| 摘要 |
<p>POSITION SENSING APPARATUS The present invention relates to a sensing apparatus for sensing the displacement of a movable object relative to its ideal vertical path of travel. The apparatus includes two elongate reference wires extending parallel to the ideal vertical path of travel of the object. The apparatus further includes two sensing devices mounted for movement with the object. Each of the sensing devices is normally positioned a predetermined distance from a respective one of the reference wires such that engagement of the reference wire by the sensing device indicates that the object has been displaced about or from its expected predetermined path of travel.</p> |
