Patent ID: 6317035
Filing Date: 2001-11-13
Classification: B60R,G07C

Abstract:
An apparatus for enabling and/or activating/deactivating a security device, in particular an access device for a motor vehicle, in which, after receiving a stimulation sequence which is transmitted by a transmitter of a transmission device, coded information (enable signal) is transmitted by a portable transmission unit (radio key) and is received by a receiver in the transmission device, a controller comparing the received enable signal with predetermined coded information and, if they match, emitting an actuation signal to the security device, wherein the stimulation sequence (challenge signal) (13) comprises a first message part (13') with an identity of the security device, and a second message part (13""), in which case the first message part (13') excites those radio keys (1, 1a to 1d) which are located in a predetermined area of the transmitter (9) of the transmission device (2) and match the security device to each emit a response signal (16a, 16b, 16c) with a mutual offset at different times during the transmission of the second message part (13""), and wherein the controller (7) uses the response signals (16a, 16b, 16c) to select a suitable radio key (1a) from the set (1, 1a to 1d) and to emit a selection signal (13'"") which causes the selected radio key (1a) to emit the enable signal (14).