Optical film stack for display devices

Patent metadata

Field	Value
Publication number	US-2016282541-A1
Application number	US-201514668893-A
Country	US
Kind code	A1
Filing date	Mar 25, 2015
Priority date	Mar 25, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

This disclosure provides systems, methods and apparatus for providing stacks of optical films that may be used to provide increased on-axis display brightness. In one aspect, an apparatus or system may be provided that includes a light source, a first optical film having triangular cross-section, prismatic light-turning structures, and a second optical film having trapezoidal cross-section, prismatic light-turning structures. The first optical film may be interposed between the light source and the second optical film. In further aspects, a third optical film, similar to the first optical film, may be interposed between the light source and the first optical film. In yet further aspects, one or more additional optical films, similar to the second optical film, may be positioned in the stack such that the second optical film is between the first optical film and the additional optical film(s).

First claim

What is claimed is:

1 . An apparatus comprising:
a first optical film having a first surface and a second surface located opposite the first surface of the first optical film; and a second optical film having a first surface facing the first optical film and a second surface located opposite the first surface of the second optical film, wherein:
the second surface of the first optical film is defined by a plurality of prismatic light-turning structures,
each prismatic light-turning structure that is included in the plurality of prismatic light-turning structures that defines the second surface of the first optical film has a substantially triangular cross-section,
the second optical film includes a plurality of prismatic light-turning structures,
each prismatic light-turning structure of the plurality of prismatic light-turning structures included in the second optical film has a trapezoidal cross-section,
each trapezoidal cross-section widens with increasing distance from the first optical film, and
the first optical film and the second optical film are positioned in a stacked arrangement with the second surface of the first optical film facing towards the first surface of the second optical film.

2 . The apparatus of claim 1 , further comprising a light source, wherein the first optical film is interposed between the light source and the second optical film.

3 . The apparatus of claim 1 , further comprising:
a display pixel layer having a plurality of display elements, wherein the second optical film is interposed between the first optical film and the display pixel layer.

4 . The apparatus of claim 3 , wherein the display pixel layer includes
an aperture plate having a plurality of apertures, wherein:
each display element includes a shutter,
each shutter is associated with one or more of the apertures, and
each shutter is configured to be transitioned between a first position in which the shutter occludes the one or more of the associated apertures and a second position in which the shutter permits light to pass through the one or more associated apertures.

5 . The apparatus of claim 3 , wherein the display pixel layer is a liquid crystal display layer.

6 . The apparatus of claim 1 , wherein the prismatic light-turning structures in the plurality of prismatic light-turning structures that defines the second surface of the first optical film have a continuous sawtooth profile when viewed along a direction parallel to the prismatic light-turning structures of the first optical film.

7 . The apparatus of claim 6 , wherein the sawtooth profile is defined by alternating peaks and valleys, each of which forms an angle between 88° and 92° degrees.

8 . The apparatus of claim 6 , wherein the first surface of the first optical film is flat.

9 . The apparatus of claim 1 , further comprising a third optical film having a first surface and a second surface located on a side of the third optical film opposite the first surface of the third optical film, wherein:
the second surface of the third optical film is defined by a plurality of prismatic light-turning structures, each prismatic light-turning structure that is included in the plurality of prismatic light-turning structures that defines the second surface of the third optical film has a substantially triangular cross-section, the third optical film is positioned in the stacked arrangement with the second surface of the third optical film facing towards the first surface of the first optical film, and the third optical film is oriented such that the prismatic light-turning structures in the plurality of prismatic light-turning structures that defines the second surface of the third optical film are oriented along a first direction substantially perpendicular to a second direction along which the prismatic light-turning structures in the plurality of prismatic light-turning structures that defines the second surface of the first optical film are oriented.

10 . The apparatus of claim 9 , wherein:
the prismatic light-turning structures in the plurality of prismatic light-turning structures that defines the second surface of the first optical film have a continuous sawtooth profile when viewed along a direction parallel to the prismatic light-turning structures of the first optical film, and the prismatic light-turning structures in the plurality of prismatic light-turning structures that defines the second surface of the third optical film have a continuous sawtooth profile when viewed along a direction parallel to the prismatic light-turning structures of the second optical film.

11 . The apparatus of claim 1 , further comprising one or more additional optical films, wherein:
the second optical film is interposed between the first optical film and the one or more additional optical films, each additional optical film includes a plurality of prismatic light-turning structures, and each prismatic light-turning structure of the plurality of prismatic light-turning structures included in each of the one or more additional optical films has a trapezoidal cross-section.

12 . The apparatus of claim 1 , wherein:
each prismatic light-turning structure of the plurality of prismatic light-turning structures included in the second optical film includes a first sloped wall portion, a second sloped wall portion, and a base portion that is substantially in-plane with the second optical film and spans between the first sloped wall portion and the second sloped wall portion.

13 . The apparatus of claim 12 , wherein the second optical film includes interstitial portions that are located between each pair of adjacent base portions and are substantially in-plane with the first surface of the second optical film, wherein each interstitial portion includes reflective material facing towards the first optical film.

14 . The apparatus of claim 12 , wherein:
the first sloped wall portion and the second sloped wall portion of each prismatic light-turning structure of the plurality of prismatic light-turning structures included in the second optical film form an angle between them selected from the group consisting of: an angle greater than or equal to 5° and less than or equal to 45°, an angle eater than or equal to 5° and less than or equal to 15°, and an angle of approximately 10°.

15 . The apparatus of claim 12 , wherein:
the second optical film includes interstitial portions that are located between each pair of adjacent base portions, and the interstitial portions and the base portions are substantially equal in width.

16 . The apparatus of claim 12 , wherein, for each pair of adjacent prismatic light-turning structures in the plurality of trapezoidal light-turning structures included in the second optical film, the first sloped wall portion of one of the prismatic light-turning structures in the pair of adjacent prismatic light-turning structures in the plurality of prismatic light-turning structures included in the second optical film and the second sloped wall portion of the other of the prismatic light-turning structures in the pair of adjacent light-turning structures in the plurality of prismatic light-turning structures included in the second optical film are provided by opposing walls of a V-shaped groove in the first surface of the second optical film.

17 . The apparatus of claim 16 , wherein the V-shaped grooves are coated or filled with a material selected from the group consisting of: a reflective material and a material having a lower index of refraction as compared with the m

Assignees

• Pixtronix Inc

Inventors

• Shi Jianru
• Yao Yuhong
• Lu Lu
• Gandhi Jignesh
• Mi Xiang-Dong
• Eakin James
• Myers Robert
• Mohammad Waseem
• Sampsell Matthew Brian

Classifications

• G02B6/0036

  2-D arrangement of prisms, protrusions, indentations or roughened surfaces · CPC title

• G02B6/0055

  Reflecting element, sheet or layer · CPC title

• G02B6/0053 Primary

  Prismatic sheet or layer; Brightness enhancement element, sheet or layer · CPC title

• G02B26/02

  for controlling the intensity of light {(G02B26/004 takes precedence)} · CPC title

• G02B5/045

  Prism arrays · CPC title