Noncontact tag, control method therefor and noncontact ID identification system

• US 7,392,947 B2
• Filed: 02/24/2006
• Issued: 07/01/2008
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Fujitsu Semiconductor Memory Solution Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Limited
• Inventors: Higashi, Noriyuki
• Primary Examiner(s): Lee; Seung H
• Application Number:
  US11/360,587
• Publication Number:
  US 20070075143A1
• Time in Patent Office: 858 Days
• Field of Search: 235/380, 235/451, 235/449, 235/476, 235/492, 235/493, 375/324
• US Class Current: 235/449
• 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

Abstract

The present invention is to provide a noncontact tag, comprising: a clock extraction unit for extracting a clock from a received carrier wave; a demodulation unit for outputting a demodulated signal comprising a logic signal whose logic state changes responding to each of a non-modulation period and modulation period of the carrier wave; a division unit for generating a division clock from the clock input from the clock extraction unit and also restraining the division clock from being output according to a logic state of the demodulated signal; and a decoding unit for decoding information included in the carrier wave by using a value of counter driven by the division clock.

Claims

1. A noncontact tag, comprising:

a clock extraction unit for extracting a clock from a received carrier wave;

a demodulation unit for outputting a demodulated signal comprising a logic signal whose logic state changes responding to each of a non-modulation period and modulation period of the carrier wave;

a division unit for generating a division clock from the clock input from the clock extraction unit and also restraining the division clock from being output according to a logic state of the demodulated signal; and

a decoding unit for decoding information included in the carrier wave by using a value of counter driven by the division clock.

2. The noncontact tag according to claim 1, wherein

said decoding unit decodes said information by detecting a position of said modulation period in a data frame of a predetermined time width by said counter value.

3. The noncontact tag according to claim 1, wherein

said decoding unit decodes said information by detecting a length of said non-modulation period by said counter value.

4. The noncontact tag according to claim 1, wherein

said carrier wave carries said information by either a modulation factor 100% or a modulation factor 10%, and transitions of said counter values identify with each other in the modulation factor 100% and modulation factor 10% for the same information.

5. The noncontact tag according to claim 1, wherein

said carrier wave carries said information by either a 100% amplitude modulation or 10% amplitude modulation, and restrains said division clock from outputting during a period of an amplitude being modulated by the 100% amplitude modulation and during a period of an amplitude being modulated by the 10% amplitude modulation.

6. The noncontact tag according to claim 1, wherein

said division unit comprises a flip-flop, by receiving said clock as an input, for outputting said division clock from a Q terminal by feeding back an output from an XQ terminal to a D terminal, and an logic gate for inputting to an enable (EN) terminal of the flip-flop by carrying out an logic operation of said demodulated signal and enable signal;

and

makes the division clock stopped according to a logic state of the demodulated signal.

7. The noncontact tag according to claim 1, wherein

said division unit comprises a flip-flop, by receiving said clock as an input, for outputting said division clock from a Q terminal by feeding back an output from an XQ terminal to a D terminal, and an logic gate for inputting to a clear (CL) terminal of the flip-flop by carrying out an logic operation of a clear signal of the flip-flop and said demodulated signal;

and

makes the division clock stopped according to a logic state of the demodulated signal.

8. The noncontact tag according to claim 1, wherein

said division unit comprises a flip-flop, by receiving said clock as an input, for outputting said division clock from a Q terminal by feeding back an output from an XQ terminal to a D terminal, and an logic gate for inputting to a D terminal of the flip-flop by carrying out an logic operation of an output of the XQ terminal and said demodulated signal;

and

makes the division clock stopped according to a logic state of the demodulated signal.

9. The noncontact tag according to claim 1

is a passive type noncontact tag further comprising a rectifier unit for extracting a direct current from said carrier wave.

10. A control method for a noncontact tag, comprising the steps of

extracting a clock from a received carrier wave;

outputting a demodulated signal comprising a logic signal whose logic state changes responding to each of a non-modulation period and modulation period of the carrier wave;

restraining the division clock from being output according to a logic state of the demodulated signal when generating a division clock from the clock input from a clock extraction unit; and

decoding information included in the carrier wave by using a count value of the division clock.

11. The control method for a noncontact tag according to claim 10, wherein

said step of decoding said information is to decode the information by detecting a position of said modulation period within a data frame of a predetermined time width by said count value.

12. The control method for a noncontact tag according to claim 10, wherein

said step of decoding said information is to decode the information by detecting a length of said modulation period by said count value.

13. The control method for a noncontact tag according to claim 10, wherein

said carrier wave carries said information by either a 100% modulation factor or a 10% modulation factor, and

transitions of said counter values identify with each other in the modulation factor 100% and modulation factor 10% for the same information in said step of decoding said information.

14. A noncontact ID identification system including an access apparatus for transmitting command information by way of an ASK modulated carrier wave and a noncontact tag for responding to the access apparatus with identifier information by receiving the command information, wherein

the noncontact tag includes

a clock extraction unit for extracting a clock from the carrier wave received from the access apparatus;

a demodulation unit for outputting a demodulated signal comprising a logic signal whose logic state changes responding to each of a non-modulation period and modulation period of the carrier wave;

a division unit for generating a division clock from the clock input from the clock extraction unit and also restraining the division clock from being output according to a logic state of the demodulated signal; and

a decoding unit for decoding information included in the carrier wave by using a value of counter driven by the division clock.

15. The noncontact ID identification system according to claim 14, wherein

said access apparatus transmits said command information by modulating said carrier wave by a modulation factor 100% or modulation factor 10%.

16. The noncontact ID identification system according to claim 14, wherein

said decoding unit decodes the information by detecting a position of said modulation period within a data frame of a predetermined time width by said count value.

17. The noncontact ID identification system according to claim 14, wherein

said decoding unit decodes said information by detecting a length of said non-modulation period by said counter value.