| 摘要 |
PURPOSE:To enable accurate judgement of a distance of an object in a wide range by monitoring outputs of light receiving elements along with the determina tion of output ratios of the light receiving elements to judge whether the outputs are above a specified value or not. CONSTITUTION:Light receiving elements 4 are made up of elements D1, D2 and D3 in the order from far side to close side according to the position of reflected light from an object to determine distance of the object from output ratios of the light receiving elements. Here, the quantity of light coming into the element 4 is monitored to judge whether outputs of photometry circuits 7 and 8 exceed a fixed level K or not with a comparator 15. Then, an output ratio of D2/D1 is determined to be valid when an output of the D2 is above the level K while an output ratio of D3/D2 is determined to be valid when an output of the D3 above the level K. When the output is below the level K, information involved should be infinity position information or invalid information. Thus, the ratio of the element outputs can be judged valid or invalid, thereby the distance of the object can be determined. |
