Imaging device and focusing control method

Patent metadata

Field	Value
Publication number	US-9794471-B2
Application number	US-201615202114-A
Country	US
Kind code	B2
Filing date	Jul 5, 2016
Priority date	Feb 7, 2014
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

The present invention provides an imaging device and a focusing control method capable of reliably preventing the accuracy of a focusing control from being lowered even in a case where a signal level of a phase difference detection pixel is low. A system control unit ( 11 ) calculates, using detections signals of phase difference detection pixels ( 52 A, 52 B) obtained by each of two instances of imaging which are consecutively performed by an imaging element ( 5 ), first defocus amounts for each instance of imaging, adds up detection signals corresponding to the detection signals of the phase difference detection pixels ( 52 ), among captured image signals obtained by each of two instances of imaging, calculates a second defocus amount using signals after addition, and compares the plural of first defocus amounts and the second defocus amount to determine whether to perform a focusing control based on the second defocus amount.

First claim

What is claimed is:

1. An imaging device comprising:
an imaging element that includes a first signal detection unit including a plurality of pixels that detects a signal corresponding to one beam among a pair of beams that passes through different portions in a pupil region of an imaging optical system and a second signal detection unit including a plurality of pixels that detects a signal corresponding to the other beam among the pair of beams, and images a subject through the imaging optical system; and
a processing circuitry configured to:
calculate a plurality of first defocus amounts using detection signals of the first signal detection units and detection signals of the second signal detection units in a range corresponding to an area which is a focusing target on an imaging surface of the imaging element, among captured image signals obtained through each of a plurality of instances of imaging consecutively performed by the imaging element;
add up, with respect to the detection signals of the first signal detection units in the range among the captured image signals obtained through each of the plurality of instances of imaging, detection signals of the pixels at the same position among the plurality of pixels of the first signal detection units in the range, add up, with respect to the detection signals of the second signal detection units in the range among the captured image signals obtained through each of the plurality of instances of imaging, detection signals of the pixels at the same position among the plurality of pixels of the second signal detection units in the range, and calculate a second defocus amount using the detection signals of the first signal detection units and the detection signals of the second signal detection units after addition; and
determine whether to perform a focusing control of the imaging optical system based on the second defocus amount through comparison of the plurality of first defocus amounts and the second defocus amount.

2. The imaging device according to claim 1 ,
wherein in a case where differences between each of the plurality of first defocus amounts and the second defocus amount are all smaller than a first threshold value, the processing circuitry determines that the focusing control of the imaging optical system based on the second defocus amount is to be performed.

3. The imaging device according to claim 1 ,
wherein in a case where a variation of differences between each of the plurality of first defocus amounts and the second defocus amount is smaller than a second threshold value, the processing circuitry determines that the focusing control of the imaging optical system based on the second defocus amount is to be performed.

4. The imaging device according to claim 1 ,
wherein in a case where the brightness of the subject to be imaged by the imaging element is lower than a threshold value, the processing circuitry performs the determination.

5. The imaging device according to claim 2 ,
wherein in a case where the brightness of the subject to be imaged by the imaging element is lower than a threshold value, the processing circuitry performs the determination.

6. The imaging device according to claim 3 ,
wherein in a case where the brightness of the subject to be imaged by the imaging element is lower than a threshold value, the processing circuitry performs the determination.

7. The imaging device according to claim 1 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

8. The imaging device according to claim 2 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

9. The imaging device according to claim 3 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

10. The imaging device according to claim 4 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

11. The imaging device according to claim 5 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

12. The imaging device according to claim 6 , wherein the processing circuitry is further configured to:
notify, in a case where it is determined that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, that the focusing control of the imaging optical system is not possible.

13. The imaging device according to claim 1 ,
wherein in a case where it is determined by the by the processing circuitry that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, the focusing control is not performed, or is performed according to a predetermined focusing position.

14. The imaging device according to claim 2 ,
wherein in a case where it is determined by the processing circuitry that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, the focusing control is not performed, or is performed according to a predetermined focusing position.

15. The imaging device according to claim 3 ,
wherein in a case where it is determined by the processing circuitry that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, the focusing control is not performed, or is performed according to a predetermined focusing position.

16. The imaging device according to claim 4 ,
wherein in a case where it is determined by the processing circuitry that the focusing control of the imaging optical system based on the second defocus amount is not to be performed, the focusing control is not performed, or is performed according to a predetermined focusing position.

17. The imaging device according to claim 1 ,
wherein the processing circuitry performs the determination before an execution instruction of the focusing control of the imaging optical system is given.

18. The imaging device according to claim 1 , wherein the processing circuitry is further configured to:
detect whether a moving body is included in the subject which is being imaged using the captured image signals obtained through each of the plurality of instances of imaging,
wherein in a case where it is detected that a moving body is included in the subject, the processing circuitry moves the range set with respect to the captured image signals obtained through the plurality of instances of imaging according to a movement of the moving body to calculate the first defocus amounts, and
wherein in a case where it is d

Assignees

• Fujifilm Corp

Inventors

• Tanaka Koichi

Classifications

• H04N23/634

  Warning indications · CPC title

• H04N25/704

  Pixels specially adapted for focusing, e.g. phase difference pixel sets · CPC title

• H04N23/672 Primary

  based on the phase difference signals · CPC title

• H04N25/134

  based on three different wavelength filter elements · CPC title

• H04N5/3696

  Electricity · mapped topic