Bistable Electrowetting Picture Element

Abstract

A bistable electrowetting picture element that has both stable “On” and “Off” states in which no power is consumed, and a switching voltage threshold is disclosed. Displays using such picture elements may be either passive or active matrix addressed. A picture element contains two immiscible, fluids within a space between two surfaces. One of the fluids is an electro-conductive, polar liquid, such as to water. The other fluid is a non-polar liquid such as silicone oil. The picture element is electrically switchable between two states, both of which are maintained without a voltage being applied. In one state the light absorbing, non-polar liquid adjoins a region of one of the surfaces, while in the second state it adjoins another region on the other surface. The region adjoined to in the second state differs in area from the region adjoined to in the first state, thereby providing “On” and “Off” states.

What is claimed: 
     
         1 . A bistable, electrowetting picture element, comprising:
 a first fluid and a second fluid, immiscible with each other, contained within a space between a first surface and a confronting, non-contiguous second surface;   said second fluid being electro-conductive or polar;   said picture element being electrically switchable between a first state maintainable without a voltage being applied and a second state maintainable without a voltage being applied, and in which in said first state said first fluid adjoins a first region of said first surface, while in said second state said first fluid adjoins a second region of said second surface, and wherein said first region differs in area from said second region.   
     
     
         2 . A method of modulating light, comprising:
 providing a bistable, electrowetting picture element comprising:
 a first fluid and a second fluid, immiscible with each other, contained within a space between a first surface and a confronting, non-contiguous second surface; 
 said second fluid being electro-conductive or polar; 
   electrically switching said picture element from a first state, maintainable without an applied voltage, and a second state maintainable without a voltage being applied, and in which in said first state said first fluid adjoins a first region of said first surface, while in said second state said first fluid adjoins a second region of said second surface, and wherein said first region differs in area from said second region.