Patent ID: 8087191

Claim:
A display device having at least one pixel, comprising: a colored fluid and a carrier fluid that are immiscible; an image compartment in which said colored liquid is receivable in part or entirely and the content of which is visible to an observer; a reservoir compartment in which the colored fluid is receivable in part or entirely and the content of which is visible to an observer; a connecting duct that fluidically couples said image compartment with said reservoir compartment; and at least one return duct which fluidically couples said image compartment and said reservoir compartment; wherein said connecting duct and said return duct are formed as a unitary duct, having in a cross section in a direction perpendicular to a direction of fluid flow along its entire length and along a dimension of said cross section a sharp-edged duct width transition that divides said duct cross section in a first area having a first width and a second area having a second width that it less than that first width thereby forming a capillary leap so that liquid that is contained in said return duct does not reach into said connecting duct.