| 摘要 |
An imaging apparatus for automatic focusing, includes an imaging device for imaging an image light from an objective through a lens system, a signal processing circuit for processing a video signal output from the imaging device, and an edge extracting element for extracting high-frequency band components from signals outputted from the signal processing circuit. The apparatus further comprises a characteristics conversion circuit for converting characteristics in signals outputted from the edge extracting element in the manner that a value is set to substantially zero after extracted signals are calculated by a cubic differential of a lens moving amount of the lens system; a calculation circuit for obtaining the lens moving amount to a focal point by calculating a proportion between a linear differential and a quadratic differential; and drive circuit for driving the lens system corresponding to the lens moving amount to the focal point and outputted from the calculation circuit. In the calculation circuit, the linear differential is obtained by calculating a linear differential of a characteristics conversion signal outputted from the characteristics conversion circuit by the lens moving amount, and the quadratic differential is obtained by calculating a quadratic differential of the characteristics conversion signal by the lens moving amount.
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