Imaging device having autofocus capability
Herein disclosed is an imaging device having an imaging optical system, the device including: an imaging element configured to include a plurality of first pixels and a plurality of second pixels arranged along a predetermined direction; a first processor configured to execute focal detection processing by a phase difference detection system based on charge signals obtained from the plurality of second pixels; and a second processor configured to execute specific processing based on charge signals obtained from the plurality of first pixels, the specific processing being different from the focal detection processing by a phase difference detection system and being necessary for a function of the imaging device.
1. An imaging device, comprising:
an imager configured to:
generate an image signal of a subject;
detect a contrast focus based on a first part of the image signal read from a first pixel of the imager;
detect a phase difference focus based on a second part of the image signal read from a second pixel of the imager; and
determine a focus position of a focus lens of the imager based on the contrast focus and the phase difference focus; and
at least one processor configured to drive the focus lens to a first focal position that corresponds to a first focus evaluation value of a plurality of focus evaluation values, wherein the focus lens is driven based on determination that a first ratio of the first focus evaluation value to a second focus evaluation value prior to the first focus evaluation value is within a range of values.
2. The imaging device according to claim 1 , wherein the image signal is associated with at least one of the first pixel or the second pixel, wherein the first pixel and the second pixel are along a direction.
3. The imaging device according to claim 1 ,
wherein the first pixel is configured to receive a light beam passed through an area of an exit pupil of the imager, and the second pixel is configured to receive the light beam passed through a pair of partial areas of the exit pupil, wherein the partial areas are obtained by division of the area of the exit pupil.
4. The imaging device according to claim 1 , wherein the contrast focus is associated with a contrast type auto-focus and the phase difference focus is associated with a phase difference type auto-focus, wherein the phase difference type auto-focus is different from the contrast type auto-focus.
5. The imaging device according to claim 1 , wherein in the second pixel, a plurality of photoelectric converters are along a direction, wherein at least one photoelectric converter of the plurality of photoelectric converters is configured to generate the image signal, and wherein the image signal corresponds to one of a pair of image sequences.
6. The imaging device according to claim 1 , further comprising an amplifier configured to amplify the first part of the image signal by a first amplification factor and amplify the second part of the image signal by a second amplification factor, wherein the second amplification factor is different from the first amplification factor.
7. The imaging device according to claim 1 , wherein the first pixel comprises a first color filter and the second pixel comprises a second color filter, and wherein the first color filter and the second color filter are of the same color.
8. The imaging device according to claim 1 , further comprising:
a display unit configured to display an image; and
a display controller configured to:
create a preview image associated with a first preview of the image; and
control the display unit to display a second preview of the subject based on the created preview image.
9. The imaging device according to claim 1 , wherein the plurality of focus evaluation values is related to the detected phase difference focus, wherein the first focus evaluation value corresponds to a peak of the plurality of focus evaluation values.
10. The imaging device according to claim 9 , wherein the second focus evaluation value corresponds to a second focal position, wherein the second focal position is prior to the first focal position in movement of the focus lens.
11. The imaging device according to claim 9 , wherein the at least one processor is further configured to drive the focus lens to the first focal position that corresponds to the first focus evaluation value in a number of iterations.
12. The imaging device according to claim 11 , wherein the at least one processor is further configured to set the imager to a live read mode based on determination that a second ratio of the first focus evaluation value to the second focus evaluation value is within the range of values.
13. The imaging device according to claim 10 , wherein the at least one processor is further configured to iteratively drive the focus lens to the first focal position that corresponds to the first focus evaluation value based on determination that a second ratio of the first focus evaluation value to the second focus evaluation value is outside the range of values, and wherein the focus lens is iteratively driven to the first focal position by an offset in each iteration.
14. The imaging device according to claim 10 , wherein the at least one processor is further configured to acquire information associated with the contrast focus from the first pixel based on determination that a second ratio of the first focus evaluation value to the second focus evaluation value is greater than the range of values.
15. The imaging device according to claim 10 , wherein the at least one processor is further configured to calculate a third ratio of first information associated with the contrast focus at the first focal position to second information associated with the contrast focus at the second focal position, and
wherein the third ratio is calculated based on determination that a second ratio of the first focus evaluation value to the second focus evaluation value is greater than the range of values.
16. The imaging device according to claim 15 , wherein the first focal position is a final focal position and the second focal position is a focal position after the focus lens is driven by an amount equivalent to a focal depth.
17. The imaging device according to claim 1 , wherein the plurality of focus evaluation values is obtained based on movement of the focus lens.
18. A non-transitory computer-readable medium having stored thereon, computer-executable instructions, which when executed by an imaging device, cause the imaging device to execute operations, the operations comprising:
generating an image signal of a subject;
detecting a contrast focus based on a first part of the image signal read from a first pixel of the imaging device;
detecting a phase difference focus based on a second part of the image signal read from a second pixel of the imaging device;
determining a focus position of a focus lens of the imaging device based on the contrast focus and the phase difference focus; and
driving the focus lens to a first focal position that corresponds to a first focus evaluation value of a plurality of focus evaluation values, wherein the focus lens is driven based on determination that a ratio of the first focus evaluation value to a second focus evaluation value prior to the first focus evaluation value is within a range of values.
19. A method, comprising:
in an imaging device:
generating an image signal of a subject;
detecting a contrast focus based on a first part of the image signal read from a first pixel of the imaging device;
detecting a phase difference focus based on a second part of the image signal read from a second pixel of the imaging device;
determining a focus position of a focus lens of the imaging device based on the contrast focus and the phase difference focus; and
driving the focus lens to a first focal position that corresponds to a first focus evaluation value of a plurality of focus evaluation values, wherein the focus lens is driven based on determination that a ratio of the first focus evaluation value to a second focus evaluation value prior to the first focus evaluation value is outside a range of values.