Optical polarizer

• US 20050122587A1
• Filed: 12/15/2004
• Published: 06/09/2005
• Est. Priority Date: 12/21/1993
• Status: Abandoned Application

• 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., Jonza, James M.
• Application Number:
  US11/012,651
• Publication Number:
  US 20050122587A1
• Time in Patent Office: Days
• US Class Current: 359/490
• 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 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

A reflective polarizer and a dichroic polarizer are combined to provide an improved optical polarizer. The dichroic and reflective polarizers are typically in close proximity to each other, and are preferably bonded together to eliminate the air gap between the polarizers. The combination of the two polarizers provides a high reflectivity of one polarization and high transmission for the perpendicular polarization from the reflective polarizer side of the combined polarizer, and high absorption and transmission for light of orthogonal polarization from the dichroic polarizer side. The combination also reduces iridescence as seen in transmission and when viewed in reflection from the dichroic polarizer side. The increased extinction ratio and low reflectivity of the optical polarizer allows use of a lower extinction ratio dichroic polarizer in applications requiring a given extinction ratio and high transmission.

Claims

1. A display, comprising:

a liquid crystal display module;

a backlight;

a broadband reflective polarizer having anisotropic refractive indices such that light having a first polarization state is reflected and light having a second polarization state is transmitted, the reflective polarizer having a viewing side facing the liquid crystal display module and an opposing side facing the backlight; and

an absorbing polarizer disposed between the reflective polarizer and the liquid crystal display module and being aligned to absorb light of the first polarization and to transmit light of the second polarization such that light of the first polarization reflected by the opposing side of the reflective polarizer is used to increase brightness of the display while providing antireflection to the viewing side of the reflective polarizer by absorbing light of the first polarization.

2. An optical display as recited in claim 1, wherein absorbing polarizer is boned to the viewing side of the reflective polarizer.

3. A display as recited in claims 1, wherein the reflective polarizer comprises an polymeric material.

4. A display as recited in claim 1, wherein the reflective polarizer comprises a multilayer stack of two different materials.

5. A display as recited in claim 1, wherein the reflective polarizer exploits constructive interference to reflect light of the first polarization.

6. A display as recited in claim 4, wherein the reflective polarizer wherein the multilayer stack comprises alternating layers of crystalline naphthalene dicarboxilic acid and a copolyester of naphthalene dicarboxilic acid and tetephthalic acid.