In-focus detection apparatus using video signal
First Claim
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1. An in-focus detection apparatus, comprising:
- image sensing means for converting an object image formed by a photographing optical system into an electrical image signal;
edge width detection means for detecting a plurality of edge widths of the object in a prescribed area of an image sensing plane based on said image signal to provide edge width data;
lens driving amount calculation means for calculating the driving amount of a focusing lens to the in-focus point based on the distribution state of said edge width data; and
driving means for driving the focusing lens based on the output of said lens driving amount calculation means.
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Abstract
An in-focus detection apparatus used for a video camera includes edge width detector for detecting a plurality of edge widths of an object, and an calculation device for calculating the amount of driving a lens based on the distribution state of these plurality of edge width data. The apparatus uses a video signal and provides the in-focus state of an actual object with a high accuracy without requiring slight movement of a focusing lens.
66 Citations
23 Claims
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1. An in-focus detection apparatus, comprising:
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image sensing means for converting an object image formed by a photographing optical system into an electrical image signal; edge width detection means for detecting a plurality of edge widths of the object in a prescribed area of an image sensing plane based on said image signal to provide edge width data; lens driving amount calculation means for calculating the driving amount of a focusing lens to the in-focus point based on the distribution state of said edge width data; and driving means for driving the focusing lens based on the output of said lens driving amount calculation means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An in-focus detection apparatus, comprising:
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imaging sensing means for converting object images formed by a photographing optical system into electrical image signals; edge width detection means for detecting a plurality of edge widths of an object in a prescribed area of an image sensing plane based on the image signals to provide edge width data; contrast detection means for detecting a plurality of contrasts of said object in said prescribed area; a first frequency distribution producing means for producing a first frequency distribution from the edge widths and frequencies based on said detected edge width data; a second frequency distribution producing means for producing a second frequency distribution from the contrast values and frequencies based on said detected plurality of contrast data; focus detection means for detecting a focus point based on either said first or second frequency distribution; and selection means for selecting one of said first and second frequency distributions for use depending upon focus condition. - View Dependent Claims (9, 10)
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11. An in-focus detection apparatus, comprising:
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image sensing means for converting an object image formed by photographing optical system into an electrical image signal; contrast detection means for detecting the respective contrasts of the object at a plurality of points in a prescribed area of an image sensing plane to provide contrast data; and driving direction determining means for determining the direction of driving a focusing lens based on the distribution state of said contrast data. - View Dependent Claims (12)
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13. An in-focus detection apparatus, comprising:
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imaging sensing means for converting an object image formed by a photographing optical system into an electrical image signal; contrast detecting means for detecting contrasts of said object in a prescribed area of an image sensing plane based on said image signal; peak judging means for judging whether the detected contrast is a peak; edge width detection means for detecting a plurality of edge widths of the object in said prescribed area to provide edge width data; frequency distribution producing means for producing a frequency distribution from the edge widths and frequencies based on said detected edge width data and outputting a representative value in the distribution as an evaluation value for an in-focus determination; comparison means for comparing said representative value to a prescribed value for in-focus determination; and in-focus determination means for determining that an in-focus state is reached or not based on the outputs of both said comparison means and peak judging means. - View Dependent Claims (14)
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15. An in-focus detection apparatus, comprising:
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image sensing means for converting an object image formed by a photographing optical system into an electrical image signal; image sensing plane dividing means for dividing an image sensing plane into a plurality of small areas; edge width detection means for detecting the edge widths of the object and the total number of edges for every small area, based on said image signal; a first weighting coefficient output means for outputting a first weighting coefficient in accordance with the position of each small area in the image sensing plane; a second weighting coefficient output means for outputting a second weighting coefficient in accordance with edge width data in each small area; multiplication means for calculating the product of the edge total number ×
the first weighting coefficient ×
the second weighting coefficient for every small area; andfocus detection area determination means for determining where the focus detection area is placed in said image sensing plane based on the products for said small areas. - View Dependent Claims (16, 17, 18, 19, 20)
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21. An in-focus detection apparatus, comprising:
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image sensing means for converting an object image formed by a photographing optical system into an electrical image signal; image sensing plane division means for dividing the image sensing plane into a plurality of small areas; edge width detection means for detecting the edge widths of the object for every small area based on said image signal; and focus point detection area determination means for determining where the focus detection area is placed in said image sensing plane, based on the edge width data for every small area detected by said edge width detection means. - View Dependent Claims (22, 23)
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Specification