| 摘要 |
PURPOSE:To automatically adjust focus by performing servocontrol by setting the point where the level of the high frequency components of a video signal is an extremal value, as a reference point. CONSTITUTION:The optical information imaged on the target surface 141 of an image pickup element 14 is converted to a video signal E24 by a video processing circuit 52. The 1st means 64 inputted with the video signal E24 takes out the high frequency components thereof and outputs a level signal E34 of said components. The signal E34 is inputted to the 2nd means 70, by which the deviation of the signal E34 from the best focus position where it is an extremal value is detected and this detected value is inputted to the 3rd means 96. The output signal E12 of the 3rd detecting means is the control target of a servoloop consisting of a potentiometer 36 detecting the relative positions of the lens system and the target surface, a subtractor 38, an amplifier 42 and a motor 32. |
