Color Liquid Crystal Display and Compensation Panel

A method of producing an optically anisotropic compensation panel based on an ordered guest-host system and having spectral dependencies of principal refractive indices nx(λ), ny(λ) and nz(λ), wherein at least one of them possesses an anomalous spectral dispersion in at least one subrange of the visible spectral range and which includes the following steps:

• a) assignment of spectral dependencies of principal refractive indices nx(λ), ny(λ) and nz(λ), so that at least one difference of the principal refractive indices Δv(λ) defining the optical anisotropy satisfies the condition ∂Δv(λ)/∂λ≧0 in the visible spectral range, wherein subscript v is selected from the list comprising in and out;
• b) numerical designation and variation of principal absorption coefficient spectra kx,cal(λ) ky,cal(λ), and kz,cal(λ) until the spectral dependencies nx(λ)=KK(kx(λ)), ny(λ)=KK(ky(λ)) and nz(λ)=KK(kz(λ)) evaluated according to Kramers-Kronig relation satisfy the spectral dependencies for the refractive indices as specified in step (a);
• c) selection of at least one organic compound substantially transparent to electromagnetic radiation in the visible spectral range which serves as a host component capable of forming an optically anisotropic host matrix with normal spectral dispersion in the visible range that is characterized by the absorption coefficients kx,h(λ), ky,h(λ) and kz,h(λ) in the UV spectral range;
• d) selection of at least one type of guest particles which are capable of absorbing electromagnetic radiation in at least one subrange of the wavelength range from 250 to 2500 nm, to fit into the host matrix as a guest component, and which are characterized by the absorption coefficients kx,g(λ), ky,g(λ) and kz,g(λ);
• e) optimization of the guest-components quantity which minimizes inconsistence between the calculated absorption spectra kx, cal(λ) ky, cal(λ) and kz, cal(λ) according to step b) and appropriate functions kx,h(λ)+kx,g(λ), ky,h(λ)+ky,g(λ), and kz,h(λ)+kz,g(λ) in the wavelength range from 250 to 2500 nm;
• f) formation of a coating solution according to previous steps, wherein at least one organic compound transparent to electromagnetic radiation in the visible spectral range and at least one type of guest particles capable of absorbing electromagnetic radiation in at least one subrange of the wavelength range from 250 to 2500 nm are used;
• g) application of the coating solution onto a substrate to form a liquid layer;
• h) application of an external alignment action upon the liquid layer,
• i) drying with formation of a solid guest-host layer, and
• j) measurements of experimental spectra kx,(λ), ky,(λ), and kz,(λ) for the solid guest-host layer and repeating steps c) to i) until an inconsistence between the measured and calculated absorption spectra kx, cal(λ), ky, cal(λ), and kz, cal(λ) is minimal.

A color liquid crystal display comprising

• a liquid crystal cell,
• first and second polarizers arranged on each side of the liquid crystal cell, and
• at least one compensation panel located between said polarizers,
• wherein the compensation panel comprises at least one optically anisotropic layer based on an ordered guest-host system,
• wherein the guest-host system comprising
• an anisotropic host matrix comprising an organic compound transparent to electromagnetic radiation in the visible spectral range, and
• a guest component comprising guest particles,
• wherein the guest particles provide an absorption additional to an absorption of the anisotropic host matrix, and
• wherein said additional absorption is realized in at least one principal direction of the anisotropic host matrix in at least one subrange of the wavelength range from approximately 250 to 2500 nm.