| 摘要 |
A broadly tuned transducer system for pulse echo ranging systems has a rigid plate (1), to a planar radiating front surface of which is applied at least one layer of acoustic coupling material (6) having a density intermediate between that of the plate and an atmosphere into which the transducer is to be coupled. Three or more driver assemblies spaced apart in a two dimensional array are rigidly secured to a rear surface of the plate, each assembly having a loading block (3) and a piezoelectric element (2) compressed between the block and the plate (1). The driver assemblies all have the same resonant frequency on axes perpendicular to the plate and are driven in phase; they occupy not less than one fifth and not more than four fifths of the area of the rear surface of the plate, which is rigid enough to prevent the excitement of significant flexural oscillations. The arrangement permits the transducer to have a large planar radiating surface whilst using quite small piezoelectric elements (2). |
