| 摘要 |
PURPOSE:To automatically execute focusing with high accuracy, and also to shorten a focusing time, by freely setting optical path length of a pair of subimage pickup elements for controlling an image forming optical system by a definition detecting system. CONSTITUTION:Definition signals Q, R by subimage pickup elements 31, 41 being at a symmetrical position against a main image pickup element 21 for outputting an image forming definition signal P are processed by a subtractor 54, and movement of a lens 112 is controlled through a composite control signal generator 56, a changeover switch 57, a driving mechanism 61, etc. By this definition detecting system, the element is automatically focused with high accuracy without being influenced by a kind, a position, a contrast, a motion, etc. of an object to be photographed. On the other hand, when most of signals P-R become zero due to large focusing blur, and relation of the signals P-R is different from the reference condition, an output of a logical operation unit 53 is inverted to a low level through comparators 52, 55, and the optical path length of the elements 31, 41 is varied by a search signal generator 58A, and an electromagnetic coil 815, etc. In this way, a difference between the signals Q and R is generated, the lens 112 is not moved to both ends of draw-out and lead-in, and focusing is executed in a short time. |
