Direct view display device with array of tapered waveguide on viewer side

• US 5,481,385 A
• Filed: 07/01/1993
• Issued: 01/02/1996
• Est. Priority Date: 07/01/1993
• Status: Expired due to Term

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Zimmerman, Scott M., Beeson, Karl W., McFarland, Michael J., Yardley, James T., Ferm, Paul M.
• Primary Examiner(s): GROSS, ANITA P
• Application Number:
  US08/086,414
• Time in Patent Office: 915 Days
• Field of Search: 359/40, 359/41, 359/42
• US Class Current: 349/62
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides

Abstract

A direct view display including a light generating means for generating light, a modulating means for modulating light from said light generating means to form an image, and an image display means for displaying said image from said modulating means positioned adjacent to the light output surface of said modulating means, said display means comprising an array of tapered optical waveguides on a planar substrate the tapered end of each of said waveguides extending outward from said substrate and having a light input surface adjacent said substrate and a light output surface distal from said light input surface. The area of the light input surface of each waveguide is greater than the area of its light output surface, and the center-to-center distance between the light input surfaces of adjacent waveguides in said array is equal to the center-to-center distance between the light output surfaces thereof, so that the angular distribution of light emerging from the output surfaces of the waveguides is larger than the angular distribution of light entering the waveguides. Also, the waveguides in said array are separated by interstitial regions with a lower refractive index than the refractive index of said waveguides.

Claims

1. A direct view flat panel display comprising:

(a) a light generating means for generating light;

(b) a modulating means for modulating light from said light generating means to form an image; and

(c) an image display means for displaying said image from said modulating means positioned adjacent to the light output surface of said modulating means, said display means comprising an array of tapered optical waveguides on a planar substrate the tapered end of each of said waveguides extending outward from said substrate and having a light input surface adjacent said substrate and a light output surface distal from said light input surface, wherein;

(i) the area of the light input surface of each waveguide is greater than the area of its light output surface, and the center-to-center distance between the light input surfaces of adjacent waveguides in said array is equal to the center-to-center distance between the light output surfaces thereof, so that the angular distribution of light emerging from the output surfaces of the waveguides is larger than the angular distribution of light entering the waveguides; and

(ii) the waveguides in said array are separated by interstitial regions with a lower refractive index than the refractive index of said waveguides.

2. The device of claim 1 wherein said waveguides are striated.

3. The device of claim 1 wherein said waveguides contain scattering centers.

4. The device of claim 1 which further comprises a fiber-optic face plate.

5. The direct view flat panel display of claim 1 wherein said angular distribution of light entering said waveguides ranges from about -6 to about +6 degrees.

6. The direct view flat panel display of claim 1 wherein said angular distribution of light entering said waveguides ranges from about -10 to about +10 degrees.

7. The direct view flat panel display of claim 1 wherein said angular distribution of light emerging from the output surfaces of the waveguides ranges from about -30 to about +30 degrees.

8. The direct view flat panel display of claim 1 wherein said angular distribution of light emerging from the output surfaces of the waveguides ranges from about -60 to about +60 degrees.

9. The direct view flat panel display of claim 1 wherein said angular distribution of light emerging from the output surfaces of the waveguides ranges from about -80 to about +80 degrees.

10. The device of claim 1 wherein said modulating means is a liquid crystal modulator.

11. The device of claim 10 which futher comprises:

(d) an input light polarizing means positioned between said light generating means and said modulating means for polarizing light generated by said light generating means; and

(e) an output light polarizing means positioned between said modulating means and said image display means for polarizing light emitted from said modulating means.

12. The device of claim 1, 10 or 11 wherein all or a portion of said interstitial regions are opticially absorptive.

13. The device of claim 12 wherein all or a portion of said interstitial regions contain an optically absorptive material.

14. The device of claim 13 wherein all or a portion of said material is in particulate form.

15. The device of claim 14 wherein said material is carbon black.

16. The device of claim 1, 10 or 11 wherein the tapered optical waveguides are constructed from organic polymeric material.

17. The device of claim 1, 10 or 11 wherein the shape of said waveguides is selected from the group consisting of right circular cones, right oval cones, right square pyramids, and right rectangular pyramids, which may be whole or truncated,

18. The device of claim 17 wherein the shape of said waveguides is a truncated right circular cone.

19. The device of claim 17 wherein the shape of said waveguides is a truncated right square pyramid.

20. The device of claim 1, 10 or 11 wherein the tapered optical waveguides possess a light input surface with largest dimension less than 100 microns across and a height of at least 200 microns with the ratio of input area to output area of at least 2.1.

21. The device of claim 1, 10 or 11 wherein said device further comprises a protective layer bonded to said waveguide array, said protective layer being positioned to receive output from the light output surfaces of the waveguides in said array.

22. The device of claim 21 wherein said protective layer has an anti-reflective coating.

23. The device of claim 11 wherein said device further comprises a protective layer bonded to said waveguide array, said protective layer being positioned to receive output from the light output surfaces of the waveguides in said array and said protective layer containing an array of negative lenses.

24. The device of claim 11 which further comprises a light-collimating means for collimating light from said generating means positioned adjacent to the light input surface of the input polarizer of said modulating means, said light-collimating means comprising an array of tapered optical waveguides on a planar substrate, the tapered end of each waveguide extending outward from said substrate and having a light output surface adjacent said substrate and a light input surface distal said light output surface, wherein:

(i) the area of the light input surface of each waveguide is smaller than the area of its light output surface, and the center-to-center distance between the light input surfaces of adjacent waveguides in said array is equal to the center-to-center distance between the light output surfaces thereof, so that the divergent light from an uncollimated illumination system is partially collimated upon emergence from their output surfaces; and

(ii) the waveguides in said array are separated by interstitial regions with a lower refractive index than the refractive index of said waveguides.

25. A direct view flat panel display comprising:

(a) a light generating means for generating light;

(b) a modulating means for modulating light from said light generating means to form an image wherein said modulating means has pixels; and

(c) an image display means for displaying said image from said modulating means positioned adjacent to the light output surface of said modulating means, said display means comprising an array of tapered optical waveguides on a planar substrate the tapered end of each of said waveguides extending outward from said substrate and having a light input surface adjacent said substrate and a light output surface distal from said light input surface, wherein;

(i) the area of the light input surface of each waveguide is greater than the area of its light output surface, and the center-to-center distance between the light input surfaces of adjacent waveguides in said array is equal to the center-to-center distance between the light output surfaces thereof, so that the angular distribution of light emerging from the output surfaces of the waveguides is larger than the angular distribution of light entering the waveguides;

(ii) the waveguides in said array are separated by interstitial regions with a lower refractive index than the refractive index of said waveguides; and

(iii) said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is less than the center-to-center distance between adjacent pixels of said modulating means.

26. The direct view flat panel display of claim 25 wherein the ratio of said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides to said center-to-center distance between said adjacent pixels of said modulating means is from about 0.025 to less than 1.

27. The direct view flat panel display of claim 25 wherein the ratio of said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides to said center-to-center distance between said adjacent pixels of said modulating means is from about 0.125 to about 0.50.

28. The direct view flat panel display of claim 25 wherein the ratio of the length of each of said tapered optical waveguides to said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is from about 0.25 to about 20.

29. The direct view flat panel display of claim 25 wherein the ratio of the length of each of said tapered optical waveguides to said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is from about 1 to about 8.

30. The direct view flat panel display of claim 25 wherein said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is from about 5 to less than 200 microns.

31. The direct view flat panel display of claim 25 wherein said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is from about 15 to less than 200 microns.

32. The direct view flat panel display of claim 25 wherein said center-to-center distance between said light input surfaces of adjacent tapered optical waveguides is from about 25 to about 100 microns.

33. The direct view flat panel display of claim 25 wherein the length of each of said tapered optical waveguides is up to 4,000 microns.

34. The direct view flat panel display of claim 25 wherein the length of each of said tapered optical waveguides is from about 5 to about 1,600 microns.

35. The direct view flat panel display of claim 25 wherein the length of each of said tapered optical waveguides is from about 10 to about 800 microns.

36. The direct view flat panel display of claim 25 wherein said light output surface area of each of said tapered optical waveguides is from about 1 to about 50 percent of the light input surface area of each of said tapered optical waveguides.

37. The direct view flat panel display of claim 25 wherein said light output surface area of each of said tapered optical waveguides is from about 3 to about 25 percent of the light input surface area of each of said tapered optical waveguides.