System for non-uniformly illuminating an original and capturing an image therof
View Patent ↗An imaging device having an imaging unit for illuminating and capturing an original positioned on the imaging surface. The imaging surface is illuminated by an illumination system including a plurality of light sources that non-uniformly illuminates the imaging surface such that the corner areas of imaging surface is illuminated more than the non-corner areas of the imaging surface. In one embodiment the light sources are arranged around the perimeter of the imaging surface. In an alternate embodiment the light sources are located outside the field of view of a lens of the image capturing unit.
1. A system for non-uniformly illuminating and imaging an original in an imaging device, the system comprising:
an imaging surface for holding the original, the imaging surface having a perimeter, corner areas, and non-corner areas;
an imaging member for capturing an image of the original placed on the imaging surface;
a plurality of light sources arranged around the perimeter of the imaging surface for non-uniformly illuminating the original placed on the imaging surface, the plurality of light sources illuminating the corner areas of the imaging surface with the illumination of the corner areas being adjusted until a photo response non-uniformity (PRNU) level of between 10% and 50% is achieved at the imaging member; and
a lens disposed below the imaging surface and above the imaging member, the lens having a field of view angle equal to or greater than 50 degrees and a focal length equal to or greater than 200 mm and less than 500 mm.
2. The system according to claim 1 , the plurality of light sources comprising a first plurality of light sources illuminating the corner areas of the imaging surface and a second plurality of light sources illuminating the non-corner areas of the imaging surface, the first plurality of light sources having a higher number of light sources compared to the second plurality of light sources wherein the illumination of the corner areas by the first plurality of light sources is greater than the illumination of the non-corner areas by the second plurality of light sources.
3. The system according to claim 1 , the plurality of light sources comprising a first plurality of light sources illuminating the corner areas of the imaging surface and a second plurality of light sources illuminating the non-corner areas of the imaging surface, the first plurality of light sources having a first lumens output greater than a second lumens output of the second plurality of light sources wherein the illumination of the corner areas by the first plurality of light sources is greater than the illumination of the non-corner areas by the second plurality of light sources.
4. The system according to claim 1 , wherein the plurality of light sources are arranged uniformly around the perimeter of the imaging surface.
5. The system according to claim 1 , wherein the imaging member is a monochromatic imaging member.
6. The system according to claim 1 , wherein the plurality of light sources are controllable to focus illumination on a particular location on the imaging surface.
7. The system according to claim 6 , wherein the plurality of light sources are arranged uniformly around a perimeter of the imaging surface.
8. The system according to claim 1 , wherein the plurality of light sources includes a red LED, a green LED, and a blue LED.
9. The system according to claim 1 , wherein the plurality of light sources illuminate the corner areas at least 40 percent greater than the non-corner areas.
10. A system for non-uniformly illuminating and imaging an original in an imaging device, the system comprising:
an imaging surface for holding the original, the imaging surface having a perimeter, corner areas, and non-corner areas;
a lens positioned below the imaging surface, the lens having a field of view that includes an entire area of the imaging surface;
a plurality of light sources disposed adjacent the imaging surface outside the field of view of the lens, the plurality of light sources oriented towards the imaging surface for illuminating the original placed on the imaging surface;
an imaging member positioned below the lens for capturing an image of the illuminated original placed on the imaging surface;
and
a lens positioned on the plurality of light sources and operative to diverge light from the plurality of light sources to illuminate the corner areas of the imaging surface with the illumination of the corner areas being adjusted until a photo response non-uniformity (PRNU) level of between 10% and 50% is achieved at the imaging member.
11. The system according to claim 10 , wherein the illumination by the plurality of light sources at the corner areas is at least 40% greater than at the non-corner areas.
12. A method for non-uniformly illuminating and imaging an original in an imaging device, the method comprising:
positioning the original on an imaging surface having a perimeter, corner areas, and non-corner areas;
non-uniformly illuminating the original using a plurality of light sources arranged around the perimeter of the imaging surface; and
capturing an illuminated image of the original, the plurality of light sources illuminating the corner areas of the imaging surface with the illumination of the corner areas being adjusted until a photo response non-uniformity (PRNU) level of between 10% and 50% is achieved at an imaging member.
13. The method according to claim 12 , wherein the plurality of light sources includes a red LED, a green LED, and a blue LED.
14. The method according to claim 12 , wherein adjusting the illumination of the corner areas of the imaging surface comprises having the plurality of light sources illuminate the corner areas at least 40% greater than the non-corner areas.
15. The method according to claim 12 , wherein illuminating the original using the plurality of light sources comprises illuminating the corner areas of the imaging surface with a first plurality of light sources at a first lumens output and illuminating the non-corner areas of the imaging surface with a second plurality of light sources at a second lumens output, wherein the first lumens output is greater than the second lumens output and is adjusted until the photo response non-uniformity (PRNU) level of between 10% and 50% is achieved at the imaging member.
16. The method according to claim 15 , wherein a number of the first plurality of light sources is equal to a number of the second plurality of light sources.
17. The method according to claim 12 , further comprising uniformly positioning the plurality of light sources around the perimeter of the imaging surface.
18. The method according to claim 12 , wherein non-uniformly illuminating the original using the plurality of light sources further comprises illuminating the original by providing greater illumination at the corner areas than at the non-corner areas of the imaging surface.
19. The method according to claim 18 , wherein capturing the illuminated image of the original further comprises receiving light reflected from the corner areas and light reflected from the non-corner areas at substantially the same intensity at a lens disposed below the imaging surface and above the imaging member, and providing, by the lens, the received light from the corner areas and non-corner areas substantially uniformly to the imaging member such that the PRNU level of between 10% and 50% is achieved at the imaging member.
20. The method according to claim 19 , wherein the lens comprises a fisheye lens.