Diffuser for flat panel display

• US 7,824,747 B2
• Filed: 12/28/2007
• Issued: 11/02/2010
• Est. Priority Date: 02/28/2003
• Status: Active Grant

• Current Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Original Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Inventors: Hoeks, Theodorus Lambertus, Capaldo, Kevin P., Leslie, Scott, Cojocariu, Gheorghe, Ghosal, Anshu, Loehr, Todd M., Hoffman, Nathan D., Kumar, Karkala Arun, Hay, Grant, Schottland, Philippe, Graf, John F.
• Primary Examiner(s): TON, ANABEL
• Application Number:
  US12/003,572
• Publication Number:
  US 20080131625A1
• Time in Patent Office: 1,040 Days
• Field of Search: 362/607, 362/557, 362/600, 524/165, 524/912, 428/1.1, 428/1.51
• US Class Current: 428/1.51
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/051 Inorganic, e.g. glass or silicon oxide
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses

Abstract

A light diffusing film for a back light display is described. The light diffusing film includes a unitary film consisting essentially of polycarbonate and a uniformly dispersed anti-static material in an amount sufficient to impart anti-static properties to the film. The anti-static material may comprise a fluorinated phosphonium sulfonate. The film may additionally include at least one textured surface for the low scattering of light. Alternatively, the film may additionally include a uniformly dispersed acrylic bulk scattering additive of particles having a mean particle size of from about 3 to about 10 microns and present in an amount from about 2 to about 7 percent by weight percent for the high scattering of light.

Claims

1. A light diffusing film for a back light display comprising:

a unitary film consisting essentially of polycarbonate and a uniformly dispersed anti-static material comprising a fluorinated phosphonium sulfonate in an amount sufficient to impart anti-static properties to the film, the surface resistivity of the film being below about 10¹⁵ ohm/square.

2. A light diffusing film comprising:

a polycarbonate material; and

an ultraviolet absorber (UVA) component in an effective amount to reduce discoloration of the film when exposed to ultraviolet (UV) light, wherein the color shift of the film after 200 hours of accelerated weathering according to the ASTM D4674 method 3 is dx<

0.0005 and dy<

0.0005, where dx is the shift in the x chromaticity coordinate and dy is the shift in the y chromaticity coordinate according to CIE 1931, and wherein the color shift is measured in reflectance mode using a D65 illuminant and an observer angle of 10°

.

3. A light diffusing film comprising:

a polycarbonate material; and

an ultraviolet absorber (UVA) component in an effective amount to reduce discoloration of the film when exposed to ultraviolet (UV) light, wherein the color shift after 50,000 hours operational use in a single lamp LCD is dx<

0.0005 and dy<

0.0005, where dx is the shift in the x chromaticity coordinate and dy is the shift in the y chromaticity coordinate according to CIE 1931.

4. The light diffusing film as set forth in claim 3, wherein a color shift of a resin material of the film after five minutes at 600°

F. is dy<

0.0040, where dy is the shift in the y chromaticity coordinate according to CIE 1931.

5. The light diffusing film as set forth in claim 3, wherein a color shift of a resin material of the film after five minutes at 600°

F. is dy<

0.0020, where dy is the shift in the y chromaticity coordinate according to CIE 1931.

6. The light diffusing film as set forth in claim 3, wherein the addition of the UVA component induces a change in yellowness index (YI) in the film, Δ

YI<

1.

7. The light diffusing film as set forth in claim 3, wherein the addition of the UVA component induces a change in yellowness index (YI) in the film, Δ

YI<

0.1.