| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the presence/absence of an electronic key in a prescribed area by issuing a signal of a prescribed code from a transmitter, when the transmitter is judged to be stored in a storage means. SOLUTION: A receiver part receives a weak electric wave transmitted from a transmitter 20 via a receiver antenna, shapes the waveform of the received signal, and outputs it to a microcomputer. The transmitter part transmits a trigger according to the command from the microcomputer via a transmitter antenna. The transmitter 20A incorporates magnet 33 and a storage means 40 has a magnet sensitive element 43 so that, whether the transmitter 20 is inserted in a slot 41 or not is judged by the magnet sensitive element 43 reacting to the magnet 33. When the insertion of the transmitter 20 is recognized, a trigger is transmitted from a trigger antenna 44 provided in the storage means 40, the trigger is received by a power conversion part via loop antenna, and a prescribed code is transmitted from the transmitter 20.
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