Method for selecting and writing into RFID-transponders

• US 6,639,514 B1
• Filed: 02/25/2002
• Issued: 10/28/2003
• Est. Priority Date: 10/18/1999
• Status: Expired due to Term

• Current Assignee: Bibliotheca RFID Library Systems AG (Bibliotheca Group GmbH)
• Original Assignee: Lucatron AG
• Inventors: Müller, Philipp
• Primary Examiner(s): Wu, Daniel J.
• Assistant Examiner(s): LAI, ANNE VIET NGA
• Application Number:
  US10/049,630
• Time in Patent Office: 610 Days
• Field of Search: 340/572--57, 340/572.7, 340/5.92, 340/10.1, 340/10.2, 340/10.51, 340/10.52, 340/10.3, 340/10.34, 235/385
• US Class Current: 340/572.5
• CPC Class Codes: G06K 19/07796 arrangements on the record carrier to allow stacking of a plurality of similar record carriers, e.g. to avoid interference between the non-contact communication of the plurality of record carriers
• 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 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08

Abstract

Method and system for reading out and writing to RFID-transponders with inductive coupling including a read/write unit with a transmission frequency f_s1 defined as a basic transmission frequency and a plurality of transponders operated at a resonance frequency f_R. The resonance frequency f_R is fixedly predetermined, then for operating conditions with a high distance range, the resonance frequency f_R equal to the basic transmission frequency f_s1 is selected. For operating conditions with a high recognition rate with a plurality of transponders located within a detection field, the basic transmission frequency f_s1 is reduced to a fixed alternative value f_s2 . This procedure guarantees reliable communication between the transponders and the read/write unit.

Claims

1. Method for reading out and writing to RFID-transponders with inductive coupling comprising a read/write unit with a transmission frequency f_sl defined as a basic transmission frequency and a plurality of transponders operated at a resonance frequency f_R, comprising the steps of:

fixedly predetermining the resonance frequency f_R,

for operating conditions with a high distance range, selecting the resonance frequency f_R equal to the basic transmission frequency f_s1, and

for operating conditions with a high recognition rate with a plurality of transponders located within a detection field, reducing the basic transmission frequency f_s1 to a fixed alternative value f_s2,

thereby guaranteeing reliable communication between the transponders and the read/write unit.

2. Method according to claim 1, wherein the alternative value f_s2 for the transmission frequency is half of the basic transmission frequency f_s1.

3. Method according to claim 1, wherein several alternative transmission frequencies below the basic transmission frequency f_s1 are used.

4. Method according to claim 1, wherein the resonance frequency is 13.56 MHz and as transmission frequencies are 13.56 MHz and 6.78 MHz.

5. Method according to claim 1, wherein the resonance frequency is 27.125 MHz and the transmission frequencies are 27.125 MHz, 13.56 MHz and 6.78 MHz.

6. System for reading out and writing to inductively coupled RFID-transponders for implementing the method in accordance with claim 1, comprising:

a transponder disposed on a carrier and having a resonance circuit with a resonance frequency f_R,

a receiving unit, and

a read/write unit with a transmitter/receiver and transmission frequency f_s1 defined as a basic transmission frequency,

wherein the resonance circuit has a fixed resonance frequency f_R and the transmitter/receiver of the read/write unit has a transmission basic frequency f_s1 equal to the resonance frequency f_R of the transponder and a fixed alternative lower transmission frequency f_s2.

7. System according to claim 6, wherein the transmitter/receiver is adjustable to transmit a plurality of alternative lower transmission frequencies.