| 摘要 |
PURPOSE: To detect image contrast of excellent reproducibility by detecting difference of the maximum value and the minimum value of contour component signals, setting amplitude as a contrast signal, and automatically focusing by the contrast signal. CONSTITUTION: Contour signals A are A/D-converted in sufficient fine sampling blocks SP, maximum digital data is by a maximum value comparison circuit 64, minimum digital data is by a minimum value comparison circuit 65, respectively obtained, difference of the maximum and the minimum is computed at timing completing the contour signals A, and hence contour components C are obtained. Respective contour components Cn are obtained on respective lines in the component extraction range, and they are added together to obtain image contrast F. Further, for softening noise components superimposed on the maximum value and the minimum value, the respective contour components C1-Cn are obtained on the respective lines on the prescribed component extraction range, and they are added together to obtain a contrast signal. A drive pulse is output by a drive control circuit 67 so as to make it maximum by the contrast component F, and a drive motor 13 is driven.
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