Variable focus liquid lens

A variable focus liquid lens of which focus can be adjusted by an electrical signal, comprising:

• a lens barrel having an electric conductivity, which is configured to include a first cavity to contain first and second liquids which are not mixed with each other in upper and lower portions of the first cavity, respectively;
• a fluid pressure driving unit which is configured to include a second cavity connected to the first cavity, a fluid pressure generating groove connected to the second cavity, and an actuator generating a fluid pressure on the second liquid contained in the second cavity and the fluid pressure generating groove so as to adjust the fluid pressure of the second liquid contained in the fluid pressure generating groove by using the actuator;
• a first transparent elastic membrane which is disposed on an upper portion of the lens barrel to seal an upper portion of the first cavity of the lens barrel and of which the curvature is changed according to the fluid pressure of the first and second liquids contained in the first cavity;
• and
• a conductive transparent substrate having an electric conductivity, which is disposed on a lower portion of the fluid pressure driving unit to seal a lower portion of the second cavity of the fluid pressure driving unit and which is made of a transparent material,
• wherein a focal length is adjusted by changing the curvatures of the surfaces of the first and second liquids contained in the first cavity of the lens barrel and the curvature of the first transparent elastic membrane by using a voltage applied to the lens barrel and the conductive transparent substrate and the fluid pressure of the first and second liquids.