Display with reflective polarizer and randomizing cavity

• US 6,025,897 A
• Filed: 11/27/1996
• Issued: 02/15/2000
• Est. Priority Date: 12/21/1993
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Cobb, Sanford Jr., Weber, Michael F., Ouderkirk, Andrew J., Stover, Carl A., Benson, Olester Jr., Jonza, James M., Wortman, David L.
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US08/758,624
• Time in Patent Office: 1,175 Days
• Field of Search: 359/63, 359/487, 359/494, 359/483, 359/497, 359/498, 349/62, 349/65, 349/67, 349/96, 349/97, 349/113, 362/19, 40/548
• US Class Current: 349/96
• CPC Class Codes: A47J 36/28 Warming devices generating the heat by exothermic reactions, e.g. heat released by the contact of unslaked lime with water
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29K 2995/003 Reflective
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133507 Films for enhancing the luminance
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A multiple layer reflective polarizer 12 is described. This element is placed between and optical cavity 24 and an LCD module 16 to form an optical display. The reflective polarizer reflects some light into the optical cavity 24 where it is randomized and may ultimately emerge with the correct polarization to be transmitted out of the display.

Claims

1. A display comprising:

a light source having a reflective optical cavity configured to randomize direction and polarization of light reflected by the optical cavity;

a display module;

a geometric structured surface material disposed between the light source and the display module, the structure surface material redirecting a portion of light incident on the structured surface material from an incidence angle to a transmission angle, the transmission angle being less than the incidence angle measured from an axis normal to the plane of the display module;

a reflective polarizer disposed between the light source and the display module, the reflective polarizer having a birefringent material arranged such that light of a first polarization encounters changes in refractive indices, as the light of the first polarization propagates in the reflective polarizer, sufficient to reflect the light of the first polarization toward the optical cavity, while light of a second polarization is substantially transmitted through the reflective polarizer toward the display; and

an absorbing polarizer disposed between the reflective polarizer and the display module.

2. A display as recited in claim 1, wherein the structured surface material is disposed between the light source and the reflective polarizer.

4. A display as recited in claim 1, further comprising an absorbing polarizer disposed between the reflective polarizer and the display module.

5. A display as recited in claim 1, further comprising an absorbing polarizer bonded directly to the reflective polarizer.

6. A display as recited in claim 1, wherein the light sources comprises:

a lamp; and

a light guide, light from the lamp being coupled into an edge of the light guide and exiting through an exit surface of the light guide.

8. A display as recited in claim 1, wherein the reflective polarizer reflects at least 70% of light of the first polarization incident on the reflective polarizer at a normal angle.

9. A display as recited in claim 1, wherein the reflective polarizer reflects at least 80% of light of the first polarization incident on the reflective polarizer at a normal angle.

10. A display as recited in claim 1, wherein the display brightness along the axis normal to the plane of the display module is at least twice as bright as a display without the structured surface material and the reflective polarizer.

11. A display as recited in claim 1, wherein the structured surface material comprises a plurality of prisms disposed on a first surface of the structured surface material.

12. A display as recited in claim 11, wherein the first surface of the structured surface material faces the display module.

14. A display as recited in claim 11, further comprising a second structured surface material having a plurality of prisms disposed on a first surface of the second structured material, the second structured surface material being disposed between the first structured surface material and the display module, the prisms of the second structured surface material facing the display module, a longitudinal axes of the prisms of the first and second structured surface materials being substantially orthogonal.

3. A display comprising:

a light source;

a display module having optical states which can be altered to display information;

a structured surface material disposed between the light source and the display module, the structure surface material redirecting a portion of light incident on the structured surface material from an incidence angle to a transmission angle, the transmission angle being less than the incidence angle measured from an axis normal to the plane of the display module; and

a reflective polarizer disposed between the light source and the display module, the reflective polarizer having a birefringent material arranged such that light of a first polarization encounters changes in refractive indices, as the light of the first polarization propagates in the reflective polarizer, sufficient to reflect the light of the first polarization, while light of a second polarization encounters substantially uniform refractive indices and is substantially transmitted through the reflective polarizer toward the display,

wherein the structured surface material is disposed between the reflective polarizer and the display module.

7. A display comprising:

a light source;

a display module having optical states which can be altered to display information;

a structured surface material disposed between the light source and the display module, the structure surface material redirecting a portion of light incident on the structured surface material from an incidence angle to a transmission angle, the transmission angle being less than the incidence angle measured from an axis normal to the plane of the display module; and

a reflective polarizer disposed between the light source and the display module, the reflective polarizer having a birefringent material arranged such that light of a first polarization encounters changes in refractive indices, as the light of the first polarization propagates in the reflective polarizer, sufficient to reflect the light of the first polarization, while light of a second polarization encounters substantially uniform refractive indices and is substantially transmitted through the reflective polarizer toward the display, wherein the reflective polarizer comprises a isotropic material alternatingly layered with the birefringent material, the refractive index of the isotropic material substantially matching at least one refractive index of the birefringent material.

13. A display comprising:

a light source;

a display module having optical states which can be altered to display information;

a structured surface material having a plurality of prisms disposed on a first surface of the structured surface material, the structured surface material being disposed between the light source and the display module, the structure surface material redirecting a portion of light incident on the structured surface material from an incidence angle to a transmission angle, the transmission angle being less than the incidence angle measured from an axis normal to the plane of the display module; and

a reflective polarizer disposed between the light source and the display module, the reflective polarizer having a birefringent material arranged such that light of a first polarization encounters changes in refractive indices, as the light of the first polarization propagates in the reflective polarizer, sufficient to reflect the light of the first polarization, while light of a second polarization encounters substantially uniform refractive indices and is substantially transmitted through the reflective polarizer toward the display,

wherein the first surface of the structured surface material faces away from the reflective polarizer.

15. A display comprising:

a lamp;

a light guide having an edge adjacent the lamp, light from the lamp being coupled into the edge of the light guide and exiting the light guide through an exit surface of the light guide;

a display module;

a structured surface material disposed between the light guide and the display module, the structure surface material redirecting a portion of light exiting the light guide at a first angle from normal to the exit surface of the light guide to a second angle which is more normal to the exit surface of the light guide; and

a reflective polarizer, disposed between the light guide and the display module, having at least one birefringent material and at least one second material arranged such that light of a first polarization is substantially reflected by the reflective polarizer while light of a second polarization is substantially transmitted through the reflective polarizer.

16. A display as recited in claim 15, wherein the birefringent material and the second material are disposed in optical repeating units designed to be operable over a wide range of incident light.

17. A display as recited in claim 15, wherein the reflective polarizer has a transmission of the second polarization of at least 80% over a wide range of wavelengths.

18. A display as recited in claim 15, wherein the structured surface material comprises a plurality of structures disposed on a first surface of the structured surface material.

19. A display as recited in claim 18, wherein the first surface of the structured surface material faces the display module.

20. A display as recited in claim 18, wherein the first surface of the structured surface material faces away from the reflective polarizer.

21. A display as recited in claim 18, wherein the structures comprise plurality of prisms.

22. A display, comprising:

a light source;

a display module; and

a reflective polarizer, disposed between the light source and the display module, having at least one birefringent material and at least one second material having a refractive index selected in reference to the birefringent material and being arranged to have a plurality of interfaces between the birefringent material and the second material such that light of a first polarization is substantially reflected by the reflective polarizer while light of a second polarization is substantially transmitted through the reflective polarizer.