| 摘要 |
PURPOSE:To exactly and speedily detect a focal point. CONSTITUTION:Light is photoelectrically converted by an imaging device 2, and the high frequency component is extracted by a filter 4 as a focusing voltage Y. First and second arithmetic units 6a and 6b calculate inclinations theta1 and theta2 of line segments connecting sample points PA-PC from the differential value of focusing voltages Y among the sampling points PA-PC and difference DELTAX at a position X of a lens 1, and a third arithmetic unit 6c calculates a ratio beta between the inclinations theta1 and theta2. A focus driving part 6d controls the driving of a focus lens motor 7 and moves the lens 1 in a focal direction at optimum speed corresponding to the ratio beta. |
