The invention relates to bimesogenic compounds of formula I

##STR00001##

to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

A liquid crystal composition includes a component A composed of one or more liquid crystals with negative dielectric anisotropy and a component B composed of one or more compounds selected from a general formula I, where the optical anisotropy of the liquid crystal composition is larger than 0.14. The elastic coefficient of a liquid crystal system is adjusted by introducing a bi-mesogenic compound into a negative liquid crystal or a negative liquid crystal mixture. When the liquid crystal composition is used for the dimming device, the minimum light transmittance of the dimming device in the dark state can be significantly reduced, the adjustment range of the light transmittance in the light state and the dark state can be expanded, and the haze in the dark state can be increased, thereby broadening the use range.

##STR00001##

A liquid crystal composition includes a component A composed of one or more liquid crystals with negative dielectric anisotropy and a component B composed of one or more compounds selected from a general formula I, where the optical anisotropy of the liquid crystal composition is larger than 0.14. The elastic coefficient of a liquid crystal system is adjusted by introducing a bi-mesogenic compound into a negative liquid crystal or a negative liquid crystal mixture. When the liquid crystal composition is used for the dimming device, the minimum light transmittance of the dimming device in the dark state can be significantly reduced, the adjustment range of the light transmittance in the light state and the dark state can be expanded, and the haze in the dark state can be increased, thereby broadening the use range.

##STR00001##

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12 and CG.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12, X.sup.11, X.sup.12 and Sp.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

The invention relates to bimesogenic compounds of formula I

##STR00001##

wherein R.sup.11, R.sup.12, MG.sup.11, MG.sup.12, X.sup.11, X.sup.12 and Sp.sup.1 have the meaning given in claim 1, to the use of bimesogenic compounds of formula I in liquid crystal media and particular to flexoelectric liquid crystal devices comprising a liquid crystal medium according to the present invention.

A liquid crystal (LC) mixture for a pitch variable optical element is provided. The LC mixture includes a host LC and one or more LC dimers dissolved as a guest in the host LC. The host LC and the one or more LC dimers have respective dielectric anisotropies of opposite signs in nematic phase. A net dielectric anisotropy of the LC mixture is substantially neutral.

A liquid crystal (LC) mixture for a pitch variable optical element is provided. The LC mixture includes a host LC and one or more LC dimers dissolved as a guest in the host LC. The host LC and the one or more LC dimers have respective dielectric anisotropies of opposite signs in nematic phase. A net dielectric anisotropy of the LC mixture is substantially neutral.

Provided is a liquid crystal composition satisfying at least one or having suitable balance regarding at least two of characteristics such as high maximum or low minimum temperature of a nematic phase, large optical anisotropy, large positive dielectric anisotropy and high stability to ultraviolet light, and a liquid crystal display device including such a composition, particularly an encapsulated liquid crystal display device, and a liquid crystal display device serving as a constituent of 3D lenses. The liquid crystal composition contains a specific compound having large optical anisotropy as a first component, and a specific compound having large optical anisotropy and large positive dielectric anisotropy as a second component; a specific compound having large positive dielectric anisotropy as a third component; and a specific compound having large optical anisotropy and further having high maximum or low minimum temperature as a fourth component, and the liquid crystal display device includes the composition.

Provided is a liquid crystal composition satisfying at least one or having suitable balance regarding at least two of characteristics such as high maximum or low minimum temperature of a nematic phase, large optical anisotropy, large positive dielectric anisotropy and high stability to ultraviolet light, and a liquid crystal display device including such a composition, particularly an encapsulated liquid crystal display device, and a liquid crystal display device serving as a constituent of 3D lenses. The liquid crystal composition contains a specific compound having large optical anisotropy as a first component, and a specific compound having large optical anisotropy and large positive dielectric anisotropy as a second component; a specific compound having large positive dielectric anisotropy as a third component; and a specific compound having large optical anisotropy and further having high maximum or low minimum temperature as a fourth component, and the liquid crystal display device includes the composition.