Patent Publication Number: US-2022224163-A1

Title: Wireless power transmitter and method for detecting rfid/nfc card

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/252,509, filed on Dec. 15, 2020, which is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2019/007294, filed on Jun. 17, 2019, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0068795, filed on Jun. 15, 2018, the contents of which are all incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     The present disclosure relates to wireless power transmission, and more particularly, to a method and apparatus for wireless power transmission that performs a detection of other communication cards. 
     Related Art 
     A contactless wireless charging method is an energy transfer method for electromagnetically transferring energy without using a wire in a method for sending energy through an existing wire so that the energy is used as power for an electronic device. The contactless wireless transmission method includes an electromagnetic induction method and a resonant method. In the electromagnetic induction method, a power transmission unit generates a magnetic field through a power transmission coil (i.e., a primary coil), and a power reception coil (i.e., a secondary coil) is placed at the location where an electric current may be induced so that power is transferred. In the resonant method, energy is transmitted using a resonant phenomenon between the transmission coil and the reception coil. In this case, a system is configured so that the primary coil and the secondary coil have the same resonant frequency, and resonant mode energy coupling between the transmission and reception coils is used. 
     In the case that a Radio-Frequency Identification (RFID) card or a Near Field Communication (NFC) card is placed between a power transmitter (e.g., wireless charger) and a power receiver (e.g., mobile device, etc.), the power transmission without an RFID/NFC card detection function is unable to detect the RFID/NFC card. In addition, the power transmitter and receiver are unable to detect the RFID/NFC card with the FOD method defined in WPC, which is a standard related to a wireless power transmission/reception system. The reason is, in the FOD method defined in WPC, a foreign object is detected based on an amount of loss of power transmitted to the power receiver from the power transmitter (e.g., the case that it is detected a transmission efficiency is under a predetermined level, etc.). However, a power loss does not occur even in the case that the RFID/NFC card is placed between the power transmitter and the power receiver. Furthermore, since an operation frequency (e.g., about 100 to 205 kHz) of the power transmitter/receiver defined in WPC is different from an operation frequency (e.g., about 13.56 MHz) of the RFID/NFC card, a detection of the RFID/NFC card is unavailable even in the case of using the frequencies. 
     As such, in the case that a wireless power transmitter/receiver is unavailable to detect a presence of the RFID/NFC card and maintains a power transfer, the RFID/NFC card continuously exposed to a strong magnetic field may be damaged eventually, and there is a problem that it gives financial damage to a user. Furthermore, a safety problem caused by a heat generation of the RFID/NFC card may also be presented. 
     SUMMARY 
     The present disclosure provides a method and apparatus for wireless power transmission that detects a function or module such as NFC or RFID, and a method and apparatus for reception therefor. 
     In an aspect of the present disclosure, provided is a wireless power receiver able to detect other communication card. The apparatus may include a power pickup unit configured to receive a wireless power generated based on magnetic coupling from a wireless power transmitter in a power transfer phase; and a communication/control unit configured to transmit a first end power transfer (EPT) packet to the wireless power transmitter to detect other communication cards and perform a detection of the other communication card during a re-ping time secured based on the first EPT packet in a negotiation phase, and the first EPT packet may be used for a request of removing a power signal during a predetermined time. 
     In an aspect, the communication/control unit may be configured to: transmit a request packet to request information related to the other communication card to the wireless power transmitter in the negotiation phase, and receive other communication card detection ability information for that the wireless power transmitter does not have the ability of other communication card detection from the wireless power transmitter. 
     In another aspect, the request packet may be a general request packet or a specific request packet. 
     In still another aspect, the other communication card detection ability information may be included in a foreign object detection (FOD) packet, and the FOD packet may include at least one of a first field of 1 bit for that whether the wireless power transmitter is provided with the ability of other communication card detection or a second field of 1 bit for that whether the wireless power transmitter detects the other communication card. 
     In still another aspect, the other communication card detection ability information may be included in a capability packet, and the capability packet may include at least one of a first field of 1 bit for that whether the wireless power transmitter is provided with the ability of other communication card detection or a second field of 1 bit for that whether the wireless power transmitter detects the other communication card. 
     In still another aspect, based on that the other communication card is detected, the communication/control unit may transmit a second EPT packet using for a stop of the power transfer owing to the detection of the other communication card to the wireless power transmitter. 
     In still another aspect, the other communication card may be an RFID or NFC. 
     In another aspect of the present disclosure, provided is a wireless power transmitter available to detect other communication card. The apparatus may include a power conversion unit configured to transmit a wireless power generated based on magnetic coupling to a wireless power receiver in a power transfer phase; and a communication/control unit configured to receive a first end power transfer (EPT) packet to detect other communication card from the wireless power receiver and minimize or stop the magnetic coupling to detect the other communication card during a re-ping time secured based on the first EPT packet in a negotiation phase, and the first EPT packet may is used for a request of removing a power signal during a predetermined time. 
     In an aspect, the communication/control unit may be configured to: receive a request packet to request information related to the other communication card from the wireless power receiver in the negotiation phase, and transmit other communication card detection ability information for that the wireless power transmitter does not have the ability of other communication card detection to the wireless power receiver in response to the request packet. 
     In another aspect, the request packet may be a general request packet or a specific request packet. 
     In still another aspect, the other communication card detection ability information may be included in a foreign object detection (FOD) packet, and the FOD packet may include at least one of a first field of 1 bit for that whether the wireless power transmitter is provided with the ability of other communication card detection or a second field of 1 bit for that whether the wireless power transmitter detects the other communication card. 
     In still another aspect, the other communication card detection ability information may be included in a capability packet, and the capability packet may include at least one of a first field of 1 bit for that whether the wireless power transmitter is provided with the ability of other communication card detection or a second field of 1 bit for that whether the wireless power transmitter detects the other communication card. 
     In still another aspect, based on that the other communication card is detected, the communication/control unit may receive a second EPT packet using for a stop of the power transfer owing to the detection of the other communication card from the wireless power receiver. 
     In still another aspect, the other communication card may be an RFID or NFC. 
     Advantageous Effects 
     A procedure is clearly defined for detecting other communication card such as RFID or NFC between a wireless power transmitter and a wireless power receiver, and a problem that the other communication card is damaged by a wireless power may be prevented in advance, and accordingly, a stable wireless power transmission becomes available. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a wireless power system ( 10 ) according to an exemplary embodiment of the present disclosure. 
         FIG. 2  is a block diagram of a wireless power system ( 10 ) according to another exemplary embodiment of the present disclosure. 
         FIG. 3A  shows an exemplary embodiment of diverse electronic devices adopting a wireless power transfer system. 
         FIG. 3B  shows an example of a WPC NDEF in a wireless power transfer system. 
         FIG. 4A  is a block diagram of a wireless power transfer system according to another exemplary embodiment of the present disclosure. 
         FIG. 4B  is a diagram illustrating an example of a Bluetooth communication architecture to which an embodiment according to the present disclosure may be applied. 
         FIG. 4C  is a block diagram illustrating a wireless power transfer system using BLE communication according to an example. 
         FIG. 4D  is a block diagram illustrating a wireless power transfer system using BLE communication according to another example. 
         FIG. 5  is a state transition diagram for describing a wireless power transfer procedure. 
         FIG. 6  shows a power control method according to an exemplary embodiment of the present disclosure. 
         FIG. 7  is a block diagram of a wireless power transmitter according to another exemplary embodiment of the present disclosure. 
         FIG. 8  shows a wireless power receiver according to another exemplary embodiment of the present disclosure. 
         FIG. 9  shows a communication frame structure according to an exemplary embodiment of the present disclosure. 
         FIG. 10  is a structure of a sync pattern according to an exemplary embodiment of the present disclosure. 
         FIG. 11  shows operation statuses of a wireless power transmitter and a wireless power receiver in a shared mode according to an exemplary embodiment of the present disclosure. 
         FIG. 12  is a flowchart for a method for detecting RFID or NFC according to an embodiment. 
         FIG. 13  illustrates a structure of an FOD packet according to an example. 
         FIG. 14  illustrates a structure of an FOD packet according to another example. 
         FIG. 15  illustrates a structure of a capability packet according to an example. 
         FIG. 16  illustrates a structure of a capability packet according to another example. 
         FIG. 17  illustrates a structure of an EPT packet according to an example. 
         FIG. 18  is a diagram illustrated for describing an operation for the wireless power receiver to detect other communication card throughout the entire periods of a state diagram for a wireless power transmission according to an embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The term “wireless power”, which will hereinafter be used in this specification, will be used to refer to an arbitrary form of energy that is related to an electric field, a magnetic field, and an electromagnetic field, which is transferred (or transmitted) from a wireless power transmitter to a wireless power receiver without using any physical electromagnetic conductors. The wireless power may also be referred to as a wireless power signal, and this may refer to an oscillating magnetic flux that is enclosed by a primary coil and a secondary coil. For example, power conversion for wirelessly charging devices including mobile phones, cordless phones, iPods, MP3 players, headsets, and so on, within the system will be described in this specification. Generally, the basic principle of the wireless power transfer technique includes, for example, all of a method of transferring power by using magnetic coupling, a method of transferring power by using radio frequency (RF), a method of transferring power by using microwaves, and a method of transferring power by using ultrasound (or ultrasonic waves). 
       FIG. 1  is a block diagram of a wireless power system ( 10 ) according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 1 , the wireless power system ( 10 ) include a wireless power transmitter ( 100 ) and a wireless power receiver ( 200 ). 
     The wireless power transmitter ( 100 ) is supplied with power from an external power source (S) and generates a magnetic field. The wireless power receiver ( 200 ) generates electric currents by using the generated magnetic field, thereby being capable of wirelessly receiving power. 
     Additionally, in the wireless power system ( 10 ), the wireless power transmitter ( 100 ) and the wireless power receiver ( 200 ) may transceive (transmit and/or receive) diverse information that is required for the wireless power transfer. Herein, communication between the wireless power transmitter ( 100 ) and the wireless power receiver ( 200 ) may be performed (or established) in accordance with any one of an in-band communication, which uses a magnetic field that is used for the wireless power transfer (or transmission), and an out-band communication, which uses a separate communication carrier. Out-band communication may also be referred to as out-of-band communication. Hereinafter, out-band communication will be largely described. Examples of out-band communication may include NFC, Bluetooth, Bluetooth low energy (BLE), and the like. 
     Herein, the wireless power transmitter ( 100 ) may be provided as a fixed type or a mobile (or portable) type. Examples of the fixed transmitter type may include an embedded type, which is embedded in in-door ceilings or wall surfaces or embedded in furniture, such as tables, an implanted type, which is installed in out-door parking lots, bus stops, subway stations, and so on, or being installed in means of transportation, such as vehicles or trains. The mobile (or portable) type wireless power transmitter ( 100 ) may be implemented as a part of another device, such as a mobile device having a portable size or weight or a cover of a laptop computer, and so on. 
     Additionally, the wireless power receiver ( 200 ) should be interpreted as a comprehensive concept including diverse home appliances and devices that are operated by being wirelessly supplied with power instead of diverse electronic devices being equipped with a battery and a power cable. Typical examples of the wireless power receiver ( 200 ) may include portable terminals, cellular phones, smartphones, personal digital assistants (PDAs), portable media players (PDPs), Wibro terminals, tablet PCs, phablet, laptop computers, digital cameras, navigation terminals, television, electronic vehicles (EVs), and so on. 
     In the wireless power system ( 10 ), one wireless power receiver ( 200 ) or a plurality of wireless power receivers may exist. Although it is shown in  FIG. 1  that the wireless power transmitter ( 100 ) and the wireless power receiver ( 200 ) send and receive power to and from one another in a one-to-one correspondence (or relationship), as shown in  FIG. 2 , it is also possible for one wireless power transmitter ( 100 ) to simultaneously transfer power to multiple wireless power receivers ( 200 - 1 ,  200 - 2 , . . . ,  200 -M). Most particularly, in case the wireless power transfer (or transmission) is performed by using a magnetic resonance method, one wireless power transmitter ( 100 ) may transfer power to multiple wireless power receivers ( 200 - 1 ,  200 - 2 , . . . ,  200 -M) by using a synchronized transport (or transfer) method or a time-division transport (or transfer) method. 
     Additionally, although it is shown in  FIG. 1  that the wireless power transmitter ( 100 ) directly transfers (or transmits) power to the wireless power receiver ( 200 ), the wireless power system ( 10 ) may also be equipped with a separate wireless power transceiver, such as a relay or repeater, for increasing a wireless power transport distance between the wireless power transmitter ( 100 ) and the wireless power receiver ( 200 ). In this case, power is delivered to the wireless power transceiver from the wireless power transmitter ( 100 ), and, then, the wireless power transceiver may transfer the received power to the wireless power receiver ( 200 ). 
     Hereinafter, the terms wireless power receiver, power receiver, and receiver, which are mentioned in this specification, will refer to the wireless power receiver ( 200 ). Also, the terms wireless power transmitter, power transmitter, and transmitter, which are mentioned in this specification, will refer to the wireless power transmitter ( 100 ). 
       FIG. 3  shows an exemplary embodiment of diverse electronic devices adopting a wireless power transfer system. 
     As shown in  FIG. 3 , the electronic devices included in the wireless power transfer system are sorted in accordance with the amount of transmitted power and the amount of received power. Referring to  FIG. 3 , wearable devices, such as smart watches, smart glasses, head mounted displays (HMDs), smart rings, and so on, and mobile electronic devices (or portable electronic devices), such as earphones, remote controllers, smartphones, PDAs, tablet PCs, and so on, may adopt a low-power (approximately 5 W or less or approximately 20 W or less) wireless charging method. 
     Small-sized/Mid-sized electronic devices, such as laptop computers, robot vacuum cleaners, TV receivers, audio devices, vacuum cleaners, monitors, and so on, may adopt a mid-power (approximately SOW or less or approximately 200 W or less) wireless charging method. Kitchen appliances, such as mixers, microwave ovens, electric rice cookers, and so on, and personal transportation devices (or other electric devices or means of transportation), such as powered wheelchairs, powered kick scooters, powered bicycles, electric cars, and so on may adopt a high-power (approximately 2 kW or less or approximately 22 kW or less) wireless charging method. 
     The electric devices or means of transportation, which are described above (or shown in  FIG. 1 ) may each include a wireless power receiver, which will hereinafter be described in detail. Therefore, the above-described electric devices or means of transportation may be charged (or re-charged) by wirelessly receiving power from a wireless power transmitter. 
     Hereinafter, although the present disclosure will be described based on a mobile device adopting the wireless power charging method, this is merely exemplary. And, therefore, it shall be understood that the wireless charging method according to the present disclosure may be applied to diverse electronic devices. 
     A standard for the wireless power transfer (or transmission) includes a wireless power consortium (WPC), an air fuel alliance (AFA), and a power matters alliance (PMA). 
     The WPC standard defines a baseline power profile (BPP) and an extended power profile (EPP). The BPP is related to a wireless power transmitter and a wireless power receiver supporting a power transfer of SW, and the EPP is related to a wireless power transmitter and a wireless power receiver supporting the transfer of a power range greater than SW and less than 30 W. 
     Diverse wireless power transmitters and wireless power receivers each using a different power level may be covered by each standard and may be sorted by different power classes or categories. 
     For example, the WPC may categorize (or sort) the wireless power transmitters and the wireless power receivers as PC- 1 , PC 0 , PC 1 , and PC 2 , and the WPC may provide a standard document (or specification) for each power class (PC). The PC- 1  standard relates to wireless power transmitters and receivers providing a guaranteed power of less than 5 W. The application of PC- 1  includes wearable devices, such as smart watches. 
     The PC 0  standard relates to wireless power transmitters and receivers providing a guaranteed power of 5 W. The PC 0  standard includes an EPP having a guaranteed power ranges that extends to 30 W. Although in-band (IB) communication corresponds to a mandatory communication protocol of PC 0 , out-of-band (OB) communication that is used as an optional backup channel may also be used for PC 0 . The wireless power receiver may be identified by setting up an OB flag, which indicates whether or not the OB is supported, within a configuration packet. A wireless power transmitter supporting the OB may enter an OB handover phase by transmitting a bit-pattern for an OB handover as a response to the configuration packet. The response to the configuration packet may correspond to an NAK, an ND, or an 8-bit pattern that is newly defined. The application of the PC 0  includes smartphones. 
     The PC 1  standard relates to wireless power transmitters and receivers providing a guaranteed power ranging from 30 W to 150 W. OB corresponds to a mandatory communication channel for PC 1 , and IB is used for initialization and link establishment to OB. The wireless power transmitter may enter an OB handover phase by transmitting a bit-pattern for an OB handover as a response to the configuration packet. The application of the PC 1  includes laptop computers or power tools. 
     The PC 2  standard relates to wireless power transmitters and receivers providing a guaranteed power ranging from 200 W to 2 kW, and its application includes kitchen appliances. 
     As described above, the PCs may be differentiated in accordance with the respective power levels. And, information on whether or not the compatibility between the same PCs is supported may be optional or mandatory. Herein, the compatibility between the same PCs indicates that power transfer/reception between the same PCs is possible. For example, in case a wireless power transmitter corresponding to PC x is capable of performing charging of a wireless power receiver having the same PC x, it may be understood that compatibility is maintained between the same PCs. Similarly, compatibility between different PCs may also be supported. Herein, the compatibility between different PCs indicates that power transfer/reception between different PCs is also possible. For example, in case a wireless power transmitter corresponding to PC x is capable of performing charging of a wireless power receiver having PC y, it may be understood that compatibility is maintained between the different PCs. 
     The support of compatibility between PCs corresponds to an extremely important issue in the aspect of user experience and establishment of infrastructure. Herein, however, diverse problems, which will be described below, exist in maintaining the compatibility between PCs. 
     In case of the compatibility between the same PCs, for example, in case of a wireless power receiver using a lap-top charging method, wherein stable charging is possible only when power is continuously transferred, even if its respective wireless power transmitter has the same PC, it may be difficult for the corresponding wireless power receiver to stably receive power from a wireless power transmitter of the power tool method, which transfers power non-continuously. Additionally, in case of the compatibility between different PCs, for example, in case a wireless power transmitter having a minimum guaranteed power of 200 W transfers power to a wireless power receiver having a maximum guaranteed power of 5 W, the corresponding wireless power receiver may be damaged due to an overvoltage. As a result, it may be inappropriate (or difficult) to use the PS as an index/reference standard representing/indicating the compatibility. 
     Wireless power transmitters and receivers may provide a very convenient user experience and interface (UX/UI). That is, a smart wireless charging service may be provided, and the smart wireless charging service may be implemented based on a UX/UI of a smartphone including a wireless power transmitter. For these applications, an interface between a processor of a smartphone and a wireless charging receiver allows for “drop and play” two-way communication between the wireless power transmitter and the wireless power receiver. 
     As an example, a user may experience a smart wireless charging service in a hotel. When the user enters a hotel room and puts a smartphone on a wireless charger in the room, the wireless charger transmits wireless power to the smartphone and the smartphone receives wireless power. In this process, the wireless charger transmits information on the smart wireless charging service to the smartphone. When it is detected that the smartphone is located on the wireless charger, when it is detected that wireless power is received, or when the smartphone receives information on the smart wireless charging service from the wireless charger, the smartphone enters a state of inquiring the user about agreement (opt-in) of supplemental features. To this end, the smartphone may display a message on a screen in a manner with or without an alarm sound. An example of the message may include the phrase “Welcome to ###hotel. Select“Yes” to activate smart charging functions: Yes|No Thanks.” The smartphone receives an input from the user who selects Yes or No Thanks, and performs a next procedure selected by the user. If Yes is selected, the smartphone transmits corresponding information to the wireless charger. The smartphone and the wireless charger perform the smart charging function together. 
     The smart wireless charging service may also include receiving WiFi credentials auto-filled. For example, the wireless charger transmits the WiFi credentials to the smartphone, and the smartphone automatically inputs the WiFi credentials received from the wireless charger by running an appropriate application. 
     The smart wireless charging service may also include running a hotel application that provides hotel promotions or obtaining remote check-in/check-out and contact information. 
     As another example, the user may experience the smart wireless charging service in a vehicle. When the user gets in the vehicle and puts the smartphone on the wireless charger, the wireless charger transmits wireless power to the smartphone and the smartphone receives wireless power. In this process, the wireless charger transmits information on the smart wireless charging service to the smartphone. When it is detected that the smartphone is located on the wireless charger, when wireless power is detected to be received, or when the smartphone receives information on the smart wireless charging service from the wireless charger, the smartphone enters a state of inquiring the user about checking identity. 
     In this state, the smartphone is automatically connected to the vehicle via WiFi and/or Bluetooth. The smartphone may display a message on the screen in a manner with or without an alarm sound. An example of the message may include a phrase of “Welcome to your car. Select “Yes” to synch device with in-car controls: Yes|No Thanks.” Upon receiving the user&#39;s input to select Yes or No Thanks, the smartphone performs a next procedure selected by the user. If Yes is selected, the smartphone transmits corresponding information to the wireless charger. In addition, the smartphone and the wireless charger may run an in-vehicle smart control function together by driving in-vehicle application/display software. The user may enjoy the desired music and check a regular map location. The in-vehicle applications/display software may include an ability to provide synchronous access for passers-by. 
     As another example, the user may experience smart wireless charging at home. When the user enters the room and puts the smartphone on the wireless charger in the room, the wireless charger transmits wireless power to the smartphone and the smartphone receives wireless power. In this process, the wireless charger transmits information on the smart wireless charging service to the smartphone. When it is detected that the smartphone is located on the wireless charger, when wireless power is detected to be received, or when the smartphone receives information on the smart wireless charging service from the wireless charger, the smartphone enters a state of inquiring the user about agreement (opt-in) of supplemental features. To this end, the smartphone may display a message on the screen in a manner with or without an alarm sound. An example of the message may include a phrase such as “Hi xxx, Would you like to activate night mode and secure the building?: Yes|No Thanks.” The smartphone receives a user input to select Yes or No Thanks and performs a next procedure selected by the user. If Yes is selected, the smartphone transmits corresponding information to the wireless charger. The smartphones and the wireless charger may recognize at least user&#39;s pattern and recommend the user to lock doors and windows, turn off lights, or set an alarm. 
     Hereinafter, ‘profiles’ will be newly defined based on indexes/reference standards representing/indicating the compatibility. More specifically, it may be understood that by maintaining compatibility between wireless power transmitters and receivers having the same ‘profile’, stable power transfer/reception may be performed, and that power transfer/reception between wireless power transmitters and receivers having different ‘profiles’ cannot be performed. The ‘profiles’ may be defined in accordance with whether or not compatibility is possible and/or the application regardless of (or independent from) the power class. 
     For example, the profile may be sorted into 3 different categories, such as i) Mobile, ii) Power tool and iii) Kitchen. 
     For another example, the profile may be sorted into 4 different categories, such as i) Mobile, ii) Power tool, iii) Kitchen, and iv) Wearable. 
     In case of the ‘Mobile’ profile, the PC may be defined as PC 0  and/or PC 1 , the communication protocol/method may be defined as IB and OB communication, and the operation frequency may be defined as 87 to 205 kHz, and smartphones, laptop computers, and so on, may exist as the exemplary application. 
     In case of the ‘Power tool’ profile, the PC may be defined as PC 1 , the communication protocol/method may be defined as IB communication, and the operation frequency may be defined as 87 to 145 kHz, and power tools, and so on, may exist as the exemplary application. 
     In case of the ‘Kitchen’ profile, the PC may be defined as PC 2 , the communication protocol/method may be defined as NFC-based communication, and the operation frequency may be defined as less than 100 kHz, and kitchen/home appliances, and so on, may exist as the exemplary application. 
     In the case of power tools and kitchen profiles, NFC communication may be used between the wireless power transmitter and the wireless power receiver. The wireless power transmitter and the wireless power receiver may confirm that they are NFC devices with each other by exchanging WPC NFC data exchange profile format (NDEF). The WPC NDEF may include, for example, an application profile field (e.g., 1B), a version field (e.g., 1B), and profile specific data (e.g., 1B). The application profile field indicates whether the corresponding device is i) mobile and computing, ii) power tool, and iii) kitchen, and an upper nibble in the version field indicates a major version and a lower nibble indicates a minor version. In addition, profile-specific data defines content for the kitchen. 
     In case of the ‘Wearable’ profile, the PC may be defined as PC- 1 , the communication protocol/method may be defined as IB communication, and the operation frequency may be defined as 87 to 205 kHz, and wearable devices that are worn by the users, and so on, may exist as the exemplary application. 
     It may be mandatory to maintain compatibility between the same profiles, and it may be optional to maintain compatibility between different profiles. 
     The above-described profiles (Mobile profile, Power tool profile, Kitchen profile, and Wearable profile) may be generalized and expressed as first to nth profile, and a new profile may be added/replaced in accordance with the WPC standard and the exemplary embodiment. 
     In case the profile is defined as described above, the wireless power transmitter may optionally perform power transfer only to the wireless power receiving corresponding to the same profile as the wireless power transmitter, thereby being capable of performing a more stable power transfer. Additionally, since the load (or burden) of the wireless power transmitter may be reduced and power transfer is not attempted to a wireless power receiver for which compatibility is not possible, the risk of damage in the wireless power receiver may be reduced. 
     PC 1  of the ‘Mobile’ profile may be defined by being derived from an optional extension, such as OB, based on PC 0 . And, the ‘Power tool’ profile may be defined as a simply modified version of the PC 1  ‘Mobile’ profile. Additionally, up until now, although the profiles have been defined for the purpose of maintaining compatibility between the same profiles, in the future, the technology may be evolved to a level of maintaining compatibility between different profiles. The wireless power transmitter or the wireless power receiver may notify (or announce) its profile to its counterpart by using diverse methods. 
     In the AFA standard, the wireless power transmitter is referred to as a power transmitting unit (PTU), and the wireless power receiver is referred to as a power receiving unit (PRU). And, the PTU is categorized to multiple classes, as shown in Table 1, and the PRU is categorized to multiple classes, as shown in Table 2. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 Minimum value 
               
               
                   
                   
                   
                 for a maximum 
               
               
                   
                   
                 Minimum category 
                 number of 
               
               
                 PTU 
                 P TX     —     IN     —     MAX   
                 support requirement 
                 supported devices 
               
               
                   
               
             
            
               
                 Class 1 
                  2 W 
                 1x Category 1 
                 1x Category 1 
               
               
                 Class 2 
                 10 W 
                 1x Category 3 
                 2x Category 2 
               
               
                 Class 3 
                 16 W 
                 1x Category 4 
                 2x Category 3 
               
               
                 Class 4 
                 33 W 
                 1x Category 5 
                 3x Category 3 
               
               
                 Class 5 
                 50 W 
                 1x Category 6 
                 4x Category 3 
               
               
                 Class 6 
                 70 W 
                 1x Category 7 
                 5x Category 3 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                 Exemplary 
               
               
                   
                 PRU 
                 P RX     —     OUT     —     MAX   
                 application 
               
               
                   
                   
               
             
            
               
                   
                 Category 1 
                 TBD 
                 Bluetooth headset 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Category 2 
                 3.5 
                 W 
                 Feature phone 
               
               
                   
                 Category 3 
                 6.5 
                 W 
                 Smartphone 
               
               
                   
                 Category 4 
                 13 
                 W 
                 Tablet PC, Phablet 
               
               
                   
                 Category 5 
                 25 
                 W 
                 Small form factor laptop 
               
               
                   
                 Category 6 
                 37.5 
                 W 
                 General laptop 
               
               
                   
                 Category 7 
                 50 
                 W 
                 Home appliance 
               
               
                   
                   
               
            
           
         
       
     
     As shown in Table 1, a maximum output power capability of Class n PTU may be equal to or greater than the P TX_IN_MAX  of the corresponding class. The PRU cannot draw a power that is higher than the power level specified in the corresponding category. 
       FIG. 4 a    is a block diagram of a wireless power transfer system according to another exemplary embodiment of the present disclosure. 
     Referring to  FIG. 4 a   , the wireless power transfer system ( 10 ) includes a mobile device ( 450 ), which wirelessly receives power, and a base station ( 400 ), which wirelessly transmits power. 
     As a device providing induction power or resonance power, the base station ( 400 ) may include at least one of a wireless power transmitter ( 100 ) and a system unit ( 405 ). The wireless power transmitter ( 100 ) may transmit induction power or resonance power and may control the transmission. The wireless power transmitter ( 100 ) may include a power conversion unit ( 110 ) converting electric energy to a power signal by generating a magnetic field through a primary coil (or primary coils), and a communications &amp; control unit ( 120 ) controlling the communication and power transfer between the wireless power receiver ( 200 ) in order to transfer power at an appropriate (or suitable) level. The system unit ( 405 ) may perform input power provisioning, controlling of multiple wireless power transmitters, and other operation controls of the base station ( 400 ), such as user interface control. 
     The primary coil may generate an electromagnetic field by using an alternating current power (or voltage or current). The primary coil is supplied with an alternating current power (or voltage or current) of a specific frequency, which is being outputted from the power conversion unit ( 110 ). And, accordingly, the primary coil may generate a magnetic field of the specific frequency. The magnetic field may be generated in a non-radial shape or a radial shape. And, the wireless power receiver ( 200 ) receives the generated magnetic field and then generates an electric current. In other words, the primary coil wirelessly transmits power. 
     In the magnetic induction method, a primary coil and a secondary coil may have randomly appropriate shapes. For example, the primary coil and the secondary coil may correspond to copper wire being wound around a high-permeability formation, such as ferrite or a non-crystalline metal. The primary coil may also be referred to as a transmitting coil, a primary core, a primary winding, a primary loop antenna, and so on. Meanwhile, the secondary coil may also be referred to as a receiving coil, a secondary core, a secondary winding, a secondary loop antenna, a pickup antenna, and so on. 
     In case of using the magnetic resonance method, the primary coil and the secondary coil may each be provided in the form of a primary resonance antenna and a secondary resonance antenna. The resonance antenna may have a resonance structure including a coil and a capacitor. At this point, the resonance frequency of the resonance antenna may be determined by the inductance of the coil and a capacitance of the capacitor. Herein, the coil may be formed to have a loop shape. And, a core may be placed inside the loop. The core may include a physical core, such as a ferrite core, or an air core. 
     The energy transmission (or transfer) between the primary resonance antenna and the second resonance antenna may be performed by a resonance phenomenon occurring in the magnetic field. When a near field corresponding to a resonance frequency occurs in a resonance antenna, and in case another resonance antenna exists near the corresponding resonance antenna, the resonance phenomenon refers to a highly efficient energy transfer occurring between the two resonance antennas that are coupled with one another. When a magnetic field corresponding to the resonance frequency is generated between the primary resonance antenna and the secondary resonance antenna, the primary resonance antenna and the secondary resonance antenna resonate with one another. And, accordingly, in a general case, the magnetic field is focused toward the second resonance antenna at a higher efficiency as compared to a case where the magnetic field that is generated from the primary antenna is radiated to a free space. And, therefore, energy may be transferred to the second resonance antenna from the first resonance antenna at a high efficiency. The magnetic induction method may be implemented similarly to the magnetic resonance method. However, in this case, the frequency of the magnetic field is not required to be a resonance frequency. Nevertheless, in the magnetic induction method, the loops configuring the primary coil and the secondary coil are required to match one another, and the distance between the loops should be very close-ranged. 
     Although it is not shown in the drawing, the wireless power transmitter ( 100 ) may further include a communication antenna. The communication antenna may transmit and/or receive a communication signal by using a communication carrier apart from the magnetic field communication. For example, the communication antenna may transmit and/or receive communication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE, ZigBee, NFC, and so on. 
     The communications &amp; control unit ( 120 ) may transmit and/or receive information to and from the wireless power receiver ( 200 ). The communications &amp; control unit ( 120 ) may include at least one of an IB communication module and an OB communication module. 
     The IB communication module may transmit and/or receive information by using a magnetic wave, which uses a specific frequency as its center frequency. For example, the communications &amp; control unit ( 120 ) may perform in-band (IB) communication by transmitting information on the magnetic wave through the primary coil or by receiving information on the magnetic wave through the primary coil. At this point, the communications &amp; control unit ( 120 ) may load information in the magnetic wave or may interpret the information that is carried by the magnetic wave by using a modulation scheme, such as binary phase shift keying (BPSK) or amplitude shift keying (ASK), and so on, or a coding scheme, such as Manchester coding or non-return-to-zero level (NZR-L) coding, and so on. By using the above-described IB communication, the communications &amp; control unit ( 120 ) may transmit and/or receive information to distances of up to several meters at a data transmission rate of several kbps. 
     The OB communication module may also perform out-of-band communication through a communication antenna. For example, the communications &amp; control unit ( 120 ) may be provided to a near field communication module. Examples of the near field communication module may include communication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee, NFC, and so on. 
     The communications &amp; control unit ( 120 ) may control the overall operations of the wireless power transmitter ( 100 ). The communications &amp; control unit ( 120 ) may perform calculation and processing of diverse information and may also control each configuration element of the wireless power transmitter ( 100 ). 
     The communications &amp; control unit ( 120 ) may be implemented in a computer or a similar device as hardware, software, or a combination of the same. When implemented in the form of hardware, the communications &amp; control unit ( 120 ) may be provided as an electronic circuit performing control functions by processing electrical signals. And, when implemented in the form of software, the communications &amp; control unit ( 120 ) may be provided as a program that operates the communications &amp; control unit ( 120 ). 
     By controlling the operating point, the communications &amp; control unit ( 120 ) may control the transmitted power. The operating point that is being controlled may correspond to a combination of a frequency (or phase), a duty cycle, a duty ratio, and a voltage amplitude. The communications &amp; control unit ( 120 ) may control the transmitted power by adjusting any one of the frequency (or phase), the duty cycle, the duty ratio, and the voltage amplitude. Additionally, the wireless power transmitter ( 100 ) may supply a consistent level of power, and the wireless power receiver ( 200 ) may control the level of received power by controlling the resonance frequency. 
     The mobile device ( 450 ) includes a wireless power receiver ( 200 ) receiving wireless power through a secondary coil, and a load ( 455 ) receiving and storing the power that is received by the wireless power receiver ( 200 ) and supplying the received power to the device. 
     The wireless power receiver ( 200 ) may include a power pick-up unit ( 210 ) and a communications &amp; control unit ( 220 ). The power pick-up unit ( 210 ) may receive wireless power through the secondary coil and may convert the received wireless power to electric energy. The power pick-up unit ( 210 ) rectifies the alternating current (AC) signal, which is received through the secondary coil, and converts the rectified signal to a direct current (DC) signal. The communications &amp; control unit ( 220 ) may control the transmission and reception of the wireless power (transfer and reception of power). 
     The secondary coil may receive wireless power that is being transmitted from the wireless power transmitter ( 100 ). The secondary coil may receive power by using the magnetic field that is generated in the primary coil. Herein, in case the specific frequency corresponds a resonance frequency, magnetic resonance may occur between the primary coil and the secondary coil, thereby allowing power to be transferred with greater efficiency. 
     Although it is not shown in  FIG. 4 a   , the communications &amp; control unit ( 220 ) may further include a communication antenna. The communication antenna may transmit and/or receive a communication signal by using a communication carrier apart from the magnetic field communication. For example, the communication antenna may transmit and/or receive communication signals corresponding to Wi-Fi, Bluetooth, Bluetooth LE, ZigBee, NFC, and so on. 
     The communications &amp; control unit ( 220 ) may transmit and/or receive information to and from the wireless power transmitter ( 100 ). The communications &amp; control unit ( 220 ) may include at least one of an IB communication module and an OB communication module. 
     The IB communication module may transmit and/or receive information by using a magnetic wave, which uses a specific frequency as its center frequency. For example, the communications &amp; control unit ( 220 ) may perform IB communication by loading information in the magnetic wave and by transmitting the information through the secondary coil or by receiving a magnetic wave carrying information through the secondary coil. At this point, the communications &amp; control unit ( 120 ) may load information in the magnetic wave or may interpret the information that is carried by the magnetic wave by using a modulation scheme, such as binary phase shift keying (BPSK) or amplitude shift keying (ASK), and so on, or a coding scheme, such as Manchester coding or non-return-to-zero level (NZR-L) coding, and so on. By using the above-described IB communication, the communications &amp; control unit ( 220 ) may transmit and/or receive information to distances of up to several meters at a data transmission rate of several kbps. 
     The OB communication module may also perform out-of-band communication through a communication antenna. For example, the communications &amp; control unit ( 220 ) may be provided to a near field communication module. 
     Examples of the near field communication module may include communication modules, such as Wi-Fi, Bluetooth, Bluetooth LE, ZigBee, NFC, and so on. 
     The communications &amp; control unit ( 220 ) may control the overall operations of the wireless power receiver ( 200 ). The communications &amp; control unit ( 220 ) may perform calculation and processing of diverse information and may also control each configuration element of the wireless power receiver ( 200 ). 
     The communications &amp; control unit ( 220 ) may be implemented in a computer or a similar device as hardware, software, or a combination of the same. When implemented in the form of hardware, the communications &amp; control unit ( 220 ) may be provided as an electronic circuit performing control functions by processing electrical signals. And, when implemented in the form of software, the communications &amp; control unit ( 220 ) may be provided as a program that operates the communications &amp; control unit ( 220 ). 
     When the communication/control circuit  120  and the communication/control circuit  220  are Bluetooth or Bluetooth LE as an OB communication module or a short-range communication module, the communication/control circuit  120  and the communication/control circuit  220  may each be implemented and operated with a communication architecture as shown in  FIG. 4B . 
       FIG. 4B  is a diagram illustrating an example of a Bluetooth communication architecture to which an embodiment according to the present disclosure may be applied. 
     Referring to  FIG. 4B , (a) of  FIG. 4B  shows an example of a protocol stack of Bluetooth basic rate (BR)/enhanced data rate (EDR) supporting GATT, and (b) shows an example of Bluetooth low energy (BLE) protocol stack. 
     Specifically, as shown in (a) of  FIG. 4B , the Bluetooth BR/EDR protocol stack may include an upper control stack  460  and a lower host stack  470  based on a host controller interface (HCI)  18 . 
     The host stack (or host module)  470  refers to hardware for transmitting or receiving a Bluetooth packet to or from a wireless transmission/reception module which receives a Bluetooth signal of 2.4 GHz, and the controller stack  460  is connected to the Bluetooth module to control the Bluetooth module and perform an operation. 
     The host stack  470  may include a BR/EDR PHY layer  12 , a BR/EDR baseband layer  14 , and a link manager layer  16 . 
     The BR/EDR PHY layer  12  is a layer that transmits and receives a 2.4 GHz radio signal, and in the case of using Gaussian frequency shift keying (GFSK) modulation, the BR/EDR PHY layer  12  may transmit data by hopping 79 RF channels. 
     The BR/EDR baseband layer  14  serves to transmit a digital signal, selects a channel sequence for hopping 1400 times per second, and transmits a time slot with a length of 625 us for each channel. 
     The link manager layer  16  controls an overall operation (link setup, control, security) of Bluetooth connection by utilizing a link manager protocol (LMP). 
     The link manager layer  16  may perform the following functions.
         Performs ACL/SCO logical transport, logical link setup, and control.   Detach: It interrupts connection and informs a counterpart device about a reason for the interruption.   Performs power control and role switch.   Performs security (authentication, pairing, encryption) function.       

     The host controller interface layer  18  provides an interface between a host module and a controller module so that a host provides commands and data to the controller and the controller provides events and data to the host. 
     The host stack (or host module,  470 ) includes a logical link control and adaptation protocol (L2CAP)  21 , an attribute protocol  22 , a generic attribute profile (GATT)  23 , a generic access profile (GAP)  24 , and a BR/EDR profile  25 . 
     The logical link control and adaptation protocol (L2CAP)  21  may provide one bidirectional channel for transmitting data to a specific protocol or profile. 
     The L2CAP  21  may multiplex various protocols, profiles, etc., provided from upper Bluetooth. 
     L2CAP of Bluetooth BR/EDR uses dynamic channels, supports protocol service multiplexer, retransmission, streaming mode, and provides segmentation and reassembly, per-channel flow control, and error control. 
     The generic attribute profile (GATT)  23  may be operable as a protocol that describes how the attribute protocol  22  is used when services are configured. For example, the generic attribute profile  23  may be operable to specify how ATT attributes are grouped together into services and may be operable to describe features associated with services. 
     Accordingly, the generic attribute profile  23  and the attribute protocols (ATT)  22  may use features to describe device&#39;s state and services, how features are related to each other, and how they are used. 
     The attribute protocol  22  and the BR/EDR profile  25  define a service (profile) using Bluetooth BR/EDR and an application protocol for exchanging these data, and the generic access profile (GAP)  24  defines device discovery, connectivity, and security level. 
     As shown in (b) of  FIG. 4B , the Bluetooth LE protocol stack includes a controller stack  480  operable to process a wireless device interface important in timing and a host stack  490  operable to process high level data. 
     First, the controller stack  480  may be implemented using a communication module that may include a Bluetooth wireless device, for example, a processor module that may include a processing device such as a microprocessor. 
     The host stack  490  may be implemented as a part of an OS running on a processor module or as an instantiation of a package on the OS. 
     In some cases, the controller stack and the host stack may be run or executed on the same processing device in a processor module. 
     The controller stack  480  includes a physical layer (PHY)  32 , a link layer  34 , and a host controller interface  36 . 
     The physical layer (PHY, wireless transmission/reception module)  32  is a layer that transmits and receives a 2.4 GHz radio signal and uses Gaussian frequency shift keying (GFSK) modulation and a frequency hopping scheme including 40 RF channels. 
     The link layer  34 , which serves to transmit or receive Bluetooth packets, creates connections between devices after performing advertising and scanning functions using 3 advertising channels and provides a function of exchanging data packets of up to 257 bytes through  37  data channels. 
     The host stack includes a generic access profile (GAP)  45 , a logical link control and adaptation protocol (L2CAP,  41 ), a security manager (SM)  42 , and an attribute protocol (ATT)  43 , a generic attribute profile (GATT)  44 , a generic access profile  45 , and an LE profile  46 . However, the host stack  490  is not limited thereto and may include various protocols and profiles. 
     The host stack multiplexes various protocols, profiles, etc., provided from upper Bluetooth using L2CAP. 
     First, the logical link control and adaptation protocol (L2CAP)  41  may provide one bidirectional channel for transmitting data to a specific protocol or profile. 
     The L2CAP  41  may be operable to multiplex data between higher layer protocols, segment and reassemble packages, and manage multicast data transmission. 
     In Bluetooth LE, three fixed channels (one for signaling CH, one for security manager, and one for attribute protocol) are basically used. Also, a dynamic channel may be used as needed. 
     Meanwhile, a basic channel/enhanced data rate (BR/EDR) uses a dynamic channel and supports protocol service multiplexer, retransmission, streaming mode, and the like. 
     The security manager (SM)  42  is a protocol for authenticating devices and providing key distribution. 
     The attribute protocol (ATT)  43  defines a rule for accessing data of a counterpart device in a server-client structure. The ATT has the following 6 message types (request, response, command, notification, indication, confirmation). 
     {circle around (1)} Request and Response message: A request message is a message for requesting specific information from the client device to the server device, and the response message is a response message to the request message, which is a message transmitted from the server device to the client device. 
     {circle around (2)} Command message: It is a message transmitted from the client device to the server device in order to indicate a command of a specific operation. The server device does not transmit a response with respect to the command message to the client device. 
     {circle around (3)} Notification message: It is a message transmitted from the server device to the client device in order to notify an event, or the like. The client device does not transmit a confirmation message with respect to the notification message to the server device. 
     {circle around (4)} Indication and confirmation message: It is a message transmitted from the server device to the client device in order to notify an event, or the like. Unlike the notification message, the client device transmits a confirmation message regarding the indication message to the server device. 
     In the present disclosure, when the GATT profile using the attribute protocol (ATT)  43  requests long data, a value regarding a data length is transmitted to allow a client to clearly know the data length, and a characteristic value may be received from a server by using a universal unique identifier (UUID). 
     The generic access profile (GAP)  45 , a layer newly implemented for the Bluetooth LE technology, is used to select a role for communication between Bluetooth LED devices and to control how a multi-profile operation takes place. 
     Also, the generic access profile (GAP)  45  is mainly used for device discovery, connection generation, and security procedure part, defines a scheme for providing information to a user, and defines types of attributes as follows. 
     {circle around (1)} Service: It defines a basic operation of a device by a combination of behaviors related to data 
     {circle around (2)} Include: It defines a relationship between services 
     {circle around (3)} Characteristics: It is a data value used in a server 
     {circle around (4)} Behavior: It is a format that may be read by a computer defined by a UUID (value type). 
     The LE profile  46 , including profiles dependent upon the GATT, is mainly applied to a Bluetooth LE device. The LE profile  46  may include, for example, Battery, Time, FindMe, Proximity, Time, Object Delivery Service, and the like, and details of the GATT-based profiles are as follows. 
     {circle around (1)} Battery: Battery information exchanging method 
     {circle around (2)} Time: Time information exchanging method 
     {circle around (3)} FindMe: Provision of alarm service according to distance 
     {circle around (4)} Proximity: Battery information exchanging method 
     {circle around (5)} Time: Time information exchanging method 
     The generic attribute profile (GATT)  44  may operate as a protocol describing how the attribute protocol (ATT)  43  is used when services are configured. For example, the GATT  44  may operate to define how ATT attributes are grouped together with services and operate to describe features associated with services. 
     Thus, the GATT  44  and the ATT  43  may use features in order to describe status and services of a device and describe how the features are related and used. 
     Hereinafter, procedures of the Bluetooth low energy (BLE) technology will be briefly described. 
     The BLE procedure may be classified as a device filtering procedure, an advertising procedure, a scanning procedure, a discovering procedure, and a connecting procedure. 
     Device Filtering Procedure 
     The device filtering procedure is a method for reducing the number of devices performing a response with respect to a request, indication, notification, and the like, in the controller stack. 
     When requests are received from all the devices, it is not necessary to respond thereto, and thus, the controller stack may perform control to reduce the number of transmitted requests to reduce power consumption. 
     An advertising device or scanning device may perform the device filtering procedure to limit devices for receiving an advertising packet, a scan request or a connection request. 
     Here, the advertising device refers to a device transmitting an advertising event, that is, a device performing an advertisement and is also termed an advertiser. 
     The scanning device refers to a device performing scanning, that is, a device transmitting a scan request. 
     In the BLE, in a case in which the scanning device receives some advertising packets from the advertising device, the scanning device should transmit a scan request to the advertising device. 
     However, in a case in which a device filtering procedure is used so a scan request transmission is not required, the scanning device may disregard the advertising packets transmitted from the advertising device. 
     Even in a connection request process, the device filtering procedure may be used. In a case in which device filtering is used in the connection request process, it is not necessary to transmit a response with respect to the connection request by disregarding the connection request. 
     Advertising Procedure 
     The advertising device performs an advertising procedure to perform undirected broadcast to devices within a region. 
     Here, the undirected broadcast is advertising toward all the devices, rather than broadcast toward a specific device, and all the devices may scan advertising to make a supplemental information request or a connection request. 
     In contrast, directed advertising may make a supplemental information request or a connection request by scanning advertising for only a device designated as a reception device. 
     The advertising procedure is used to establish a Bluetooth connection with an initiating device nearby. 
     Or, the advertising procedure may be used to provide periodical broadcast of user data to scanning devices performing listening in an advertising channel. 
     In the advertising procedure, all the advertisements (or advertising events) are broadcast through an advertisement physical channel. 
     The advertising devices may receive scan requests from listening devices performing listening to obtain additional user data from advertising devices. The advertising devices transmit responses with respect to the scan requests to the devices which have transmitted the scan requests, through the same advertising physical channels as the advertising physical channels in which the scan requests have been received. 
     Broadcast user data sent as part of advertising packets are dynamic data, while the scan response data is generally static data. 
     The advertisement device may receive a connection request from an initiating device on an advertising (broadcast) physical channel. If the advertising device has used a connectable advertising event and the initiating device has not been filtered according to the device filtering procedure, the advertising device may stop advertising and enter a connected mode. The advertising device may start advertising after the connected mode. 
     Scanning Procedure 
     A device performing scanning, that is, a scanning device performs a scanning procedure to listen to undirected broadcasting of user data from advertising devices using an advertising physical channel. 
     The scanning device transmits a scan request to an advertising device through an advertising physical channel in order to request additional data from the advertising device. The advertising device transmits a scan response as a response with respect to the scan request, by including additional user data which has requested by the scanning device through an advertising physical channel. 
     The scanning procedure may be used while being connected to other BLE device in the BLE piconet. 
     If the scanning device is in an initiator mode in which the scanning device may receive an advertising event and initiates a connection request. The scanning device may transmit a connection request to the advertising device through the advertising physical channel to start a Bluetooth connection with the advertising device. 
     When the scanning device transmits a connection request to the advertising device, the scanning device stops the initiator mode scanning for additional broadcast and enters the connected mode. 
     Discovering Procedure 
     Devices available for Bluetooth communication (hereinafter, referred to as “Bluetooth devices”) perform an advertising procedure and a scanning procedure in order to discover devices located nearby or in order to be discovered by other devices within a given area. 
     The discovering procedure is performed asymmetrically. A Bluetooth device intending to discover other device nearby is termed a discovering device, and listens to discover devices advertising an advertising event that may be scanned. A Bluetooth device which may be discovered by other device and available to be used is termed a discoverable device and positively broadcasts an advertising event such that it may be scanned by other device through an advertising (broadcast) physical channel. 
     Both the discovering device and the discoverable device may have already been connected with other Bluetooth devices in a piconet. 
     Connecting Procedure 
     A connecting procedure is asymmetrical, and requests that, while a specific Bluetooth device is performing an advertising procedure, another Bluetooth device should perform a scanning procedure. 
     That is, an advertising procedure may be aimed, and as a result, only one device may response to the advertising. After a connectable advertising event is received from an advertising device, a connecting request may be transmitted to the advertising device through an advertising (broadcast) physical channel to initiate connection. 
     Hereinafter, operational states, that is, an advertising state, a scanning state, an initiating state, and a connection state, in the BLE technology will be briefly described. 
     Advertising State 
     A link layer (LL) enters an advertising state according to an instruction from a host (stack). In a case in which the LL is in the advertising state, the LL transmits an advertising packet data unit (PDU) in advertising events. 
     Each of the advertising events include at least one advertising PDU, and the advertising PDU is transmitted through an advertising channel index in use. After the advertising PDU is transmitted through an advertising channel index in use, the advertising event may be terminated, or in a case in which the advertising device may need to secure a space for performing other function, the advertising event may be terminated earlier. 
     Scanning State 
     The LL enters the scanning state according to an instruction from the host (stack). In the scanning state, the LL listens to advertising channel indices. 
     The scanning state includes two types: passive scanning and active scanning. Each of the scanning types is determined by the host. 
     Time for performing scanning or an advertising channel index are not defined. 
     During the scanning state, the LL listens to an advertising channel index in a scan window duration. A scan interval is defined as an interval between start points of two continuous scan windows. 
     When there is no collision in scheduling, the LL should listen in order to complete all the scan intervals of the scan window as instructed by the host. In each scan window, the LL should scan other advertising channel index. The LL uses every available advertising channel index. 
     In the passive scanning, the LL only receives packets and cannot transmit any packet. 
     In the active scanning, the LL performs listening in order to be relied on an advertising PDU type for requesting advertising PDUs and advertising device-related supplemental information from the advertising device. 
     Initiating State 
     The LL enters the initiating state according to an instruction from the host (stack). 
     When the LL is in the initiating state, the LL performs listening on advertising channel indices. 
     During the initiating state, the LL listens to an advertising channel index during the scan window interval. 
     Connection State 
     When the device performing a connection state, that is, when the initiating device transmits a CONNECT_REQ PDU to the advertising device or when the advertising device receives a CONNECT_REQ PDU from the initiating device, the LL enters a connection state. 
     It is considered that a connection is generated after the LL enters the connection state. However, it is not necessary to consider that the connection should be established at a point in time at which the LL enters the connection state. The only difference between a newly generated connection and an already established connection is a LL connection supervision timeout value. 
     When two devices are connected, the two devices play different roles. 
     An LL serving as a master is termed a master, and an LL serving as a slave is termed a slave. The master adjusts a timing of a connecting event, and the connecting event refers to a point in time at which the master and the slave are synchronized. 
     Hereinafter, packets defined in a Bluetooth interface will be briefly described. BLE devices use packets defined as follows. 
     Packet Format 
     The LL has only one packet format used for both an advertising channel packet and a data channel packet. 
     Each packet includes four fields of a preamble, an access address, a PDU, and a CRC. 
     When one packet is transmitted in an advertising physical channel, the PDU may be an advertising channel PDU, and when one packet is transmitted in a data physical channel, the PDU may be a data channel PDU. 
     Advertising Channel PDU 
     An advertising channel PDU has a 16-bit header and payload having various sizes. 
     A PDU type field of the advertising channel PDU included in the heater indicates PDU types defined in Table 3 below. 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 PDU Type 
                 Packet Name 
               
               
                   
               
             
            
               
                 0000 
                 ADV_IND 
               
               
                 0001 
                 ADV_DIRECT_IND 
               
               
                 0010 
                 ADV_NONCONN_IND 
               
               
                 0011 
                 SCAN_REQ 
               
               
                 0100 
                 SCAN_RSP 
               
               
                 0101 
                 CONNECT_REQ 
               
               
                 0110 
                 ADV_SCAN_IND 
               
               
                 0111-1111 
                 Reserved 
               
               
                   
               
            
           
         
       
     
     Advertising PDU The following advertising channel PDU types are termed advertising PDUs and used in a specific event. 
     ADV_IND: Connectable undirected advertising event 
     ADV_DIRECT_IND: Connectable directed advertising event 
     ADV_NONCONN_IND: Unconnectable undirected advertising event 
     ADV_SCAN_IND: Scannable undirected advertising event 
     The PDUs are transmitted from the LL in an advertising state, and received by the LL in a scanning state or in an initiating state. 
     Scanning PDU 
     The following advertising channel DPU types are termed scanning PDUs and are used in a state described hereinafter. 
     SCAN_REQ: Transmitted by the LL in a scanning state and received by the LL in an advertising state. 
     SCAN_RSP: Transmitted by the LL in the advertising state and received by the LL in the scanning state. 
     Initiating PDU 
     The following advertising channel PDU type is termed an initiating PDU. 
     CONNECT_REQ: Transmitted by the LL in the initiating state and received by the LL in the advertising state. 
     Data Channel PDU 
     The data channel PDU may include a message integrity check (MIC) field having a 16-bit header and payload having various sizes. 
     The procedures, states, and packet formats in the BLE technology discussed above may be applied to perform the methods proposed in the present disclosure. 
     Referring to  FIG. 4 a   , the load ( 455 ) may correspond to a battery. The battery may store energy by using the power that is being outputted from the power pick-up unit ( 210 ). Meanwhile, the battery is not mandatorily required to be included in the mobile device ( 450 ). For example, the battery may be provided as a detachable external feature. As another example, the wireless power receiver may include an operating means that may execute diverse functions of the electronic device instead of the battery. 
     As shown in the drawing, although the mobile device ( 450 ) is illustrated to be included in the wireless power receiver ( 200 ) and the base station ( 400 ) is illustrated to be included in the wireless power transmitter ( 100 ), in a broader meaning, the wireless power receiver ( 200 ) may be identified (or regarded) as the mobile device ( 450 ), and the wireless power transmitter ( 100 ) may be identified (or regarded) as the base station ( 400 ). 
     When the communication/control circuit  120  and the communication/control circuit  220  include Bluetooth or Bluetooth LE as an OB communication module or a short-range communication module in addition to the IB communication module, the wireless power transmitter  100  including the communication/control circuit  120  and the wireless power receiver  200  including the communication/control circuit  220  may be represented by a simplified block diagram as shown in  FIG. 4C . 
       FIG. 4C  is a block diagram illustrating a wireless power transfer system using BLE communication according to an example. 
     Referring to  FIG. 4C , the wireless power transmitter  100  includes a power conversion circuit  110  and a communication/control circuit  120 . The communication/control circuit  120  includes an in-band communication module  121  and a BLE communication module  122 . 
     Meanwhile, the wireless power receiver  200  includes a power pickup circuit  210  and a communication/control circuit  220 . The communication/control circuit  220  includes an in-band communication module  221  and a BLE communication module  222 . 
     In one aspect, the BLE communication modules  122  and  222  perform the architecture and operation according to  FIG. 4B . For example, the BLE communication modules  122  and  222  may be used to establish a connection between the wireless power transmitter  100  and the wireless power receiver  200  and exchange control information and packets necessary for wireless power transfer. 
     In another aspect, the communication/control circuit  120  may be configured to operate a profile for wireless charging. Here, the profile for wireless charging may be GATT using BLE transmission. 
     Referring to  FIG. 4D , the communication/control circuits  120  and  220  respectively include only in-band communication modules  121  and  221 , and the BLE communication modules  122  and  222  may be provided to be separated from the communication/control circuits  120  and  220 . 
     Hereinafter, the coil or coil unit includes a coil and at least one device being approximate to the coil, and the coil or coil unit may also be referred to as a coil assembly, a coil cell, or a cell. 
       FIG. 5  is a state transition diagram for describing a wireless power transfer procedure. 
     Referring to  FIG. 5 , the power transfer (or transfer) from the wireless power transmitter to the wireless power receiver according to an exemplary embodiment of the present disclosure may be broadly divided into a selection phase ( 510 ), a ping phase ( 520 ), an identification and configuration phase ( 530 ), a negotiation phase ( 540 ), a calibration phase ( 550 ), a power transfer phase ( 560 ), and a renegotiation phase ( 570 ). 
     If a specific error or a specific event is detected when the power transfer is initiated or while maintaining the power transfer, the selection phase ( 510 ) may include a shifting phase (or step)—reference numerals S 502 , S 504 , S 508 , S 510 , and S 512 . Herein, the specific error or specific event will be specified in the following description. Additionally, during the selection phase ( 510 ), the wireless power transmitter may monitor whether or not an object exists on an interface surface. If the wireless power transmitter detects that an object is placed on the interface surface, the process step may be shifted to the ping phase ( 520 ). During the selection phase ( 510 ), the wireless power transmitter may transmit an analog ping having a power signal (or a pulse) corresponding to an extremely short duration, and may detect whether or not an object exists within an active area of the interface surface based on a current change in the transmitting coil or the primary coil. 
     In case an object is sensed (or detected) in the selection phase ( 510 ), the wireless power transmitter may measure a quality factor of a wireless power resonance circuit (e.g., power transfer coil and/or resonance capacitor). According to the exemplary embodiment of the present disclosure, during the selection phase ( 510 ), the wireless power transmitter may measure the quality factor in order to determine whether or not a foreign object exists in the charging area along with the wireless power receiver. In the coil that is provided in the wireless power transmitter, inductance and/or components of the series resistance may be reduced due to a change in the environment, and, due to such decrease, a value of the quality factor may also be decreased. In order to determine the presence or absence of a foreign object by using the measured quality factor value, the wireless power transmitter may receive from the wireless power receiver a reference quality factor value, which is measured in advance in a state where no foreign object is placed within the charging area. The wireless power transmitter may determine the presence or absence of a foreign object by comparing the measured quality factor value with the reference quality factor value, which is received during the negotiation phase ( 540 ). However, in case of a wireless power receiver having a low reference quality factor value—e.g., depending upon its type, purpose, characteristics, and so on, the wireless power receiver may have a low reference quality factor value—in case a foreign object exists, since the difference between the reference quality factor value and the measured quality factor value is small (or insignificant), a problem may occur in that the presence of the foreign object cannot be easily determined. Accordingly, in this case, other determination factors should be further considered, or the present or absence of a foreign object should be determined by using another method. 
     According to another exemplary embodiment of the present disclosure, in case an object is sensed (or detected) in the selection phase ( 510 ), in order to determine whether or not a foreign object exists in the charging area along with the wireless power receiver, the wireless power transmitter may measure the quality factor value within a specific frequency area (e.g., operation frequency area). In the coil that is provided in the wireless power transmitter, inductance and/or components of the series resistance may be reduced due to a change in the environment, and, due to such decrease, the resonance frequency of the coil of the wireless power transmitter may be changed (or shifted). More specifically, a quality factor peak frequency that corresponds to a frequency in which a maximum quality factor value is measured within the operation frequency band may be moved (or shifted). 
     In the ping phase ( 520 ), if the wireless power transmitter detects the presence of an object, the transmitter activates (or Wakes up) a receiver and transmits a digital ping for identifying whether or not the detected object corresponds to the wireless power receiver. During the ping phase ( 520 ), if the wireless power transmitter fails to receive a response signal for the digital ping—e.g., a signal intensity packet—from the receiver, the process may be shifted back to the selection phase ( 510 ). Additionally, in the ping phase ( 520 ), if the wireless power transmitter receives a signal indicating the completion of the power transfer—e.g., charging complete packet—from the receiver, the process may be shifted back to the selection phase ( 510 ). 
     If the ping phase ( 520 ) is completed, the wireless power transmitter may shift to the identification and configuration phase ( 530 ) for identifying the receiver and for collecting configuration and status information. 
     In the identification and configuration phase ( 530 ), if the wireless power transmitter receives an unwanted packet (i.e., unexpected packet), or if the wireless power transmitter fails to receive a packet during a predetermined period of time (i.e., out of time), or if a packet transmission error occurs (i.e., transmission error), or if a power transfer contract is not configured (i.e., no power transfer contract), the wireless power transmitter may shift to the selection phase ( 510 ). 
     The wireless power transmitter may confirm (or verify) whether or not its entry to the negotiation phase ( 540 ) is needed based on a Negotiation field value of the configuration packet, which is received during the identification and configuration phase ( 530 ). Based on the verified result, in case a negotiation is needed, the wireless power transmitter enters the negotiation phase ( 540 ) and may then perform a predetermined FOD detection procedure. Conversely, in case a negotiation is not needed, the wireless power transmitter may immediately enter the power transfer phase ( 560 ). 
     In the negotiation phase ( 540 ), the wireless power transmitter may receive a Foreign Object Detection (FOD) status packet that includes a reference quality factor value. Or, the wireless power transmitter may receive an FOD status packet that includes a reference peak frequency value. Alternatively, the wireless power transmitter may receive a status packet that includes a reference quality factor value and a reference peak frequency value. At this point, the wireless power transmitter may determine a quality coefficient threshold value for FO detection based on the reference quality factor value. The wireless power transmitter may determine a peak frequency threshold value for FO detection based on the reference peak frequency value. 
     The wireless power transmitter may detect the presence or absence of an FO in the charging area by using the determined quality coefficient threshold value for FO detection and the currently measured quality factor value (i.e., the quality factor value that was measured before the ping phase), and, then, the wireless power transmitter may control the transmitted power in accordance with the FO detection result. For example, in case the FO is detected, the power transfer may be stopped. However, the present disclosure will not be limited only to this. 
     The wireless power transmitter may detect the presence or absence of an FO in the charging area by using the determined peak frequency threshold value for FO detection and the currently measured peak frequency value (i.e., the peak frequency value that was measured before the ping phase), and, then, the wireless power transmitter may control the transmitted power in accordance with the FO detection result. For example, in case the FO is detected, the power transfer may be stopped. However, the present disclosure will not be limited only to this. 
     In case the FO is detected, the wireless power transmitter may return to the selection phase ( 510 ). Conversely, in case the FO is not detected, the wireless power transmitter may proceed to the calibration phase ( 550 ) and may, then, enter the power transfer phase ( 560 ). More specifically, in case the FO is not detected, the wireless power transmitter may determine the intensity of the received power that is received by the receiving end during the calibration phase ( 550 ) and may measure power loss in the receiving end and the transmitting end in order to determine the intensity of the power that is transmitted from the transmitting end. In other words, during the calibration phase ( 550 ), the wireless power transmitter may estimate the power loss based on a difference between the transmitted power of the transmitting end and the received power of the receiving end. The wireless power transmitter according to the exemplary embodiment of the present disclosure may calibrate the threshold value for the FOD detection by applying the estimated power loss. 
     In the power transfer phase ( 560 ), in case the wireless power transmitter receives an unwanted packet (i.e., unexpected packet), or in case the wireless power transmitter fails to receive a packet during a predetermined period of time (i.e., time-out), or in case a violation of a predetermined power transfer contract occurs (i.e., power transfer contract violation), or in case charging is completed, the wireless power transmitter may shift to the selection phase ( 510 ). 
     Additionally, in the power transfer phase ( 560 ), in case the wireless power transmitter is required to reconfigure the power transfer contract in accordance with a status change in the wireless power transmitter, the wireless power transmitter may shift to the renegotiation phase ( 570 ). At this point, if the renegotiation is successfully completed, the wireless power transmitter may return to the power transfer phase ( 560 ). 
     In this embodiment, the calibration step  550  and the power transfer phase  560  are divided into separate steps, but the calibration step  550  may be integrated into the power transfer phase  560 . In this case, operations in the calibration step  550  may be performed in the power transfer phase  560 . 
     The above-described power transfer contract may be configured based on the status and characteristic information of the wireless power transmitter and receiver. For example, the wireless power transmitter status information may include information on a maximum amount of transmittable power, information on a maximum number of receivers that may be accommodated, and so on. And, the receiver status information may include information on the required power, and so on. 
       FIG. 6  shows a power control method according to an exemplary embodiment of the present disclosure. 
     As shown in  FIG. 6 , in the power transfer phase ( 560 ), by alternating the power transfer and/or reception and communication, the wireless power transmitter ( 100 ) and the wireless power receiver ( 200 ) may control the amount (or size) of the power that is being transferred. The wireless power transmitter and the wireless power receiver operate at a specific control point. The control point indicates a combination of the voltage and the electric current that are provided from the output of the wireless power receiver, when the power transfer is performed. 
     More specifically, the wireless power receiver selects a desired control point, a desired output current/voltage, a temperature at a specific location of the mobile device, and so on, and additionally determines an actual control point at which the receiver is currently operating. The wireless power receiver calculates a control error value by using the desired control point and the actual control point, and, then, the wireless power receiver may transmit the calculated control error value to the wireless power transmitter as a control error packet. 
     Also, the wireless power transmitter may configure/control a new operating point—amplitude, frequency, and duty cycle—by using the received control error packet, so as to control the power transfer. Therefore, the control error packet may be transmitted/received at a constant time interval during the power transfer phase, and, according to the exemplary embodiment, in case the wireless power receiver attempts to reduce the electric current of the wireless power transmitter, the wireless power receiver may transmit the control error packet by setting the control error value to a negative number. And, in case the wireless power receiver intends to increase the electric current of the wireless power transmitter, the wireless power receiver transmit the control error packet by setting the control error value to a positive number. During the induction mode, by transmitting the control error packet to the wireless power transmitter as described above, the wireless power receiver may control the power transfer. 
     In the resonance mode, which will hereinafter be described in detail, the device may be operated by using a method that is different from the induction mode. In the resonance mode, one wireless power transmitter should be capable of serving a plurality of wireless power receivers at the same time. However, in case of controlling the power transfer just as in the induction mode, since the power that is being transferred is controlled by a communication that is established with one wireless power receiver, it may be difficult to control the power transfer of additional wireless power receivers. Therefore, in the resonance mode according to the present disclosure, a method of controlling the amount of power that is being received by having the wireless power transmitter commonly transfer (or transmit) the basic power and by having the wireless power receiver control its own resonance frequency. Nevertheless, even during the operation of the resonance mode, the method described above in  FIG. 6  will not be completely excluded. And, additional control of the transmitted power may be performed by using the method of  FIG. 6 . 
       FIG. 7  is a block diagram of a wireless power transmitter according to another exemplary embodiment of the present disclosure. This may belong to a wireless power transfer system that is being operated in the magnetic resonance mode or the shared mode. The shared mode may refer to a mode performing a several-for-one (or one-to-many) communication and charging between the wireless power transmitter and the wireless power receiver. The shared mode may be implemented as a magnetic induction method or a resonance method. 
     Referring to  FIG. 7 , the wireless power transmitter ( 700 ) may include at least one of a cover ( 720 ) covering a coil assembly, a power adapter ( 730 ) supplying power to the power transmitter ( 740 ), a power transmitter ( 740 ) transmitting wireless power, and a user interface ( 750 ) providing information related to power transfer processing and other related information. Most particularly, the user interface ( 750 ) may be optionally included or may be included as another user interface ( 750 ) of the wireless power transmitter ( 700 ). 
     The power transmitter ( 740 ) may include at least one of a coil assembly ( 760 ), an impedance matching circuit ( 770 ), an inverter ( 780 ), a communication unit ( 790 ), and a control unit ( 710 ). 
     The coil assembly ( 760 ) includes at least one primary coil generating a magnetic field. And, the coil assembly ( 760 ) may also be referred to as a coil cell. 
     The impedance matching circuit ( 770 ) may provide impedance matching between the inverter and the primary coil(s). The impedance matching circuit ( 770 ) may generate resonance from a suitable frequency that boosts the electric current of the primary coil(s). In a multi-coil power transmitter ( 740 ), the impedance matching circuit may additionally include a multiplex that routes signals from the inverter to a subset of the primary coils. The impedance matching circuit may also be referred to as a tank circuit. 
     The impedance matching circuit ( 770 ) may include a capacitor, an inductor, and a switching device that switches the connection between the capacitor and the inductor. The impedance matching may be performed by detecting a reflective wave of the wireless power that is being transferred (or transmitted) through the coil assembly ( 760 ) and by switching the switching device based on the detected reflective wave, thereby adjusting the connection status of the capacitor or the inductor or adjusting the capacitance of the capacitor or adjusting the inductance of the inductor. In some cases, the impedance matching may be carried out even though the impedance matching circuit ( 770 ) is omitted. This specification also includes an exemplary embodiment of the wireless power transmitter ( 700 ), wherein the impedance matching circuit ( 770 ) is omitted. 
     The inverter ( 780 ) may convert a DC input to an AC signal. The inverter ( 780 ) may be operated as a half-bridge inverter or a full-bridge inverter in order to generate a pulse wave and a duty cycle of an adjustable frequency. Additionally, the inverter may include a plurality of stages in order to adjust input voltage levels. 
     The communication unit ( 790 ) may perform communication with the power receiver. The power receiver performs load modulation in order to communicate requests and information corresponding to the power transmitter. Therefore, the power transmitter ( 740 ) may use the communication unit ( 790 ) so as to monitor the amplitude and/or phase of the electric current and/or voltage of the primary coil in order to demodulate the data being transmitted from the power receiver. 
     Additionally, the power transmitter ( 740 ) may control the output power to that the data may be transferred through the communication unit ( 790 ) by using a Frequency Shift Keying (FSK) method, and so on. 
     The control unit ( 710 ) may control communication and power transfer (or delivery) of the power transmitter ( 740 ). The control unit ( 710 ) may control the power transfer by adjusting the above-described operating point. The operating point may be determined by, for example, at least any one of the operation frequency, the duty cycle, and the input voltage. 
     The communication unit ( 790 ) and the control unit ( 710 ) may each be provided as a separate unit/device/chipset or may be collectively provided as one unit/device/chipset. 
       FIG. 8  shows a wireless power receiver according to another exemplary embodiment of the present disclosure. This may belong to a wireless power transfer system that is being operated in the magnetic resonance mode or the shared mode. 
     Referring to  FIG. 8 , the wireless power receiver ( 800 ) may include at least one of a user interface ( 820 ) providing information related to power transfer processing and other related information, a power receiver ( 830 ) receiving wireless power, a load circuit ( 840 ), and a base ( 850 ) supporting and covering the coil assembly. Most particularly, the user interface ( 820 ) may be optionally included or may be included as another user interface ( 820 ) of the wireless power receiver ( 800 ). 
     The power receiver ( 830 ) may include at least one of a power converter ( 860 ), an impedance matching circuit ( 870 ), a coil assembly ( 880 ), a communication unit ( 890 ), and a control unit ( 810 ). 
     The power converter ( 860 ) may convert the AC power that is received from the secondary coil to a voltage and electric current that are suitable for the load circuit. According to an exemplary embodiment, the power converter ( 860 ) may include a rectifier. The rectifier may rectify the received wireless power and may convert the power from an alternating current (AC) to a direct current (DC). The rectifier may convert the alternating current to the direct current by using a diode or a transistor, and, then, the rectifier may smooth the converted current by using the capacitor and resistance. Herein, a full-wave rectifier, a half-wave rectifier, a voltage multiplier, and so on that are implemented as a bridge circuit may be used as the rectifier. Additionally, the power converter may adapt a reflected impedance of the power receiver. 
     The impedance matching circuit ( 870 ) may provide impedance matching between a combination of the power converter ( 860 ) and the load circuit ( 840 ) and the secondary coil. According to an exemplary embodiment, the impedance matching circuit may generate a resonance of approximately 100 kHz, which may reinforce the power transfer. The impedance matching circuit ( 870 ) may include a capacitor, an inductor, and a switching device that switches the combination of the capacitor and the inductor. The impedance matching may be performed by controlling the switching device of the circuit that configured the impedance matching circuit ( 870 ) based on the voltage value, electric current value, power value, frequency value, and so on, of the wireless power that is being received. In some cases, the impedance matching may be carried out even though the impedance matching circuit ( 870 ) is omitted. This specification also includes an exemplary embodiment of the wireless power receiver ( 200 ), wherein the impedance matching circuit ( 870 ) is omitted. 
     The coil assembly ( 880 ) includes at least one secondary coil, and, optionally, the coil assembly ( 880 ) may further include an element shielding the metallic part of the receiver from the magnetic field. 
     The communication unit ( 890 ) may perform load modulation in order to communicate requests and other information to the power transmitter. 
     For this, the power receiver ( 830 ) may perform switching of the resistance or capacitor so as to change the reflected impedance. 
     The control unit ( 810 ) may control the received power. For this, the control unit ( 810 ) may determine/calculate a difference between an actual operating point and a target operating point of the power receiver ( 830 ). Thereafter, by performing a request for adjusting the reflected impedance of the power transmitter and/or for adjusting an operating point of the power transmitter, the difference between the actual operating point and the target operating point may be adjusted/reduced. In case of minimizing this difference, an optimal power reception may be performed. 
     The communication unit ( 890 ) and the control unit ( 810 ) may each be provided as a separate device/chipset or may be collectively provided as one device/chipset. 
       FIG. 9  shows a communication frame structure according to an exemplary embodiment of the present disclosure. This may correspond to a communication frame structure in a shared mode. 
     Referring to  FIG. 9 , in the shared mode, different forms of frames may be used along with one another. For example, in the shared mode, a slotted frame having a plurality of slots, as shown in (A), and a free format frame that does not have a specified format, as shown in (B), may be used. More specifically, the slotted frame corresponds to a frame for transmitting short data packets from the wireless power receiver ( 200 ) to the wireless power transmitter ( 100 ). And, since the free format frame is not configured of a plurality of slots, the free format frame may correspond to a frame that is capable of performing transmission of long data packets. 
     Meanwhile, the slotted frame and the free format frame may be referred to other diverse terms by anyone skilled in the art. For example, the slotted frame may be alternatively referred to as a channel frame, and the free format frame may be alternatively referred to as a message frame. 
     More specifically, the slotted frame may include a sync pattern indicating the starting point (or beginning) of a slot, a measurement slot, nine slots, and additional sync patterns each having the same time interval that precedes each of the nine slots. 
     Herein, the additional sync pattern corresponds to a sync pattern that is different from the sync pattern that indicates the starting point of the above-described frame. More specifically, the additional sync pattern does not indicate the starting point of the frame but may indicate information related to the neighboring (or adjacent) slots (i.e., two consecutive slots positioned on both sides of the sync pattern). 
     Among the nine slots, each sync pattern may be positioned between two consecutive slots. In this case, the sync pattern may provide information related to the two consecutive slots. 
     Additionally, the nine slots and the sync patterns being provided before each of the nine slots may have the same time interval. For example, the nine slots may have a time interval of 50 ms. And, the nine sync patterns may have a time length of 50 ms. 
     Meanwhile, the free format frame, as shown in (B) may not have a specific format apart from the sync pattern indicating the starting point of the frame and the measurement slot. More specifically, the free format frame is configured to perform a function that is different from that of the slotted frame. For example, the free format frame may be used to perform a function of performing communication of long data packets (e.g., additional owner information packets) between the wireless power transmitter and the wireless power receiver, or, in case of a wireless power transmitter being configured of multiple coils, to perform a function of selecting any one of the coils. 
     Hereinafter, a sync pattern that is included in each frame will be described in more detail with reference to the accompanying drawings. 
       FIG. 10  is a structure of a sync pattern according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 10 , the sync pattern may be configured of a preamble, a start bit, a response field, a type field, an info field, and a parity bit. In  FIG. 10 , the start bit is illustrated as ZERO. 
     More specifically, the preamble is configured of consecutive bits, and all of the bits may be set to 0. In other words, the preamble may correspond to bits for matching a time length of the sync pattern. 
     The number of bits configuring the preamble may be subordinate to the operation frequency so that the length of the sync pattern may be most approximate to 50 ms but within a range that does not exceed 50 ms. For example, in case the operation frequency corresponds to 100 kHz, the sync pattern may be configured of two preamble bits, and, in case the operation frequency corresponds to 105 kHz, the sync pattern may be configured of three preamble bits. 
     The start bit may correspond to a bit that follows the preamble, and the start bit may indicate ZERO. The ZERO may correspond to a bit that indicates a type of the sync pattern. Herein, the type of sync patterns may include a frame sync including information that is related to a frame, and a slot sync including information of the slot. More specifically, the sync pattern may be positioned between consecutive frames and may correspond to a frame sync that indicate a start of the frame, or the sync pattern may be positioned between consecutive slots among a plurality of slots configuring the frame and may correspond to a sync slot including information related to the consecutive slots. 
     For example, in case the ZERO is equal to 0, this may indicate that the corresponding slot is a slot sync that is positioned in-between slots. And, in case the ZERO is equal to 1, this may indicate that the corresponding sync pattern is a frame sync being located in-between frames. 
     A parity bit corresponds to a last bit of the sync pattern, and the parity bit may indicate information on a number of bits configuring the data fields (i.e., the response field, the type field, and the info field) that are included in the sync pattern. For example, in case the number of bits configuring the data fields of the sync pattern corresponds to an even number, the parity bit may be set to when, and, otherwise (i.e., in case the number of bits corresponds to an odd number), the parity bit may be set to 0. 
     The response field may include response information of the wireless power transmitter for its communication with the wireless power receiver within a slot prior to the sync pattern. For example, in case a communication between the wireless power transmitter and the wireless power receiver is not detected, the response field may have a value of ‘00’. Additionally, if a communication error is detected in the communication between the wireless power transmitter and the wireless power receiver, the response field may have a value of ‘01’. The communication error corresponds to a case where two or more wireless power receivers attempt to access one slot, thereby causing collision to occur between the two or more wireless power receivers. 
     Additionally, the response field may include information indicating whether or not the data packet has been accurately received from the wireless power receiver. More specifically, in case the wireless power transmitter has denied the data packet, the response field may have a value of “10” (10—not acknowledge (NAK)). And, in case the wireless power transmitter has confirmed the data packet, the response field may have a value of “11” (11—acknowledge (ACK)). 
     The type field may indicate the type of the sync pattern. More specifically, in case the sync pattern corresponds to a first sync pattern of the frame (i.e., as the first sync pattern, in case the sync pattern is positioned before the measurement slot), the type field may have a value of ‘1’, which indicates a frame sync. 
     Additionally, in a slotted frame, in case the sync pattern does not correspond to the first sync pattern of the frame, the type field may have a value of ‘0’, which indicates a slot sync. 
     Moreover, the information field may determine the meaning of its value in accordance with the sync pattern type, which is indicated in the type field. For example, in case the type field is equal to 1 (i.e., in case the sync pattern type indicates a frame sync), the meaning of the information field may indicate the frame type. More specifically, the information field may indicate whether the current frame corresponds to a slotted frame or a free-format frame. For example, in case the information field is given a value of ‘00’, this indicates that the current frame corresponds to a slotted frame. And, in case the information field is given a value of ‘01’, this indicates that the current frame corresponds to a free-format frame. 
     Conversely, in case the type field is equal to 0 (i.e., in case the sync pattern type indicates a slot sync), the information field may indicate a state of a next slot, which is positioned after the sync pattern. More specifically, in case the next slot corresponds to a slot that is allocated (or assigned) to a specific wireless power receiver, the information field is given a value of ‘00’. In case the next slot corresponds to a slot that is locked, so as to be temporarily used by the specific wireless power receiver, the information field is given a value of ‘01’. Alternatively, in case the next slot corresponds to a slot that may be freely used by a random wireless power receiver, the information field is given a value of ‘10’. 
       FIG. 11  shows operation statuses of a wireless power transmitter and a wireless power receiver in a shared mode according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG. 11 , the wireless power receiver operating in the shared mode may be operated in any one of a selection phase ( 1100 ), an introduction phase ( 1110 ), a configuration phase ( 1120 ), a negotiation phase ( 1130 ), and a power transfer phase ( 1140 ). 
     Firstly, the wireless power transmitter according to the exemplary embodiment of the present disclosure may transmit a wireless power signal in order to detect the wireless power receiver. More specifically, a process of detecting a wireless power receiver by using the wireless power signal may be referred to as an Analog ping. 
     Meanwhile, the wireless power receiver that has received the wireless power signal may enter the selection phase ( 1100 ). As described above, the wireless power receiver that has entered the selection phase ( 1100 ) may detect the presence or absence of an FSK signal within the wireless power signal. 
     In other words, the wireless power receiver may perform communication by using any one of an exclusive mode and a shared mode in accordance with the presence or absence of the FSK signal. 
     More specifically, in case the FSK signal is included in the wireless power signal, the wireless power receiver may operate in the shared mode, and, otherwise, the wireless power receiver may operate in the exclusive mode. 
     In case the wireless power receiver operates in the shared mode, the wireless power receiver may enter the introduction phase ( 1110 ). In the introduction phase ( 1110 ), the wireless power receiver may transmit a control information (CI) packet to the wireless power transmitter in order to transmit the control information packet during the configuration phase, the negotiation phase, and the power transfer phase. The control information packet may have a header and information related to control. For example, in the control information packet, the header may correspond to 0X53. 
     In the introduction phase ( 1110 ), the wireless power receiver performs an attempt to request a free slot for transmitting the control information (CI) packet during the following configuration phase, negotiation phase, and power transfer phase. At this point, the wireless power receiver selects a free slot and transmits an initial CI packet. If the wireless power transmitter transmits an ACK as a response to the corresponding CI packet, the wireless power receiver enters the configuration phase. If the wireless power transmitter transmits a NAK as a response to the corresponding CI packet, this indicates that another wireless power receiver is performing communication through the configuration and negotiation phase. In this case, the wireless power receiver re-attempts to perform a request for a free slot. 
     If the wireless power receiver receives an ACK as a response to the CI packet, the wireless power receiver may determine the position of a private slot within the frame by counting the remaining sync slots up to the initial frame sync. In all of the subsequent slot-based frames, the wireless power receiver transmits the CI packet through the corresponding slot. 
     If the wireless power transmitter authorizes the entry of the wireless power receiver to the configuration phase, the wireless power transmitter provides a locked slot series for the exclusive usage of the wireless power receiver. This may ensure the wireless power receiver to proceed to the configuration phase without any collision. 
     The wireless power receiver transmits sequences of data packets, such as two identification data packets (IDHI and IDLO), by using the locked slots. When this phase is completed, the wireless power receiver enters the negotiation phase. During the negotiation state, the wireless power transmitter continues to provide the locked slots for the exclusive usage of the wireless power receiver. This may ensure the wireless power receiver to proceed to the negotiation phase without any collision. 
     The wireless power receiver transmits one or more negotiation data packets by using the corresponding locked slot, and the transmitted negotiation data packet(s) may be mixed with the private data packets. Eventually, the corresponding sequence is ended (or completed) along with a specific request (SRQ) packet. When the corresponding sequence is completed, the wireless power receiver enters the power transfer phase, and the wireless power transmitter stops the provision of the locked slots. 
     In the power transfer phase, the wireless power receiver performs the transmission of a CI packet by using the allocated slots and then receives the power. The wireless power receiver may include a regulator circuit. The regulator circuit may be included in a communication/control unit. The wireless power receiver may self-regulate a reflected impedance of the wireless power receiver through the regulator circuit. In other words, the wireless power receiver may adjust the impedance that is being reflected for an amount of power that is requested by an external load. This may prevent an excessive reception of power and overheating. 
     In the shared mode, (depending upon the operation mode) since the wireless power transmitter may not perform the adjustment of power as a response to the received CI packet, in this case, control may be needed in order to prevent an overvoltage state. 
     NFC/RFID Detection Method 
     In the case that a Radio-Frequency Identification (RFID) card or a Near Field Communication (NFC) card is placed between a power transmitter (e.g., wireless charger) and a power receiver (e.g., mobile device, etc.), the power transmission without an RFID/NFC card detection function is unable to detect the RFID/NFC card. In addition, the power transmitter and receiver are unable to detect the RFID/NFC card with the FOD method defined in WPC, which is a standard related to a wireless power transmission/reception system. The reason is that, in the FOD method defined in WPC, a foreign object is detected based on an amount of loss of power transmitted to the power receiver from the power transmitter (e.g., the case that it is detected a transmission efficiency is under a predetermined level, etc.). However, a power loss does not occur even in the case that the RFID/NFC card is placed between the power transmitter and the power receiver. Furthermore, since an operation frequency (e.g., about 100 to 205 kHz) of the power transmitter/receiver defined in WPC is different from an operation frequency (e.g., about 13.56 MHz) of the RFID/NFC card, a detection of the RFID/NFC card is unavailable even in the case of using the frequencies. 
     As such, in the case that a wireless power transmitter/receiver is unavailable to detect a presence of the RFID/NFC card and maintain a power transmission, the RFID/NFC card continuously exposed to a strong magnetic field may be damaged eventually, and there is a problem that it gives financial damage to a user. Furthermore, a safety problem caused by a heat generation of the RFID/NFC card may also be presented. For example, most of the RFID or NFC card used for a finance (bank) related card or a smart card may be safe in a digital ping level but may be damaged in a power compensation stage or a power transmission stage. Furthermore, a safety problem due to heat generation of the RFID/NFC card may be raised. 
     Accordingly, in the present disclosure, a method is proposed to detect the RFID/NFC card or module. 
     According to the present disclosure, the RFID card or the NFC card may be detected by both of a wireless power transmitter and a wireless power reception device. 
     In one example, the wireless power transmitter may be implemented to be provided with an RFID/NFC detector that may detect RFID/NFC within a near field. 
     In another example, the wireless power receiver may be implemented to be provided with an RFID/NFC detector that may detect RFID/NFC within a near field. 
     In another example, the wireless power receiver may be implemented to be provided with an NFC function in an embedded form that may detect RFID/NFC within a near field. 
     In order to attain the method, a method for exchanging a packet (or information) needs to be defined for RFID/NFC detection (or protection) between the wireless power transmitter and the wireless power reception device. 
     Particularly, the wireless power reception device is required to know whether the wireless power transmitter is provided with a performance or ability to detect the RFID/NFC card. In addition, in the case that the wireless power reception device itself is provided with the RFID/NFC card detection function, the wireless power reception device is required to know whether the RFID/NFC card or tag is detected. Furthermore, in the case that the wireless power reception device detects RFID/NFC, the wireless power reception device is required to transfer the related information to the wireless power transmitter and is required to prevent the wireless power transmitter from entering a further power transmission stage. 
     According to the embodiment, the wireless power transmitter may indicate or inform whether the wireless power transmitter is provided with an ability or performance to detect the RFID/NFC card to the wireless power reception device. In addition, the wireless power transmitter may transmit performance information for detecting the RFID/NFC card in the proximity to the wireless power reception device. 
       FIG. 12  is a flowchart for a method for detecting RFID or NFC according to an embodiment. The method according to  FIG. 12  may be performed in a negotiation stage, for example. 
     Referring to  FIG. 12 , in order to identify whether the wireless power transmitter has an ability to detect other communication card, the wireless power reception device transmits a request packet to the wireless power transmitter (step, S 1200 ). Here, the other communication card includes an RFID card or an NFC card. The other communication card detection ability information may also be called RFID/NFC card detection ability information. 
     The wireless power reception device is required to know whether the wireless power transmitter has an ability to detect other communication card to determine whether to activate a function for detecting other communication card embedded thereon. Therefore, in the negotiation stage, the wireless power reception device may inquire whether the wireless power transmitter has the ability to detect other communication card and/or in the case that the wireless power transmitter has the ability to detect other communication card, whether other communication card is detected to the wireless power transmitter. In this case, the request packet may be used. 
     In one example, the request packet may be a general request packet. In order to read an FOD packet of the wireless power transmitter, the general request packet may indicate a value of 0X31, for example. 
     In another example, the request packet may be a specific request packet. The specific request packet may indicate a value of 0x05, for example, as a new code value in relation to the safety of the other communication card. The wireless power transmitter that receives the specific request packet may transmit at least three types of response information (ACK, NAK, ND) to the wireless power reception device. In the case that the wireless power transmitter fails to detect the other communication card (RFID, NFC, etc.), the wireless power transmitter may transmit ACK response information to the wireless power reception device. In the case that the wireless power transmitter detects the other communication card (RFID, NFC, etc.), the wireless power transmitter may transmit NACK response information to the wireless power reception device. In the case that the wireless power transmitter fails to identify the new code value or fails to know whether the other communication card (RFID, NFC, etc.) is present clearly, the wireless power transmitter may transmit ND response information to the wireless power reception device. 
     Next, when the wireless power transmitter receives the request packet, the wireless power transmitter transmits the other communication card detection ability information to the wireless power reception device (step, S 1205 ). The other communication card detection ability information may include at least one of protection ability present (PAP) information that indicates whether the wireless power transmitter has a protection ability of other communication card and card detection (CD) information that indicates whether the wireless power transmitter detects other communication card. 
     In one example, the other communication card detection ability information may be transmitted in an FOD packet. Here, the structure of the FOD packet according to the embodiment may be as shown in  FIG. 13 , for example. 
     Referring to  FIG. 13 , as 8 bits, the FOD packet may include an FOD field of 1 bit that indicates a detection of foreign object (FO), a reserved bit, a protection ability present (PAP) field, and a card detection field. 
     The protection ability present (PAP) field is 1 bit, for example. In the case that the field value is 0 (or ‘00’b), this indicates that the wireless power transmitter does not have the ability to detect other communication card (or the ability to detect other communication card is not present, e.g., NFC protected=‘00’ b), and in the case that the field value is 1, this indicates that the wireless power transmitter has the ability to detect other communication card (or the ability to detect other communication card is present, e.g., NFC protected=‘01’b). 
     The card detection field is 1 bit, for example. In the case that the field value is 0, this indicates that the wireless power transmitter does not detect other communication card, and in the case that the field value is 1, this indicates that the wireless power transmitter detects other communication card. 
     The FOD field is 1 bit, for example. In the case that the field value is 0, this indicates that the wireless power transmitter does not detect a foreign object, and in the case that the field value is 1, this indicates that the wireless power transmitter detects a foreign object. 
     Here, in the case that the other communication card is an NFC card, for example, the FOD packet structure of  FIG. 13  may be replaced by the fields having the names shown in  FIG. 14 , for example. In  FIG. 14 , the information indicated by the NFCPAP field is the same as that of the protection ability present field of  FIG. 13 , and the information indicated by the NFCCD field is the same as that of the card detection field of  FIG. 13 . 
     In another example, the other communication card detection ability information may be transmitted with being included in a capability packet of the wireless power transmitter. Here, the structure of the capability packet according to the embodiment may be as shown in  FIG. 15 , for example. 
     Referring to  FIG. 15 , a TX capability packet is 3 bytes, and may include a protection ability present field and a card detection field, each is 1 bit. The information indicated by the protection ability present field and the card detection field they are the same as described with reference to  FIG. 13 . In the case that the other communication card is an NFC card, for example, the TX capability packet structure shown in  FIG. 15  may be replaced by the fields having the same names as shown in  FIG. 16 . That is, in  FIG. 16 , the information indicated by NFCPAP field is the same as that of the protection ability present field shown in  FIG. 15 , and the information indicated by NFCCD field is the same as that of the card detection field shown in  FIG. 15 . 
     Referring to  FIG. 12  again, in the case that the other communication card detection ability information indicates that the wireless power transmitter does not have the other communication card detection ability (e.g., card protection=‘00’b) (step, S 1210 ), the wireless power receiver transmits a first end power transfer (EPT) packet to the wireless power transmitter (step, S 1215 ). In this case, a re-ping packet may be transmitted together with the first EPT packet. Table 4 represents an example of code values indicated by the EPT packet. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 &gt; 0x00—EPT/nul—use if none of the other codes is appropriated.&gt; 0x01—Reserved&gt; 
               
               
                 0x02—EPT/if—internal fault; use if an internal logic error has been encountered.&gt; 
               
               
                 0x03—EPT/ot—over temperature; use if (e.g.) the battery temperature exceeds a limit.&gt; 
               
               
                 0x04—EPT/ov—over voltage; use if a voltage exceeds a limit.&gt; 0x05—EPT/oc—over 
               
               
                 current; use if the current exceeds a limit.&gt; 0x06—Reserved&gt; 0x08—Reserved.&gt; 
               
               
                 0x0A—Reserved.&gt; 0x0B—EPT/rst—restart; use to restart the power transfer. NOTE 
               
               
                 Typically, a Power Transmitter engages in FOD after stopping the power transfer and before 
               
               
                 restarting it. For details about this procedure, see the Qi Specification, Foreign Object 
               
               
                 Detection.&gt; 0x0C—EPT/rep—re-ping; use to restart the power transfer after a specified delay 
               
               
                 (the re-ping delay).NOTE A Power Receiver should use this End Power Transfer Code only 
               
               
                 if it has verified that the Power Transmitter complies with version 1.3 or higher of the Qi 
               
               
                 Specification.&gt; EPT/for RFID detection — to turn off the magnetic field from PTx 
               
               
                 temporarily to detect RFID cards without interference&gt; EPT/fod — Pre-power FOD and re- 
               
               
                 calibration 
               
               
                   
               
            
           
         
       
     
     Referring to Table 4, the first EPT packet may indicate EPT/for RFID detection or 0x0C, for example. When receiving the first EPT packet, the wireless power transmitter stops the power transfer. 
     The wireless power receiver may halt the magnetic field (i.e., wireless power) generated by the wireless power transmitter temporarily by transmitting the first EPT packet and perform a detection of other communication card during a re-ping time in a state that an interference due to the magnetic field is not present (step, S 1220 ). That is, the wireless power receiver activates an embedded RFID/NFC card detector (or detection function) during the re-ping time and detects the RFID/NFC card. 
     In the case that the other communication card (RFID and/or NFC card) is detected during the re-ping time, the wireless power receiver transmits a second EPT packet to the wireless power transmitter again (step, S 1225 ), and forces (or requests) the wireless power transmitter to remove a power signal on a starting time of a ping step. In this case, the second EPT packet value may be a value of other communication card detection, for example, 0X0D. The second EPT packet may have the structure shown in  FIG. 17 , for example. Here, the value (or code) indicated by the second EPT value may be a new value different from the existing code, for example, a reason why the other communication card (RFID and/or NFC card) is detected in an adjacent position. 
     Table 5 represents another example of code values indicated by the EPT packet. 
     
       
         
           
               
             
               
                 TABLE 5 
               
               
                   
               
             
            
               
                 &gt; 0x00—EPT/nul—use if none of the other codes is appropriate.&gt; 0x01—Reserved&gt; 
               
               
                 0x02—EPT/if—internal fault; use if an internal logic error has been encountered.&gt; 
               
               
                 0x03—EPT/ot—over temperature; use if (e.g.) the battery temperature exceeds a limit.&gt; 
               
               
                 0x04—EPT/ov—over voltage; use if a voltage exceeds a limit.&gt; 0x05—EPT/oc—over 
               
               
                 current; use if the current exceeds a limit.&gt; 0x06—Reserved&gt; 0x08—Reserved.&gt; 
               
               
                 0x0A—Reserved.&gt; 0x0B—EPT/rst—restart; use to restart the power transfer.NOTE 
               
               
                 Typically, a Power Transmitter engages in FOD after stopping the power transfer and 
               
               
                 before restarting it. For details about this procedure, see the Qi Specification, Foreign 
               
               
                 Object Detection.&gt; 0x0C—EPT/rep—re-ping; use to restart the power transfer after a 
               
               
                 specified delay (the re-ping delay).NOTE A Power Receiver should use this End Power 
               
               
                 Transfer Code only if it has verified that the Power Transmitter complies with version 1.3 
               
               
                 or higher of the Qi Specification.&gt; EPT/rfid—RFID/NFC card; use if an RFID/NFC card 
               
               
                 has been detected&gt; EPT/fod — Pre-power FOD and re-calibration 
               
               
                   
               
            
           
         
       
     
     When receiving the second EPT packet, the wireless power transmitter identifies that other communication card is detected and removes even a power signal in the ping step (step, S 1230 ). 
     In the case that the other communication card detection ability information of the wireless power transmitter according to an embodiment has both the protection ability present information and the card detection information, Table 6 represents an example of an interpretation method and an operation method of each apparatus. 
     
       
         
           
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 Protection 
                   
                   
               
               
                 ability 
                   
                 Operation of the wireless 
               
               
                 present 
                 Card detection 
                 power transmitter 
               
               
                   
               
             
            
               
                 0 
                 does not matter 
                 Other communication card detection 
               
               
                 0 
                 does not matter 
                 function is activated (since the wireless 
               
               
                   
                   
                 power transmitter does not have the other 
               
               
                   
                   
                 communication card detection function, the 
               
               
                   
                   
                 wireless power transmitter may activate the 
               
               
                   
                   
                 detection function autonomously) - If the 
               
               
                   
                   
                 wireless power receiver detects other 
               
               
                   
                   
                 communication card autonomously, the 
               
               
                   
                   
                 wireless power t reception apparatus 
               
               
                   
                   
                 transmits an EPT packet 
               
               
                 1 
                 0 
                 The wireless power transmitter fails to 
               
               
                   
                   
                 detect other communication card. - The 
               
               
                   
                   
                 wireless power receiver and the wireless 
               
               
                   
                   
                 power transmitter enter a power 
               
               
                   
                   
                 compensation step and a power transmission 
               
               
                   
                   
                 step. 
               
               
                 1 
                 1 
                 The wireless power transmitter detects other 
               
               
                   
                   
                 communication card - Both the wireless 
               
               
                   
                   
                 power receiver and the wireless power 
               
               
                   
                   
                 transmitter cut off entering a power 
               
               
                   
                   
                 transmission step until the other 
               
               
                   
                   
                 communication card is removed. 
               
               
                   
               
            
           
         
       
     
     In the case that the other communication card detection ability information of the wireless power transmitter according to an embodiment is the FOD packet shown in  FIG. 14 , Table 7 represents an example of an interpretation method and an operation method of each apparatus. That is, an operation of the wireless power receiver may be determined according to a combination of the values indicated by the FOD field, the NFCPAP field and the NFCCD. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 FOD 
                 NFCPAP 
                 NFCCD 
                 Operation of the wireless power receiver 
               
               
                   
               
             
            
               
                 0 
                 0 
                 does not matter 
                 Other communication card detection function is 
               
               
                 0 
                 0 
                 does not matter 
                 activated (since the wireless power transmitter does 
               
               
                   
                   
                   
                 not have the other communication card detection 
               
               
                   
                   
                   
                 function, the wireless power transmitter may activate 
               
               
                   
                   
                   
                 the detection function autonomously) - If the 
               
               
                   
                   
                   
                 wireless power receiver detects other 
               
               
                   
                   
                   
                 communication card autonomously, the wireless 
               
               
                   
                   
                   
                 power t reception apparatus transmits an EPT packet. 
               
               
                 1 
                 0 
                 does not matter 
                 The wireless power transmitter detects a foreign 
               
               
                   
                   
                   
                 object. - The wireless power transmitter informs a 
               
               
                   
                   
                   
                 user to remove the foreign object - The wireless 
               
               
                   
                   
                   
                 power receiver and the wireless power transmitter 
               
               
                   
                   
                   
                 enter a power compensation step and a power 
               
               
                   
                   
                   
                 transmission step until other communication card is 
               
               
                   
                   
                   
                 removed. 
               
               
                 0 
                 1 
                 0 
                 The wireless power transmitter fails to detect a 
               
               
                   
                   
                   
                 foreign object and other communication card. - The 
               
               
                   
                   
                   
                 wireless power receiver and the wireless power 
               
               
                   
                   
                   
                 transmitter enter a power compensation step and a 
               
               
                   
                   
                   
                 power transmission step. 
               
               
                 1 
                 1 
                 1 
                 The wireless power transmitter detects both a 
               
               
                   
                   
                   
                 foreign object and other communication card. - The 
               
               
                   
                   
                   
                 wireless power transmitter informs a user to remove 
               
               
                   
                   
                   
                 the foreign object and the other communication card 
               
               
                   
                   
                   
                 (RFID, NFC). - Both the wireless power receiver and 
               
               
                   
                   
                   
                 the wireless power transmitter cut off entering a 
               
               
                   
                   
                   
                 power transmission step until the other 
               
               
                   
                   
                   
                 communication card is removed. 
               
               
                   
               
            
           
         
       
     
     In the embodiment described above, as a subject of performing the RFID/NFC detection operation, the wireless power receiver is mainly described, but the present disclosure is not limited thereto, and the wireless power transmitter may also function as a subject of performing the RFID/NFC detection operation. However, in order to perform the RFID/NFC detection operation, it is assumed that the wireless power transmitter is also embedded/mounted with an RFID/NFC reader unit (or NFC functional unit) which is available to detect RFID/NFC (in an adjacent position). 
     The wireless power transmitter according to the embodiments shown in  FIG. 12  to  FIG. 17  corresponds to the wireless power transmitter, the wireless power transmitter or the power transmitter described with reference to  FIG. 1  to  FIG. 11 . Accordingly, the operation of the wireless power transmitter in this embodiment may be implemented by one or a combination of two or more of the elements of the wireless power transmitter shown in  FIG. 1  to  FIG. 11 . For example, the operation of transmitting wireless power in this embodiment may be performed by a power transform unit  110 . In addition, in this embodiment, the operation of receiving a request packet, the operation of detecting other communication card, the operation of generating and transmitting other communication card detection ability information, the operation of receiving a first EPT packet, the operation of receiving a second EPT packet, and the like may be performed by a communication/control unit  120 . 
     Furthermore, the wireless power receiver according to the embodiments shown in  FIG. 12  to  FIG. 17  corresponds to the wireless power receiver, the wireless power receiver or the power receiver described with reference to  FIG. 1  to  FIG. 11 . Accordingly, the operation of the wireless power receiver in this embodiment may be implemented by one or a combination of two or more of the elements of the wireless power receiver shown in  FIG. 1  to  FIG. 11 . For example, the operation of receiving wireless power in this embodiment may be performed by a power pickup unit  210 . In addition, in this embodiment, the operation of generating and transmitting a request packet, the operation of receiving other communication card detection ability information, the operation of generating and transmitting a first EPT packet, the operation of detecting other communication card, the operation of generating and transmitting a second EPT packet, and the like may be performed by a communication/control unit  220 . 
       FIG. 18  is a diagram illustrated for describing an operation for the wireless power receiver to detect other communication card throughout the entire periods of a state diagram for a wireless power transmission according to an embodiment. 
     Referring to  FIG. 18 , in a selection stage, while the wireless power transmitter transmits an analog ping signal (step, S 1800 ), in the case that the wireless power transmitter identifies that the wireless power receiver PRx is placed on a part in which a power reception is available (step, S 1805 ), the wireless power transmitter may enter a ping step, an identification and configuration step, and a negotiation step, sequentially (steps, S 1810 , S 1815  and S 1820 ). 
     In the negotiation step, the wireless power receiver identifies other communication card detection ability of the wireless power transmitter as shown in  FIG. 12 , and then, determines to activate other communication card detection function (step, S 1825 ). This embodiment is described under the assumption that the wireless power transmitter does not have the other communication card detection ability. 
     Accordingly, during the re-ping time, other communication card detection is performed by the wireless power transmitter (step, S 1830 ). 
     In the case that other communication card is not detected by the wireless power receiver, the wireless power transmitter and the wireless power receiver perform a power transmission by entering the power transmission step (S 1855 ) through the ping step (S 1835 ), the identification and configuration step (S 1840 ), the negotiation step (S 1845 ) and the power compensation step (S 1850 ). 
     On the other hand, in the case that other communication card is detected by the wireless power receiver, the wireless power transmitter and the wireless power receiver transmit the EPT packet and induce stopping the power transmission of the wireless power transmitter (step, S 1860 ). 
     The wireless power transmitter according to the embodiments shown in  FIG. 18  corresponds to the wireless power transmitter, the wireless power transmitter or the power transmitter described with reference to  FIG. 1  to  FIG. 11 . Accordingly, the operation of the wireless power transmitter in this embodiment may be implemented by one or a combination of two or more of the elements of the wireless power transmitter shown in  FIG. 1  to  FIG. 11 . For example, the operation of transmitting wireless power in this embodiment may be performed by a power transform unit  110 . In addition, in this embodiment, the operation of receiving a request packet, the operation of detecting other communication card, the operation of generating and transmitting other communication card detection ability information, the operation of receiving a first EPT packet, the operation of receiving a second EPT packet, and the like may be performed by a communication/control unit  120 . 
     Furthermore, the wireless power receiver according to the embodiments shown in  FIG. 18  corresponds to the wireless power receiver, the wireless power receiver or the power receiver described with reference to  FIG. 1  to  FIG. 11 . Accordingly, the operation of the wireless power receiver in this embodiment may be implemented by one or a combination of two or more of the elements of the wireless power receiver shown in  FIG. 1  to  FIG. 11 . For example, the operation of receiving wireless power in this embodiment may be performed by a power pickup unit  210 . In addition, in this embodiment, the operation of generating and transmitting a request packet, the operation of receiving other communication card detection ability information, the operation of generating and transmitting a first EPT packet, the operation of detecting other communication card, the operation of generating and transmitting a second EPT packet, and the like may be performed by a communication/control unit  220 . 
     Since the wireless power transmitting method and apparatus or the wireless power receiver and method according to an embodiment of the present disclosure do not necessarily include all the elements or operations, the wireless power transmitter and method and the wireless power transmitter and method may be performed with the above-mentioned components or some or all of the operations. Also, embodiments of the above-described wireless power transmitter and method, or receiving apparatus and method may be performed in combination with each other. Also, each element or operation described above is necessarily performed in the order as described, and an operation described later may be performed prior to an operation described earlier. 
     The description above is merely illustrating the technical spirit of the present disclosure, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present disclosure. Therefore, the embodiments of the present disclosure described above may be implemented separately or in combination with each other. 
     Therefore, the embodiments disclosed in the present disclosure are intended to illustrate rather than limit the scope of the present disclosure, and the scope of the technical spirit of the present disclosure is not limited by these embodiments. The scope of the present disclosure should be construed by claims below, and all technical spirits within a range equivalent to claims should be construed as being included in the right scope of the present disclosure.