| 摘要 |
PURPOSE:To improve the amplitude frequency characteristics of a low frequency area by arranging comb-like electrodes so that the phase surface of a signal excited by the electrodes and reflected by an end surface is shifted from the phase surface of a signal excited by the electrodes. CONSTITUTION:The comb-like electrodes 2, 3 having inclination theta from the end surface of a base plate 1 consisting of a lithium niobate monocrystal plate are attached to the surface of the base plate 1. When a signal is supplied to the comb-like electrode 2, its excited wave is advanced in the horizontal direction of the electrode 2. The excited wave advanced in the reversed direction against the electrode 3 is absorbed by an acoustical absorbent 5, but a part of the exicted wave is reflected by the end surface AB of the base plate 1. The signal reflected by the end surface AB is absorbed again by the acoustical absorbent 5 and then advanced in the direction of the electrode 3. Since the inclination theta is determined so that the equiphase surface of a signal excited by the electrode 2 is shifted from that of a reflected wave from the end surface AB, fine characteristics can be obtained even if the size of the base plate 1 is reduced and the length of the acoustical adsorbents 5, 6 is unsufficient. |
