Patent ID: 8501038

Claim:
A liquid crystal compound represented by formula (a): wherein R a and R b are independently hydrogen, alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons; the ring A 1 and the ring A 2 are independently 1,4-phenylene, trans-1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and the ring A 1 and the ring A 2 are not simultaneously 1,4-phenylene; L 1 , L 2 , L 3 and L 4 are independently hydrogen or fluorine, and at least three of them are fluorine; and Z 1 and Z 2 are independently a single bond, —CH 2 CH 2 —, —CH═CH—, —C≡C—, —CH 2 O—, —OCH 2 —, —COO— or —OCO—.