| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable distance detection device to identify plural stationary article, the device being used in detecting a distance to a target by transmitting and receiving a sound wave.SOLUTION: A sound-wave sensor performs: enhancing a set sensitivity for obtaining a reflection wave after elapsing a response period since transmitting a sound wave, the response period corresponding to a reference distance that is within a distance in which plural targets with different sizes of surfaces for receiving the sound wave can be identified (S130-S160); determining presence of a target and a distance thereto by comparing a reception level of the reflection wave obtained as a result of the transmitted wave being reflected on the target with a pre-set threshold (S170). Thus enhancing the sensitivity for a zone farther than the reference distance makes it possible to detect both targets with a small reflection surface and a large reflection surface. Further, thus lowering sensitivity for a zone closer to the reference distance detects no target with a small reflection surface, while enabling detection of a target with a large reflection surface.</p> |
