Anticollision method that marks the time slots

• US 20050237156A1
• Filed: 07/18/2003
• Published: 10/27/2005
• Est. Priority Date: 07/25/2002
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Scherabon, Christian
• Granted Patent: US 7,498,924 B2
• Time in Patent Office: Days
• US Class Current: 340/10.200
• 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 7/10039 interrogator driven, i.e. synchronous

Abstract

During the implementation of an anticollision method by a reader station (1) to identify all data carriers (2, 3, 4) in the communication field (HF), in order to shorten the time slots (S) in which none of the data carriers (2, 3, 4) is responding or in which a collision of multiple responses from the data carriers (2, 3, 4) occurs, a time-slot progressing information (ZWI) is sent by the reader station (1). The time-slot progressing information (ZWI) contains a time-slot number (ZN), which identifies the time slot (Si) next in line after the current time slot (S).

Claims

1. An anticollision method to identify data carriers arranged in a communication field of a reader station, which method involves the following steps:

sending interrogation information from the reader station to all data carriers arranged in the communication field, as a result of which the start of a quantity of N successive time slots is defined;

sending response information from the data carriers to the reader station, wherein each data carrier selects one of the N time slots to send its response information identifying the data carrier;

sending a time-slot progressing information, for progressing from the current time slot to the time slot following next in line, from the reader station to the data carriers, characterized in that the time-slot progressing information comprises a time-slot characterizing information, which identifies one of the N time slots, and which is evaluated by the data carriers in order to establish the current time slot in each case.

2. An anticollision method as claimed in claim 1, characterized in that the time-slot progressing information is sent by the reader station if it has been established by the reader station that the current time slot is inappropriate for identifying one of the data carriers.

3. An anticollision method as claimed in claim 1, characterized in that the time-slot characterizing information is formed by two pulses, wherein the time duration of a pulse interval between the two pulses identifies one of the N time slots.

4. An anticollision method as claimed in claim 1, characterized in that the time-slot characterizing information is formed by multiple pulses, which identify a consecutive time-slot number.

5. An anticollision method as claimed in claim 4, characterized in that the time-slot characterizing information contains a checksum of the time-slot number.

6. An anticollision method as claimed in claim 1, characterized in that the reader station sends the time-slot progressing information if has been established by the reader station that more than one of the data carriers are responding in the current time slot, or if it has been established by the reader station that none of the data carriers is responding in the current time slot.

7. A data carrier to respond to an interrogation information received from a reader station with a response information identifying the data carrier during one of N time slots, with receiver means to receive the interrogation information and the time-slot progressing information from the reader station, and with time-slot definition means, which are designed to define the sequence of the N time slots as a function of the instant of reception of the interrogation information, wherein, on receipt of the time-slot progressing information, progressing takes place from the current time slot to the time slot following next in line, and with

sending-definition means to define one of the N time slots as a return time slot in which the data carrier sends the response information to the reader station;

and with

sending means to send the response information to the reader station, characterized in that the time-slot progressing information comprises a time-slot characterizing information, which identifies one of the N time slots, and that the time-slot definition means are designed to evaluate the time-slot characterizing information in order to determine the current time slot in each case.

8. A data carrier as claimed in claim 7, characterized in that the time-slot definition means comprise a counter, which is designed to determine the time duration of a pulse interval between two pulses of the time-slot characterizing information.

9. A data carrier as claimed in claim 7, characterized in that the time-slot definition means are designed to evaluate multiple pulses of the time-slot characterizing information, wherein the pulses identify a consecutive time-slot numbers.

10. A data carrier as claimed in claim 9, characterized in that the time-slot definition means are designed to evaluate a checksum of the time-slot number contained in the time-slot characterizing information.

11. A reader station to identify data carriers which are arranged in a communication field of the reader station, with sending means to send an interrogation information and a time-slot progressing information to all data carriers arranged in the communication field, wherein, as a result of the interrogation information, the start of a quantity of N successive time slots is defined, and wherein, as a result of the time-slot progressing information, progressing takes place from the current time slot to the time slot following next in line, and with receiver means to receive a response information from the data carriers in the communication field, wherein each data carrier individually selects one of the N time slots as the return time slot to send its response information identifying the data carrier;

and with

time-slot evaluation means to evaluate the response information received from the data carriers in the particular time slot. characterized in that the reader station is designed to send a time-slot progressing information comprising a time-slot characterizing information, wherein the time-slot characterizing information identifies one of the N time slots, and is evaluated by the data carriers in order to establish the current time slot in each case.

12. A reader station as claimed in claim 11, characterized in that the sender means are designed to send the time-slot progressing information if it has been established by the time-slot evaluation means that the current time slot is inappropriate for identifying one of the data carriers.

13. A reader station as claimed in claim 11, characterized in that the time-slot characterizing information is formed by two pulses, wherein the time duration of a pulse interval between the two pulses identifies one of the N time slots.

14. A reader station as claimed in claim 11, characterized in that the time-slot characterizing information is formed by multiple pulses, which identify a consecutive time-slot number.

15. A reader station as claimed in claim 14, characterized in that the time-slot characterizing information contains a checksum of the time-slot number.

16. A reader station as claimed in claim 11, characterized in that the reader station sends the time-slot progressing information if it has been established by the time-slot evaluation means that more than one of the data carriers are responding in the current time slot, or if it has been established by the time-slot evaluation means that none of the data carriers is responding in the current time slot.