| 摘要 |
A reflex proximity sensor (20) includes a light emitting source (22) which directs a beam (16) by way of a beamsplitter (28) toward a retroreflective surface (18), which reflects incident light back towards the source. A non-uniform (eccentric) convex lens (38) is positioned in the beam path to produce a beam of light (16) which is dispersed along a sensing axis (T), so that an eccentric cross-section beam is directed toward the retroflective surface. The portion of the beam which reflects off the retroreflective surface passes back through the non-uniform convex lens and reflects off of the beamsplitter, and is directed to a photodetector (46). As an object (14) traverses the beam in the direction of the sensing axis, the leading (or trailing) edge establishes a change in the intensity level of the beam portion that reaches the detector. The output of the detector provides a signal representative of the edge portion of the object. |
