| 摘要 |
PROBLEM TO BE SOLVED: To provide a radio communication system in which the user of a portable information terminal can know the presence of an object in the vicinity of the user. SOLUTION: The radio communication system 100 comprises a portable information terminal, i.e., a portable telephone 10, and a proximity sensor unit 30 performing radio communication with the portable telephone 10. The proximity sensor unit 30 comprises a proximity sensor 36 for detecting an object 50 in a detection zone proximate to the portable telephone 10 and producing a detection signal, and a transmitting/receiving circuit 38 for transmitting a detection signal produced from the proximity sensor 36 to the portable telephone 10. The portable telephone 10 comprises a transmitting/receiving circuit 18 for receiving a detection signal from the proximity sensor unit 30, and a display 29 for displaying a detection signal received by the transmitting/receiving circuit 18.
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