Patent ID: 7636187

Claim:
An optical shutter for controlling the amount of transmission of light emitted from a display device, the optical shutter comprising: a partition wall configured to surround and isolate a light-transmitting portion through which the light is transmitted; a polar liquid having polarity, allowing transmission of light, and placed at the light-transmitting portion surrounded by the partition wall; a nonpolar liquid having no polarity, blocking transmission of light, and placed at the light-transmitting portion surrounded by the partition wall; an insulator having hydrophobic properties and disposed over the entire light-transmitting portion surrounded by the partition wall; a first electrode; and a second electrode different from the first electrode, wherein when no voltage is applied across the first electrode and the second electrode, the nonpolar liquid spreads near the insulator, becomes stable, and thus blocks transmission of the light; when a voltage is applied across the first electrode and the second electrode, the polar liquid gravitates toward the insulator because of a change in wettability of the insulator against the polar liquid and causes the nonpolar liquid to collect in a part of the light-transmitting portion according to the level of the voltage, thereby controlling the amount of transmission of the light; and the following conditions are satisfied, 100 μm 2 ≦A≦30000 μm 2 1 μm≦H≦10 μm where A denotes the area of a light-transmitting surface of the light-transmitting portion surrounded by the partition wall, the light-transmitting surface being orthogonal to a traveling direction of the light, and H denotes the height of the partition wall.