Imaging device having autofocus capability

1. An imaging device comprises:

(a) an imaging element configured to generate an image signal of a subject;

(b) a contrast detection information acquisition unit configured to detect contrast focus detection information of a contrast detection system based on the image signal;

(c) a phase difference detection unit configured to detect phase difference focus detection information of a phase difference detection system;

(d) a processing unit configured to (i) store history information of the contrast focus detection information in each focal position while a focus lens is driven by a driving unit based on the phase difference focus detection information, (ii) drive the focus lens to an in-focus position based on the phase difference detection system, and (iii) drive the focus lens to a final focal position by the contrast detection system using the history information after the focus lens is driven to the in-focus position.

2. The imaging device according to claim 1 , in which the image signal represents a plurality of first pixels and a plurality of second pixels arranged along a predetermined direction.

3. The imaging device according to claim 2 ,

in which phase difference focus detection is based on charge signals obtained from the plurality of second pixels and contrast focus detection is based on charge signals obtained from the plurality of first pixels, and

in which the plurality of first pixels receive a subject light beam that has passed through an entire area of an exit pupil of an imaging optical system, and the plurality of second pixels receive subject light beams that have passed through a pair of partial areas of the exit pupil.

4. The imaging device according to claim 3 , in which the contrast focus detection information pertains to a contrast type auto-focus and the phase difference focus detection information pertains to a phase difference type auto-focus which is different from the contrast type auto-focus.

5. The imaging device according to claim 4 , in which in the second pixel, a plurality of photoelectric converters are arranged along the predetermined direction, and the plurality of photoelectric converters include photoelectric converters that generate charge signals each relating to a respective one of a pair of image sequences.

6. The imaging device according to claim 4 , further comprising an amplifier configured to amplify a charge signal output from the imaging element,

in which the amplifier amplifies a charge signal from the first pixel by a first amplification factor, and amplifies a charge signal from the second pixel by a second amplification factor different from the first amplification factor.

7. The imaging device according to claim 4 , wherein the plurality of second pixels each have a color filter of the same color.

8. The imaging device according to claim 4 , further comprising:

a display unit configured to display an image; and

a display controller configured to cause a preview image relating to preview displaying to be created and to cause the display unit to perform the preview displaying of the subject based on the created preview image.

9. The imaging device according to claim 1 , wherein the processing unit is configured to drive the focus lens to the final focal position in a case the history information satisfies a predetermined condition.

10. The imaging device according to claim 9 , wherein the predetermined condition is whether a predetermined ratio has a value within a predetermined range, in which the predetermined ratio is a ratio of the contrast focus detection information of the in-focus position to the contrast focus detection information of a respective focal position adjacent to the in-focus position.

11. A non-transitory computer readable medium having stored thereon a program to cause an imaging device to perform a method comprising:

generating an image signal of a subject;

detecting contrast focus detection information of a contrast detection system based on the image signal;

detecting phase difference focus detection information of a phase difference detection system;

storing history information of the contrast focus detection information in each focal position while a focus lens is driven by a driving unit based on the phase difference focus detection information;

driving the focus lens to an in-focus position based on the phase difference detection system; and

driving the focus lens to a final focal position by the contrast detection system using the history information after the focus lens is driven to the in-focus position.