Method of interrogating a plurality of transponders arranged in the transmission range of an interrogating device and transponders for use in the said method
US5294931A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 29, 1992 |
| Grant date | Mar 15, 1994 |
| Priority date | — |
| Expiry date | Apr 29, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K7/0008
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A single interrogation device interrogates a plurality of transponders arranged within the range of transmission of the interrogation device and identifies them without any mutual interference. The interference free operation is obtained by the interrogation device sequentially transmitting a plurality of RF interrogation pulses, separated from each other in time and whose energy changes from one pulse to the next one, to transponders which have an energy storage element and which respond to the interrogation pulses with an answer signal in dependence upon the condition that, at the end of each interrogation pulse, the charge voltage present at the energy storage element falls within a predetermined voltage range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.