NEAR-FIELD COMMUNICATION (NFC) SYSTEM AND METHOD FOR HIGH PERFORMANCE NFC AND WIRELESS POWER TRANSFER WITH SMALL ANTENNAS

• US 20170288736A1
• Filed: 03/17/2017
• Published: 10/05/2017
• Est. Priority Date: 04/01/2016
• Status: Active Grant

• Current Assignee: Hangzhou Chivotech Limited
• Original Assignee: Fusens Technology Limited
• Inventors: ZHOU, Ruogu, WANG, Qingbin
• Granted Patent: US 10,666,325 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 1/248 provided with an AC/DC converting device, e.g. rectennas
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A method for a near-field communication (NFC) tag to perform NFC and wireless power transfer (WPT) with an NFC reader, the NFC tag having an antenna resonant circuit, of which a quality factor (Q-factor) is no lower than 50 in a high-Q mode of the NFC tag, and no higher than 25 in a low-Q mode of the NFC tag. The method includes continuously preforming steps of detecting an NFC radio frequency (RF) field generated by the NFC reader, measuring strength of the NFC RF field, operating in the high-Q mode for the WPT upon determining that the strength of the NFC RF field is larger than a predetermined threshold, operating in the low-Q mode for the NFC upon determining that the strength of the NFC RF field is smaller than the predetermined threshold, and transmitting a response back to the NFC reader.

Claims

1. A near-field communication (NFC) reader for concurrent NFC and wireless power transfer (WPT) with an NFC tag, the NFC reader comprising:

a high-Q-factor antenna resonant circuit of which a quality factor (Q-factor) is no lower than 50, and

a low-Q-factor antenna resonant circuit of which the Q-factor is no higher than 25, wherein

the NFC reader is configured to generate an oscillating NFC radio frequency (RF) magnetic field, and

to transmit first data to the NFC tag for the NFC, using the low-Q-factor antenna resonant circuit, and

to transmit energy to the NFC tag for the WPT and to receive second data from the NFC tag, using the high-Q-factor antenna resonant circuit.

2. The NFC reader of claim 1, wherein the NFC reader activates one of the high-Q-factor antenna resonant circuit and the low-Q-factor antenna resonant circuit at a time by routing a transmission signal to the one antenna resonant circuit.

3. A near-field communication (NFC) tag for concurrent NFC and wireless power transfer (WPT) with an NFC reader, comprising:

a high-Q-factor antenna resonant circuit of which a quality factor (Q-factor) is no lower than 50, and

a low-Q-factor antenna resonant circuit of which the Q-factor is no higher than 25, wherein

the NFC tag is to configured to

receive a first NFC signal transmitted by the NFC reader using the low-Q-factor antenna resonant circuit, and

receive energy contained in a NFC radio frequency (RF) magnetic field transferred by the NFC reader in the WPT, and transmit a second NFC signal to the NFC reader, using the high-Q-factor antenna resonant circuit.

4. The NFC tag of claim 3, wherein the NFC tag is powered by the energy received through the WPT, and is configured to power an external device connected thereto.

5. The NFC tag of claim 3, wherein

the high-Q-factor and lower-Q-factor antenna resonant circuits have at least one shared component, and

the high-Q-factor and lower-Q-factor antenna resonant circuits are configured to be activated one at a time.

6. The NFC tag of claim 3, wherein the high-Q-factor and lower-Q-factor antenna resonant circuits have no shared component, and are configured to be activated simultaneously.

7. A method for a near-field communication (NFC) reader to perform NFC and wireless power transfer (WPT) with an NFC tag, the NFC reader including

a high-Q-factor antenna resonant circuit of which a quality factor (Q-factor) is no lower than 50, and

a low-Q-factor antenna resonant circuit of which the Q-factor is no higher than 25, and

being operable in one of

a high-Q mode using the high-Q-factor antenna resonant circuit, and

a low-Q mode using the low-Q-factor antenna resonant circuit,

the method comprising:

repeatedly performing steps of

generating an NFC radio frequency (RF) field that has a central frequency of 13.56 Mhz in the high-Q mode using the high-Q-factor antenna resonant circuit;

transmitting a modulated signal in the low-Q mode using the low-Q-factor antenna resonant circuit; and

waiting to receive a response from the NFC tag in the high-Q mode, and

if the response is received within a predetermined time, continuing to generate the NFC RF field in the high-Q mode, and

if no response is received within the predetermined time, stopping generating the NFC RF field.

8. The method of claim 7, wherein the NFC reader starts to perform the step of generating the NFC RF field upon power-up.

9. The method of claim 7, wherein

the NFC reader switches to the low-Q mode before transmitting the modulated signal;

and

the switching to the low-Q mode is at least a time t2 after start of the NFC RF field generation, t2 being a time interval between the start of the NFC RF field generation and first data transmission as defined in ISO14443 standards.

10. The method of claim 9, wherein the transmitting the modulated signal is a time t7 after the switching to the low-Q mode, t7 being a time when an amplitude of the NFC RF field reaches 90-110% of a stable level after the switching.

11. The method of claim 7, wherein after transmitting the modulated signal, the NFC reader switches to the high-Q mode, and waits at least a time t3 for the response, t3 being a maximum time interval that the NFC tag responds after the transmission by the NFC reader as defined in ISO14443 standards.

12. The method of claim 11, wherein if no response from the NFC tag is received within the time t3, the NFC retries transmission or attempts transmission with another NFC protocol, and stops the NFC RF field generation if all attempts have failed.

13. The method of claim 11, wherein if the response is received within the time t3, the NFC reader switches to the low-Q mode after at least a time t6, and transmits another modulated signal, t6 being larger than a minimum time interval between the response from the NFC tag and a next NFC reader transmission as defined in ISO14443 standards.

14. The method of claim 7, wherein the NFC reader re-starts the generation of the NFC RF field a time t4 after the stopping of the RF field generation, t4 being determined according to a maximum allowed tag detection delay and an energy budget, and having a value between 0.1s to 1s.

15. A method for a near-field communication (NFC) tag to perform NFC and wireless power transfer (WPT) with an NFC reader, the NFC tag having an antenna resonant circuit, of which a quality factor (Q-factor) is

no lower than 50 in a high-Q mode of the NFC tag, and

no higher than 25 in a low-Q mode of the NFC tag,

the method comprising:

repeatedly preforming steps of

detecting an NFC radio frequency (RF) field generated by the NFC reader;

measuring strength of the NFC RF field,

upon determining that the strength of the NFC RF field is higher than a predetermined threshold, operating in the high-Q mode for the WPT,

upon determining that the strength of the NFC RF field is lower than the predetermined threshold, operating in the low-Q mode for the NFC, and

transmitting a response back to the NFC reader.

16. The method of claim 15, wherein the NFC tag is configured to supply power to an external device, and, after determining that the strength of the NFC RF field is higher or lower than the predetermined threshold, connects or disconnects the power supply to the external device, respectively.

17. The method of claim 15, wherein the predetermined threshold has a hysteretic value that is predetermined based on a load level of an external device connected to the NFC tag.

18. The method of claim 15, wherein the NFC tag detects a modulated NFC signal transmitted by NFC reader in both the high-Q mode and the low-Q mode.

19. The method of claim 18, wherein the NFC tag, upon detecting the modulated NFC signal, operates in the low-Q mode, and starts signal reception.

20. The method of claim 19, wherein after the signal reception, the NFC tag switches to the high-Q mode and transmits the response within a time t1, t1 being smaller than a maximum time interval between a transmission time by the NFC reader and a response time by the NFC tag as defined in ISO14443 standards.

21. A method for a battery-powered near-field communication (NFC) tag to perform NFC with an NFC reader, the NFC tag having an antenna resonant circuit, of which a quality factor (Q-factor) is adjustable, the method comprising:

repeatedly preforming steps of

operating the NFC tag in a low-Q mode by adjusting the Q-factor of the antenna resonant circuit to be no higher than 25, to thereby detect an NFC radio frequency (RF) field generated by the NFC reader;

receiving a modulated signal from the NFC reader in the low-Q mode, and

operating the NFC tag in a high-Q mode by adjusting the Q-factor of the antenna resonant circuit to be no lower than 25, to thereby transmit a response back to the NFC reader.

22. A method for a near-field communication (NFC) tag to perform NFC and wireless power transfer (WPT) with an NFC reader, the NFC tag having

a high-Q-factor antenna resonant circuit of which a quality factor (Q-factor) is no lower than 50, and

a low-Q-factor antenna resonant circuit of which the Q-factor is no higher than 25, the high-Q-factor and low-Q-factor antenna resonant circuits being separate from each other,

the method comprising:

repeatedly preforming steps of

detecting an NFC radio frequency (RF) field generated by the NFC reader, and measuring strength of the NFC RF field, using either the high-Q-factor antenna resonant circuit or the low-Q-factor antenna resonant circuit;

upon determining that the strength of the NFC RF field is higher than a predetermined threshold, performing the WPT using the high-Q-factor antenna resonant circuit,

upon determining that the strength of the NFC RF field is not higher than the predetermined threshold, performing the NFC using the low-Q-factor antenna resonant circuit, and

transmitting a response back to the NFC reader.

23. The method of claim 22, wherein

the NFC tag is configured to supply power to an external device,

upon determining that the strength of the NFC RF field is higher than the predetermined threshold, the NFC tag connects the power supply to the external device, and

upon determining that the strength of the NFC RF field is not higher than the predetermined threshold, the NFC tag disconnects the power supply to the external device.

24. The method of claim 23, wherein the predetermined threshold has a hysteretic value that is predetermined based on a load level of an external device connected to the NFC tag.

25. The method of claim 22, wherein the NFC tag detects and receives a modulated NFC signal transmitted by the NFC reader during the NFC using the low Q-factor antenna resonant circuit.

26. The method of claim 25, wherein after receiving the modulated NFC signal, the NFC tag transmits the response within a time t1 using the high Q-factor antenna resonant circuit, t1 being smaller than a maximum time interval between a transmission time by the NFC reader and a response time by the NFC tag as defined in ISO14443 standards.