Brightness enhancement film having curved prism units and light scattering particles

• US 20070121227A1
• Filed: 01/17/2007
• Published: 05/31/2007
• Est. Priority Date: 07/02/2004
• Status: Abandoned Application

• Current Assignee: EFUN Technology Company Limited
• Original Assignee: EFUN Technology Company Limited
• Inventors: Tang, Shih-Chieh, Wu, Ching-Chin, Chen, Jian-Zhi, Wang, Jing-Wei
• Application Number:
  US11/653,995
• Publication Number:
  US 20070121227A1
• Time in Patent Office: Days
• US Class Current: 359/831
• 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 5/0278 used in transmission
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

A brightness enhancement film includes a substrate, a plurality of curved prism units and a plurality of light scattering particles. The curved prism units are extended in parallel and formed on a first surface of the substrate. Each of the curved prism units includes at least one meandering surface to provide with changes in curvature. Thus, the meandering surface of the curved prism unit is able to refract incident light in two dimensions with respect to the substrate that may enhance entire light-collecting efficiency in two dimensions. The light scattering particles are disposed in the curved prism units.

Claims

1. A brightness enhancement film, said brightness enhancement film being arranged to be used in a liquid crystal display, comprising:

a substrate including a first surface and a second surface substantially parallel to said first surface, and vertically transmitting light between the first surface and the second surface;

a plurality of curved prism units juxtaposed on the first surface of the substrate, each of the curved prism units having a longitudinal direction and including a ridge, a trough line, and at least one meandering surface located between said ridge and trough line, said ridge and said meandering surface extending and meandering with respect to the longitudinal direction to provide changes in curvature that are able to refract light in two dimensions, wherein directions of said ridge and said meandering surface relative to said longitudinal direction vary along a length of each of the prism units; and

a plurality of light scattering particles disposed in the curved prism units, said light scattering particles being capable of diffusing light in the curved prism units.

2. The brightness enhancement film as defined in claim 1, wherein a predetermined amount of the light scattering particles occupy in the range of weight percentage from 1 to 35 within a total material of 100 weight percentage of the curved prism units.

3. The brightness enhancement film as defined in claim 1, wherein the light scattering particles are made from plastic or glass.

4. The brightness enhancement film as defined in claim 1, wherein the light scattering particles are made from a material selected from the group consisting of SiO₂, Al₂O₃, B₂O₃, CaO, MgO, silicon resin, polyester resin, styrene resin and mixtures thereof.

5. The brightness enhancement film as defined in claim 1, wherein the light scattering particles are in a range of sizes from 0.5 μ

m to 30 μ

m.

6. The brightness enhancement film as defined in claim 1, wherein the light scattering particle is in the form of sphere, roughly shaped sphere, olive, ovum and irregular faceted particle.

7. The brightness enhancement film as defined in claim 1, wherein the curved prism unit includes a plurality of lateral ridges arranged on the meandering surface.

8. The brightness enhancement film as defined in claim 1, wherein the curved prism unit includes a first meandering surface and a second meandering surface.

9. The brightness enhancement film as defined in claim 8, wherein each of the first meandering surface and the second meandering surface includes a plurality of lateral ridges;

and wherein the lateral ridges of the first meandering surface and the lateral ridges of the second meandering surface are arranged in staggered manner in a longitudinal direction to provide changes in curvature.

10. The brightness enhancement film as defined in claim 8, wherein an included angle formed between the first meandering surface and the second meandering surface located at the ridge of the curved prism unit is in the range of 70 degrees to 160 degrees.

11. The brightness enhancement film as defined in claim 1, wherein each meandering surface of the curved prism units provides regular changes in curvature.

12. The brightness enhancement film as defined in claim 1, wherein each meandering surface of the curved prism units provides free of regular changes in curvature.

13. The brightness enhancement film as defined in claim 1, wherein each of the curved prism units has a vertical height with respect to the first surface of the substrate;

and wherein the vertical height of the curved prism unit is in the range of 10 μ

m to 100 μ

m.

14. The brightness enhancement film as defined in claim 1, wherein each of the curved prism units has a horizontal width with respect to the first surface of the substrate;

and wherein the horizontal width of the curved prism unit is in the range of 10 μ

m to 250 μ

m.

15. The brightness enhancement film as defined in claim 1, wherein the substrate is made from a flexible, transparent material.

16. The brightness enhancement film as defined in claim 15, wherein the flexible, transparent material of the substrate is selected from the group consisting of polyethylene-terephthalate (PET), polyethylene (PE), polyethylene napthalate (PEN), polycarbonate (PC), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), macromolecule and mixtures thereof.

17. The brightness enhancement film as defined in claim 1, wherein the light scattering particles enhance a degree of transmittance of incident light greater 10% to 90% than that of a particle-free brightness enhancement film within an incident angle of 10 degrees.