Electrofluidic chromatophore (EFC) display apparatus

1. A display apparatus comprising a circuit board having row and column electrodes arranged thereon to connect a driver to a plurality of electrofluidic chromatophore (EFC) pixel cells provided on the circuit board, wherein each pixel cell comprises:

a fluid holder for holding a polar fluid and a non-polar fluid having differing display properties;

wherein the fluid holder comprises a reservoir having an orifice with a small visible area projected in the direction of a viewer, and wherein the fluid holder further comprises a channel with a geometry having a large visible area projected in the direction of a viewer, the channel being connected to the reservoir via said orifice so as to enable free movement of the polar fluid and non-polar fluid between the channel and the reservoir, at least part of a surface of the channel comprising a wetting property and at least two pixel cell terminals connectable to the row and column electrodes on the circuit board and being configured to supply a supply voltage to at least part of the surface of the channel comprising the wetting property for supply voltage controlled movement of polar fluid; the at least two pixel cell terminals dielectrically separated from the polar fluid;

wherein the reservoir is formed in a stacked structure of homogenous film layers arranged on the circuit board, the structure at least comprising an orifice film layer and a reservoir film layer, wherein the reservoir arranged in the reservoir layer is obscured in the direction of a viewer by the orifice film layer, said orifice film layer defining a smallest orifice area that is smaller than a cross sectional area formed in the reservoir film layer; and

wherein the reservoir stack structure includes a reservoir layer forming a reservoir with a reservoir height ranging between 15-50 micrometer, and an orifice layer with a thickness ranging between 1 and 15 micrometer.

2. The display apparatus according to claim 1 , wherein the orifice film layer is formed by a laminate resin layer of a homogenous thickness that is laminated in the stacked structure.

3. The display apparatus according to claim 1 , wherein the reservoir film layer is formed by a laminate resin layer of a homogenous thickness that is laminated in the stacked structure.

4. The display apparatus according to claim 1 , wherein any of the film layers in the stack structure is formed by laminate resin film layers of a homogenous thickness.

5. The display apparatus according to claim 1 , wherein the film layers have mutually differing thicknesses, with the orifice film layer having a thickness smaller than the reservoir layer.

6. The display apparatus according to claim 1 , wherein the film layers are formed by a dry film curable resist layer forming the orifice and/or reservoir walls with zero inclination.

7. The display apparatus according to claim 1 , wherein the orifice and/or reservoir layer have a coinciding wall to form the orifice.

8. The display apparatus according to claim 1 , wherein the reservoir film layer comprises a reservoir structure with support spacers supporting the orifice layer.

9. A method of manufacturing a display apparatus comprising a circuit board having row and column electrodes arranged thereon to connect a driver to a plurality of electrofluidic chromatophore (EFC) pixel cells provided on the circuit board, the method comprises:

providing a fluid holder for holding a polar fluid and a non-polar fluid having differing display properties and at least two pixel cell terminals connectable to the row and column electrodes on the circuit board;

wherein the fluid holder is with a reservoir having an orifice with a small visible area projected in the direction of a viewer, and wherein the fluid holder is provided a channel with a geometry having a large visible area projected in the direction of a viewer, the channel being connected to the reservoir via said orifice so as to enable free movement of the polar fluid and non-polar fluid between the channel and the reservoir, at least part of a surface of the channel comprising a wetting property and at least two pixel cell terminals connectable to the row and column electrodes on the circuit board and being configured to supply a supply voltage to at least part of the surface of the channel comprising the wetting property for supply voltage controlled movement of polar fluid; the at least two pixel cell terminals dielectrically separated from the polar fluid;

wherein the reservoir is formed in a stacked structure of homogenous film layers arranged on the circuit board, the structure at least comprising an orifice film layer and a reservoir film layer, wherein the reservoir arranged in the reservoir layer is obscured in the direction of a viewer by the orifice film layer, said orifice film layer defining a smallest orifice area that is smaller than a cross sectional area formed in the reservoir film layer; and

wherein the reservoir stack structure includes a reservoir layer forming a reservoir with a reservoir height ranging between 15-50 micrometer, and an orifice layer with a thickness ranging between 1 and 15 micrometer.

10. A method according to claim 9 , wherein the orifice film layer is formed by laminating the orifice layer as a dry film resin layer of homogenous thickness on a reservoir layer in the stacked structure.