| 摘要 |
PURPOSE:To obtain a constant directional patter by flattening of the transmission-reception surface of a plate form piezoelectric transducing element, enlarging a thickness from a center part to a peripheral part in a back face and changing a resonance point according to a frequency. CONSTITUTION:The back face 11b of the piezoelectric transducing element consisting of a ceramic oscillator 11 for mutually transducing the electric signal to/from the ultrasonic wave signal of a prescribed frequency is covered by a mold material through a sound absorbing material 13 and a flange 14 and a surface 11a is directly covered by the mold material 16. The surface 11a of the ceramic oscillator 11 is flattened to have the transmission-reception surface. In the back face 11b, the thickness is enlarged from the center part to the peripheral part to change a resonance frequency. On the transmission- reception surface 11a and the back face 11b of the oscillator 11, electrodes 12a, 12b are formed, a lead wire is passed through the hole 14a of the flange 14 to connect to a calbe 15. Thereby, the resonance point is moved according to the fluctuation of the frequency and the almost constant directional pattern is maintained.
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