| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain the desired acoustic pressure outside the vehicle regardless of the road surface state in a parametric speaker that radiates the ultrasonic wave to the lower side of the vehicle. <P>SOLUTION: The ultrasonic wave radiated from the ultrasonic speaker 2 to the lower side of the vehicle is reflected by an under cover 3 disposed under the ultrasonic wave speaker 2 and turned forward of the vehicle. The surface of an inclined part 3a (reflecting surface) of the under cover 3 is constant regardless of the road surface and can always stably reflect the ultrasonic wave forward of the vehicle. As a result, even if the road surface state changes, desired acoustic pressure can be obtained at any time outside the vehicle. Moreover, because the radiation aperture of the ultrasonic speaker 2 turns downward, the trouble that the rain water accompanying the vehicle running wind is infiltrated inside the ultrasonic speaker 2 can be evaded. In addition, even if the under cover 3 is used as a diffusion plate of the ultrasonic wave, the diffusion of the ultrasonic wave can be always and stably carried out regardless of the road surface state. <P>COPYRIGHT: (C)2012,JPO&INPIT |
