Light fixture having a multilayer polymeric film

• US 6,396,631 B1
• Filed: 06/12/2000
• Issued: 05/28/2002
• Est. Priority Date: 04/06/1994
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Ouderkirk, Andrew J.
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US09/592,504
• Time in Patent Office: 715 Days
• Field of Search: 359/485,487,488,490,495,498,500,584,589 362/19,257,260,296 428/212,421,480,483,522
• US Class Current: 359/485.03
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/287 comprising at least one layer of organic material
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0048 with stepwise taper
• 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 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/0066 characterised by the light source being coupled to the light guide
• CPC Class Codes: G02B 6/0071 with elongated shape, e.g. tube
• 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
• CPC Class Codes: Y10S 428/91 Product with molecular orientation
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers
• 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

A polarized light source includes a diffuse light source and a reflective polarizing element placed: proximate thereto. The reflective polarizing element transmits light of a desired polarization and reflects light of another polarization back into the diffuse source where it is randomized. Some of the initially rejected light is thus converted into the desired polarization and is transmitted through the reflective polarizing element. This process continues, and the repeated reflections and subsequent randomization of light of the undesired polarization increases the amount of light of the desired polarization that is emitted by the polarized light source.

Claims

1. A light fixture comprising:

(a) a light source;

(b) a multilayer mirror positioned to reflect light emitted by the light source toward an output side of the light fixture; and

(c) a reflective polarizer positioned to transmit light of a desired polarization, and to reflect light of another polarization back into the light source and the mirror,

wherein the multilayer mirror comprises alternating layers of at least a first layer type comprising a first polymeric material and a second layer type comprising a second polymeric material, wherein a difference in indices of refraction between the two layer types is Δ

x along a first in-plane axis, Δ

y along a second in-plane axis perpendicular to the first in-plane axis, and Δ

z along a third axis mutually orthogonal to the first and second axes, and wherein |Δ

z| is less than about 0.5k, where k is the larger of |Δ

x| and |Δ

y|.

2. The light fixture of claim 1, wherein the fixture comprises a task light.

3. The light fixture of claim 1, wherein the light source is a source which emits light having a high degree of scatter or randomization for polarization and direction of light.

4. The light fixture of claim 1, wherein the light source is an incandescent lamp, a fluorescent lamp, a solid-state source, or an electroluminescent light source.

5. The light fixture of claim 1, wherein said mirror comprises alternating layers of PEN and PMMA.

6. The light fixture of claim 1, wherein said mirror has a reflectivity of greater than 99%.

7. The light fixture of claim 1, wherein said reflective polarizer comprises alternating layers of PEN and coPEN.

8. The light fixture of claim 1, wherein the polarizer is wrapped at least partly around the light source.

9. The light fixture of claim 8, wherein the light source is a fluorescent lamp.