| 摘要 |
PURPOSE:To rapidly and accurately detect that the distance up to an object becomes the dangerous distance between cars by automatically forming the image of the object when the object comes to a preset focal distance to output an operation signal. CONSTITUTION:When the object A obtained through an optical lens 1 comes to the position of a preset focal distance, the image B of the object is automatically formed and a focus matching signal is also outputted. In this automatic focus detecting mechanism 2, the theory reverse to that of an existing automatic focus camera is used. In the case of this automatic focus lens, when the distance up to the object A is changed, the focal distance of the aforementioned lens 1 is automatically changed and the image B of the object A projected on a detection surface 4 is formed. Therefore, contrarily, when the focal distance is set constant, a focus matching signal can be outputted when the image B of the object A present at the focal distance is formed. |
