Flat panel display

• US 5,781,257 A
• Filed: 03/20/1995
• Issued: 07/14/1998
• Est. Priority Date: 01/30/1995
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Space Operations Company (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Space Operations Company (Martin Marietta Corporation)
• Inventors: Gal, George, Herman, Bruce J.
• Primary Examiner(s): GROSS, ANITA P
• Application Number:
  US08/406,720
• Time in Patent Office: 1,212 Days
• Field of Search: 359/40, 359/49, 359/68, 359/619, 349/57, 349/62, 349/95
• US Class Current: 349/57
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• CPC Class Codes: G02B 5/1895 such optical elements having dioptric power

Abstract

A flat panel display incorporates an array of color separation microlenses. Each color separation microlens in the array is a single, micro-optical element which disperses color by orders to distinct color spots and focuses these color spots to related liquid crystal sub-pixels located in a common plane. Substantially all of the areas of the color spots fall directly and only on the liquid crystal sub-pixels. Little, if any, light energy is lost by falling outside areas occupied by the individual liquid crystal sub-pixels. Because the color separation microlenses provide the color separation, no color filter is required in the flat panel display. Eliminating the color filters eliminates light losses which are incurred when transmitting light through a color filter. The flat panel display makes more efficient use of light transmitted through the components of the display than was possible with prior art flat panel displays.

Claims

1. A flat panel display for displaying color images and comprising,

back illuminating light source means for supplying a collimated spectral band of illuminating light,

polarizing means for polarizing at least a portion of the illuminating light to a single polarization,

unit cell train array means for receiving the single polarized light from the polarizing means and for providing an array of pixels in the flat panel display,

said unit cell train array means comprising a plurality of individual unit cell trains, each individual cell train comprising,

(a) a unitary, color separation microlens which separates colors of the spectral band by diffraction orders and which focuses the separated colors in separate, distinct spots in a common plane,

(b) a liquid crystal unit cell positioned at said common plane and having a separate liquid crystal element at each said distinct spot of separate color,

each said separate liquid crystal element being selectively controllable to modulate the transmission of the separated color from said spot, and

(c) a mask for viewing the color or colors transmitted from said spots of separated colors through said separate liquid crystal elements, and

wherein the flat panel display displays a color image in the array of elements without the use of color filters.

2. The invention defined in claim 1 wherein an individual unit cell train comprises the mask having individual openings for transmitting the colors from the separate liquid crystal elements.

3. The invention defined in claim 1 wherein the back illuminating light source means includes a light source which generates uncollimated light and collimating means which collimate the light supplied to said polarizing means.

4. A flat panel display for displaying color images and comprising,

back illuminating light source means for supplying a collimated spectral band of illuminating light,

polarizing means for polarizing at least a portion of the illuminating light to a single polarization,

unit cell train array means for receiving the single polarized light from the polarizing means and for providing an array of pixels in the flat panel display,

said unit cell train array means comprising a plurality of individual unit cell trains,

each individual cell train comprising,

(a) a unitary, color separation microlens which separates colors of the spectral band by diffraction orders and which focuses the separated colors in separate, distinct spots in a common plane,

(b) a liquid crystal unit cell positioned at said common plane and having a separate liquid crystal element at each said distinct spot of separate color,

each said separate liquid crystal element being selectively controllable to modulate the transmission of the separated color from said spot, and

(c) a mask for viewing the color or colors transmitted from said spots of separated colors through said separate liquid crystal elements, and

wherein the flat panel display displays a color image in the array of elements without the use of color filters and wherein an individual unit cell train includes an anamorphic microlens for displaying the color in the element in a selected field of view.

5. A flat panel display for displaying color images and comprising,

back illuminating light source means for supplying a collimated spectral band of illuminating light,

polarizing means for polarizing at least a portion of the illuminating light to a single polarization,

unit cell train array means for receiving the single polarized light from the polarizing means and for providing an array of pixels in the flat panel display,

said unit cell train array means comprising a plurality of individual unit cell trains, each individual cell train comprising,

(a) a unitary, color separation microlens which separates colors of the spectral band by diffraction orders and which focuses the separated colors in separate, distinct spots in a common plane,

(b) a liquid crystal unit cell positioned at said common plane and having a separate liquid crystal element at each said distinct spot of separate color,

each said separate liquid crystal element being selectively controllable to modulate the transmission of the separated color from said spot, and

a mask for viewing the color or colors transmitted from said spots of separated colors through said separate liquid crystal elements, and

wherein the flat panel display displays a color image in the array of elements without the use of color filters and wherein the polarizing means includes a beam splitter having an inlet for receiving a single beam of unpolarized light and having an outlet for outputting two beams of a single polarized light.

6. The invention defined in claim 5 including a condensing lens at the inlet of the beam splitter for reducing the width of the incoming beam to one half of the combined widths of the two output beams from the beam splitter.

7. A flat panel display for displaying color images and comprising,

back illuminating light source means for supplying a collimated spectral band of illuminating light,

polarizing means for polarizing at least a portion of the illuminating light to a single polarization,

unit cell train array means for receiving the single polarized light from the polarizing means and for providing an array of pixels in the flat panel display,

said unit cell train array means comprising a plurality of individual unit cell trains, each individual cell train comprising,

(a) a unitary, color separation microlens which separates colors of the spectral band by diffraction orders and which focuses the separated colors in separate, distinct spots in a common plane,

(b) a liquid crystal unit cell positioned at said common plane and having a separate liquid crystal element at each said distinct spot of separate color,

each said separate liquid crystal element being selectively controllable to modulate the transmission of the separated color from said spot, and

(c) a mask for viewing the color or colors transmitted from said spots of separated colors through said separate liquid crystal elements, and

wherein the flat panel display displays a color image in the array of elements without the use of color filters and wherein the back illuminating light source means comprises light panel means and collimating optic means and wherein the light panel means comprise a series of mirrors and a series of associated light tubes with each light tube conducting light from an illuminating source to a related mirror and wherein the collimating optics means comprise a plurality of collimating microlenses and wherein each collimating microlens is positioned to receive light reflected from a reflecting mirror and to transmit the reflected light as a collimated light output from the collimating microlens.

8. A flat panel display for displaying color images and comprising,

a back illuminating light source for supplying a collimated spectral band of illuminating light,

a polarizer for receiving the collimated illuminating light from the back illuminating light source and for polarizing at least a portion of the illuminating light to a single polarization at an outlet of the polarizer,

an array of color separation microlenses positioned at the outlet of the polarizer, said array of color separation microlenses comprising a plurality of unitary, color separation microlenses each of which is constructed to separate colors of a spectral band by diffraction orders and to focus the separated colors in separate, distinct spots in a common place,

a liquid crystal wafer located at said common plane and providing a plurality of unit cells with each unit cell having a separate, liquid crystal element at each said distinct spot of separated color,

each said separate liquid crystal element being separately controllable to modulate the transmission of the separated color from said spot,

a mask having separate apertures for viewing the colors transmitted through the unit cells in the liquid crystal array, and

wherein the flat panel display displays a color image in the array of elements without the use of color filters.