| 摘要 |
PURPOSE:To execute the automatic focusing at high-speed response and with high accuracy, by varying a lens driving speed in accordance with whether a lens is within a prescribed range in the proximity of a focusing position or not. CONSTITUTION:Outputs of the first and second photoelectric element groups 1, 2 are inputted to space frequency component extracting circuits 3, 4, and signals V1, V1' showing the first space frequency components, signals V2, V2' showing the second space frequency component, and total light quantity signals r0, r0' of an incident light beam are outputted. The signals showing the first and second space frequency components are inputted to circuits 14-17, and their absolute values r1, r2, r1' and r2' are outputted. These signals are brought to a prescribed operation, and after that, a correlation output (¦V1-V1'¦+¦V2-V2'¦+¦r0 -ro'¦)/(r1+r2+ r1'+r2') is obtained as an input of a comparing circuit 20. When the lens is within the prescribed range in the proximity of the focusing position, an H level output is outputted from the comparing circuit, a motor is driven intermittently, and its speed is decreased. |
