Patent ID: 7126654
Filing Date: 2006-10-24
Classification: G02B,G02F,H04N

Abstract:
1. A liquid crystal switchable color filter for switching between a first, a second and a third color band, with a light path including a light input side and a light output side, the color filter comprising: a first switchable liquid crystal cell capable of at least two switching states; a first retarder layer which acts for the first color band as a quarter-wave plate; a first cholesteric filter including a selective reflection band for the first color band; a second cholesteric filter including a selective reflection band for the second color band; a second retarder layer which acts for the second color band as a quarter-wave plate; a second switchable liquid crystal cell capable of at least two switching states; a third retarder layer which acts for the second color band as a quarter-wave plate; a third cholesteric filter including a selective reflection band for the second color band; a fourth cholesteric filter including a selective reflection band for the third color band; a fourth retarder layer which acts for the third color band as a quarter-wave plate; a third switchable liquid crystal cell capable of at least two switching states; and a polarization blocking element; wherein the handedness of the second cholesteric filter is equal to the handedness of the third cholesteric filter and opposite to the handedness of the first and fourth cholesteric filter; and wherein, for the blocking state of the respective color band the optic axis of the corresponding switchable liquid crystal cell is either substantially parallel or substantially perpendicular to the light polarization direction.