| 摘要 |
<p>PURPOSE:To provide an approach detecting device which, according to the time from transmission of intermittent ultrasonic codes to reception of an individual identification code at a responding sub-station, detects that the corresponding individual approaches and then outputs the individual identification code. CONSTITUTION:A sub-station 16 transmits a particular individual identification code when receiving an ultrasonic signal intermittently emitting a fixed code and coming from a main station 15. At the main station 15, the time difference from transmission of the code to the reception of the individual identification code, the individual identification code, and the order of generation of codes responded by the sub-station 16 are stored in memory 13. If someone approaches and goes into the range below the threshold of approach distance or approaches at a speed greater than the threshold of approaching speed, an individual identification code extractor 14 outputs the corresponding individual identification code.</p> |
