| 摘要 |
An acoustic transmitting and/or receiving unit (3) for transmitting and/or receiving acoustic energy through a planar member (2) is formed by an acoustic driver (7, 8, 9) acting on the planar member through an aperture (5) in a plate (4). The plate is attached to the planar member across its surface and the plate has greater stiffness than the planar member. In the transmitting mode, transducer (8) bends in oscillating motion, causing the portion of the planar member (2) in front of the aperture (5) to move in and out, thereby generating acoustic signals in the air which then radiate outwards. In the receiving mode, when acoustic signals strike the bumper bar (2), oscillations of the portion of the bumper bar (2) in front of the aperture (5) drive transducer (8), thereby generating electrical signals. <IMAGE> |
