Key cylinder device

A key cylinder device comprising:

• a key including a signal transmitting circuit for transmitting an air propagation signal and a power source for said signal transmitting circuit;
• a rotor having a key inserting inlet;
• a casing in which said rotor is rotatably fitted;
• a shutter mounted by said rotor for swinging movement between open and closed positions, said shutter blocking said key inserting inlet in said closed position and being swung to said open position in response to the key being inserted into said key inserting inlet, said shutter being made of magnetic material;
• a permanent magnet installed on said rotor in such a manner that said permanent magnet is located near said shutter;
• and
• magnetism detecting means for receiving a magnetic force of said permanent magnet, said magnetism detecting means being mounted by said casing, said shutter interrupting said magnetic force of said permanent magnet on said magnetism detecting means while in said open position;
• and
• a primary coil mounted on said casing, said detecting means enabling energization of said primary coil while said shutter is in said open position;
• said key further including a secondary coil transformer coupled with said primary coil while said key is inserted in said key inserting inlet, said secondary coil generating an electromotive force in response to a variation of a current flowing in said primary coil to power said signal transmitting circuit.