| 摘要 |
Sonic transducers utilize resonant cavities of varying depths to achieve wide operational bandwidth. The transducers (29) may include a conductive membrane (38) spaced apart from one or more backplate electrodes (32a,32b). In one approach, spacing is achieved using a dielectric spacer (34) having a series of depressions (36) arranged in a pattern, the depressions forming cavities each resonant at a predetermined frequency. In another approach, the conductive membrane (62) is piezoelectrically active, and the transducer is simultaneously driven in both piezoelectric and electrostatic modes. <IMAGE> |
