Information processing terminal, IC card, portable communication device, wireless communication method, and program

• US 7,975,907 B2
• Filed: 04/18/2007
• Issued: 07/12/2011
• Est. Priority Date: 04/20/2006
• Status: Active Grant

• Current Assignee: FeliCa Networks, Inc (Sony Group Corp.)
• Original Assignee: FeliCa Networks, Inc (Sony Group Corp.)
• Inventors: Yoshida, Yuko
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US11/736,993
• Publication Number:
  US 20070246546A1
• Time in Patent Office: 1,546 Days
• Field of Search: 235/375, 235/493, 235/492, 332/174, 375/295, 340/2.4, 340/5.4, 340/5.41, 340/5.6, 340/5.61
• US Class Current: 235/375
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/28 using the near field of leaky cables, e.g. of leaky coaxial cables
• CPC Class Codes: H04B 5/72 for local intradevice communication

Abstract

An information processing terminal is disclosed that is allowed to carry out contactless data transmission or reception with a reading or writing device by use of a magnetic field. The information processing terminal includes a data transmitter or receiver, a signal processor, and a load modulator. The data transmitter or receiver is configured to generate an induced voltage from a magnetic field generated from the reading or writing device at the time of data reception, and send a transmission signal to the read/write reading or writing device at the time of data transmission. The signal processor is configured to generate a response signal based on the induced voltage. The load modulator controls a variable resistance based on the induced voltage and carries out load modulation relating to the transmission signal based on the response signal and the variable resistance.

Claims

1. An information processing terminal that carries out contactless data transmission or reception with a reading or writing device by use of a magnetic field, the information processing terminal comprising:

a data transmitter or receiver configured to generate an induced voltage from a magnetic field generated by the reading or writing device at the time of data reception, and send a transmission signal to the reading or writing device at the time of data transmission, wherein the induced voltage is direct current voltage;

a signal processor configured to generate a response signal based on the induced voltage; and

a load modulator configured to control a variable resistance based on the induced voltage and carry out load modulation of the transmission signal based on the response signal and the variable resistance.

2. The information processing terminal according to claim 1, wherein the load modulator comprises:

a resistance variable circuit configured to change a value of the variable resistance;

a load variation level control circuit configured to generate a control signal to control the variable resistance based on the induced voltage; and

a connection circuit that allows the load modulation based on the response signal.

3. The information processing terminal according to claim 2, wherein the connection circuit is configured to connect the resistance variable circuit to ground based on the level of the response signal.

4. The information processing terminal according to claim 2, wherein the power consumed by the resistance variable circuit is configured to be adjusted according to the induced voltage and the variable resistance.

5. The information processing terminal according to claim 1, further comprising:

an internal power supply; and

an internal supply voltage detector configured to detect an internal supply voltage output from the internal power supply and output an internal supply voltage signal dependent upon the internal supply voltage,

wherein the load modulator comprises;

a resistance variable circuit configured to change a value of the variable resistance,

a load variation level control circuit configured to generate a control signal to control the variable resistance based on the induced voltage and the internal supply voltage signal; and

a connection circuit that allows the load modulation based on the response signal.

6. The information processing terminal according to claim 1, wherein the load modulator increases the variable resistance when the induced voltage is low and decreases the variable resistance when the induced voltage is high.

7. An IC card that carries out contactless data transmission or reception with a reading or writing device by use of a magnetic field, the IC card comprising:

a data transmitter or receiver configured to generate an induced voltage from a magnetic field generated by the reading or writing device at the time of data reception, and send a transmission signal to the reading or writing device at the time of data transmission, wherein the induced voltage is direct current voltage;

a signal processor configured to generate a response signal based on the induced voltage; and

a load modulator configured to control a variable resistance based on the induced voltage and carry out load modulation of the transmission signal based on the response signal and the variable resistance.

8. The IC card according to claim 7, further comprising:

an internal power supply; and

an internal supply voltage detector configured to detect an internal supply voltage output from the internal power supply and output an internal supply voltage signal dependent upon the internal supply voltage, wherein

the load modulator comprises;

a resistance variable circuit configured to change a value of the variable resistance;

a load variation level control circuit configured to generate a control signal to control the variable resistance based on the induced voltage and the internal supply voltage signal; and

a connection circuit that allows the load modulation based on the response signal.

9. The IC card according to claim 8, wherein the connection circuit is configured to connect the resistance variable circuit to ground based on the level of the response signal.

10. The IC card according to claim 8, wherein the power consumed by the power resistance variable circuit is configured to be adjusted according to the induced voltage and the variable resistance.

11. The IC card according to claim 7, wherein the load modulator increases the variable resistance when the induced voltage is low and decreases the variable resistance when the induced voltage is high.

12. A portable communication device that carries out contactless data transmission or reception with a reading or writing device by use of a magnetic field, the portable communication device comprising:

a data transmitter or receiver configured to generate an induced voltage from a magnetic field generated by the reading or writing device at the time of data reception, and send a transmission signal to the reading or writing device at the time of data transmission, wherein the induced voltage is direct current voltage;

a signal processor configured to generate a response signal based on the induced voltage; and

a load modulator configured to control a variable resistance based on the induced voltage and carry out load modulation of the transmission signal based on the response signal and the variable resistance.

13. The portable communication device according to claim 12, further comprising:

an internal power supply; and

an internal supply voltage detector configured to detect an internal supply voltage output from the internal power supply and output an internal supply voltage signal dependent upon the internal supply voltage, wherein

the load modulator comprises;

a resistance variable circuit configured to change a value of the variable resistance;

a load variation level control circuit configured to generate a control signal to control the variable resistance based on the induced voltage and the internal supply voltage signal; and

a connection circuit that allows the load modulation based on the response signal.

14. The portable communication device according to claim 13, wherein the connection circuit is configured to connect the power resistance variable circuit to ground based on the level of the response signal.

15. The portable communication device according to claim 13, wherein the power consumed by the resistance variable circuit is configured to be adjusted according to the induced voltage and the variable resistance.

16. The portable communication device according to claim 12, wherein the load modulator increases the variable resistance when the induced voltage is low and decreases the variable resistance when the induced voltage is high.

17. A wireless communication method for contactless data transmission or reception with a reading or writing device by use of a magnetic field, the method comprising the steps of:

generating an induced voltage from a magnetic field generated by the reading or writing device, wherein the induced voltage is direct current voltage;

changing a value of a variable resistance based on the induced voltage; and

carrying out load modulation based on the response signal and the variable resistance.

18. The wireless communication method according to claim 17, wherein changing a value of a variable resistance includes increasing the value of the variable resistance when the induced voltage is low and decreasing the value of the variable resistance when the induced voltage is high.

19. A computer-readable medium comprising instructions executable by a computer processor to implement a method for contactless data transmission or reception with a reading or writing device by use of a magnetic field, the method comprising:

generating an induced voltage from a magnetic field generated by the reading or writing device, wherein the induced voltage is direct current voltage;

changing a value of a variable resistance based on the induced voltage; and

carrying out load modulation based on the response signal and the variable resistance.

20. The computer-readable medium according to claim 19, wherein changing a value of a variable resistance includes increasing the value of the variable resistance when the induced voltage is low and decreasing the value of the variable resistance when the induced voltage is high.