| 摘要 |
PURPOSE:To adjust sensitivity characteristics and frequency characteristics of an ultrasonic transmitter-receiver freely by varying the heights of a stuck type piezoelectric element from a terminal plate and a case. CONSTITUTION:A stuck type piezoelectric element 2 made of piezoelectric ceramics having a diaphragm 1 in the center is fitted to a supporting part 4 with an elastic adhesive 3 and the supporting part 4 is arranged at the center part of a terminal plate 6 having a terminal 5 and made of synthetic resin, etc. The tip of an adjustment screw 8 screwed into a screw hole 7 under the terminal plate 6 is pressed against the center part of the reverse surface of the supporting part 4 to adjust the height of the supporting part 4. In a case 10 wherein a sound collection hole 11 is formed, the distance between the hole 11 and the top surface of a terminal plate 9 is adjusted by the screw, etc., of the terminal plate 6. When the height (h) of the piezoelectric element 2 from the top surface of the terminal plate 6 is varied like h1, h2 and h3 (h1>h2>h3), the frequency characteristics of the sensitive of an ultrasonic transmitter-receiver are as shown by curves (a), (b), and (c). |
