Luminance enhancement structure for reflective display devices

• US 8,120,836 B2
• Filed: 03/08/2010
• Issued: 02/21/2012
• Est. Priority Date: 03/09/2009
• Status: Active Grant

• Current Assignee: E Ink Holdings Incorporated
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Lin, Craig, Sprague, Robert A.
• Primary Examiner(s): PINKNEY, DAWAYNE
• Application Number:
  US12/719,702
• Publication Number:
  US 20100225999A1
• Time in Patent Office: 715 Days
• Field of Search: 359/296, 359/245, 359253-254, 359/265, 359290-291, 349/33, 345/107, 430 31- 32
• US Class Current: 359/296
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1677 Structural association of cells with optical devices, e.g. reflectors or illuminating devices

Abstract

The present invention is directed to luminance enhancement structures for reflective display devices. The structure comprises columns and grooves, wherein each of said grooves has a cross-section comprising an apex angle and two edge lines. The structure increases the overall reflectance by reducing the total internal reflection, and as a result, the brightness of a display device is increased.

Claims

1. A display device assembly comprising

a) a display panel which comprises an array of display cells filled with a display fluid;

and

b) a one-dimensional luminance enhancement structure comprising columns and grooves, wherein each of said grooves has a cross-section comprising an apex angle in the range of about 5-50° and

two edge lines, and said columns and grooves are in an alternating order and in a continuous form in one direction,

wherein the luminance enhancement structure is on the viewing side of the display device to allow incoming light from a light source to transmit through the luminance enhancement structure and strike the display panel and then to be reflected from the luminance enhancement structure.

2. The assembly of claim 1, wherein said two edge lines are straight lines and the apex angles of the grooves are not the same throughout the structure.

3. The assembly of claim 2, wherein the two edge lines of the cross-section are substantially equal for all grooves.

4. The assembly of claim 2, wherein the two edge lines are substantially equal for some of the grooves and the two edge lines are not equal for the remaining grooves.

5. The assembly of claim 2, wherein the two edge lines are not equal for all grooves.

6. The assembly of claim 2, wherein the heights of the grooves are substantially equal throughout the structure.

7. The assembly of claim 2, wherein the heights of the grooves vary.

8. The assembly of claim 2, wherein the pitches of the grooves are substantially equal for all grooves throughout the structure.

9. The assembly of claim 2, wherein the pitches of the grooves vary.

10. The assembly of claim 1, wherein each of the two edge lines comprise two or more segments of straight line and the different segments of the straight line have different edge line angles.

11. The assembly of claim 10, wherein the apex angles of the grooves are substantially equal for all grooves throughout the structure.

12. The assembly of claim 10, wherein the edge lines appear curved.

13. The assembly of claim 10, wherein the curved edge lines have more than one curvature.

14. The assembly of claim 1, wherein the two edge lines of a single groove have different numbers of segments of the straight line.

15. The assembly of claim 1, wherein said apex angle is in the range of about 20°

to about 40°

.

16. The assembly of claim 1, wherein the surface of the grooves is not coated.