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AssigneeThe Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorsLawrence Kam Ming Chan, George W. Gray, Kenneth J. Toyne, David Lacey, Rudolf Eidenschink, Michael Romer
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Novel terphenyls having a relatively high clearing point and which are suitable for use in liquid crystal materials or in the preparation of compounds for use in such material are characterized by a formula: ##STR1## wherein: R.sub.1 is selected from H, alkyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy; R.sub.2 is selected from H, alkyl, alkoxy; X.sub.1 is selected from H and fluorine; X.sub.2 is selected from H and fluorine; and ##STR2## provided that one of X.sub.1 and X.sub.2 is fluorine. Compounds wherein ##STR3## are generally useful as liquid crystal compounds.
A liquid crystal device including two dielectric substrates at least one of which is optically transparent, a layer of liquid material sandwiched between the substrates and electrodes on the inner surfaces of the substrates to enable an electric field to be applied across the layer of liquid crystal material to provide an electro-optical effect therein, characterized in that the liquid material is a mixture of compounds at least one of which is a compound having the formula:
A device as claimed in claim 2 and wherein ##STR45##
Dependencies are inferred from the claim text.