Automatic focusing device utilizing a trend of variation and degree of reliability of a focusing evaluation value signal to improve image focusing
First Claim
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1. An automatic focusing device comprising:
- lens means for changing a focused field of an object;
moving means for moving said lens means;
extracting means for image-sensing the object through said lens means to extract a luminance signal;
signal outputting means for outputting a focusing evaluation value signal for evaluating a focusing condition of the object on the basis of said extracted luminance signal;
determination means for determining reliability of the focusing evaluation value signal; and
control means for controlling said moving means on the basis of the determined reliability to improve focusing of the object;
wherein said signal outputting means outputs the focusing evaluation signal for every field or every frame;
wherein said determination means calculates a trend of variation and reliability based on a variation of the focusing evaluation value signal output for each field or each frame;
wherein said determination means determines the trend of variation and reliability of the focusing evaluation value signal using an approximation method;
wherein said control means controls said moving means so that said lens means is still when the determined reliability is less than a predetermined value.
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Abstract
An automatic focusing device including a lens group by which movement of a focused field of an object changes, a drive motor for moving the lens group, a luminance processing circuit for image-sensing the object through the lens group to extract a luminance signal, an accumulating circuit for outputting a focusing evaluation value signal for evaluating a focal condition of the object on the basis of the extracted luminance signal, a least squares circuit for determining reliability of the output focusing evaluation value signal, and a control circuit for controlling the drive motor to improve the focal condition of the object on the basis of the determined reliability.
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Citations
4 Claims
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1. An automatic focusing device comprising:
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lens means for changing a focused field of an object; moving means for moving said lens means; extracting means for image-sensing the object through said lens means to extract a luminance signal; signal outputting means for outputting a focusing evaluation value signal for evaluating a focusing condition of the object on the basis of said extracted luminance signal; determination means for determining reliability of the focusing evaluation value signal; and control means for controlling said moving means on the basis of the determined reliability to improve focusing of the object; wherein said signal outputting means outputs the focusing evaluation signal for every field or every frame; wherein said determination means calculates a trend of variation and reliability based on a variation of the focusing evaluation value signal output for each field or each frame; wherein said determination means determines the trend of variation and reliability of the focusing evaluation value signal using an approximation method; wherein said control means controls said moving means so that said lens means is still when the determined reliability is less than a predetermined value. - View Dependent Claims (2, 3, 4)
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Specification