Focus control device of video camera

Abstract

PURPOSE:To attain the smooth and minute movement of a focusing lens by quickening the driving of the focusing lens if an object image is out of focus and driving it slowly when the focus is matched to a degree. CONSTITUTION:A distance signal outputted from an A/D converter 8 and corresponding to the distance to the object and a lens position signal representing the position of the focusing lens are inputted to a comparator section 13, where both the signals are discriminated for the level and the direction of revolution of a drive motor 11 is indicated. On the other hand, a high-order 2-bit of the distance signal being an output of the converter 8 and a high-order 2-bit being an output of a lens position detector 9 are inputted to a subtraction section 14 and an absolute value of the difference of the both is outputted. When the absolute value is large, a lens drive section 15 increases a torque of the lens drive motor and as the absolute value decreases, the section 15 decreases the torque.

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    Publication numberPublication dateAssigneeTitle
    EP-0268246-A2May 25, 1988Sanyo Electric Co., Ltd.Circuit de focalisation automatique pour associer automatiquement la focalisation en fonction du signal vidéo