| 摘要 |
PURPOSE:To produce satisfactorily a single pulse having spectrum of a wide band, by reducing gradually the intensity of polarization toward the shortest direction between plural driving electrodes on a single face of a plate type piezoelectric material and a counter electrode on the other side of said piezoelectric material. CONSTITUTION:Driving electrodes 2a-2n are provided to a piezoelectric plate 1, and lead wires 3a-3n are connected to those driving electrodes respectively. A counter electrode 4 is coated on the entire surface of the other side of the plate 1 and grounded via a lead wire. The intensity of polarization of a piezoelectric electrode 1 set right under the electrodes 2a-2n is gradually reduced toward the electrode 4 as shown by a curve (a). At the same time the direction of polarization is set vertical to produce polarities opposite to each other with each group of adjacent electrodes. As a result, no point of sensitivity 0 exists for the frequency characteristics. This enables an impulse response of a wide range of spectrum. |
