Backlighting system including a specular partial reflector and a circular-mode reflective polarizer

• US 9,488,859 B2
• Filed: 08/11/2014
• Issued: 11/08/2016
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: O'Neill, Mark B., Watson, Philip E., Johnson, Matthew B., Haag, Adam D., Kotchick, Keith M., Lamansky, Sergey
• Primary Examiner(s): DUONG, THOI V
• Application Number:
  US14/456,830
• Publication Number:
  US 20140347604A1
• Time in Patent Office: 820 Days
• Field of Search: 349/114, 349/113, 349/117, 349/96, 349/62, 349/98, 349/119, 349/118, 349/115, 349/120, 349/102, 349/65, 349/9, 349/99, 362/19, 362/611, 362/607, 362/608, 362/97.1, 362/97.2, 359/485.01, 359/489.07, 359/489.01, 313/112, 313/113, 313/501, 313/509
• US Class Current: 1/1
• 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: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• 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 1/133541 Circular polarisers
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

A backlight that includes an illumination device that has at least one light source, a circular-mode reflective polarizer, and a specular partial reflector is disclosed. The specular partial reflector is disposed between the illumination device and the circular-mode reflective polarizer. Furthermore, the specular partial reflector is in substantially direct polarization communication with the circular-mode reflective polarizer.

Claims

1. A backlight, comprising:

an illumination device comprising at least one light source;

a circular-mode reflective polarizer; and

a birefringent specular partial reflector disposed between the illumination device and the circular-mode reflective polarizer, wherein the specular partial reflector has an orthogonal reflection fraction value of at least 2%;

wherein the birefringent specular partial reflector is in substantially direct polarization communication with the circular-mode reflective polarizer.

2. The backlight of claim 1, wherein the circular-mode polarizer comprises a linear-mode reflective polarizer and a retarder, wherein the retarder in conjunction with the linear-mode reflective polarizer performs conversion of linear to one of circular, near-circular, or elliptical polarization.

3. The backlight of claim 1, wherein the birefringent specular partial reflector includes a low density surface textured film.

4. The backlight of claim 1, wherein different polarization components of light are reflected by the specular partial reflector at different magnitudes.

5. A backlight, comprising:

an illumination device comprising at least one light source;

a circular-mode reflective polarizer, wherein the circular-mode polarizer comprises a linear-mode reflective polarizer and a retarder, and wherein the retarder in conjunction with the linear-mode reflective polarizer performs conversion of linear to one of circular, near-circular, or elliptical polarization; and

a specular partial reflector disposed between the illumination device and the circular-mode reflective polarizer, wherein the specular partial reflector has an orthogonal reflection fraction value of at least 2%;

wherein the specular partial reflector is in substantially direct polarization communication with the circular-mode reflective polarizer.