Focus detection device and image-capturing apparatus
A focus detection device includes: a plurality of first pixels having first color filters, via which a pair of first signals, to be used for split-pupil phase detection, are output; a plurality of second pixels having second color filters, via which a pair of second signals, to be used for the split-pupil phase detection, are output; a phase difference detection unit that detects a phase difference manifested by the first signals or a phase difference manifested by the second signals; and a defocus amount calculation unit that calculates a defocus amount by using a first conversion coefficient corresponding to the first color when the phase difference detection unit has detected the phase difference manifested by the first signals and by using a second conversion coefficient corresponding to the second color when the phase difference detection unit has detected the phase difference manifested by the second signals.
1. A focus detection device, comprising:
a plurality of first pixels that output first signals constituted with two signals corresponding to a light amount of a first color;
a plurality of second pixels that output second signals constituted with two signals corresponding to a light amount of a second color;
a microcomputer and associated memory that:
detect an extent of offset between the two signals constituting the first signals or between the two signals constituting the second signals; and
calculate (i) a defocus amount by using a first coefficient corresponding to the first color with the extent of offset that has been detected by using the two signals constituting the first signals, or (ii) a defocus amount by using a second coefficient corresponding to the second color with the extent of offset that has been detected by using the two signals constituting the second signals.
2. A focus detection device according to claim 1 , wherein:
the first color is a color among a red color, a green color and a blue color;
the second color is either of remaining two colors among the red color, the green color and the blue color;
the first coefficient and the second coefficient are each a coefficient among a coefficient corresponding to the red color, a coefficient corresponding to the green color and a coefficient corresponding to the blue color; and
the coefficient corresponding to the red color is greater than the coefficient corresponding to the green color, and the coefficient corresponding to the green color is greater than the coefficient corresponding to the blue color.
3. A focus detection device according to claim 1 , wherein the microcomputer further:
selects two signals, which are either the two signals constituting the first signals or the two signals constituting the second signals, that meet a predetermined condition, and
detects the extent of offset between the selected two signals meeting the predetermined condition.
4. A focus detection device according to claim 3 , wherein:
the microcomputer further calculates a plurality of contrast values each indicating contrast in the first signals or the second signals, and
the two signals that meet the predetermined condition constitute either the first signals or the second signals that correspond to a contrast value, among the plurality of contrast values, taking a greatest value.
5. A focus detection device according to claim 3 , further comprising:
a light source color detection sensor that estimates a light source color, wherein:
the two signals that meet the predetermined condition constitute either the first signals or the second signals that correspond to the light source color estimated by the light source color detection sensor.
6. A focus detection device according to claim 3 , further comprising:
a plurality of image-capturing pixels disposed around the plurality of first pixels and the plurality of second pixels, which include a plurality of first image-capturing pixels having first color filters disposed thereat and a plurality of second image-capturing pixels having second color filters disposed thereat, wherein:
the first color filters correspond to the first color;
the second color filters correspond to the second color; and
in case that outputs of a plurality of imaging signals provided from the plurality of first image-capturing pixels, among outputs of a plurality of imaging signals provided from the plurality of image-capturing pixels, are greatest, the two signals that meet the predetermined condition constitute the first signals.
7. A focus detection device according to claim 3 , wherein:
the microcomputer further reads out a specific color from an optical system at which an optical system color filter corresponding to the specific color is mounted, and
the two signals that meet the predetermined condition constitute either the first signals or the second signals that correspond to the specific color.
8. A focus detection device according to claim 1 , wherein the microcomputer further:
sets a first offset quantity corresponding to the first color and a second offset quantity corresponding to the second color, and
calculates (i) the defocus amount by adding the first offset quantity to a product of the first coefficient multiplied by the extent of offset between the two signals constituting the first signals which have been detected, or (ii) the defocus amount by adding the second offset quantity to a product of the second coefficient multiplied by the extent of offset between the two signals constituting the second signals which have been detected.
9. A focus detection device according to claim 1 , further comprising:
a plurality of third pixels that output third signals constituted with two signals corresponding to a light amount of a third color, wherein:
the microcomputer further:
detects an extent of offset among the extent of offset between the two signals constituting the first signals, the extent of offset between the two signals constituting the second signals and an extent of offset between the two signals constituting the third signals; and
calculates (i) the defocus amount by multiplying the first coefficient by the extent of offset between the two signals constituting the first signals which have been detected, (ii) the defocus amount by multiplying the second coefficient by the extent of offset between the two signals constituting the second signals which have been detected, or (iii) the defocus amount by multiplying a third coefficient corresponding to the third color by the extent of offset between the two signals constituting the third signals which have been detected;
the first color, the second color and the third color are each a color among a red color, a green color and a blue color; and
the first coefficient, the second coefficient and the third coefficient are each a coefficient among a coefficient corresponding to the red color, a coefficient corresponding to the green color and a coefficient corresponding to the blue color.
10. A focus detection device according to claim 1 , wherein:
a group of focus detection pixels that includes the plurality of first pixels and the plurality of second pixels disposed thereat and a group of focus detection pixels that includes the plurality of second pixels and the plurality of third pixels disposed thereat are set adjacent to each other.
11. A focus detection device according to claim 1 , wherein the microcomputer further:
selects a focus detection position that is either a first focus detection position in correspondence to which a first set of groups of focus detection pixels are disposed or a second focus detection position in correspondence to which a second set of groups of focus detection pixels are disposed, and
once the first focus detection position is selected as the focus detection position, detects the extent of offset based upon the first signals and the second signals respectively output from the plurality of first pixels and the plurality of second pixels forming the first set of groups of focus detection pixels.
12. A focus detection device, comprising:
a plurality of first pixels that output first signals constituted with two signals corresponding to a light amount of a first color;
a plurality of second pixels that output second signals constituted with two signals corresponding to a light amount of a second color;
a microcomputer and associated memory configured to:
detect a first extent of offset between the two signals constituting the first signals and a second extent of offset between the two signals constituting the second signals; and
calculate a defocus amount based upon a value obtained by multiplying a first coefficient corresponding to the first color by the first extent of offset and a value obtained by multiplying a second coefficient corresponding to the second color by the second extent of offset.
13. An image-capturing apparatus, comprising:
a focus detection device according to claim 1 ; and
a drive control circuit that drives an optical system to a focus position based upon the calculated defocus amount, wherein
the microcomputer further obtains image data based upon outputs from a plurality of focus detection pixels, each of which provides signals constituted with two signals, and outputs from a plurality of image-capturing pixels, each of which provides an imaging signal.
14. A focus detection device according to claim 1 , wherein:
the microcomputer further detects
the extent of offset between the two signals constituting the first signals at the plurality of first pixels in an array, or
the extent of offset between the two signals constituting the second signals at the plurality of second pixels in an array.
15. A focus detection device according to claim 1 , wherein:
the defocus amount is used for driving an optical system to a focus position.