| 摘要 |
Water (3) on the outside surface (1) of a vehicle windscreen (7) causes a light beam (5) to be partially transmitted through screen (7), while a clean screen (7) provides substantially total internal reflection of beam (5). This difference is detected by light sensor (6). The presence of water is used initially to trigger the windscreen wipers and once activated, the characteristics of the signal from sensor (6) received during one wiper action are used to set the characteristics of the next wiper action, e.g. time delay, or wiper blade speed. The light beam (5) is an infra-red light. |
