| 摘要 |
The liquid crystal display device with electrical control comprises a layer of liquid crystal of twisted nematic type positioned between two polarizers (2,5), and uniaxial compensation means with negative birefringence associated with the layer inside optical cavity formed by the polarizers. The compensation means are in the form of a layer of discotic liquid crystal (11), which is with a homogeneous molecular pre-inclination. The liquid crystal layer contained between two transparent support plates (3,4), in the absence of control electric field, has molecular orientations helical as in a cylindrical zone (7), which are adjusted so to rotate by 90 deg. angle the linear polarization of light wave propagating in the normal direction (Z) with respect to the main faces of device; the application of control electric field modifies the molecular orientations as in a cylindrical zone (8). The polarizers (2,5), that is a polarizer-analyser pair, are of crossed type, so that the crossed polarizations are aligned with the linear polarization of light wave at the level of main faces. The optical axis of compensator (11) has an inclination with respect to the normal direction (Z), and the inclination angle is to eliminate a displacement of angular distribution of contrast ratio (CR) with respect to the vertical(Theta=0). The inclination angle is in the range from 0 to 15 deg. A system for image projection onto a screen comprising an objective, also comprises a display device according to the invention with the main faces perpendicular and centred with respect to the optical axis of objective. |
