An optical element is provided. The optical element includes a positive-C film including a liquid crystal (“LC”) layer. The optical element also includes a positive-A film. The optical element also includes a negative biaxial retardation film disposed between the positive-A film and the positive-C film.

A compound retarder that creates independent control of R.sub.e and R.sub.th. This can be done by forming a three-layer compound retarder, including a pair of matched −A-plates, combined with single +A-plate. The +A-plate is typically an MD-stretched film, with retardation that is specific to the in-plane requirements (R.sub.e) of the application. The pair of −A-plates have their optic axes crossed, such that R.sub.e=0, with an optic axis aligned parallel to the +A-plate. A single retardation value for the −A-plate can produce improved field-of-view performance over a broad range of R.sub.e values, making it a very practical means of universal compensation. While R.sub.th is typically associated with a single retarder, retarder stacks with a diverse range of optic-axis orientations can be considered to have a compound (or composite) R.sub.th value (R.sub.th.sup.c). The three-layer compound retarder has the practical benefit of enabling field-of-view compensation across a broad range of normal-incidence polarization transformations.

This application relates to a liquid crystal display which comprises: an upper polarizer; a lower polarizer; and a liquid crystal panel provided between the upper polarizer and the lower polarizer, in which the upper polarizer and the lower polarizer are provided so that absorption axes of the upper and lower polarizers are parallel to each other, a first half wave plate, a positive C plate, and a second half wave plate are sequentially comprised between the upper polarizer and the liquid crystal panel, and the liquid crystal panel is a vertical alignment liquid crystal mode.

A display device includes a first substrate and a second substrate which face each other, a first retarder which is disposed between the first substrate and the second substrate and is a positive C plate and a second retarder which is disposed on an outer side of the second substrate and is a negative biaxial film.

A copolymer includes a fumaronitrile residue represented by following General Formula I and an aromatic vinyl monomer residue represented by following General Formula II: ##STR00001##
wherein, in General-Formula II, R.sup.1 is a hydrogen atom, a methyl-group or a phenyl-group, and R.sup.2 is a hydrogen atom or a substituted or unsubstituted aryl-group having 6 to 12 carbon atoms, and each of R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 independently represents a hydrogen atom, a halogen atom, a hydroxy-group, an alkoxy-group having 1 to 4 carbon atoms, an acyloxy-group having 2 to 5 carbon atoms, a cyanomethyl-group, or an alkyl-group having 1 to 8 carbon atoms, and at least two of R.sup.2, R.sup.3 and R.sup.4 may be bonded to form a ring, and at least two of arbitrary substituents of R.sup.3, R.sup.4, R.sup.5, R.sup.6 and R.sup.7 may be bonded to form a ring.

An optical film includes a negative C-plate, a light diffusion layer on the negative C-plate, and a polarizer on the negative C-plate where the polarizer includes a linear polarizer and a retardation plate on the linear polarizer, the light diffusion layer includes a first light-transmissive base and a plurality of first rods that have a different refractive index from that of the first light-transmissive base and are aligned at a first inclination angle within the first light-transmissive base, and the negative C-plate has an x-axis refractive index Nx, a y-axis refractive index Ny, and a z-axis refractive index Nz, where “Nx>Nz” and “Ny>Nz.”

A display comprises a polarised output spatial light modulator, switchable liquid crystal retarder, absorbing polarizer and touch panel electrodes. The switchable liquid crystal layer is stabilised by a cured reactive mesogen material during application of an applied voltage. Light scatter in privacy mode is reduced and visual security level enhanced. Visibility of disclinations during application of applied pressure, for example from a finger on a touch screen is minimised.

An improvement in image quality is achieved by compensating for a phase difference occurring in tilted light to achieve an improvement in contrast while suppressing luminance irregularity when in black display. An optical compensation device includes: a first optical compensation unit configured to generate a phase difference that has a substantially equal amount and a reverse sign in light with each incidence angle within a predetermined incidence angle range on a vertical alignment type liquid crystal panel with respect to a phase difference occurring from the liquid crystal panel; and a second optical compensation unit configured to generate a phase difference in an in-plane direction. The first optical compensation unit can appropriately compensate for a phase difference occurring in tilted light passing through a liquid crystal panel and the second optical compensation unit can suppress luminance irregularity when in black display.

A light modulating device is disclosed herein. In some embodiments, a light modulating device includes a first substrate, a second substrate, a light modulation layer, and a retardation film, wherein each of the first and second substrates has a first surface and a second surface, wherein the first and second surfaces are disposed opposite to each other, wherein the first surfaces of the first and second substrates face each other, wherein the light modulation layer is disposed between the first and second substrates, wherein the retardation film is formed on the second surface of the first substrate or the second substrate, and wherein the retardation film has an in-plane phase difference in a range of 100 nm to 300 nm for light having a wavelength of 550 nm. The light modulating device can be control omnidirectional light leakage in a black mode while having excellent optical properties and mechanical properties.

A novel copolymer suitable for an optical film which is excellent in optical characteristics and has high retardation even in a thin film state, and an optical film containing the same are provided. A copolymer excellent in optical characteristics and easy to form a composite with a different polymer, and an optical film composed of the same are also provided.