Key code correlation security
First Claim
1. A key code correlation security arrangement, comprising:
- a key;
a transponder associated with the key, the transponder having a memory for storing a predetermined key code, and means for transmitting that key code in response to a key code request transmitted thereto; and
an interrogator for transmitting general and specific key code requests to the transponder, the interrogator having a memory for storing one or more predetermined key codes identifying authorized keys, means for receiving a key code from the transponder in response to a key code request, and means for comparing a received key code with the key codes stored in interrogator memory, the interrogator also having a key code request changing means for differentiating key code requests for a plurality of key codes, and interference determination means for determining whether or not answer signals responding to a key code request interfere with one another, and wherein if the interference determination means has determined that there is interference of two or more key code responses from transponders in response to a general key code request, the interrogator then transmits specific key code requests that are specific to individual keys, and compares responses received with the key codes of such specific key code requests.
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Accused Products
Abstract
A transponder type key security system having a plurality of authorized keys efficiently correlates a key code transmitted by a key-based transponder unit with codes stored in an interrogator unit while inhibiting reception interference by multiple signals transmitted by a plurality of key-based transponder units. The interrogator unit transmits a general request for key-based transponder units having pre-stored key codes allocated thereto to respond by giving their respective key codes. A transponder unit, upon receiving the request, transmits its key code to the interrogator unit. The interrogator unit compares a received key code with key codes previously stored to determine if the transponder unit responding is authorized or not. In the event that multiple transponder units respond to the request, the interrogator unit transmits a key-specific request so that only the targeted key-based transponder unit will respond. This prevents multiple transponder requests from interfering with one another. Usually only a single key is present and there is no need to transmit key-specific requests. Thus, the number of key code requests to be transmitted is reduced and a determination of whether a key is authorized or not can be carried out efficiently.
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Citations
14 Claims
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1. A key code correlation security arrangement, comprising:
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a key;
a transponder associated with the key, the transponder having a memory for storing a predetermined key code, and means for transmitting that key code in response to a key code request transmitted thereto; and
an interrogator for transmitting general and specific key code requests to the transponder, the interrogator having a memory for storing one or more predetermined key codes identifying authorized keys, means for receiving a key code from the transponder in response to a key code request, and means for comparing a received key code with the key codes stored in interrogator memory, the interrogator also having a key code request changing means for differentiating key code requests for a plurality of key codes, and interference determination means for determining whether or not answer signals responding to a key code request interfere with one another, and wherein if the interference determination means has determined that there is interference of two or more key code responses from transponders in response to a general key code request, the interrogator then transmits specific key code requests that are specific to individual keys, and compares responses received with the key codes of such specific key code requests. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A key code authorization method, comprising the steps of:
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storing a plurality of correlation key codes in an interrogator;
transmitting by the interrogator a key code request;
receiving by a transponder associated with a key the key code request transmitted by the interrogator;
transmitting by the transponder a key code allocated to its associated key; and
receiving by the interrogator the key code transmitted by the transponder;
if it has been determined by the interrogator that there are two or more answer signals responding to the key code request that interfere with one another, transmitting by the interrogator key code requests for specific keys, and comparing received key codes with key codes previously stored in the interrogator. - View Dependent Claims (12, 13, 14)
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Specification