CARD DETECTION FOR A NFC (NEAR FIELD COMMUNICATION) READER SYSTEM

• US 20200134270A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Abandoned Application

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Hueber, Gernot, Macnamara, Ian Thomas
• Application Number:
  US16/177,290
• Publication Number:
  US 20200134270A1
• Time in Patent Office: Days
• CPC Class Codes: G06K 7/10128 the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device
• CPC Class Codes: G06K 7/10148 the step consisting of dynamically tuning the resonant circuit of the interrogation device that is emitting the interrogation signal, e.g. for impedance matching inside of the interrogation device for tuning related to loop aerials in general H01Q7/00
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil

Abstract

This specification discloses methods and devices for NFC/RFID (near field communication/radio frequency identification) reader systems to detect an external target device (e.g., tag or card device) within communication distance. In some embodiments, this is achieved by: (i) directing a Tx (transmitter) unit to generate a Tx signal, (ii) sweeping through a first Tx output (e.g., Tx voltage) in an increasing manner, and then (iii) monitoring a second Tx output (e.g., Tx current). During monitoring, a step change in the second Tx output (e.g., Tx current) would indicate detection of an external target device.

Claims

1. A method for operating a device that communicates via inductive coupling to detect an external tag device, the method comprising:

generating, by a Tx (transmitter) unit of the device, a transmitted signal to a matching network that sends the transmitted signal to an antenna, wherein the antenna and matching network receive data passed to a Rx (receiver) unit,

wherein a Tx (transmitter) control unit of the device is configured for controlling the Tx (transmitter) unit of the device;

sweeping through, by the Tx (transmitter) control unit of the device, a first output of the transmitted signal;

monitoring, by the Tx control unit a second output of the transmitted signal based on the Tx control unit sensing the Rx (receiver) unit,

wherein a change in the second output of the transmitted signal indicates detection of the external tag device.

2. The method of claim 1 further comprising:

controlling and tuning a Tx (transmitter) supply by a first signal, a Tx (transmitter) driver by a second signal, and the matching network by a third signal.

3. The method of claim 1, wherein sweeping through the first output of the transmitted signal comprises:

increasing or decreasing the first output of the transmitted signal.

4. The method of claim 3, wherein sweeping through the first output of the transmitted signal comprises:

increasing or decreasing the first output of the transmitted signal so that a step change in the second output of the transmitted signal is detected, wherein the step in the second output indicates detection of the external tag device.

5. The method of claim 1, wherein the first output of the transmitted signal comprises one of the following:

a voltage of the transmitted signal,

a power of the transmitted signal,

a current of the transmitted signal.

6. The method of claim 1, wherein the second output of the transmitted signal comprises one of the following:

a current of the transmitted signal,

a voltage of the transmitted signal,

a power of the transmitted signal,

wherein the second output is not the same as the first output.

7. The method of claim 3, wherein sweeping through the first output of the transmitted signal comprises using one or more of the following output waveforms:

a linear slope,

a nonlinear slope,

a staircase,

a pulse mode with increasing or decreasing pulse heights,

any other waveform.

8. The method of claim 1, wherein monitoring, by the device, the second output of the transmitted signal, comprises:

monitoring, by the Tx (transmitter) control unit of the device, the second output of the transmitted signal.

9. The method of claim 8, wherein the Tx (transmitter) control unit of the device monitors the second output of the transmitted signal based on sensing by one or more of the following:

a Tx (transmitter) driver unit of the device,

a Tx (transmitter) supply unit of the device.

10. The method of claim 8, wherein the Tx (transmitter) control unit of the device monitors the second output of the transmitted signal based on one or more of the following:

sensing a current of a Tx (transmitter) driver unit of the device,

sensing a current of a Tx (transmitter) supply unit of the device,

sensing a voltage of a Rx (receiver) unit of the device.

11. The method of claim 1, wherein the external tag device is one of the following:

a passive tag,

a card device,

a headset,

a speaker.

12. The method of claim 1, wherein the step of sweeping through the first output of the transmitted signal occurs in a duty-cycled or a pulsed mode, wherein the step of sweeping through is only activated for a portion of a total time and the device is in idle for the remainder of the total time.

13. The method of claim 2, wherein the minimum power is used to determine an effective current and/or power consumption of the external tag device.

14. The method of claim 2, wherein sweeping through the first output of the transmitted signal is fast enough such that impact of changing a distance between the device and the external tag device does not affect accuracy of determining the minimum power needed for communication between the device and the external tag device.

15. A computer program product comprising executable instructions encoded in a non-transitory computer readable medium which, when executed by the device, carry out or control the method of claim 1.

16. A device for detecting an external tag device in communications with the device via inductive coupling, the device comprising:

a matching network;

an antenna;

a Rx (receiver unit), wherein the data is received from the antenna and the matching unit and passed to the Rx (receiver) unit;

a Tx (transmitter) unit, the Tx (transmitter) unit configured to generate a transmitted signal that is transmitted through the matching network and the antenna, the Tx (transmitter) unit comprising a Tx (transmitter) control unit,

wherein the Tx control unit is configured for controlling the Tx (transmitter) unit,

wherein the Tx control unit is further configured for detecting the external tag device by;

directing the Tx (transmitter) unit to generate the transmitted signal,

directing the Tx (transmitter) unit to sweep through a first output of the transmitted signal,

monitoring a second output of the transmitted signal by sensing the Rx (receiver) unit,

detecting the external tag device when there is a change in the second output of the transmitted signal.

17. The device of claim 16, wherein the Tx control unit is further configured for determining a minimum power needed for communication between the device and the external tag device.

18. The device of claim 16, wherein the first output of the transmitted signal comprises one of the following:

a voltage of the transmitted signal,

a power of the transmitted signal,

a current of the transmitted signal.

19. The device of claim 16, wherein the second output of the transmitted signal comprises one of the following:

a current of the transmitted signal,

a voltage of the transmitted signal,

a power of the transmitted signal,

wherein the second output is not the same as the first output.

20. The device of claim 16 further comprising:

controlling and tuning a Tx (transmitter) supply by a first signal, a Tx (transmitter) driver by a second signal, and the matching network by a third signal.