| 摘要 |
PURPOSE:To suppress noise component due to external light low for signal components and to perform high-precision focus detection by dividing and using one of two photodetecting elements which detect the focusing state of a photographic lens. CONSTITUTION:Photodetecting elements 10 and 11 which constitute the 1st photodetecting element and the 2nd photodetecting element 20 are arranged on a photodetection surface in a line at right angles to an optical axis to an object 6 and displaced in one body at right angles to the optical axis to the object 6 according to the quantity of extension of the photographic lens, so that signal reflected light from the object 6 is photodetected by the elements 10 and 20 fifty-fifty. When the object 6 is a little bit behind the focusing position of the photographic lens, the signal reflected light strikes more on the element 20 than on the element 10 and when the object 6 is a little bit before the focusing position, the light strikes more on the element 11. Consequently, a focusing, front-focus, or rear-focus state is decided from which of the elements 10, 11, and 20 the quantity of the incident light deviates to. |
