Patent ID: 6147621
Filing Date: 2000-11-14
Classification: G07C

Abstract:
An access control systemfor controlling access to at least one space via at least one doorand which includes a transponder communication device for providing contactless communication with at least one transponder which controls authorization to access via the at least one door,and which includes at least two transmission coils each having a given receiving range for receiving transponder signals which each contain at least one type of authorization informationsaid coils being connected to the transponder communication device for detecting identification information representative of at least a part of a received transponder signal,and which includes a first activation device for activation by an authorized person,said first activation device being associated with the first transmission coil and the first door for initiating access to its associated first doorsaid first activation device being connected to the transponder communication device for generating first activation information representing the activated first activation device,and which includes at least one door opener for activation by the transponder communication device so as to open a door,and which includes a logic device for activating the door opener of the first door upon receipt of identification information representing at least a part of a transponder signal received by the first transmission coil, and of first activation information,characterized in thatthe transmission coils have arbitrarily large receiving ranges,the first transmission coil and at least one further transmission coil are followed by amplitude detection means by which the amplitudes of the transponder signals supplied by these transmission coils are detected and by which, after the amplitudes have been detected, amplitude information is generated as identification information,the amplitude information generated by the amplitude detection means is applied to the logic device as identification information,the logic device detects a condition in which the amplitude of the transponder signal supplied by the first transmission coil is greater than the amplitude supplied by the at least one further transmission coil,the door opener of the first door being activated only by means of the logic device upon detection of this condition.