High efficiency optical devices

• US 20050260384A1
• Filed: 07/11/2005
• Published: 11/24/2005
• Est. Priority Date: 06/26/1995
• 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., Wortman, David L.
• Granted Patent: US 7,147,903 B2
• Time in Patent Office: Days
• US Class Current: 428/137
• CPC Class Codes: B32B 2250/05 5 or more layers
• CPC Class Codes: B32B 2250/42 Alternating layers, e.g. ABAB(C), AABBAABB(C)
• CPC Class Codes: B32B 2307/42 Polarizing, birefringent, filtering
• CPC Class Codes: B32B 2307/518 bi-axially
• CPC Class Codes: B32B 2307/704 Crystalline
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/30 comprising vinyl (co)polymers; comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/304 comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• CPC Class Codes: B32B 27/322 comprising halogenated polyolefins, e.g. PTFE
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/023 Optical properties
• CPC Class Codes: G02B 5/0841 comprising organic materials, e.g. polymers
• 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: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• 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: G02B 6/0096 : the lights guides being of the hollow type
• CPC Class Codes: G02F 1/133545 : Dielectric stack polarisers
• CPC Class Codes: G02F 1/133615 : Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/13362 : providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: Y10S 428/91 : Product with molecular orientation
• CPC Class Codes: Y10T 428/13 : Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]
• CPC Class Codes: Y10T 428/24322 : Composite web or sheet
• CPC Class Codes: Y10T 428/24942 : including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24967 : Absolute thicknesses specified
• CPC Class Codes: Y10T 428/31504 : Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31935 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31938 : Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Optical devices according to the present invention include a multilayer optical film in which at least one of the layers comprises an oriented birefringent polymer. The multilayer optical film exhibits low absorptivity and can reflect light approaching at shallow angles as well as normal to the film.

Claims

1. A backlight assembly, comprising:

a light guide comprising opposing optical surfaces, wherein at least a portion of the opposing optical surfaces comprises a multilayer optical film that comprises alternating layers of at least two materials, wherein the multilayer optical film reflects light over a wavelength band of interest as a function of thicknesses of the alternating layers, wherein at least one of the materials has a stress induced birefringence, and further wherein at least one opposing optical surface comprises a plurality of voids formed in the multilayer optical film; and

at least one light source positioned between the opposing optical surfaces, wherein at least one void of the plurality of voids is capable of transmitting light emitted by the at least one light source.

2. The assembly of claim 1, wherein the multilayer optical film comprises a mirror.

3. The assembly of claim 1, wherein at least one void of the plurality of voids comprises a physical aperture.

4. The assembly of claim 1, wherein at least one void of the plurality of voids comprises a transparent area.

5. The assembly of claim 1, wherein the multilayer optical film comprises alternating first and second polymeric materials, wherein the first polymeric material is birefringent and the second polymeric material is isotropic.

6. The assembly of claim 1, wherein the light guide is hollow.

7. The assembly of claim 1, wherein the multilayer optical film comprises alternating first and second polymeric materials, wherein the absolute value of the difference in index of refraction between the first and second polymeric materials is Δ

nx along an in-plane direction of the film and is Δ

nz along a thickness direction of the film, and wherein Δ

nx is at least 0.05 and Δ

nz is less than Δ

nx.

8. The assembly of claim 1, wherein the multilayer optical film is laminated to a support.

9. The assembly of claim 1, wherein the plurality of voids are uniformly distributed in the opposing optical surface.

10. The assembly of claim 1, wherein the plurality of voids are randomly distributed in the opposing optical surface.

11. The assembly of claim 1, wherein each void of the plurality of voids is of equal size.

12. A backlight assembly, comprising:

a light guide comprising opposing optical surfaces and an opening substantially orthogonal to the opposing optical surfaces, wherein at least a portion of the opposing optical surfaces comprises a multilayer optical film that comprises alternating layers of at least two materials, wherein the multilayer optical film reflects light over a wavelength band of interest as a function of thicknesses of the alternating layers, wherein at least one of the materials has a stress induced birefringence, and further wherein at least one opposing optical surface comprises a plurality of voids formed in the multilayer optical film; and

at least one light source positioned proximate the opening, wherein at least one void of the plurality of voids is capable of transmitting light emitted by the at least one light source.

13. The assembly of claim 12, wherein the multilayer optical film comprises a mirror.

14. The assembly of claim 12, wherein at least one void of the plurality of voids comprises a physical aperture.

15. The assembly of claim 12, wherein at least one void of the plurality of voids comprises a transparent area.

16. The assembly of claim 12, wherein the opposing optical surfaces converge towards each other as the distance from the opening into the light guide increases.

17. The assembly of claim 12, wherein the multilayer optical film comprises alternating first and second polymeric materials, wherein the first polymeric material is birefringent and the second polymeric material is isotropic.

18. The assembly of claim 12, wherein the light guide is hollow.

19. The assembly of claim 12, wherein the multilayer optical film comprises alternating first and second polymeric materials, wherein the absolute value of the difference in index of refraction between the first and second polymeric materials is Δ

nx along an in-plane direction of the film and is Δ

nz along a thickness direction of the film, and wherein Δ

nx is at least 0.05 and Δ

nz is less than Δ

nx.