Full color liquid crystal display

• US 5,019,808 A
• Filed: 11/14/1988
• Issued: 05/28/1991
• Est. Priority Date: 10/23/1986
• Status: Expired due to Fees

• Current Assignee: 1294339 Ontario, Inc.
• Original Assignee: L3 Technologies ESS, Inc. (L3Harris Technologies, Inc.)
• Inventors: Farrell, James F., Prince, John C.
• Primary Examiner(s): Brier, Jeffery A.
• Assistant Examiner(s): Fatahi Yar, M.
• Application Number:
  US07/270,074
• Time in Patent Office: 925 Days
• Field of Search: 340/765, 340/784, 340/805, 340/719, 350/330, 350/333, 350/334, 350/339 F, 358/231, 358/233
• US Class Current: 345/88
• 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. A matrix of (primary color emitting) phosphors, each in alignment with a transparent electrode, is fixed to a surface of a fiber optic 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 late 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 layer of liquid crystal material;

b) a planar array of transparent control electrodes associated with said layer of liquid crystal material for forming a planar array of adjacent modulated light-conducting cells;

c) a planar matrix of discrete phosphor elements, each of said elements in light-conducting communication with a rear end of a light pipe of a fiber optic plane disposed behind said layer of liquid crystal material and in front of said planar matrix of discrete phosphor elements;

d) said plate including a plurality of adjacent and parallel light-conducting pipes, each pipe comprising a plurality of optical fibers wherein said phosphor elements are distributed into groupings of adjacent elements comprising differing emission spectra such that the color of light emitted from each of said groupings can span the full spectrum of visible light;

e) an ultraviolet light source located behind said planar matrix of discrete phosphor elements for irradiating said elements with ultraviolet light;

f) a first filter means located behind said planar matrix of discrete phosphor elements and in front of said ultraviolet light source for transmitting ultraviolet light to said phosphor layer and for reflecting visible ambient light incident thereupon;

g) a second filter means located in front of said planar matrix and behind said plate for transmitting visible ambient light to said matrix and for reflecting ultraviolet light incident thereupon; and

h) said planar array of transparent control electrodes is located adjacent and in front of said layer of liquid crystal material.

2. A display as defined in claim 1 further including a transparent counter electrode layer located adjacent and behind said layer of liquid crystal material.

3. A display as defined in claim 2 further characterized in that said transparent counter electrode layer is located between said fiber optic plate and said layer of liquid crystal material.

4. A display as defined in claim 3 wherein said planar array of transparent control electrodes is formed upon an absorptive bus mask.

5. A display as defined in claim 1 additionally including:

a) a dilute color filter comprising a planar matrix of light-absorbing, wide-passband dye elements, each of said dye elements being in alignment with a like color emitting one of said phosphor elements through one of said pipes; and

b) said dilute color filter is located between said fiber optic plate and said layer of liquid crystal material.

6. A display as defined in claim 5 wherein said dilute color filter is located adjacent said fiber optic plate.

7. 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 fluorescent light;

d) a layer of liquid crystal material;

e) an array of distinct transparent control electrodes located adjacent and in front of said layer of liquid crystal material, each said electrode being in aligned registration with one of said phosphor elements through a front end of one of said pipes;

f) a source of fluorescent light located behind said plate for illuminating each of said phosphor elements with fluorescent light; and

g) said layer of liquid crystal material located adjacent to said array of electrodes, 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.

8. The display of claim 7 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.

9. The display of claim 8, wherein adjacent ones of said phosphor elements are distributed into groupings of adjacent elements comprising differing emission spectra such that the color of visible light emitted from each of said groupings can span the full spectrum of visible color.

10. The display of claim 9, wherein each said phosphor element is colored such that the color of visible light reflected by it closely matches that of its emitted spectrum.

11. The display of claim 9, further comprising a dilute color filter located between said plate and said layer of liquid crystal material, 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.

12. The display of claim 11, further comprising a transparent reference electrode deposited on a front face of said color filter and adjacent a rear face of said liquid crystal layer.

13. The display of claim 8, wherein said fiber optic plate further compromises two independent fiber optic plates assembled back-to-back.

14. The display of claim 8, 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.