INTERFACE POSITION DETECTING SENSOR

PURPOSE: To detect the interface position from the same position with a reflecting plate as a reference even when a vibrator vibrates to send a wave by arranging the reflecting plate in a position separately by a specific distance forward in the horizontal direction of a wave sending-receiving surface of an ultrasonic wave transmitter-receiver. CONSTITUTION: When electric power is supplied to an ultrasonic wave transmitter- receiver 10 through a cable 50, a vibrator built in the wave transmitter-receiver 10 is driven, and an ultrasonic wave having a prescribed frequency is sent. Since a wave sending-receiving surface 11 of the wave transmitter-receiver 10 is arranged in the horizontal direction, the ultrasonic wave advances in the horizontal direction, and reaches a reflecting plate 20. The ultrasonic wave reaching the reflecting plate 20 changes the direction by 90 degrees after it was reflected by the reflecting plate 20, and advances downward, and reaches an interface 30. After the ultrasonic wave is reflected by the interface 30, it is again reflected by the reflecting plate 20, and is received by the wave transmitter-receiver 10. When a position of the reflecting plate is set 50cm forward the wave transmitter-receiver 10, an interface position from 0cm can be detected by measuring time until the ultrasonic wave is received after it was sent with the reflecting plate 20 as a reference.