| 摘要 |
PURPOSE:To obtain a range-finding device for autofocusing device which can accurately and rapidly measure a distance to an object so as to surely focus on the object even in the case that plural objects exist. CONSTITUTION:The object is caught by light receiving sensors 10, 20 and 30, and the zero cross point of the secondary difference of brightness distribution is operated and detected. The behavior of each zero cross is stored according to a specified address in a zero cross memory circuit for each of the three light receiving sensors 10, 20 and 30. One of zero cross data of the sensors 10, 20 and 30 is taken as a reference datum, and when the datum stored at one address of the reference datum includes the zero cross point, the data in other zero cross memory circuit are successively deviated with respect to the data of address to detect a coincident point. The distance to the object is measured based on the deviation of the behavior of the zero cross of two line sensors when the coincident point is detected. |
