Display device

1. A display device comprising:

picture elements having at least one first fluid and a second fluid immiscible with each other within a space between a first support plate and a second support plate,

the second fluid being electroconductive or polar,

a picture element of the device being electrically switchable between at least a first state without a voltage applied and a second, different state with a voltage applied, in which in the second state the second fluid adjoins an area of the first support plate, and

in the first state the first fluid adjoins the said area of the first support plate, and the first fluid forum a first fluid layer and the second fluid forms a second fluid layer on the first fluid layer, the first fluid layer being arranged between the second fluid layer and the first support plate,

in which said states provide a display effect over the area, and the first fluid is confined to the space of the picture element in the first state and in the second state.

2. A display device according to 1 , in which the second fluid is confined to the space of the picture element.

3. A display device according to claim 1 , in which the second fluid forms a layer common to several picture elements.

4. A display device according to claim 3 , in which picture elements have pixel walls extending over a height less than a height of the space between the first support plate and the second support plate.

5. A display device according to claim 1 , in which the first fluid adjoins only one of the support plates in the first state and in the second state.

6. A display device according to claim 1 , in which in the second state the first fluid is absent from a volume between the first support plate and the second support plate bound by the area of the first support plate.

7. A display device according to claim 1 , in which a picture element corresponds to a defined space and in the second state the second fluid substantially completely adjoins the first support plate.

8. A display device according to claim 1 , the device comprising an inhomogeneous electric field creator for creating within a picture element an inhomogeneous electric field at the surface of a part of the first support plate.

9. A display device according to claim 8 in which a dielectric layer between an electrode and a surface of the part of the first support plate varies in thickness or has a varying dielectric constant.

10. A display device according to claim 1 , in which the surface of a part of the first support plate has a varying wettability or the first fluid layer has a varying thickness.

11. A display device according to claim 1 , in which the picture element corresponds to a defined space including a further first fluid which forms in a further first state a further first fluid layer adjoining the second support plate.

12. A display device according to claim 1 in which the picture element has a wall part dividing the space into at least two sub-picture elements, in the first state the further first fluid layer adjoining the second support plate at least partly within both sub-picture elements.

13. A display device according to claim 1 in which the first fluid layer and the further first fluid layer have different colors.

14. A display device according to claim 1 in which in the second state at least one of the first fluid layer and the further first fluid layer adjoins a wall part of the space.

15. A display device according to claim 11 which comprises a preventer to prevent part of the first fluid layer and the further first fluid layer to intermix in the second state.

16. A display device according to claim 1 which comprises a driver for obtaining intermediate states.

17. A display device according to claim 1 which comprises an absorber or a reflector configured to absorb or reflect light incident on the display device.

18. A display device according to claim 1 which comprises a reflector configured to reflect light incident on the display device, wherein the reflector is diffusive.

19. A display device according to claims 1 , in which the second fluid is a scattering, a reflective or an absorbing fluid.

20. A display device according to claim 1 , in which the second fluid is a scattering fluid and wherein the scattering fluid includes TiO 2 .

21. A display device according to claim 1 , which comprises a color filter.

22. A display device according to claim 1 , wherein said first fluid is reflective.

23. A display device according to claim 22 , wherein said first fluid includes a suitable pigment.

24. A display device according to claim 1 , wherein the first fluid is scattering.

25. A display device according to claim 1 including a diffusive reflector configured to diffusively reflect light incident on the device.

26. A display device according to claim 1 wherein in the second state said first fluid forms a droplet.

27. A display device according to claim 1 wherein in the first state the first fluid is spread out in the picture element and in the second state the first fluid is contracted in the picture element.

28. A display device according to claim 1 wherein the picture element includes a hydrophobic layer and said area of the first support plate is an area of the hydrophobic layer.

29. A display device according to claim 1 wherein the first fluid adjoins the first support plate in any state of the picture element.

30. A display device according to claim 1 wherein part of the first support plate is adjoined by first fluid in the first state and in the second state.

31. A display device according to claim 1 wherein the picture element is arranged to use electrostatic forces to switch the first fluid between the first state and the second state.

32. A display device according to claim 1 wherein the first fluid is arranged to be displaced by the second fluid in the switching from the first state to the second state.

33. A display device according to claim 1 wherein in the first state the first and second fluids adjoin each other substantially over an extent of the picture element.