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EP0285419A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Access control equipment

Assignee: Identec Ltd
•
Filing: 1988-03-30
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Granted: —
•
Expires: 2008-03-30
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Abstract

Abstract Access control equipment comprises an inter­rogation unit (IU) having means (14) for emitting an interrogation signal, and a plurality of transponders (e.g. T), each transponder (T) having a stored identity code different from that of the other transponders (T). This identity code comprises a plurality of fields each holding a selected information bit. The interrogation signal is controlled so as simultaneously to interrogate the fields of all transponders (T) within range in a serial manner. A group reply signal is sent back to the inter­rogation unit (IU) from any transponder (T) having, in the field being interrogated, a bit matching that required by the interrogation signal. The interrogation unit (IU) is arranged to determine, from the series of received reply signals, the identity of each and every valid transponder (T) within range.

Inventors

  • 👤 Brian John Dr. Stanier
  • 👤 Harold Dodd

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-29 22:30
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10009; G06K7/10019; G06K7/10029; G06K7/10039; G06K7/10049; G06K17/00; G06K17/0022; G06K7/0008; G07; G07C; G07C9/00; G07C9/20; G07C9/28; G07C9/29

Claims Analysis

Total Claims: 4
Claim 1
Independent Claim 135 words
Access control equipment comprising an interrogation unit having means for emitting an interrogation signal, and a plurality of transponders having means for receiving the interrogation signal, each transponder having a stored identity code different from that of the other transponders, the identity code comprising a plurality of fields each holding an information bit selected from a plurality of possible bits, means for controlling the interrogation signal so that it simultaneously interrogates the fields of all transponders within range in a serial manner, means for sending a group reply signal to the interrogation unit from any transponder having in the field been interrogated a bit matching that required by the interrogation signal, and means in the interrogation unit for converting the series of group reply signals to the encrypted identi­fication codes of those transponders within range.
Claim 2
Dependent Claim 135 words
Access control equipment comprising an interrogation unit having means for emitting an interrogation signal, and a plurality of transponders having means for receiving the interrogation signal, each transponder having a stored identity code different from that of the other transponders, the identity code comprising a plurality of fields each holding an information bit selected from a plurality of possible bits, means for controlling the interrogation signal so that it simultaneously interrogates the fields of all transponders within range in a serial manner, means for sending a group reply signal to the interrogation unit from any transponder having in the field been interrogated a bit matching that required by the interrogation signal, and means in the interrogation unit for converting the series of group reply signals to the encrypted identi­fication codes of those transponders within range.
Claim 3
Dependent Claim 41 words
Access control equipment as claimed in claim 1, in which the transponder reply signals differ on and during successive searches and are encrypted according to a different control code transmitted by the interrogation unit at the beginning of each interrogation cycle.
Claim 4
Dependent Claim 56 words
Access control equipment as claimed in claim 2, in which a valid transponder within range of the interrogation unit replies to its final interrogation step with an encoded signal generated from the control code transmitted at the beginning of the interrogation cycle and from a further identification code and an algorithm both held by the transponder.

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