| 摘要 |
PURPOSE:To make the titled sensor inexpensive by eliminating influence due to dust, by constituting the same from such a mechanism that an absorbing element of ultrasonic vibration is provided to the front surface of an ultrasonic transducer to sense the change in the reflection of ultrasonic vibration when an article to be sensed is inserted between both of them. CONSTITUTION:An ultrasonic transducer 11 is mounted to an upper part 12 and an ultrasonic signal absorbing element 14 is arranged to the surface 13 opposed to said transducer 11. The ultrasonic transducer 11 is constituted by such a method that two piezoelectric electrode discs each comprising Pb(Zn+Ti)O3 type ceramics and having a thickness of 0.25mm. and a diameter of 4mm. are adhered in bimorph state to be mounted onto a base disc 11-1 by a binder comprising silicone rubber while a radial shape cone 11-2 is mounted to said base disc. On the other hand, the ultrasonic signal absorbing element is constituted by providing a cavity 16 to the leg part of a frame 15 comprising a high-molecular resin having the upper part 12 equipped with the ultrasonic transducer 11 while filling said cavity with a sponge 17. |
