Display device with a brightness enhancement structure

• US 8,237,892 B1
• Filed: 11/25/2008
• Issued: 08/07/2012
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: E Ink Corporation (E Ink Holdings Incorporated)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Sprague, Robert A., Lin, Craig
• Primary Examiner(s): Peace, Rhonda
• Application Number:
  US12/323,315
• Time in Patent Office: 1,351 Days
• Field of Search: 349/95, 349/112, 349/156
• US Class Current: 349/95
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133507 Films for enhancing the luminance
• CPC Class Codes: G02F 1/133562 on the viewer side
• 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 display devices with a brightness enhancement structure comprising display cells comprising partition walls, and brightness enhancement micro-structures. The present invention is also directed to processes for the manufacture of display devices. The processes enable fabricating a display device with the micro-structures aligned with the display cells of the display device.

Claims

1. A display device comprising:

a) an electrophoretic display comprising display cells each of which is surrounded by partition walls and filled with an electrophoretic fluid; and

b) a brightness enhancement structure comprising micro-structures, wherein said micro-structures are on top of said partition walls and are separated from each other and they are not coated with a metal layer, wherein said micro-structures allow light that is reflected from the surface of the display cells and strikes the micro-structures to be deflected from the micro-structures, said light then strikes a top layer of the display device and transmits through the top layer;

wherein the width of the partition walls is substantially equal to the width of the base of the micro-structures.

2. The display device of claim 1, wherein the inner space of the micro-structures are left empty.

3. The display device of claim 1, wherein the top angle of the micro-structure is greater than 30°

.

4. The display device of claim 1, wherein the top angle of the micro-structure is greater than 40°

.

5. The display device according to claim 1, wherein said display cells are sandwiched between a first layer comprising a common electrode and a second layer comprising a center electrode and at least one in-plane electrode.

6. The color display device of claim 5, wherein the electrophoretic fluid comprises charged pigment particles dispersed in a dielectric solvent or solvent mixture.

7. The color display device of claim 6, wherein each display cell displays the color of the charged pigment particles, the color of the dielectric solvent or solvent mixture or a background color.

8. The display device of claim 1, wherein the electrophoretic fluid comprises charged pigment particles dispersed in a solvent.

9. A display device comprising:

a) an electrophoretic display comprising display cells each of which is filled with an electrophoretic fluid;

b) a brightness enhancement structure comprising micro-structures, wherein said micro-structures are separated from each other and they are not coated with a metal layer, wherein said micro-structures allow light that is reflected from the surface of the display cells and strikes the micro-structures to be deflected from the micro-structures, said light then strikes a top layer of the display device and transmits through the top layer; and

c) color filters;

wherein dead spots between the color filters are aligned with the micro-structures.

10. The display device of claim 9, wherein the micro-structures are on top of the color filters.

11. The display device of claim 9, wherein the color filters are on top of the micro-structures.

12. A process for the manufacture of a display device, which process comprises

a) forming a brightness enhancement structure comprising micro-structures;

b) coating an electrode layer on a substrate layer over the micro-structures;

c) coating a photosensitive layer over the substrate layer;

d) radiating a light onto the photosensitive layer utilizing the micro-structures as a photomask; and

e) removing the exposed areas of the photosensitive layer to form display cells.

13. The process of claim 12, further comprising filling the display cells with a display fluid and sealing the filled display cells with a polymeric sealing layer.

14. The process of claim 13, further comprising laminating a second electrode layer over the filled and sealed display cells.

15. The process of claim 12, wherein the micro-structures are formed by embossing.

16. The process of claim 12, wherein said photosensitive layer comprises a positively working photoresist.

17. The process of claim 12, wherein the display cells comprise partition walls and the micro-structures are aligned with the partition walls and sit on top of the partition walls.