06690259 is referenced by 17 patents.
A security system to enable authenticated access of an individual to a protected area, including a remote control unit (
) with a transponder (
), carried by the individual, which transmits an identification code group on reception of an interrogation signal. A control unit located within the protected area transmits an interrogation signal when activated by the individual, and verifies the identification code group received from the transponder. Access to the protected area will only be permitted on positive verification of the right to access. The transponder (
), contained within the remote control unit (
), is a passive transponder which obtains a supply voltage from the interrogation signal transmitted by the control unit (
) and then feeds this to a supply voltage rail. The remote control unit (
) contains a battery (
) that can be connected to the supply voltage rail (
) by means of a controllable battery coupling switch (
)via a high-resistance path when the remote control unit (
) is in its quiescent state, or via a low-resistance path when the remote control (
) unit is in its active state.