Contactless IC card, responding method, and program therefor

• US 20040182926A1
• Filed: 03/29/2004
• Published: 09/23/2004
• Est. Priority Date: 11/20/2001
• Status: Active Grant

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kawano, Shinji, Nakabe, Futoshi, Ebara, Hiromi, Masaki, Tadakatsu, Oozeki, Hideo
• Granted Patent: US 6,923,380 B2
• Time in Patent Office: Days
• US Class Current: 235/435
• CPC Class Codes: G06K 19/0707 the arrangement being capable of collecting energy from external energy sources, e.g. thermocouples, vibration, electromagnetic radiation G06K19/0702 takes precedence
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• 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 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: G06K 7/10059 transponder driven

Abstract

The contactless IC card, the responding method, and the program that control the collision of response to the minimum, wherein the response judgment unit judges whether there is an initial response of the other contactless IC card at a specific time, and the response slot changing unit change the specific time based on the judgment result of the response judgment unit.

Claims

1. A contactless IC card responding to a request sent from a reader/writer at a specific time, comprising:

response judgment unit operable to judge if there is a response of the other contactless IC card at the specific time; and

response slot changing unit operable to change the specific time based on the judgment result of the response judgment unit.

2. The contactless IC card according to claim 1, further comprises use deciding unit operable to decide the use or not of the response judgment unit.

3. The contactless IC card according to claim 2, wherein the use deciding unit decides the use or not of the response judgment unit at random.

4. The contactless IC card according to claim 1, wherein the specific time is selected from 1 or a plurality of time slots given by the reader/writer.

5. The contactless IC card according to claim 4, further comprising:

last slot judgment unit operable to judge if the time slot selected from the plurality of time slots given by the reader/writer is the last one or not, wherein the response slot changing unit changes the time slot to be used for response based on the judgment result of the last slot judgment unit.

6. A responding method of a contactless IC card responding to a request sent from a reader/writer at a specific time, comprising the steps of:

judging if there is an initial response of the other contactless IC card at the specific time; and

changing the specific time based on the judgment result in the step of judging the response.

7. The responding method according to claim 6, further comprising the step of:

deciding to execute the step of judging the response.

8. A program that allows a contactless IC card responding to a request sent from a reader/writer at a specific time to execute the steps of:

judging if there is an initial response of the other contactless IC card at the specific time; and

changing the specific time based on the judgment result in the step of judging the response.

9. A computer-readable recoding medium recording a program that allows a contactless IC card responding to a request sent from a reader/writer at a specific time to execute the steps of:

judging if there is an initial response of the other contactless IC card at the specific time; and

changing the specific time based on the judgment result in the step of judging the response.

10. A contactless IC card responding to a request sent from a reader/writer at a specific time, comprising:

measuring unit operable to measure electromotive force derived from the reader/writer; and

response slot deciding unit operable to decide the specific time based on the electromotive force measured by the measuring unit.

11. The contactless IC card according to claim 10, where a distance between the contactless IC card and the reader/writer is fixed, wherein the response slot deciding unit decides the specific time based on prestored information indicating relation between electromotive force and magnetic field intensity and the value of the electromotive force measured by the measuring unit.

12. The contactless IC card according to claim 11, further comprises magnetic field intensity obtaining unit operable to obtain, from the request, information regarding the magnetic field intensity of the electromagnetic waves outputted from the reader/writer.

13. The contactless IC card according to claim 10, wherein the response slot deciding unit decides the specific time based on a differential value at the transition of electromotive force and prestored information indicating relation between electromotive force and magnetic field intensity.

14. A responding method of contactless IC card responding to a request sent from a reader/writer at a specific time, comprising the steps of:

measuring the electromotive force derived from the reader/writer; and

deciding the specific time based on the measurement result measured by the measuring unit.

15. A program that allows a contactless IC card responding to a request sent from a reader/writer at a specific time to execute the steps of:

measuring the electromotive force derived from the reader/writer; and

deciding the specific time based on the measurement result measured at the step of measuring the electromotive force.

16. A computer-readable recoding medium recording a program that allows a contactless IC card responding to a request sent from a reader/writer at a specific time to execute the steps of:

measuring the electromotive force derived from the reader/writer; and

deciding the specific time based on the measurement result measured at the step of measuring the electromotive force.