RFID tag device, RFID reader/writer device, and distance measuring system

• US 20070046430A1
• Filed: 02/27/2006
• Published: 03/01/2007
• Est. Priority Date: 08/30/2005
• Status: Abandoned Application

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Gotoh, Kunihiko, Yamazaki, Daisuke, Radecki, Andrzej
• Application Number:
  US11/362,097
• Publication Number:
  US 20070046430A1
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• 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: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence

Abstract

An RFID tag device, which includes an analog/digital conversion circuit converting a size of a signal received via an antenna from an analog format to a digital format, and a transmission circuit transmitting the signal in digital format or the signal based on the signal in digital format via the antenna, is provided. Besides, an RFID reader/writer device, which includes a transmission circuit transmitting a signal via an antenna, and a conversion circuit receiving a signal representing a size of the transmitted signal via the antenna, and converting into distance information based on the received signal, is provided.

Claims

1. An RFID tag device, comprising:

an analog/digital conversion circuit converting a size of a signal received via an antenna from an analog format to a digital format; and

a transmission circuit transmitting the signal in digital format or the signal based on the signal in digital format via the antenna.

2. The RFID tag device according to claim 1, further comprising:

a rectifying circuit rectifying the received signal, and

wherein said analog/digital conversion circuit converts the size of the rectified signal from the analog format to the digital format.

3. The RFID tag device according to claim 2, further comprising:

a capacitor charging a power supply voltage based on the rectified signal.

4. The RFID tag device according to claim 3, further comprising:

a shunt regulator controlling a short-circuit current amount to keep the power supply voltage charged into said capacitor in constant.

5. The RFID tag device according to claim 1,

wherein said analog/digital conversion circuit converts a current value of the received signal from the analog format to the digital format.

6. The RFID tag device according to claim 5, further comprising:

a monitor circuit monitoring a current of the received signal, and

wherein said analog/digital conversion circuit converts the monitored current value from the analog format to the digital format.

7. The RFID tag device according to claim 1, further comprising:

a peak detecting circuit detecting a peak portion of the received signal, and

wherein said analog/digital conversion circuit converts the detected signal at the peak portion from the analog format to the digital format.

8. The RFID tag device according to claim 1, further comprising:

a bottom detecting circuit detecting a bottom portion of the received signal, and

wherein said analog/digital conversion circuit converts the detected signal at the bottom portion from the analog format to the digital format.

9. The RFID tag device according to claim 1,

wherein said analog/digital conversion circuit starts the conversion from the analog format to the digital format when a specified command is received.

10. The RFID tag device according to claim 1,

wherein said transmission circuit transmits the signal when a specified command is received.

11. The RFID tag device according to claim 1,

wherein said analog/digital conversion circuit makes the received signal value 2M times or ½

M times (M is a natural number), compares with a reference signal value based on the signal value, to thereby convert the received signal value from the analog format to the digital format.

12. The RFID tag device according to claim 11,

wherein said analog/digital conversion circuit makes the signal value which is made 2M times or ½

M times, into N/P times (N and P are natural numbers), compares the result with the reference signal value, to thereby convert the received signal value from the analog format to the digital format.

13. The RFID tag device according to claim 1,

wherein said transmission circuit converts the signal in digital format into distance information, and transmits the distance information via the antenna.

14. The RFID tag device according to claim 4,

wherein said analog/digital conversion circuit converts the current value of the received signal from the analog format to the digital format.

15. The RFID tag device according to claim 14, further comprising:

a monitor circuit monitoring a current of the rectified signal, and

wherein said analog/digital conversion circuit converts the monitored current value from the analog format to the digital format.

16. The RFID tag device according to claim 15, further comprising:

a peak detecting circuit detecting a peak portion of the monitored current, and

wherein said analog/digital conversion circuit converts the detected current value at the peak portion from the analog format to the digital format.

17. The RFID tag device according to claim 15, further comprising:

a bottom detecting circuit detecting a bottom portion of the monitored current, and

wherein said analog/digital conversion circuit converts the detected current value at the bottom portion from the analog format to the digital format.

18. An RFID reader/writer device, comprising:

a transmission circuit transmitting a signal via an antenna; and

a conversion circuit receiving a signal representing a size of the transmitted signal via the antenna, and converting into distance information based on the received signal.

19. A distance measuring system, comprising:

an RFID reader/writer device; and

an RFID tag device, and

wherein said RFID reader/writer device including;

a first transmission circuit transmitting a signal to said RFID tag device via an antenna; and

a processing circuit receiving the signal from said RFID tag device via the antenna after the transmission to obtain distance information, and

wherein said RFID tag device including;

an analog/digital conversion circuit converting a size of the signal received from said RFID reader/writer device via the antenna, from an analog format to a digital format; and

a second transmission circuit transmitting the signal in digital format or the signal based on the signal in digital format to said RFID reader/writer device via the antenna.

20. The distance measuring system according to claim 19,

wherein the processing circuit converts into the distance information based on the received signal.