Document illuminator with LED-driven phosphor

• US 7,864,381 B2
• Filed: 03/20/2007
• Issued: 01/04/2011
• Est. Priority Date: 03/20/2007
• Status: Expired due to Fees

• Current Assignee: Majandro LLC (IP Edge LLC)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Scott, Thomas R.
• Primary Examiner(s): Worku; Negussie
• Application Number:
  US11/725,860
• Publication Number:
  US 20080231911A1
• Time in Patent Office: 1,386 Days
• Field of Search: 358/474, 358/486, 358/497, 358/496, 358/487
• US Class Current: 358/474
• 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 1/02825 in combination with at least one reflector which is fixed in relation to the light source H04N1/02835 and H04N1/0284 take precedence
• CPC Class Codes: H04N 1/02835 in combination with a light guide, e.g. optical fibre, glass plate light-guides per se G02B6/00
• CPC Class Codes: H04N 1/0289 Light diffusing elements, e.g. plates or filters optical diffusing elements per se G02B5/02
• CPC Class Codes: H04N 1/02895 Additional elements in the illumination means or cooperating with the illumination means, e.g. filters H04N1/02885 takes precedence; optical elements other than lenses per se G02B5/00
• CPC Class Codes: H04N 1/0318 Integral pick-up heads, i.e. self-contained heads whose basic elements are a light-source, a lens array and a photodetector array which are supported by a single-piece frame
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence

Abstract

A scanning apparatus includes an illuminator for illuminating a portion of a document to be scanned. The illuminator includes at least one light source and an optical element positioned to redirect light emitted by the light source. A phosphor material is disposed to intercept at least a portion of the light redirected by the optical element. A photosensitive device is positioned to receive light reflected from the document for recording an image of the document.

Claims

1. A scanning apparatus comprising:

an illuminator for illuminating a portion of a document to be scanned, the illuminator comprising;

at least one light source positoned to direct light into an optical element,

the optical element positioned to redirect light emitted by the light source, and

a phosphor material disposed intermediate the light source and the document to intercept at least a portion of the light redirected by the optical element; and

a photosensitive device positioned to receive light reflected from the document for recording an image of the document.

2. The apparatus of claim 1, wherein the optical element includes the phosphor material.

3. The apparatus of claim 1, wherein the optical element includes a base portion formed of a light-transmissive material and a layer which includes the phosphor material.

4. The apparatus of claim 3, wherein the base portion includes at least one reflecting element for redirecting light from the light source toward the document.

5. The apparatus of claim 4, wherein the optical element includes opposed rear and exit faces, the light redirected by the optical element exiting through the exit face, and wherein the at least one reflecting element comprises a plurality of notches in the rear face of the optical element.

6. The apparatus of claim 4, wherein the at least one reflecting element comprises a plurality of reflective paint patches in a rear face of the optical element.

7. The apparatus of claim 3, wherein the base portion is intermediate the light source and the phosphor containing layer.

8. The apparatus of claim 1, further comprising a platen for supporting the document, the platen being disposed generally adjacent an exit face of the optical element.

9. The apparatus of claim 1, wherein the optical element and the at least one light source are supported on a movable carriage.

10. The apparatus of claim 1, wherein the phosphor material is disposed on a rear face of the optical element.

14. The apparatus of claim 1, wherein the optical element defines an entry face and an exit face, the exit face being substantially perpendicular to the entry face and wherein the light source is positioned adjacent the entry face and the phosphor material is disposed adjacent the exit face.

23. The scanning apparatus of claim 1, wherein the optical element is in the form of a prism.

11. A scanning apparatus comprising:

an illuminator for illuminating a portion of a document to be scanned, the illuminator comprising;

at least one light source, the at least one light source comprising a light emitting diode,

an optical element positioned to redirect light emitted by the light source, and

a phosphor material disposed to intercept at least a portion of the light redirected by the optical element; and

a photosensitive device positioned to receive light reflected from the document for recording an image of the document.

12. The apparatus of claim 11, wherein the phosphor material converts light from the light source to light of a different wavelength or a desired combination of wavelengths.

13. The apparatus of claim 12, wherein light emitted by the optical element, which includes the light converted by the phosphor material and unconverted light from the LED, approximates white light.

15. An illuminator comprising:

an optical element in the form of a light pipe prism which defines an entry face and opposed rear and exit faces, the exit face being substantially perpendicular to the entry face, the rear face including a plurality of reflective elements for redirecting light received from the entry face toward the front face, a particulate material being disposed between the reflecting elements and the front face for diffusing light incident thereon; and

at least one light source positioned adjacent the entry face.

16. The illuminator of claim 15, wherein the particulate material comprises at least one phosphor.

17. A scanning apparatus comprising the illuminator of claim 15 and a photosensitive device positioned to receive light reflected from a document for recording an image of the document.

18. The scanning apparatus of claim 17, wherein the scanning apparatus is a monochrome scanning apparatus.

19. The illuminator of claim 15, wherein the at least one light source comprises a light emitting diode.

20. A method for scanning a document comprising:

with a scanning device, actuating a light source to emit light;

transmitting the light through an optical element in the form of a prism which illuminates the document, the transmitting including transmitting the light through a layer of the optical element, the layer comprising a particulate material, the particulate material being disposed intermediate the light source and the document, the particulate material diffusing the transmitted light, thereby increasing uniformity of the illumination of the document.

21. The method of claim 20, wherein the transmitting further comprises:

redirecting at least a portion of the emitted light toward the layer with a plurality of reflective elements.

22. The method of claim 20, wherein the transmitting further comprises:

converting at least a portion of the light to light of longer wavelength with the phosphor material.