| 摘要 |
PROBLEM TO BE SOLVED: To obtain a waterdrop detection apparatus by which a waterdrop can be detected without the influence of a disturbance by installing an ultrasonic-wave transmission-reception means in the rear of a plate body, transmitting ultrasonic waves in the direction of the surface, monitoring their reception intensity whenever they are reflected repeatedly inside the plate body, and comparing their reception intensity after the definite neumber of times of their reflection with a reference value. SOLUTION: Ultrasonic waves which are incident vertically on a plate body 1 from the rear 1B toward the surface 1A from an ultrasonic-wave transmission-reception means 2 repeat their total reflection inside the plate body 1, and multiple echoes are observed in a waveform which is detected by a transmission-reception circuit 3. A specific echo at a peak which is attenuated by a proper amount after the definite number of times of their reflection is compared with two reference values G1, G2 (where G1 < G2) by a computing and control circuit 4. It is judged that a waterdrop does not exist when the height of the specific echo>the reference value G2, and it is judged that a large waterdrop or waterdrops in a large quantity exist when the height of the specific echo < the reference value G1. When the reference value G1 < the height of the specific echo < the reference value G2, it is judged that a foglike small waterdrop exists. The judged result is output to a waterdrop removal device 5, and the device 5 can be controlled optimally according to a waterdrop stuck state. |
