| 摘要 |
1,083,477. Transducers. MOTOROLA Inc. Dec. 8, 1965 [Jan. 6, 1965; June 17, 1965], No. 52051/65. Heading H4J. A tweeter comprises an elongated piezoelectric or magnetostrictive element 14 which is cemented at its respective ends to an elliptical spun-aluminium diaphragm 13 and a frame 24, the element being energized so as to produce longitudinal vibrations. The horn 21 and apertured pressure plate 15 are adjustable to provide a proper loading between the element, the diaphragm and the air. The element has a length #/4 at the highest frequency passed by the tweeter. It is preferably a piezo-electric ceramic body of rectangular, tapered, exponential, gaussian, stepped slab or cylindrical form (Figs. 2-5, not shown). Alternatively, a plurality of elements sandwiched between electrodes may be used (Fig. 6, not shown). If a magnetostrictive element is used it is preferably " biased " by a parallel permanent magnet 30 as to prevent frequency doubling. |
