Method for making electrowetting display device

1. A method of making an electrowetting display device having a plurality of picture elements, each picture element being defined by walls surrounding a display region, the plurality of picture elements covering a first area of a support plate, the method comprising:

applying a hydrophobic layer covering at least the first area;

lowering a hydrophobicity of the hydrophobic layer over a second area substantially outside the display regions; and

forming the walls on the hydrophobic layer over the first area.

2. A method according to claim 1 , wherein the second area is outside the first area.

3. A method according to claim 1 , wherein the second area is partly outside the first area and partly within the first area.

4. A method according to claim 1 , wherein the second area is within the first area.

5. A method according to claim 1 , wherein the second area forms an initiation area in the display region.

6. A method according to claim 1 , wherein lowering the hydrophobicity includes one of more of: reactive ion etching, plasma treatment, UV ozone treatment, and chemical treatment.

7. A method according to claim 6 , wherein the second area is at least partly within the first area and has substantially an extent of the walls, and part of the first area outside the second area is covered by a patterned layer preventing lowering of the hydrophobicity of the hydrophobic layer.

8. A method according to claim 7 , wherein the patterned layer is made using a photo-lithographic process.

9. A method according to claim 1 , including depositing an adhesion promoter to enhance an adhesion of a wall material to the hydrophobic layer.

10. A method according to claim 1 , wherein the walls are formed by depositing a wall layer on the hydrophobic layer.

11. A method according to claim 10 , wherein the wall layer is patterned by depositing wall layer material through a mask or by a photo-lithographic process on the hydrophobic layer.

12. A method according to claim 1 , wherein the second area encloses the display regions and forming the walls on the second area includes a wet process of a wall material where the wall material spontaneously positions itself on the second area after application.

13. An electrowetting display device having a plurality of picture elements, each picture element being defined by walls surrounding a display region, the electrowetting display device including a support plate covered by a hydrophobic layer having a hydrophobicity, the walls being part of a patterned wall layer arranged on the hydrophobic layer, where the hydrophobicity in an area of the hydrophobic layer adjoining the wall layer varies between a high and a low value.

14. An electrowetting display device according to claim 13 , wherein the plurality of picture elements covers a first area of the support plate, and the hydrophobicity of the hydrophobic layer has a low value in a second area of the support plate outside the first area.

15. An electrowetting display device having a plurality of picture elements, each picture element being defined by walls surrounding a display region, the electrowetting display device including a support plate covered by a hydrophobic layer having a hydrophobicity, the walls being part of a patterned wall layer arranged on the hydrophobic layer, wherein the display region includes an initiation area, the hydrophobicity having a high value in an area of the display region outside the initiation area and a low value in the initiation area and in an area between the display regions.

16. A method of making an electrowetting display device having a plurality of picture elements, each picture element being defined by walls surrounding a display region, the plurality of picture elements covering a first area of a support plate, the method comprising:

applying a hydrophobic layer covering at least the first area;

lowering a hydrophobicity of the hydrophobic layer over a second area substantially outside the display regions without lowering the hydrophobicity of the hydrophobic layer in at least part of the display regions; and

forming the walls at least partly on the second area.

17. A method according to claim 16 , wherein the second area is outside the first area.

18. A method according to claim 16 , wherein the second area is partly outside the first area and partly within the first area.

19. A method according to claim 16 , wherein the second area is within the first area.

20. A method according to claim 16 , wherein the second area forms an initiation area in the display region.

21. A method according to claim 16 , wherein lowering the hydrophobicity includes one or more of: reactive ion etching, plasma treatment, UV ozone treatment, and chemical treatment.

22. A method according to claim 21 , wherein the second area is at least partly within the first area and has substantially an extent of the walls, and part of the first area outside the second area is covered by a patterned layer preventing lowering of the hydrophobicity of the hydrophobic layer.

23. A method according to claim 22 , wherein the patterned layer is made using a photo-lithographic process.

24. A method according to claim 16 , including depositing an adhesion promoter to enhance an adhesion of a wall material to the hydrophobic layer.

25. A method according to claim 16 , wherein the walls are formed by depositing a wall layer on the hydrophobic layer.

26. A method according to claim 25 , wherein the wall layer is patterned by one or more of: depositing wall layer material through a mask, and by a photo-lithographic process on the hydrophobic layer.

27. A method according to claim 16 , wherein the second area encloses the display regions and forming the walls on the second area includes a wet process of a wall material where the wall material spontaneously positions itself on the second area after application.