| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a person from leaving a portable telephone set behind by automatically emitting a warning and to prevent other persons from illegally using the portable telephone set by automatically locking a key of the portable telephone set when the person leaves the portable telephone set behind. <P>SOLUTION: A portable telephone system is provided with the portable telephone set 10, a monitoring control circuit 30 connected to an external connection terminal 18 of the portable telephone set 10 in a freely attachable and detachable way, and a monitoring device 40 having a radio wave transmitting/receiving function. The monitoring control circuit 30 receives the feeding of power for a power supply from a power supply part 20 in the portable telephone set 10 and also has a function which is controlled by a control part 28 to transmit and receive radio waves to/from the monitoring device 40. When the user carries the monitoring device 40 together with the portable telephone set 10, leaves the portable telephone set 10 behind somewhere and leaves the spot, a warning automatically rings from a loudspeaker 44 of the monitoring device 40, a warning also rings from a loudspeaker 14 of the portable telephone set 10 and in addition, a key lock state of the portable telephone set 10 is automatically turned on. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
