High-brightness color liquid crystal display panel employing light recycling therewithin

• US 6,831,720 B2
• Filed: 05/30/2003
• Issued: 12/14/2004
• Est. Priority Date: 06/27/1994
• Status: Expired due to Fees

• Current Assignee: Reveo, Inc.
• Original Assignee: Reveo, Inc.
• Inventors: Wiley, Richard, Jiang, Yingqiu, Vartak, Sameer, Galabova, Hristina, Faris, Sadeg M., Li, Le, Hochbaum, Aharon
• Primary Examiner(s): Chowdhury, Tarifur R.
• Assistant Examiner(s): Qi, Mike
• Application Number:
  US10/452,814
• Publication Number:
  US 20040095531A1
• Time in Patent Office: 564 Days
• Field of Search: 349/96, 349/115, 349/114, 349/9, 349/130, 349/98
• US Class Current: 349/115
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: E06B 2009/2464 featuring transparency control by applying voltage, e.g. LCD, electrochromic panels
• CPC Class Codes: E06B 9/24 Screens or other constructions affording protection against light, especially against sunshine; Similar screens for privacy or appearance; Slat blindsoperating, guiding or securing devices or arrangements for roll-type closures E06B9/56; free-hanging flexible screens A47H23/00
• CPC Class Codes: F24S 50/80 for controlling collection or absorption of solar radiation
• CPC Class Codes: G01D 11/28 Structurally-combined illuminating devices
• CPC Class Codes: G02B 27/0093 with means for monitoring data relating to the user, e.g. head-tracking, eye-tracking
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133543 Cholesteric polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133623 Inclined coloured light beams
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence
• CPC Class Codes: G02F 1/13718 : based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/1393 : the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: Y02E 10/40 : Solar thermal energy, e.g. solar towers

Abstract

A color liquid crystal display using reflective color filters using layers of cholesteric liquid crystals is disclosed. The reflective color filters have two different center wavelengths and bandwidths per layer and are stacked in two layers to provide colored light for displays. With various numbers of layers in the stack, different polarization levels are provided. The pixels in the display of the invention are arranged such that multiple adjacent sub-pixels in a layer with the same color makes the color filters easier to manufacture.

Claims

1. A wide incident angle reflective broadband polarizer comprising:

a first varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broad band of wavelengths,

a first constant pitch helix cholesteric liquid crystal film for rotating the elliptical axis of light from the first varying pitch helix cholesteric liquid crystal film, adjacent the first varying pitch helix cholesteric liquid crystal film,

a first homeotropic film for compensating the phase of the light from the first constant pitch helix cholesteric liquid crystal film, adjacent the first constant pitch helix cholesteric liquid crystal film such that unpolarized light entering the first varying pitch helix cholesteric liquid crystal film exits the first homeotropic film as circularly polarized light of one handedness for small and large angles of incidence.

2. A wide incident angle reflective broadband polarizer as in claim 1 wherein:

the helical axis of the first variable pitch helix cholesteric liquid crystal film is oriented perpendicular to the film surface,

the helical axis of the first constant pitch helix cholesteric liquid crystal film is oriented perpendicular to the film surface,

the long molecular axes of the first homeotropic film are aligned perpendicular to the film surface.

3. A wide incident angle reflective broadband polarizer as in claim 1 wherein:

a second varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broad band of wavelengths, adjacent the first varying pitch helix cholesteric liquid crystal film,

a second constant pitch helix cholesteric liquid crystal film for rotating the elliptical axis of light from the second varying pitch helix cholesteric liquid crystal film, adjacent the second varying pitch helix cholesteric liquid crystal film,

a second homeotropic film for compensating the phase of the light from the second constant pitch helix cholesteric liquid crystal film, adjacent the second constant pitch helix cholesteric liquid crystal film, such that unpolarized light incident on either homeotropic film of the wide incident angle broadband polarizer is transmitted as circularly polarized light of one handedness for small and large angles of incidence and reflected as circularly polarized light of the opposite handedness for small and large angles of incidence.

4. A wide incident angle reflective broadband polarizer as in claim 3 wherein:

the wide angle broadband polarizer of claim 3 is encased in a block of transparent material diagonally to form a prism such that unpolarized light incident on one prism face will be transmitted as circularly polarized light of one handedness and reflected as circularly polarized light of the opposite handedness perpendicular to the transmitted light.

5. A wide incident angle reflective broadband polarizer as in claim 4 wherein:

a prism of claim 4 having varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broadband of wavelengths of one handedness is adjacent to,

a prism of claim 4 having a varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broadband of wavelengths of the opposite handedness,

a mirror adjacent one of the prisms for changing the handedness of the reflected light and reflecting the reflected light to the prism with the opposite handedness for reflection in the same direction as the incident light such that incident unpolarized light converts totally to transmitted circularly polarized light of one handedness.

6. A wide incident angle reflective broadband polarizer as in claim 3 wherein,

a mirror placed parallel to the wide incident angle broadband polarizer,

a light source for producing unpolarized light placed between the mirror and the wide incident angle broadband polarizer, such that light from the light source is polarized when it is transmitted through the wide incident angle broadband polarizer as circularly polarized light of one handedness.

7. A wide incident angle reflective broadband polarizer as in claim 6 wherein,

a quarter wave plate placed adjacent the wide incident angle broadband polarizer on the side opposite the mirror such that linearly polarized light from the quarter wave plate is chromatically stable at any viewing azimuthal and polar angle.

8. A wide incident angle reflective broadband polarizer as in claim 3 wherein,

the wide incident angle broadband polarizer installed in a reflective cholesteric liquid crystal color filter display corrects for color distortions over large viewing angles.

9. A wide incident angle reflective broadband polarizer as in claim 3 wherein,

the wide incident angle reflective broadband polarizer installed in a smart window corrects for color distortions over large viewing angles.

10. A wide incident angle reflective broadband polarizer as in claim 1 wherein:

a second constant pitch helix cholesteric liquid crystal film for rotating the elliptical axis of light from the first varying pitch helix liquid crystal film, adjacent the first varying pitch helix cholesteric liquid crystal film,

a second homeotropic film for compensating the phase of the light from the second constant pitch helix cholesteric liquid crystal film, adjacent the second constant pitch helix cholesteric liquid crystal film such that unpolarized light incident on either homeotropic film of the whole incident angle broadband polarizer is transmitted as circularly polarized light of one handedness for small and large angles of incidence and reflected as circularly polarized light of the opposite handedness for small and large angles of incidence.

11. A wide incident angle reflective broadband polarizer as in claim 10 wherein:

the wide angle broadband polarizer of claim 10 encased in a block of transparent material diagonally to form a prism such that unpolarized light incident on one prism face will be transmitted as circularly polarized light of one handedness and reflected as circularly polarized light of opposite handedness perpendicular to the transmitted light.

12. A wide incident angle reflective broadband polarizer as in claim 11 wherein:

a prism of claim 11 having varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broadband of wavelengths of one handedness adjacent to,

a prism of claim 11 having a varying pitch helix cholesteric liquid crystal film for reflecting and transmitting circularly polarized light over a broadband of wavelengths of the opposite handedness,

a mirror adjacent one of the prisms for changing the handedness of the reflected light and reflecting the reflected light to the prism with the opposite handedness for reflection in the same direction as the incident light such that incident unpolarized light converts totally to transmitted circularly polarized light of one handedness.

13. A wide incident angle reflective broadband polarizer as in claim 10 wherein,

the film of claim 10 is broken up into fragments and used as a pigment.

14. A wide incident angle reflective broadband polarizer as in claim 10 wherein,

the wide incident angle broadband polarizer installed in a reflective cholesteric liquid crystal color filter display corrects for color distortions over large viewing angles.

15. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

a minor placed parallel to the wide incident angle broadband polarizer,

a light source for producing unpolarized light is placed between the mirror and the wide incident angle broadband polarizer, such that light from the light source is polarized when it is transmitted through the wide incident angle broadband polarizer as circularly polarized light of one handedness.

16. A wide incident angle reflective broadband polarizer as in claim 15 wherein,

a quarter wave plate placed adjacent the wide incident angle broadband polarizer on the side opposite the mirror such that linearly polarized light from the quarter wave plate is chromatically stable at any viewing azimuthal and polar angle.

17. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the homeotropic film is polymerizable.

18. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the constant pitch helix cholesteric liquid crystal film is polymerizable.

19. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

incident unpolarized visible light is transmitted as circularly polarized light.

20. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

incident unpolarized ultraviolet light is transmitted as circularly polarized light.

21. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

incident unpolarized infrared light is transmitted as circularly polarized light.

22. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

an electric field is applied to the varying pitch helix cholesteric liquid crystal film to switch the film between a totally transmissive state and a circularly polarizing transmitting state.

23. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

a first index matching adhesive binds the first varying pitch helix cholesteric liquid crystal film to the first constant pitch helix cholesteric liquid crystal film and a second index matching adhesive binds first constant pitch helix cholesteric liquid crystal film to the first homeotropic film.

24. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the film of claim 1 is broken up into fragments and used as a pigment.

25. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the film of claim 3 is broken up into fragments and used as a pigment.

26. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the wide incident angle broadband polarizer installed in a reflective cholesteric liquid crystal color filter display corrects for color distortions over large viewing angles.

27. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the wide incident angle reflective broadband polarizer installed in a smart window corrects for color distortions over large viewing angles.

28. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

the wide incident angle reflective broadband polarizer installed in a smart window corrects for color distortions over large viewing angles.

29. A wide incident angle reflective broadband polarizer as in claim 1 wherein,

a wide incident angle broadband polarizer as in claim 1 with opposite handedness is attached to reflect all incident light.

30. A wide incident angle reflective broadband polarizer as in claim 1 wherein an electrically addressable π

phase shifter is sandwiched between the wide incident angle broadband polarizer of claim 1 with one handedness and the wide incident angle broadband polarizer of claim 1 with either handedness such that all incident light is reflected when the π

phase shifter changes the light incident thereon and transmits light when the π

phase shifter is quiescent.