Full color liquid crystal display

• US 4,799,050 A
• Filed: 10/23/1986
• Issued: 01/17/1989
• Est. Priority Date: 10/23/1986
• Status: Expired due to Fees

• Current Assignee: Litton Systems Canada Limited (L3Harris Technologies, Inc.)
• Original Assignee: Litton Systems Canada Limited (L3Harris Technologies, Inc.)
• Inventors: Farrell, James F., Prince, John C.
• Primary Examiner(s): Birmiel, Howard A.
• Application Number:
  US06/922,186
• Time in Patent Office: 817 Days
• Field of Search: 340/702, 340/784, 340/765, 313/483, 313/494, 313/358, 350/345
• US Class Current: 349/71
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell

Abstract

A liquid crystal display provides a high quality color image and efficient energy utilization. A layer of liquid crystal material is controlled by a transparent electrode matrix that is fixed to one surface of a fiber optic plate. A matrix of (primary color emitting) phosphors, each in alignment with a transparent electrode, is fixed to the opposed surface of the plate. A source of fluorescent energy excites the phosphors. A filter located behind the fiber optic plate reflects visible light, both ambient and that emitted from the phosphors. The fiber optic plate acts as a relay lens and prevents cross pixel color contamination while the generation of backlight by the phosphor conversion of fluorescent to visible energy is a highly efficient process.

Claims

1. A display comprising, in combination:

(a) a plurality of adjacent light-conducting cells disposed in a planar array, each said cell having means associated with it for modulating the amount of visible light passing therethrough;

(b) a phosphor layer behind said cell array, said layer being capable of emitting visible light through said array when irradiated from behind with ultraviolet light;

(c) an ultraviolet light source behind said phosphor layer for irradiating said phosphor layer with ultraviolet light; and

(d) a fiber optic plate disposed behind said cell array and in front of said phosphor layer, said plate including a plurality of adjacent and parallel light-conducting pipes, each said pipe comprising a bundle of optical fibers and having a front end in light-conducting communication with one of said cells, and a rear end in light-conducting communication with said phosphor layer.

2. The display of claim 1 further including:

(a) a first filter means behind said phosphor layer and in front of said ultraviolet light source for transmitting ultraviolet light to said phosphor layer and for reflecting visible ambient light incident thereon; and

(b) a second filter means in front of said phosphor layer and behind said plate for transmitting visible ambient light to said phosphor layer and for reflecting ultraviolet light incident thereon.

3. The display of claim 2, wherein said phosphor layer further comprises:

(a) a planar matrix of discrete phosphor elements, each said element being in light-conducting communication with a rear end of one of said pipes.

4. The display of claim 3, wherein adjacent ones of said phosphor elements are distributed into adjacent groups of said elements, and wherein the emission spectra of the elements of each said group differ from each other such that the color of light emitted from each said group can be adjusted through the full spectrum of visible color.

5. The display of claim 4, wherein each said phosphor element is colored such that the color of light reflected by it closely matches that of its emitted spectrum.

6. The display of claim 4, further comprising a dilute color filter in front of said array, said filter comprising a planar matrix of light-absorbing, wide-passband dye elements, each said dye element being in alignment with a like-colored one of said phosphor elements through one of said pipes.

7. The display of claim 2, wherein said second filter means further comprises a layer formed directly on a back face of said fiber optic plate, and wherein said phosphor layer is deposited directly on said layer.

8. The display of claim 3, wherein said second filter means further comprises a layer formed directly on a back face of said fiber optic plate, and wherein said matrix of phosphor elements is deposited directly on said layer.

9. The display of claim 8, wherein said array of light-conducting cells further comprises:

(a) a layer of liquid-crystal material on a front face of said fiber optic plate; and

(b) a planar array of transparent control electrodes deposited directly on said front face of said plate, each said electrode being aligned with one of said phosphor elements through one of said pipes in said plate and defining a corresponding one of said light-conducting cells in said liquid-crystal layer.

10. The display of claim 9, wherein said fiber optic plate further comprises two independent fiber optic plates assembled back-to-back.

11. The display of claim 9, wherein said liquid crystal layer is a guest-host (Heilmeier-type) material and further comprising a polarizing layer in front of said liquid crystal layer.

12. A display comprising, in combination:

(a) a light-conducting plate having front and rear faces and a plurality of adjacent and parallel optical-fiber light pipes extending between said faces, each said pipe comprising a bundle of optical fibers;

(b) a filter layer formed directly on said rear face of said plate;

(c) a matrix of distinct phosphor elements deposited directly on said filter layer, each said element being in registration with a rear end of one of said light pipes and capable of emitting visible light therethrough when illuminated by flourescent light;

(d) an array of distinct transparent control electrodes deposited directly on said front face of said plate, each said electrode being in aligned registration with one of said phosphor elements through a front end of one of said pipes;

(e) a source of flourescent light behind said plate for illuminating each said phosphor element with flourescent light; and

(g) a layer of liquid crystal material adjacent to said electrodes on said front face of said plate, said layer and said electrodes having means associated therewith for defining an array of light-conducting cells in registration with said pipes and for modulating the amount of light passing through corresponding ones of said cells and said pipes.

13. This display of claim 12 further including:

(a) said filter layer is a dichroic filter capable of transmitting visible light and reflecting fluorescent light; and

(b) filter means between said source and said plate for transmitting fluorescent light from said source and for reflecting visible ambient light thereon.

14. The display of claim 13, wherein adjacent ones of said phosphor elements are distributed into adjacent groups of said elements, and wherein the emission spectra of the elements of each said group differ from each other such that the color of visible light emitted from each said group can be adjusted through the full spectrum of visible color.

15. The display of claim 14, wherein each said phosphor element is colored such that the color of visible light reflected by it closely matches that of its emitted spectrum.

16. The display of claim 14, further comprising a dilute color filter in front of said layer, said filter comprising a planar matrix of light-absorbing, wide-passband dye elements, each said dye element being in alignment with a like-colored one of said phosphor elements.

17. The display of claim 16, further comprising a transparent reference electrode deposited of a rear face of said color filter and in close proximity to a front face of said liquid crystal layer.

18. The display of claim 13, wherein said fiber optic plate further comprises two independent fiber optic plates assembled back-to-back.

19. The display of claim 13, wherein said liquid crystal layer is a guest-host (Heilmeier-type) material and further comprising a polarizing layer in front of said liquid crystal layer.