Display having a reflective polarizer

• US 7,423,708 B2
• Filed: 07/26/2005
• Issued: 09/09/2008
• Est. Priority Date: 12/21/1993
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Weber, Michael F., Ouderkirk, Andrew J., Stover, Carl A., Benson, Olester Jr., Cobb, Sanford Jr., Jonza, James M., Wortman, David L.
• Primary Examiner(s): Nelms; David C.
• Assistant Examiner(s): Chien; Lucy P
• Application Number:
  US11/189,515
• Publication Number:
  US 20050270439A1
• Time in Patent Office: 1,141 Days
• Field of Search: 349/63
• 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;

a display module; and

a reflective polarizer disposed between the light source and the display module and including at least one material having anisotropic refractive indices, the reflective polarizer substantially reflecting light of a first polarization and substantially transmitting light of a second polarization, wherein reflection of off-axis light of the second polarization exhibits a Brewster angle minimum.

2. A display as recited in claim 1, wherein the reflective polarizer comprises a multilayer interference stack of different materials including the material having anisotropic refractive indices.

3. A display as recited in claim 2, wherein the reflective polarizer comprises alternating layers of the material having anisotropic indices and an isotropic material.

4. A display as recited in claim 3, wherein the index of refraction difference between the material having anisotropic refractive indices and the isotropic material along an axis corresponding to the polarization state transmitted through the reflective polarizer is selected to produce the Brewster angle minimum.

5. A display as recited in claim 1, wherein the light source comprises at least one diffuse element arranged to alter the polarization state of light reflected by the reflective polarizer, the light being subsequently redirected toward the reflective polarizer.

6. A display, comprising:

lighting means for generating light;

modulating means for modulating light to produce an image; and

polarizing means, disposed between the lighting means and modulating means, for substantially reflecting light of a first polarization and substantially transmitting light of a second polarization, wherein polarizing means includes means for producing a Brewster angle minimum for reflection of off axis light of the second polarization.

7. A display as recited in claim 6, further comprising means for recycling the light of the first polarization reflected by the polarizing means by converting a portion of such light to the second polarization and redirecting the light back to the polarizing means for transmission through the polarizing means.