| 摘要 |
PURPOSE:To shorten the base length and to contrive to obtain small-sized device by dividing a light emitting lens which projects infrared rays into plural small sections having different optical axes and making the quantity of light in the center part of a spot, which is formed with overlapping of plural light spots, larger than that of the other parts. CONSTITUTION:The luminous flux formed by a light emitting lens 6 is projected on an object as spots 18a and 18b because of small sections 15 and 16, and respective centers of these spots are placed vertically with a distance (d) between them. With respect to a light quantity distribution of light spots 18a and 18b, the quantity of light in the center part where two spots overlap is larger than that in the other parts. A motor 4 is rotated forward or reverse in accordance with the difference between signals outputted from two light receiving elements 7a and 7b through a photodetecting lens 8, and a distance ring 3 is rotated until the quantity of light received by the light receiving element 7a is equal to that by the light receiving element 7b, and auto-focusing of a zoom lens 1 is possible. Thus, the base length is shortened without degrading the distance measurement precision, and the small-sized device provided with this auto-focusing device is obtained. |
