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US 7,583,311 B2Granted
Automatic focusing device and focusing method
AssigneeOlympus Imaging Corp.
InventorsTsutomu Kuroki, Takeshi Kindaichi
Life of this patent
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Abstract
In an automatic focusing device generating a luminance signal by scanning a picked-up digital image signal, evaluating the contrast of the luminance signal, and driving its focusing based on the evaluation; the scanning includes at least a part where scan is performed in a zigzag-like manner. With this configuration, focusing is facilitated for an object having no high frequency components in the horizontal direction. This invention can be understood as an invention of a method.
Claims19
An automatic focusing device comprising:
- an image pick-up element for picking up an image of an object, and obtaining an image signal;
- an A/D converting circuit for converting the image signal obtained by the image pick-up element into a digital image signal;
- a contrast acquiring portion for producing a luminance signal through a scanning which contains at least a part where the scanning is performed in a zigzag manner, from the digital image signals obtained by the A/D converting circuit, and for acquiring a contrast value from the produced luminance signal,
- a cumulative adding portion for adding the contrast value obtained by the contrast acquiring section in accumulation to compute a contrast evaluating value;
- and
- a focus lens drive portion for driving a focus lens to a position where the contrast evaluating value computed by the cumulative adding portion becomes maximum,
- wherein the contrast acquiring portion includes:
- a luminance signal producing section for producing a luminance signal from the digital image signal obtained by the A/D converting circuit;
- at least one delay section for delaying the luminance signal produced by the luminance signal producing section;
- a luminance signal reordering section for reordering a luminance signal delayed by the delay section and a luminance signal produced in the luminance signal producing section so that a reordered luminance signal contains at least a part where the scanning is performed in a zigzag manner;
- and
- a contrast extracting section for scanning the luminance signal reordered in the luminance signal reordering portion so that the reordered luminance signal contains at least a part where the scanning is performed in a zigzag manner to extract a contrast value.
9 more elements
An automatic focusing device comprising:
- an image pick-up element for picking up an image of an object, and obtaining an image signal;
- an A/D converting circuit for converting the image signal obtained by the image pick-up element into a digital image signal;
- a contrast acquiring portion for producing a luminance signal through a scanning which contains at least a part where the scanning is performed in a zigzag manner, from the digital image signals obtained by the A/D converting circuit, and for acquiring a contrast value from the produced luminance signal;
- a cumulative adding portion for adding the contrast value obtained by the contrast acquiring section in accumulation to compute a contrast evaluating value;
- and
- a focus lens drive portion for driving a focus lens to a position where the contrast evaluating value computed by the cumulative adding portion becomes maximum,
- wherein the contrast acquiring portion includes:
- at least two delay sections for delaying a digital image signal obtained in the A/D converting;
- a digital image signal reordering section for reordering at least two digital image signals delayed in the delay sections and the digital image signal obtained in the A/D converting circuit so that a luminance signal, scanned so as to at least contain a part where the scanning is performed in a zigzag manner, can be obtained;
- and
- a luminance signal extracting section for scanning the digital image signal reordered in the digital image signal reordering section so as to extract the luminance signal at least containing a part where the scanning is performed in a zigzag manner.
8 more elements
A focusing method comprising:
- obtaining an image signal by picking up an image of an object;
- converting the obtained image signal into a digital image signal;
- producing a luminance signal from the digital image signal;
- delaying the luminance signal by at least one delay section for delaying the luminance signals;
- reordering the luminance signal and the delayed luminance signal so that a reordered luminance signal contains at least a part where the scanning is performed in a zigzag manner;
- obtaining a contrast value through scanning the luminance reordered signal so that the reordered luminance signal contains at least a part where the scanning is performed in a zigzag manner;
- adding in accumulation the contrast value to compute a contrast evaluating value;
- and
- driving a focus lens to a position where the computed contrast evaluating value is maximum.
6 more elements
Dependencies are inferred from the claim text.