Mask-less phase detection autofocus

Patent metadata

Field	Value
Publication number	US-10044959-B2
Application number	US-201514864153-A
Country	US
Kind code	B2
Filing date	Sep 24, 2015
Priority date	Sep 24, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

An example image capture device includes an image sensor having diodes for sensing light from a target scene, a color filter array disposed above the diodes and including color filters each positioned over one of the diodes, single-diode microlenses positioned above some color filters arranged in a Bayer pattern, and multi-diode microlenses each positioned above at least two adjacent color filters that pass the same wavelengths of light to corresponding adjacent diodes below the color filters, each multi-diode microlens formed such that light incident in a first direction is collected one of the adjacent diodes and light incident in a second direction is collected in another of adjacent diodes. An image signal processor of the image capture device can perform phase detection autofocus using signals received from the adjacent diodes and can interpolate color values for the adjacent diodes.

First claim

What is claimed is:

1. An image capture device comprising:
an image sensor comprising
a plurality of diodes configured to generate values that represent an image of a target scene;
a color filter array disposed above the plurality of diodes, the color filter array comprising a plurality of color filters each positioned over one of the plurality of diodes;
a plurality of single-diode microlenses each positioned above one of the plurality of color filters, the plurality of color filters, corresponding to the plurality of single-diode microlenses, arranged in a Bayer pattern;
a plurality of multi-diode microlenses for phase difference detection, each multi-diode microlens of the plurality of multi-diode microlenses positioned above at least two adjacent color filters of the plurality of color filters, each of the at least two adjacent color filters configured to pass the same wavelengths of light, and formed such that light incident in a first direction is collected in a first diode of at least two adjacent diodes and light incident in a second direction is collected in a second diode of the at least two adjacent diodes, wherein a first color filter of the at least two adjacent color filters positioned below a multi-diode microlens conforms to the Bayer pattern, a second color filter of the at least two adjacent color filters positioned below the multi-diode microlens deviates from the Bayer pattern; and
an image signal processor configured to
form the image of the target scene in part by, for each multi-diode microlens, summing values of diodes positioned below the multi-diode microlenses to determine a value of the first diode positioned below the first color filter, and by interpolating values of diodes positioned in a neighborhood of the second diode positioned below the second color filter to determine the value of the second diode positioned below the second color filter; and
perform phase detection autofocus using values received from the at least two adjacent diodes.

2. The image capture device of claim 1 , wherein, for each of the plurality of multi-diode microlenses, wavelengths of light that the at least two adjacent color filters are configured to pass correspond to green light.

3. The image capture device of claim 1 , wherein each of the plurality of multi-diode microlenses is positioned over two adjacent color filters and associated diodes.

4. The image capture device of claim 1 , wherein each of the plurality of multi-diode microlenses is positioned over a 2×2 cluster of color filters and associated diodes.

5. The image capture device of claim 1 , wherein, to perform phase detection autofocus, the image signal processor is further configured to:
receive, from the first diode, first image data representing light incident on the image sensor in the first direction;
receive, from the second diode, second image data representing light incident on the image sensor in the second direction;
calculate disparity between the first image data and the second image data; and
use the disparity to generate focus instructions.

6. The image capture device of claim 5 , further comprising a movable lens assembly positioned above the image sensor.

7. The image capture device of claim 6 , wherein the focus instructions comprise a distance and direction for moving the movable lens assembly to a desired focus position.

8. The image capture device of claim 7 , wherein the image signal processor is further configured to generate instructions that cause the image sensor to capture image data with the movable lens assembly positioned in the desired focus position and, based at least partly on the image data, construct a final image of the target scene.

9. The image capture device of claim 5 , further comprising a lens assembly positioned above the image sensor, wherein the image sensor is movable relative to the lens assembly.

10. The image capture device of claim 9 , wherein the focus instructions comprise a distance and direction for moving the image sensor to a desired focus position.

11. The image capture device of claim 1 , wherein the plurality of single-diode microlenses and the plurality of multi-diode microlenses arranged in a repeating pattern having the plurality of multi-diode microlenses each located one of a plurality of autofocus points in the repeating pattern.

12. An image signal processor configured with instructions for performing a process for constructing a final image, the process comprising:
receiving image data from a plurality of diodes of an image sensor, the image data comprising:
a plurality of imaging pixel values from a first subset of the plurality of diodes associated with a plurality of color filters arranged in a Bayer pattern that receives light propagating through single-diode microlenses, and
a plurality of phase detection pixel values from a second subset of the plurality of diodes associated with a plurality of color filters deviating from the Bayer pattern such that each of the plurality of phase detection pixel values comprises a green pixel value, the second subset of the plurality of diodes receiving light propagating through multi-diode microlenses and arranged in a plurality of groups of adjacent diodes, each group of adjacent diodes receiving light from a corresponding multi-diode microlens formed such that light incident in a first direction is collected in a first diode of the group and light incident in a second direction is collected in a second diode of the group, wherein the phase detection pixel value from the first diode of each group of adjacent diodes is generated by light passing through a green color filter conforming to the Bayer pattern, the phase detection pixel value from the second diode of each group of adjacent diodes is generated by light passing through a green color filter deviating from the Bayer pattern;

calculating, for each of the plurality of groups of adjacent diodes, a single green pixel value corresponding to a location of the first diode of the group;
calculating, for each of the plurality of groups of adjacent diodes, a missing blue or red pixel value corresponding to a location of the second diode of the group, wherein calculating the single green pixel value comprises using a summed value of diodes positioned below the multi-diode microlenses to determine a value of the first diode of the group; and
constructing the final image based at least partly on the plurality of imaging pixel values, the calculated missing blue or red pixel values, and the calculated single green pixel values.

13. The image signal processor of claim 12 , wherein a phase detection pixel value of the plurality of phase detection pixel values received from one diode of the plurality of diodes has a brightness value similar to brightness values of imaging pixel values received from other diodes of the plurality of diodes adjacent to the one diode.

14. The image signal processor of claim 12 , wherein constructing the final image is done at least partly via demosaicking.

15. The image signal processor of claim 12 , wherein calculating the missing blue or red pixel value for each of the plurality of groups of adjacent diodes comprises identifying, based on the Bayer pattern, whether the second diode corresponds to a blue pixel location or a red pixel location.

16. The image signal processor of claim 15 , wherein, when the second diode corresponds to the blue pixel, calculating the missing blue or red pixel value comprises:
identifying, from the plurality of imaging pixel values, a plurality of blue pixel values within a predetermined neighborhood of the

Assignees

• Qualcomm Inc

Inventors

• Galor Gluskin Micha

Classifications

• H04N23/843

  Demosaicing, e.g. interpolating colour pixel values · CPC title

• H04N25/134

  based on three different wavelength filter elements · CPC title

• H04N23/672

  based on the phase difference signals · CPC title

• H04N25/704 Primary

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

• G02B7/09 Primary

  adapted for automatic focusing or varying magnification · CPC title