| 摘要 |
PURPOSE:To obtain a distance detection sensor capable of accurately detecting the distance to an obstacle by using two photodetectors and detecting the moment an object reaches an overlap end within distance ranges which overlap partially with each other. CONSTITUTION:Measurement light 2 projected by a light projecting element 1 is diffuse-reflected by the obstacle 3 and detected by a couple of photodetectors 51a and 51b. then the element 51a detects reflected light when the obstacle 3 is at a distance between La1-La2 and the element 51b detects reflected light when the distance is Lb1-Lb2. Here, the distance ranges between La1 and La2, and Lb1 and Lb2 are so selected as to overlap partially with each other; when the obstacle 3 approaches as shown by an arrow A1, output variations of the elements 51a and 51b are observed to accurately recognize the moment the obstacle 3 reaches the distances Lb1 and Lb2. Then only when the time from the detection of the reflected light by the element 51a to the light reception by the element 51b is within a specific range, it is decided that the obstacle 3 reaches the distance Lb, thereby excluding the case wherein the obstacle 3' crosses the light as shown by an arrow A2.
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