| 摘要 |
PURPOSE: To make an error in range-finding small and to excellently perform the switching of the focus lens of automatic focusing control. CONSTITUTION: This light quantity detecting type range finder is provided with a light projecting element 10, a light receiving element 14, a stational light removing circuit 15, a comparator 16, a latch circuit 17 and a lens extending circuit 18 or the like, and the light receiving surface of the light receiving element 14 is arranged so as to make a light receiving image be half lacking on the side of long distance at the position of the light receiving surface receiving reflected light from a subject which is apart by specified distance and is a decision object. Thus, a threshold for deciding the reflected light whose reference reflectance is 36% is made to be half for the measuring of decided distance, and in the case of other reflectance it is not the half because the light quantity is in reverse proportion to the square of distance, so that an influence caused by the change of the reflectance is made to be small. For instance, in the case where the reflectance is lowered, the error in the case of deciding the distance on the side of shorted distance that the decided distance is made to be small. |
