DISPLAY HAVING A REFLECTIVE POLARIZER

• US 20050270439A1
• Filed: 07/26/2005
• Published: 12/08/2005
• Est. Priority Date: 12/21/1993
• Status: Active Grant

• 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.
• Granted Patent: US 7,423,708 B2
• Time in Patent Office: Days
• US Class Current: 349/63
• 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. An optical display comprising:

a liquid crystal module;

an optical cavity positioned proximate said liquid crystal module said optical cavity providing randomization of polarization orientation to light incident upon a surface within said optical cavity;

a reflective polarizer located between said LCD module and said optical cavity, illuminated by said optical cavity for transmitting light having a first polarization orientation, and for reflecting light that does not have said first polarization orientation toward said optical cavity.

4. The optical display of claim 1 wherein said reflective polarizer comprises a layer of stretched polymeric material.

5. The optical display of claim 1 wherein said reflective polarizer comprises a multiple layer stack of pairs of polymeric material layers, each of said pairs exhibiting a refractive index difference between layers for polarized light associated with a first direction and exhibiting essentially no refractive index difference in between layers for polarized light associated with a second direction orthogonal to said first direction.

6. The optical display of claim 1 wherein said reflective polarizer comprises alternating pairs of layers of PEN and coPEN.

7. The optical display of claim 1 wherein said reflective polarizer comprises alternating pairs of layers of PEN and coPEN where each pair of PEN and coPEN layers exhibits an optical thickness of substantially one half wavelength for light having wavelengths from approximately 400 nm to approximately 800 nm in air.

8. The optical display of claim 1 wherein said optical cavity comprises an electroluminescent panel having a diffuse reflecting surface.

9. The optical display of claim 1 wherein said display has an axis perpendicular to said liquid crystal module and said display further comprises a structured surface material such that light entering said structured surface material within a first preselected group of angles to said axis will be reflected and light entering said structured surface material within a second predetermined group of angles to said axis will be refracted such that a majority of the light in said second group of angles will form an output wedge that is narrower than its associated input wedge, said angles in said second group of angles being greater than said angles in said first group of angles.

10. The optical display of claim 9 wherein said structured surface material has a smooth surface and a structured surface, said structured surface having thereon a plurality of triangular prisms.

11. The optical display of claim 10 wherein said triangular prisms have included angles in the range of 70 degrees to 110 degrees.

12. The optical display of claim 11 wherein said triangular prisms have included angles substantially equal to 90 degrees.

2. An optical display comprising:

a front polarizer;

a rear polarizer;

a liquid crystal matrix located between said front polarizer and said rear polarizer;

a reflective polarizer for transmitting light having a first polarization orientation;

an optical cavity, for altering the polarization of light incident upon a surface within said optical cavity, said optical cavity located proximate said reflective polarizer to direct light through said reflective polarizer toward said liquid crystal matrix.

3. An optical display comprising:

a front polarizer;

a liquid crystal matrix located proximate said front polarizer;

a reflective polarizer for transmitting light having a first polarization orientation;

an optical cavity, for altering the polarization of light incident upon a surface within said optical cavity, said optical cavity located proximate said reflective polarizer to direct light through said reflective polarizer toward said liquid crystal matrix.