Liq. crystal cell with electrically-selected colour change - uses two liq. crystal layers in series one of which includes cholesteric substance

摘要

The liq. crystal display cell has two liq. crystal layers (4,8) each sandwiched between a pair of electrode plates (2,6) and having a polarisation layer (1) on the outside. One of the electrode plates (6), all of which are transparent, has electrodes (5,7) on both sides cooperating respectively with the two liquid crystal layers (4,8). One of the liq. crystal layers (8) incorporates a cholesteric substance for obtaining a definite screw structure, the other liq. crystal layer (4) pref. having a twist structure. The display cell allows a colour variation to be obtained by controlling the second cell to provide a rotation of the polarised light through 90 degs. or to cancel the rotation of the polarisation plane.