| 摘要 |
PROBLEM TO BE SOLVED: To obtain a medium which satisfies various properties required for an active matrix type liquid crystal display element, has a low threshold voltage, a wide nematic temperature range and low viscosity, shows excellent high speed response and has high retention at a high temperature by combining two kinds of compounds having a specific structure. SOLUTION: This liquid crystal medium is based on a mixture of polar compounds showing positive dielectric anisotropy and contains one or more of the compounds represented by formula I and one or more of the compounds represented by formula II (wherein in formula I R is a 1 to 15C alkyl group or the like; rings A and B are each trans-1,4-cyclohexylene, 1,4-phenylene or the like; Z1 and Z2 are each -COO-, -CH2O- or the like; X1 to X2 are each H or F; m and n are each 0, 1 or 2; and Y1 is -F, -CF3 or the like; and in formula II R is the same as in formula I; rings C and D are each 1,4-phenylene or the like; Z3 and Z4 are the same as in Z1 and Z2 in formula I respectively; X5 and X6 are each H or F; p is 0, 1 or 2; Y3 is F or Cl; and Q2 is a single bond, -CF2- or the like).
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