Thin two-dimensional local dimming backlight

A method of operating a backlight assembly for active dimming control comprising the steps of:

• providing a backlight assembly including a light source;
• a light guide optically coupled to the light source that receives light from the light source;
• a substrate including an electrode layer and a hydrophobic surface located on the electrode layer, wherein the hydrophobic surface of the substrate is spaced apart from a surface of the light guide to define a cell gap;
• and an array of conductive liquid beads located within the cell gap;
• wherein liquid beads that are subject to an actuation voltage applied to the electrode layer are in an actuated state, and liquid beads that are not subject to an actuation voltage applied to the electrode layer are in a non-actuated state;
• and
• wherein when the liquid beads are in the non-actuated state, the liquid beads are in contact with the surface of the light guide for extracting light from the light guide, and when the liquid beads are in the actuated state, the liquid beads deform such that contact of the liquid beads with the surface of the light guide is reduced relative to the non-actuated state to reduce extraction of light from the lightguide, thereby dimming the backlight assembly;
• the method further comprising sequentially operating the backlight assembly to illuminate the array of liquid beads in sequence by:
• time-sequentially switching on the light source to apply respective data for each sequence;
• and
• time-sequentially retaining an extracting zone within the array of liquid beads by maintaining the extracting zone in a non-actuated state for light extraction corresponding to the data, while generating a non-extracting zone that does not extract light by actuating liquid beads in the non-extracting zone;
• wherein the backlight assembly is sequentially operated in a time of one frame during which the array of liquid beads is illuminated.