| 摘要 |
PURPOSE:To prevent a service degradation due to the operation error of an attendant board operator by sending an output signal to show an operator presence when an output level at the time of receiving an ultrasonic sensor for reception is a prescribed threshold or above. CONSTITUTION:A sensor 111 to send an ultrasonic wave to the seating position of an operator 113 of the attendant board 110 is provided, and when the incoming call is received at the board 110, an oscillator 115 or the sensor 111 is driven and the ultrasonic wave is radiated. At the board 111, an ultrasonic sensor 114 for receiving is provided, the output of the sensor 114 is amplified by a receiver 116, given to a discriminating circuit 117, when the amplifying output level is the prescribed threshold or above for discrimination, the detecting output is sent and connected through a transistor 112 to a photocoupler 202 of a main body equipment 200. In this case, the irradiating ultrasonic wave is reflected by the operator 113 and received by the sensor 114. When the operator 113 is absent, the ultrasonic wave is the reflection such as a floor, is weaker than the time of the presence of the operator 113 and the output level of the receiver 116 is threshold or below.
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