초록 ▼

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 tra

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.

대표청구항 ▼

[ The invention claimed is:] [1.]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 theret

[ The invention claimed is:] [1.]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; andan 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, andwherein 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.