LOCKING/UNLOCKING SYSTEM FOR DOOR OF BUILDING

PROBLEM TO BE SOLVED: To prevent a locking/unlocking system for a door of a building which locks and unlocks the door of a building upon receiving a response code signal transmitted from a portable device in response to a challenge code signal and a calling code signal transmitted from the system as electromagnetic wave signals from making a malfunction which may be caused when transmitting- receiving sections respectively provided on the external and internal surfaces of the door simultaneously transmit electromagnetic wave signals. SOLUTION: The locking/unlocking system is provided with an outer transmitting-receiving section 11 having a transmission antenna 18 and a reception antenna 19 on the external surface of the door 1 and an inner transmitting- receiving section 31 having a transmission antenna 36 and a reception antenna 37 on the internal surface of the door 1 and causes the sections 11 and 31 to alternately perform transmitting and receiving operations by switching the sections 11 and 31 to each other at a prescribed time interval by means of an antenna switching circuit 13e provided to a controller 13. COPYRIGHT: (C)2004,JPO