| 摘要 |
PURPOSE:To stop an automatic focusing lens securely at a focusing position in one time focusing process by moving the focusing lens while replacing focus information following up out-of-focus characteristics of a subject image. CONSTITUTION:The photodetection surface of an automatic focusing sensor 7 is arranged at a position equivalent to the image pickup surface of an mage pickup device 6. The accumulation amount of charges of the sensor 7 is calculated for a specific time by an out-of-focus amount arithmetic circuit 9 and made to correspond to the out-of-focus amount; every time the calculation time is elapsed, a sensor driving circuit 8 is operated to start accumulating charges in the sensor 7, and the focus information is replaced. The out-of-focus amount calculated by the circuit 9 is converted by a pulse converting circuit into specific pulses, on the basis of which an out-of-focus subtracting circuit 11 performs subtraction for a specific time to eliminate the out-of-focus amount. The output of the circuit 11 is supplied to a motor driving circuit 13 through a focusing range detecting circuit 12 to drive 4 as far as the output of the circuit 9 continues, thereby moving the lens 2. The circuit 12 stops the motor 4 when the out-of- focus amount becomes smaller than a specific value. |
