| 摘要 |
PURPOSE:To appropriately set the accuracy in focus decision in accordance with a field depth and to eliminate too much accurate focus adjustment action by controlling a focus deadband according to a high frequency component included in the output of an image pickup means. CONSTITUTION:A control signal made of high frequency components being the output of a high frequency component detecting circuit 9 becomes a lower level as it has a higher deviation amount from a focus point. Since the control signal controls the width of the focus deadband in an adjustment circuit 6, the width of the deadband between the focus point and a position (g) on the broken line is narrow at an initial point t0 where the deviation amount of the focus position is maximum, and an auto matic focus adjustment signal starts a focus action. As the deviation amount becomes smaller due to the focus action, an image picked up video becomes sharper, and the high frequency component included in the video signal increases to make the control signal larger. Accordingly the width of the deadband is wider together with the focus action. The deviation amount of solid line (f) becomes smaller, and the operation enters in the deadband where a focus position gradually increases. Then, at a point t1 the automatic focus adjustment signal stops the drive of a motor and the focus action. |
