Focus detection device and accompanying optical equipment
First Claim
1. A focus detection device, including an optical system which forms first and second images, and a sensor having photodetector elements which detect said first and second images, for detecting a focus condition of an objective lens based on a relative position between said first and second images, said device comprising:
- a first focus detector which divides said first image into plural areas and detects a first relative distance between said first and second images;
a second focus detector which divides one of said areas into smaller areas and uses said smaller areas to detect a second relative distance between said first and second images; and
a calculator which calculates a final relative distance based on one of said first and second relative distances.
1 Assignment
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Accused Products
Abstract
Where a person is being photographed, for example, both light from the person located at closer range and light from the background located farther away enter the photodetector elements. Where the contrast of the background is high, the rate at which the information from the background contributes to the focus detection becomes larger, which hinders accurate focus detection with regard to the person. In this case, the focus detection device divides a predetermined focus area into smaller areas and detects focus condition in each smaller area.
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Citations
19 Claims
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1. A focus detection device, including an optical system which forms first and second images, and a sensor having photodetector elements which detect said first and second images, for detecting a focus condition of an objective lens based on a relative position between said first and second images, said device comprising:
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a first focus detector which divides said first image into plural areas and detects a first relative distance between said first and second images; a second focus detector which divides one of said areas into smaller areas and uses said smaller areas to detect a second relative distance between said first and second images; and a calculator which calculates a final relative distance based on one of said first and second relative distances. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A focus detection device, including an optical system which forms a first image and a second image, and a sensor having photodetector elements which detect said first and second images, for detecting a focus condition of an objective lens based on a relative position between said first and second images, said device comprising:
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a selector which divides said first image into plural areas and selects an area having a highest contrast in said plural areas; a first focus detector which uses a thus selected area to detect a first relative distance between said first and second images; a second focus detector which divides said selected area into smaller areas and uses said smaller areas to detect a second relative distance between said first and second images; and a calculator which calculates a final relative distance based on one of said first and second relative distances. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A focus detection device, comprising:
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a first focus detector which detects focus condition of a taking lens to a predetermined area in an object field; a determiner which determines whether or not closer and farther objects exist in said predetermined area; a divider which divides said predetermined area into smaller areas when said determiner determines closer and farther objects exist in said predetermined area; a second focus detector which detects focus condition in said smaller areas; a magnification calculator which calculates an object magnification; a controller which controls an operation of said focus detector based on said object magnification. - View Dependent Claims (16, 17)
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18. An optical apparatus having a focus detection device, said apparatus comprising:
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an objective lens; an optical system which is located behind said objective lens and forms first and second images; a sensor having photodetector elements which detect said first and second images; a first focus detector which divides said first image into plural areas and detects a first relative distance between said first and second images; a second focus detector which divides one of said areas into smaller areas and utilizes said smaller areas to detect a second relative distance between said first and second images; a calculator which calculates a final relative distance based on one of said first and second relative distances; and a controller which controls said objective lens in focus position based on said final relative distance. - View Dependent Claims (19)
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Specification