PRETILT EFFECT ON A VERTICALLY ALIGNED LIQUID CRYSTAL CELL FOR OPTICAL DISPLAYS

A nonzero pretilt angle is generally used in vertical aligned (VA) mode liquid crystal (LC) displays to aviod domain formation during molecular reorientation by electric field, as well as to reduce both driving voltage and response time. The pretilt effect on electro-optical properties of a VA LC cell has been investigated. Pretilt was controlled changing the angle of SiO(x) deposition on the substrate surfaces. The tilt angle distribution versus the applied voltage is obtained by Variable Angle Spectroscopic Ellipsometry and compared with the simulated curves. A good compromise between contrast and response time is reached in cells with different pretilt values on the two cell substrates.