Abstract A visual display device is featured which uses a new thermal addressing technique to provide a dark image upon a lighter background. The display is capable of being multiplexed to a large number of rows. The device comprises a cholesteric-smectic liquid crystal material mixed with a pleochroic dye of high order parameter. When the material experiences a transition from a higher to a lower, smectic thermal phase, two different textures or light states are developed; a transparent state and a light absorbing state. The transparent state is developed by applying a sensitizing voltage to certain portions of the medium. The pleochroic dye absorbs the light passing through the unsensitized portions of medium to provide the dark image. The row electrodes are made diffusely reflective so as to provide a double light pass through the medium to improve contrast.
A liquid crystal composition which can be thermally addressed and which can provide a dark image upon a lighter background, comprising a mixture comprising approximately from 40 to 60 weight percent of "x" and approximately from 30 to 50 weight percent of "y", and approximately 5 to 10 weight percent of "z" wherein x, y, and z are represented by the formulas; ##STR13## at least one pleochroic dye of high order parameter approximately from 0.5 to 3 weight percent based upon the total composition mixture.
Claim 2
Dependent Claim
85 words
A liquid crystal composition which can be thermally addressed and which can provide a dark image upon a lighter background, comprising a mixture comprising approximately from 40 to 60 weight percent of "x" and approximately from 30 to 50 weight percent of "y", and approximately 5 to 10 weight percent of "z" wherein x, y, and z are represented by the formulas; ##STR13## at least one pleochroic dye of high order parameter approximately from 0.5 to 3 weight percent based upon the total composition mixture.
Claim 3
Dependent Claim
13 words
The liquid crystal composition of claim 1, wherein said pleochroic dye comprises: ##STR14##
Claim 4
Dependent Claim
25 words
The liquid crystal composition of claim 1, comprising approximately 50.5 percent weight of x, 41.4 percent weight of y, and 8.1 percent weight of z.
Claim 5
Dependent Claim
13 words
The liquid crystal composition of claim 3 wherein said pleochroic dye comprises: ##STR15##
Claim 6
Dependent Claim
20 words
The liquid crystal composition of claim 4, wherein said dye is approximately 1 weight percent of the total composition mixture.