Dual frequency addressable liquid crystals and methods of use
AssigneeTektronix, Inc.
InventorRobert L. Hubbard
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Abstract
A twisted nematic liquid crystal material used in a dual-frequency addressable liquid crystal cell is disclosed. Specific materials include an eutectic mixture of 2-5 monoester compounds having the formula R--X--Y--CO.sub.2 --Z--R', wherein R and R' is a straight alkyl having 2-7 carbon atoms and where each of X, Y and Z is a phenyl or trans-cyclohexyl and at least one of X, Y and Z is a trans-cyclohexyl. Also included are up to 25 weight percent of dopants to reduce viscosity and up to 10 weight percent of additives to lower the cross-over frequency, the additives being of the formula: ##STR1## wherein X is selected from the group consisting of: ##STR2## wherein R is a straight alkyl having 2-7 carbon atoms.
Claims13
A twisted nematic liquid crystal material suitable for use in a dual-frequency addressable liquid crystal cell, the material consisting essentially of:
- (a) a base mixture consisting of at least two different base substances selected from the group of monoester compounds having the formula:
- R--X--Y--CO.sub.2 --Z--R'
- wherein each of R and R', which may be the same the different, is an alkyl having 2-7 carbon atoms, and
- wherein each of X, Y and Z, which may be the same or different, is a member selected from the group consisting of phenyl and trans-cyclohexyl, at least one of X, Y, and Z being cyclohexyl;
- (b) up to ten weight percent of an additive component that has a strong, positive dielectric anisotropy and is suitable to lower the cross-over frequency of the base mixture;
- and
- (c) up to twenty-five weight percent of a dopant to reduce the viscosity and melting point of the base mixture.
A dual-frequency addressable liquid crystal cell including
- a spaced-apart pair of electrodes addressable by control means for applying an electrical signal thereto,
- a body of liquid crystal material disposed between the electrodes, said material consisting essentially of
- (a) a base mixture of at least two different base substances selected from the group of monoester compounds having the formula:
- R--X--Y--CO.sub.2 --Z--R'
- wherein R and R' are the same or different straight chain alkyl compounds having 2-7 carbon atoms, and
- wherein X, Y and Z are the same or different members of the group consisting of phenyl and trans-cyclohexyl, at least one of X, Y and Z being cyclohexyl,
- (b) up to ten weight percent of at least one additive having the formula ##STR32## wherein X is selected from the group consisting of ##STR33## wherein R is a straight chain alkyl having 2-7 carbon atoms;
- and (c) up to twenty-five weight percent of at least one dopant of the groups having the formulas ##STR34## and
- R--X--CO.sub.2 --Y--R'
- wherein R and R' are the same or different straight alkyl having 2-7 carbon atoms, and
- wherein X and Y, which may be the same or different, each is a member selected from the group consisting of phenyl and cyclohexyl.
Dependencies are inferred from the claim text.