equation 1.

FIG. 3is a circuit diagram illustrating operation of the A4WP PRU when the switch is turned on according to the embodiment of the present invention.

Referring toFIGS. 1 and 3, when the driving voltage Vdrv of the switch SW107is increased to the threshold voltage or higher, the switch SW107is turned on, thus allowing the A4WP PRU12to operate as shown inFIG. 3. In this case, the switch SW107allows the input voltage IN_NFC210of the NFC to become almost equal to the ground voltage, and thus a signal input to the NFC module14disappears and the NFC module14does not operate. Accordingly, the NFC module14is prevented from being broken by energy received by the antenna100when the A4WP PRU12operates. In addition, since the input voltage IN_NFC210of the NFC has a low voltage swing, the switch SW107may use a low voltage element using less than 5 V.

The resonance frequency of the resonator10is determined as shown in Equation 2.

When the user terminal operates as the A4WP PRU12, the resonance frequency needs to be two times lower than the NFC frequency, and thus needs to satisfy Equation 3 below.

Assuming that the first capacitor Ca101has a capacitance of n times higher than that of the second capacitor Cb102, a condition as shown in Equation 4 is obtained.

The capacitance of the third capacitor Cc103needs to be a positive value and thus needs to satisfy a condition n<⅓. When n<⅕, the capacitance is expressed as follows.
Capacitance:Ca=Cb/5,Cc=1/9Cb

When the user terminal operates as the A4WP PRU12, excessive power is blocked from being supplied to the NFC module, which is configured to transmit and receive lower power, thereby preventing the NFC module from being broken and protecting the NFC module.

FIG. 4is a circuit diagram of the user terminal in which the NFC module and the A4WP PRU are operable using a single antenna according to the embodiment of the present invention.

Referring toFIG. 4, the user terminal includes the resonator including a single antenna100, the A4WP PRU12, and the NFC module14. The A4WP PRU12includes the rectifier121, the power converter125, and an apparatus for controlling wireless charging and short-range communication. The apparatus for controlling wireless charging and short-range communication includes a switch controller126and the switch SW107.

The user terminal may be a portable terminal that may be carried by a user. The single antenna100may perform wireless power signal reception and short-range communication. The A4WP PRU12receives a wireless power signal at a first resonance frequency at which the resonator10including the antenna100is resonated. The NFC module14performs wireless communication with an opposing NFC module at a second resonance frequency at which the resonator10including the antenna100is resonated.

The switch controller126detects a resonance frequency from an input voltage IN_A4WP200of the A4WP, determines whether the detected resonance frequency is a first frequency or a second frequency, and generates a control signal. The switch SW107is turned on or off to operate in a wireless charging mode or a short-range communication mode according to the control signal received from the switch controller126.

The switch controller126according to the embodiment receives the input voltage IN_A4WP200of the A4WP, and when a resonance frequency is detected as 6.78 MHz, confirms a wireless chargeable state and generates a driving signal Vdrv of a high level to turn the switch SW107on, to block power from being supplied to the NFC module14, and protect the NFC module14. Meanwhile, the switch controller126confirms a short-range communicable state when the input voltage IN_A4WP200of the A4WP is 13.56 MHz and generates a driving signal Vdrv of a low level to turn the switch SW107off in order to operate the NFC module14.

The switch SW107is provided as a MOSFET device, but may be provided using electrically controllable switch devices, for example, not only a BJT device, a GaN device, or a SiC device, but also a relay, a micro electro mechanical systems (MSMS) switch or the like that includes an electromagnet.

FIG. 5is a waveform chart illustrating a simulation result of the NFC module operated by receiving energy transmitted by an NFC transmitting unit according to the embodiment of the present invention.

Referring toFIGS. 2 and 5, an NFC transmitting unit supplies energy at a frequency of 13.56 MHz, and the antenna of the terminal receives the energy and supplies the received energy to the NFC module14. Referring toFIG. 5, the input voltage IN_NFC210of the NFC has a voltage swing having a peak of 7 V, but the input voltage IN_A4WP200of the A4WP is only about 500 mV. As a result, the A4WP PRU12does not operate, and thus most of the energy from the antenna is supplied to the NFC module14.

FIG. 6is a waveform chart illustrating a simulation result of the A4WP PRU operated by receiving energy transmitted by the A4WP PTU according to the embodiment of the present invention.

Referring toFIGS. 3 and 6, in a state in which the switch SW107is turned on such that the A4WP PRU12operates, the input voltage IN_A4WP200of the A4WP has a frequency of 6.78 MHz. In this case, the input voltage IN_NFC210of the NFC is almost zero. As a result, the NFC module14does not operate, and thus the NFC module14is protected.

FIG. 7is a circuit diagram of a resonator according to another embodiment of the present invention.

The resonator described with reference toFIG. 1is suitable for a single input. When two inputs having a differential form are needed, a resonance illustrated inFIG. 7may be used. A user terminal constructed using the resonance is shown inFIG. 8.

Referring toFIG. 7, the resonator includes an antenna100, a first capacitor Ca101, second capacitors Cb1and Cb2, i.e.,102-1and101-2, and third capacitors Cc1and Cc2, i.e.,103-1and103-2. A first switch SW1107-1has a source connected to a first ground voltage108-1, a drain connected to the third capacitor Cc1103-1, and a gate to which a first driving voltage Vdrv1is input. The first switch SW1107-1is turned on when the first driving voltage Vdrv1is a predetermined threshold voltage or higher, and is turned off when the first driving voltage Vdrv1is less than or equal to the predetermined threshold voltage. A second switch SW2, i.e.,107-2, has a source connected to a second ground voltage108-2, a drain connected to the third capacitor Cc2103-2, and a gate to which a second driving voltage Vdrv2is input. The second switch SW2, i.e.,107-2, is turned on when the second driving voltage Vdrv2is a predetermined threshold voltage or higher, and is turned off when the second driving voltage Vdrv2is less than the predetermined threshold voltage.

Node (A)104inFIG. 7is used as an input of an NFC module, Node (B)105inFIG. 7is used as an input of an A4WP PRU, Node (C)106inFIG. 7is used as an input of the A4WP PRU, and Node (D)110inFIG. 7is connected to the second switch SW, i.e.,107-2.

FIG. 8is a circuit diagram of the user terminal in which the NFC module and the A4WP PRU are operable using a single antenna according to another embodiment of the present invention.

Referring toFIG. 8, the NFC module14and the A4WP PRU12are implemented using the resonance suitable for a differential structure. The resonance frequency of the NFC module14is adjusted as shown in Equation 5. It is assumed that Cb1=Cb2=Cb, Cc1=Cc2=Cc

When the user terminal operates as the A4WP PRU12, the resonance frequency is expressed as shown in Equation 6.

The A4WP PRU12includes a rectifier121, a power converter125, and a switch controller126. The rectifier121includes at least one diode, for example, diodes D1, D2, D3, and D4, i.e.,121-1,121-2,121-3, and121-4, as shown inFIG. 8. The rectifier capacitor CRECT123smooths a rectifier output voltage VRECT_A4WP. The rectifier output voltage VRECT_A4WP allows a constant voltage to be supplied to a load through the power converter125. The power converter125may be a DC-to-DC converter, an LDO, or the like.

The first switch SW1107-1has the source connected to the first ground voltage108-1, the drain connected to the NFC module14, and the gate to which the first driving voltage Vdrv1is input from the switch controller126. The second switch SW2107-2has the source connected to the second ground voltage108-2, the drain connected to the NFC module14, and the gate to which the second driving voltage Vdrv2is input from the switch controller126. The NFC module14receives differential NFC input signals IN_NFC+ and IN_NFC−, and the switch controller126receives differential A4WP input signals IN_A4WP+ and IN_A4WP−.

The first switch SW1107-1and the second switch SW2107-2are provided using a MOSFET device, but may be provided using electrically controllable switch devices, for example, not only a BJT device, a GaN device, or a SiC device, but also a relay, a MSMS switch or the like that includes an electromagnet.

Although the exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art should appreciate that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the present invention. Therefore, the exemplary embodiments of the present invention have been described for illustrative purposes and not for limiting purposes. Accordingly, the scope of the present invention is not to be limited by the above embodiments but by the claims and the equivalents thereof.