LENS ARRAY ASSISTED FOCUS DETECTION

• US 20080095523A1
• Filed: 10/18/2006
• Published: 04/24/2008
• Est. Priority Date: 10/18/2006
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Border, John N., Schilling-Benz, Lynn, Palum, Russell J., Powers, Thomas F.
• Granted Patent: US 7,702,229 B2
• Time in Patent Office: Days
• US Class Current: 396/111
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

A focus detection device includes an image sensor and a plurality of lenslets. Each of the plurality of lenslets has a distinct conjugate length and is associated with a distinct portion of the image sensor.

Claims

1. A focus detection device comprising:

an image sensor; and

a plurality of lenslets, each of the plurality of lenslets having a distinct conjugate length, wherein each of the plurality of lenslets is associated with a distinct portion of the image sensor.

2. The device according to claim 1, wherein the distinct conjugate length of each of the plurality of lenslets is by virtue of each of the plurality of lenslets having a distinct focal length when compared to each other.

3. The device according to claim 1, wherein the distinct conjugate length of each of the plurality of lenslets is by virtue of each of the plurality of lenslets being positioned at distinct distances from the image sensor.

4. The device according to claim 1, further comprising:

a phase plate having a plurality of portions, the phase plate being positioned between the plurality of lenslets and the image sensor, wherein the distinct conjugate length of each of the plurality of lenslets is by virtue of each lenslet being associated with one of the plurality of portions of the phase plate.

5. The device according to claim 4, wherein each portion of the phase plate has a distinct thickness when compare to other portions of the phase plate.

6. The device according to claim 4, wherein each portion of the phase plate has a distinct refractive index when compare to other portions of the phase plate.

7. A method of detecting focus comprising:

providing a plurality of images on a first image sensor by causing light to pass through a plurality of lenslets, each of the plurality of lenslets having a distinct conjugate length;

determining relative focus quality by comparing the plurality of images to each other;

adjusting a distance between a taking lens and a second image sensor, the distance corresponding to a functional relationship between the conjugate lengths of the plurality of lenslets and the relative focus quality.

8. The method according to claim 7, wherein determining relative focus quality comprises determining relative contrast levels of each of the plurality of images.

9. The method according to claim 7, wherein determining relative focus quality comprises determining relative frequency content of each of the plurality of images.

10. The method according to claim 7, wherein determining relative focus quality comprises determining relative compressed file size of each of the plurality of images.

11. The method according to claim 7, wherein the first image sensor and the second image sensor are the same image sensor.

12. An image capture device comprising:

a focus detection device including a first image sensor; and

a plurality of lenslets, each of the plurality of lenslets having a distinct conjugate length, each of the plurality of lenslets being associated with a distinct portion of the first image sensor;

a taking lens; and

a second image sensor, the second image sensor being associated with the taking lens.

13. The device according to claim 12, wherein the first image sensor and the second image sensor are distinct image sensors.

14. The device according to claim 12, wherein the first image sensor and the second image sensor are the same image sensor.

15. The device according to claim 14, the image sensor including a plurality of portions, wherein one portion of the image sensor is associated with the taking lens, and another portion of the image sensor is associated with the focus detection device.

16. The device according to claim 12, further comprising:

an optical system associated with the image sensor, the optical system being operable to direct light from either the focus detection device or the taking lens to the image sensor.

17. A method for producing a digital image with extended dynamic range comprising:

providing a plurality of images on a first image sensor by causing light to pass through a plurality of lenslets, each of the plurality of lenslets having a distinct conjugate length;

identifying dark portions of at least one of the plurality of images;

increasing gain for pixels of a second image sensor that correspond to the dark portions of the at least one of the plurality of images; and

capturing an image with extended dynamic range with the second image sensor.