| 摘要 |
PROBLEM TO BE SOLVED: To provide a catch prevention device for a car window which is not easily affected by the deterioration with elapsed time and the external circumstance. SOLUTION: Vibration is applied at one end of a window pane 7 from a vibrator 23 parallelly to the face of the window pane 7 and the surface wave propagated through the edge of the pane is detected by a vibratory detection sensor 24 equipped at the other end of the pane. Contact of a foreign material with the upper edge 21 of the window pane 7 is detected by discriminating whether the surface wave is intercepted at the middle way of the edge 21 of the pane or not. The detection is never affected by surface oxidation, corrosion, dirt of the parts, and environmental changes such as surrounding brightness or the like. |
