Polarizing turning film

• US 7,633,679 B2
• Filed: 12/13/2005
• Issued: 12/15/2009
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: SKC Hi-Tech & Marketing Co., Ltd.
• Original Assignee: SKC Haas Display Films Co., Ltd. (Dow, Inc.)
• Inventors: Mi, Xiang-Dong
• Primary Examiner(s): Lavarias; Arnel C
• Application Number:
  US11/302,011
• Publication Number:
  US 20070132915A1
• Time in Patent Office: 1,463 Days
• Field of Search: None
• US Class Current: 359/485.02
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• 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

Abstract

A light redirecting article redirects light toward a target angle. The light redirecting article is made from a material having a refractive index greater than 1.6. The light redirecting article has an input surface for accepting incident illumination over a range of incident angles and an output surface with a plurality of light redirecting structures, each light redirecting structure having a near surface and an exit surface for emitting an output light at an emitted light angle, wherein the exit surface is at an oblique angle relative to the plane of the input surface. For incident illumination at either of at least two different principal angles, each principal angle being greater than 60 degrees from normal and the principal angles having a difference of 5 degrees or greater, the emitted light angle is within 5 degrees of the target angle.

Claims

1. A light redirecting article for redirecting light toward a target angle, the light redirecting article comprising a material having a refractive index greater than 1.6, said light redirecting article further comprising:

(a) an input surface for accepting incident illumination over a range of incident angles;

(b) an output surface comprising a plurality of light redirecting structures each light redirecting structure having a near surface and an exit surface for emitting an output light at an emitted light angle, wherein the exit surface is at an oblique angle relative to the plane of the input surface, whereby for incident illumination at either of at least two different principal angles, each principal angle being greater than 60 degrees from normal and said principal angles having a difference of 5 degrees or greater, the emitted light angle is within 5 degrees of the target angle.

2. The light redirecting article of claim 1 wherein the output light for both principal angles further has a transmittance of one polarization in excess of 85 percent.

3. The light redirecting article of claim 1 wherein the output light for both principal angles further has a transmittance of one polarization in excess of 90 percent

4. The light redirecting article of claim 2 wherein the output light for both principal angles has a transmittance of less than 55 percent for the orthogonal polarization.

5. The light redirecting article of claim 2 wherein the output light for both principal angles has a transmittance of less than 50 percent for the orthogonal polarization.

6. The light redirecting article of claim 1 wherein for incident illumination at each of at least three different principal angles, each principal angle being greater than 60 degrees from normal and said angles having a difference of 5 degrees or greater from each other, the emitted light angle is within 5 degrees of the target angle.

7. The light redirecting article of claim 1 wherein the target angle is normal with respect to the plane of the light redirecting article.