Optical devices using reflecting polarizing materials

• US 6,934,082 B2
• Filed: 06/28/2004
• Issued: 08/23/2005
• Est. Priority Date: 04/22/1999
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Wortman, David L., Cobb, Sanford Jr., Ouderkirk, Andrew J., Nevitt, Timothy J., Cross, Elisa M., Tabar, Ronald J., Kent, Susan L., Allen, Richard C.
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US10/878,911
• Publication Number:
  US 20050002098A1
• Time in Patent Office: 421 Days
• Field of Search: 359/487, 359/495, 359/500, 359/599, 362/19, 313/112, 313/113, 313/116
• US Class Current: 359/493.01
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/0236 the diffusion taking place within the volume of the element
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0284 used in reflection
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3041 comprising multiple thin layers, e.g. multilayer stacks
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement 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: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

Optical devices using reflective polarizers and, in particular, diffusely reflective polarizers are provided. Many of the optical devices utilize the diffusely reflecting and specularly transmitting properties of diffusely reflecting polarizers to enhance their optical characteristics. The optical devices include a lighting system which uses a reflector formed from a diffusely reflecting polarizer attached to a specular reflector. Another optical device is a display apparatus which uses a diffusely reflecting polarizer layer in combination with a turning lens which folds shallow angle light toward a light modulating layer. Other optical devices exploit the depolarizing characteristics of a diffusely reflecting polarizer when reflecting light. Still other optical devices use diffusely reflecting polarizers to recycle light and improve display illumination.

Claims

1. An optical device comprising:

a light source for generating light;

a specular reflector disposed to receive at least some light from the light source; and

a continuous layer of diffusely reflecting polarizer disposed between the light source and the specular reflector;

wherein at least a portion of the light having a first polarization is transmitted by the layer of diffusely reflecting polarizer, reflected by the reflector, and retransmitted through the layer of diffusely reflecting polarizer; and

wherein at least a portion of the light having a second, different, polarization is diffusely reflected by the layer of diffusely reflecting polarizer.

2. The optical device of claim 1, wherein the diffusely reflecting polarizer is fixedly attached to the specular reflector.

3. The optical device of claim 2, wherein the reflector curves about the light source.

4. The optical device of claim 3, wherein the reflector curves about the light source, so that light of the first polarization retransmitted through the layer of diffusely reflecting polarizer has a substantially uniform distribution.

5. An optical device comprising:

a light source for generating light;

a specular reflector disposed to receive at least some light from the light source; and

a diffusely reflecting polarizer disposed between the light source and the specular reflector, said diffusely reflecting polarizer fixedly attached to the specular reflector;

wherein at least a portion of the light having a first polarization is transmitted by the diffusely reflecting polarizer, reflected by the reflector, and retransmitted through the diffusely reflecting polarizer; and

wherein at least a portion of the light having a second, different, polarization is diffusely reflected by the diffusely reflecting polarizer.

6. The optical device of claim 5, wherein the reflector curves about the light source.

7. The optical device of claim 5, wherein the reflector curves about the light source, so that light of the first polarization retransmitted through the diffusely reflecting polarizer has a substantially uniform distribution.