| 摘要 |
PURPOSE: To obtain a range finder which prevents a drop in the distance measuring capability on the side of a long distance and which ensures the range of a macro region by a method wherein a position detection element is used in an ordinary photographing distance, a triangula tion operation is performed by a differential/additional signal and a distance is found on the basis of the ratio of the difference signal of the position detection element in a macrophotographing operation to the quantity of light output of an adjacent light detection element. CONSTITUTION: Infrared light from an infrared light emitting element 1 is condensed by a lens 2 for light projection, it is projected toward a subject at the front, and reflected light from the subject is received by a semiconductor position detection element (PSD) 3 and an adjacent light detection element (SPC) 4. At this time, when the subject is situated at comparatively long distances D1 , D2 , its image is formed on the PSD 3. When the subject is situated near a point Dn , its image is formed in such a way that its light receiving image is formed on both the PSD 3 and the SPC 4. Then, at a comparatively short distance (an ordinary distance), a distance up to the subject is found on the basis of the differential/additional signal of outputs I1 , I2 of the PSD 3, i.e., (I1 -I2 )/(I1 +I2 ). In a macrophotographing operation at a short distance, the distance is found on the basis of the difference signal of the PSD 3/the quantity of light output I3 of the SPC 4, i.e., (I1 -I2 )/I3 . |
