| 摘要 |
PURPOSE:To attain rapid and smooth focusing by dividing twice the differential value of a focus voltage by a differential value to determine the focusing distance of a focusing lens. CONSTITUTION:The focus voltage E(x) of a high frequency component in a video signal obtained through a photographing element 7, an amplifier 8, and AGC13 a BPF9, an A/D converter 11, etc., and calculated on the basis of the quality I is supplied to a microcomputer 3. In the equality, (x) is a distance from the focusing lens 1 up to a focusing position and (a) and (b) are factor values relating to the voltage E(x) curve. The differential value and twice differential value of the voltage E(x) are calculated, the differential value is divided by the twice differential value to determine the distance (x) and the distance (x) is converted into a moving signal of the lens 1. Thus, the autofocusing of an image pickup device can be rapidly and smoothly attained. |
