Image Illumination And Capture In A Scanning Device

• US 20080180754A1
• Filed: 01/25/2007
• Published: 07/31/2008
• Est. Priority Date: 01/25/2007
• Status: Active Grant

• Current Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: King, Anthony Michael, Miller, Mark Eric, Chelvayohan, Mahesan
• Granted Patent: US 7,746,517 B2
• Time in Patent Office: Days
• US Class Current: 358/474
• CPC Class Codes: G06F 15/02 manually operated with input through keyboard and computation using a built-in program, e.g. pocket calculators
• CPC Class Codes: H04N 1/02815 Means for illuminating the original, not specific to a particular type of pick-up head
• CPC Class Codes: H04N 1/02855 in combination with a light guide, e.g. optical fibre, glass plate light-guides per se G02B6/00
• CPC Class Codes: H04N 1/02865 using an array of light sources or a combination of such arrays, e.g. an LED bar
• CPC Class Codes: H04N 1/1013 with sub-scanning by translatory movement of at least a part of the main-scanning components H04N1/107 takes precedence
• CPC Class Codes: H04N 1/193 using electrically scanned linear arrays , e.g. linear CCD arrays
• CPC Class Codes: H04N 1/195 the array comprising a two-dimensional array or a combination of two-dimensional arrays
• CPC Class Codes: H04N 1/484 with sequential colour illumination of the original

Abstract

Scanning devices and method of use that permit the capture of high resolution images of an original that is illuminated by a light source that is located outside of the optical field of view of an image detector. In one aspect, the image detector may be a monochrome sensor that sequentially captures different color plane images of an original that is illuminated by different colors. The different color plane images may be processed to generate a full color copy of the original. Light and images may be directed through tapered optical waveguides to minimize the volume of the scanning device. The image detector may include a first associated waveguide while the light source may include a second associated waveguide.

Claims

1. A scanning device comprising:

a target bed;

an imaging unit operative to capture an image of a document placed on the target bed;

a light source operative to illuminate the document placed on the target bed;

a tapered first slab waveguide configured to receive the image of the document into a first tapered face of the first slab, the image propagating through the waveguide from the first tapered face to a first thick end of the first slab after internal reflection within the first slab, the imaging unit disposed to receive the image as it emerges from the first thick end of the first slab; and

a tapered second slab waveguide configured to receive light from the light source into a second thick end of the second slab, the light propagating through the waveguide from the second thick end of the second slab and emerging from a second tapered face of the second slab after internal reflection within the second slab, light from the light source transversely passing through the first slab to illuminate the document placed on the target bed.

2. The device of claim 1, wherein the light source comprises an array of red, green, and blue light sources.

3. The device of claim 1, wherein the first slab and the second slab are oriented so that the first thick end faces a substantially opposite direction from the second thick end.

4. The device of claim 1, wherein the first slab waveguide includes a folded first portion and second portion with a reflector disposed therebetween to fold the image from the first portion to the second portion, the first portion including the first tapered face, and the imaging unit disposed to receive the image as it emerges from the second portion.

5. The device of claim 4, the second slab waveguide is disposed between the first and second portions of the first slab waveguide.

6. The device of claim 1, wherein the second slab waveguide includes a diffuse second tapered face.

7. The device of claim 1, further comprising a redirection element disposed at the second tapered face to redirect light towards the document placed on the target bed.

8. The device of claim 1, wherein the light source and imaging unit are disposed on the same side of the first and second slab waveguides.

9. The device of claim 1, wherein the light source and imaging unit are disposed on opposite sides of the first and second slab waveguides.

10. A scanning device comprising:

a target bed;

a monochrome imaging unit operative to capture an image of a document placed on the target bed;

a light source operative to illuminate the document placed on the target bed, the light source include a plurality of individually selectable colors;

a controller configured to control the light source to illuminate the document placed on the target bed sequentially in each of the plurality of individually selectable colors, the controller further configured to control the imaging unit to capture a color plane image for each of the individually selectable colors, and process the color plane images to produce a full color duplicate of the document.

11. The device of claim 10, wherein the individually selectable colors comprise red, green, and blue.

12. The device of claim 11, wherein the light source includes an array of red, green, and blue LEDs.

13. The device of claim 12, wherein each of the array of red, green, and blue LEDs includes a variable intensity that is individually adjustable.

14. The device of claim 12, the array of red, green, and blue LEDs includes approximately twice as many red LEDs as green and blue LEDs.

15. The device of claim 10, wherein the controller accesses a color table with pixel intensities from the color plane images as input values, the color table including corresponding color information needed to construct the full color duplicate.

16. The device of claim 10, wherein the light source is disposed at an acute angle relative to the target bed.

17. The device of claim 10, wherein the light source further comprises a diffuse reflector oriented to project light from the light source onto the target bed.

18. The device of claim 10, further comprising a reflective member positioned between the imaging unit and the target bed.

19. The device of claim 10, wherein the imaging unit further comprises an associated first slab waveguide configured to receive the image of the document into a first tapered face of the first slab, the image propagating through the waveguide from the first tapered face to a first thick end of the first slab after internal reflection within the first slab.

20. The device of claim 10, wherein the light source further comprises an associated tapered second slab waveguide configured to receive light from the light source into a second thick end of the second slab, the light propagating through the waveguide from the second thick end of the second slab and emerging from a second tapered face of the second slab after internal reflection within the second slab.

21. A method of scanning an image of a document with a scanning device, the method comprising the steps of:

positioning the document on a target bed;

illuminating the document using a light source and a tapered first waveguide, the light from the light source propagating through the tapered first waveguide;

capturing an image of the document by propagating the image of the document through a tapered second waveguide and towards an imaging unit; and

causing the light from the light source to exit from a tapered surface of the first waveguide and transversely pass through the second waveguide, which is disposed between the first waveguide and the target bed.

22. The method of claim 21, wherein the step of illuminating the document using the light source and the tapered first waveguide comprises propagating the light along a first direction and the step of propagating the image of the document through the tapered second waveguide comprises propagating the image along a second opposite direction.

23. The method of claim 21, wherein the step of illuminating the document using the light source comprises sequentially illuminating the document with different colors.

24. The method of claim 23, wherein the different colors comprise red, green, and blue.

25. The method of claim 21, wherein the step of illuminating the document using the light source comprises redirecting the light between the tapered surface of the first waveguide and the target bed.

26. A method of scanning a document with a scanning device, the method comprising the steps of:

placing the document on a target bed;

illuminating the document using a first light source that includes a first color;

capturing a first color plane image of the document that is illuminated by the first color;

illuminating the document using a second light source that includes a second color;

capturing a second color plane image of the document that is illuminated by the second color; and

processing the first and second color plane images and generating a full color duplicate of the document.

27. The method of claim 26, further comprising illuminating the document using a third light source that includes a third color and capturing a third color plane image of the document that is illuminated by the third color.

28. The method of claim 27, wherein the first, second, and third colors comprise red, green, and blue.

29. The method of claim 26, further comprising individually controlling the intensity of the first and second light sources.

30. The method of claim 26, wherein the step of processing the first and second color plane images comprises accessing a color table with pixel intensities from the color plane images as input values, and reading color information for generating the full color duplicate of the document.

31. The method of claim 26, further comprising diffusing the light from the first and second light sources.

32. The method of claim 26, wherein the steps of illuminating the document comprise propagating light from the first and second light sources through a tapered slab waveguide.

33. The method of claim 26, wherein the steps of capturing the color plane images of the document comprise propagating the color plane images through a tapered slab waveguide.

34. The method of claim 26, wherein the steps of capturing the color plane images of the document comprise capturing the color plane images with a monochrome image sensor.