| 摘要 |
PURPOSE:To expand the arrival distance of a pattern and to enable high-accuracy detection while expanding a distance measurement range by arranging an optical member which has converging power only in the lengthwise direction of a light emit ting tube in front of an bar chart and projecting the image of the aperture on a subject side. CONSTITUTION:The bar chart 2 is arranged in front of the light emitting tube 3 and the pattern of the lighted bar chart 2 is projected on the subject through an optical member 1 with specific refracting power. At this time, the reflecting surface of a reflecting mirror 4 is composed of an elliptic surface or parabolic surface having its focus on the center axis of the light emitting tube 3 and luminous flux from the light emitting tube 3 is irradiated efficiently. The optical member 1 is so constituted as to have converging force in the same direction as that of the pattern that the bar chart 2 has because the bar chart 2 has the pattern only in the direction, and the pattern is projected on the subject side efficiently. The light emitting tube 3 is so controlled by a control means as to emit light manually or when a photodetecting means provided to part of the camera judges that the environment is darker than a specific value or when an automatic focus detecting means judges that the contrast of the subject is lower than a specific value. |
