| 摘要 |
<p>When a worm wheel rotates relative to an object-catching detection plate due to a foreign object being caught, then protruding portions formed on a surface of the worm wheel engage protruding portions formed on a surface of the object-catching detection plate, the first aforementioned surface and the second aforementioned surface being those which face each other. This engagement causes the object-catching detection plate to move in the direction of a shaft. At this time, the object-catching detection plate moves in the direction of the shaft, without rotating. Therefore, the object-catching detection plate comes into contact with a movable piece of an object-catching detection switch, without rotating. Consequently, no friction is created due to rotation when the object-catching detection plate comes into contact with the movable piece of the object-catching detection switch. Accordingly, the object-catching detection accuracy is prevented from deteriorating due to wear.</p> |
