Electro-optical light modulating element, electro-optical display and modulating medium

An electro-optical light modulation element comprising

• a substrate or a plurality of substrates,
• an electrode arrangement,
• an element or a plurality of elements for polarisation of the light and
• a mesogenic modulation medium, wherein
• the light modulation element is operated at the temperature at which the modulation medium in the unaddressed state is in an optically isotropic phase and
• the mesogenic modulation medium comprises a chiral component, component (A), which consists of one or more chiral compounds, at least one of which has an HTP of 30 μm−1 or more, and
• the mesogenic modulation medium comprises an achiral component, component (B), which consists of one or more achiral compounds,
• the light modulation element is operated at the temperature at which the mesogenic modulation medium has a blue phase or
• the light modulation element is operated at the temperature at which the mesogenic modulation medium is in the isotropic phase and
• the characteristic voltage for 70% relative contrast (V70) at a temperature of 2° above the characteristic temperature (Tchar) of the modulation medium in cells is 80 V.

An electro-optical light modulation element comprising

• a substrate or a plurality of substrates,
• an electrode arrangement,
• an element or a plurality of elements for polarisation of the light and
• a mesogenic modulation medium, wherein
• the light modulation element is operated at the temperature at which the modulation medium in the unaddressed state is in an optically isotropic phase and
• the mesogenic modulation medium comprises a chiral component, component (A), which consists of two or more chiral compounds, at least one of which has an HTP of 30 μm−1 or more, and
• the mesogenic modulation medium comprises an achiral component, component (B), which consists of one or more achiral compounds,
• the light modulation elemeny is operated at the temperature at which the mesogenic modulation medium has a blue phase or
• the light modulation element is operated at the temperature at which the mesogenic modulation medium is in the isotropic phase, and
• all the chiral compounds of component (A) have the same sign of the HTP at 20° C. in the reference mixture.

An electro-optical light modulation element, wherein

• a substrate or a plurality of substrates,
• an electrode arrangement,
• an element or a plurality of elements for polarisation of the light and
• a mesogenic modulation medium, wherein
• the light modulation element is operated at the temperature at which the modulation medium in the unaddressed state is in an optically isotropic phase and
• the mesogenic modulation medium comprises a chiral component, component (A), which consists of one or more chiral compounds, at least one of which has an HTP of 30 μm−1 or more, and
• the mesogenic modulation medium comprises an achiral component, component (B), which consists of one or more achiral compounds,
• the light modulation element is operated at the temperature at which the mesogenic modulation medium has a blue phase or
• the light modulation element is operated at the temperature at which the mesogenic modulation medium is in the isotropic phase
• and either
• the dielectric susceptibility (εav.) of the modulation medium at a temperature of 4 degrees above the conversion temperature from the blue phase or from the cholesteric phase into the isotropic phase is 40 or more, or
• the optical anisotropy at a temperature of 4 degrees below the transition temperature from the cholesteric phase into the isotropic phase is 0.050 or more.

A mesogenic modulation medium which comprises

• (a) a chiral component, component (A), which consists of one or more chiral compounds at least one of which has an HTP of 30 μm−1 or more, and
• (b) optionally an achiral component, component (B), which consists of one or more achiral compounds,
• the light modulation element is operated at the temperature at which the mesogenic modulation medium has a blue phase or
• the light modulation element is operated at the temperature at which the mesogenic modulation medium is in the isotropic phase, wherein
• the relative temperature dependence (dV*70/dT) of the characteristic voltage for 70% relative contrast (V70) of the modulation medium is 30%/degree or less at a temperature of 2° above the characteristic temperature (Tchar) in the range of +/−1° around this temperature.