ELECTROWETTING CELL AND METHOD FOR DRIVING IT

摘要

The electrowetting cel ( 15 ) that is primarily to be used as a variable focus lens, comprises a liquid chamber ( 50 ) containing a first and a second immiscible fluid ( 51, 52 ), which are in contact across a meniscus ( 14 ) and of which the first fluid ( 51 ) is a polar and the second ( 52 ) is electrically conductive. The liquid chamber ( 50 ) is provided with an inner face ( 18 ), at which a fluid contact layer ( 10 ) is present, which has an inherent attraction to the first liquid. An electrode is separated from the liquid chamber ( 50 ) through this fluid contact layer ( 10 ). The fluid chamber ( 50 ) is constructed such that it has a small diameter at an operating point ( 101 ) at the inner face ( 18 ) than at a point of tangency ( 102 ), while a tangent (R₁) to the operating point ( 101 ) encloses a smaller angle with the optical axis (OA) of the cell ( 15 ) than a tangent (R₂) to the second point ( 102 ). This results in the fact that the meniscus ( 14 ) that touches the inner wall ( 18 ) at the second point ( 102 ) is oriented towards the optical axis and that the cell ( 15 ) can have a low construction height.