| 摘要 |
The detector of the invention comprises a vibrating membrane 1 and its transducer 2. The membrane 1 is impervious to the fluid whose level it is desired to detect and the transducer 2 consists of a piezoelectric ceramic component 20 which is mechanically fastened to the free face of the membrane. The detector furthermore comprises means 3, 4 for electrical excitation of the variable-frequency transducer and means 5, 6, 7 for detecting the phase shift between two magnitudes which are representative of the vibrating state of the membrane. Application to the detection of fluids constituted by pulverulent or granular materials and in particular grain levels in silos. <IMAGE>
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