Phase Difference Film Oblique Tint Compensation

The phase difference film is divided into three distinct optically anisotropic layers (X, Y, and Z) with different optical characteristics. Layer X provides positive or negative A-plate functionality, layer Y provides C-plate functionality with twisted liquid crystal compounds, and layer Z provides additional phase difference control. This segmentation allows each layer to contribute specifically to minimizing tint changes while maintaining circular polarization function.

Each optically anisotropic layer is designed with specific local optical properties: layer X has controlled in-plane retardation (20-90 nm for positive A-plate or -20 to -90 nm for negative A-plate), layer Y has specific retardation (50-120 nm) with twisted liquid crystal compounds, and layer Z has controlled retardation (70-190 nm). The in-plane slow axes of layers X and Y are aligned parallel to each other, creating localized optical compensation that reduces tint changes at oblique viewing angles.

The patent combines multiple optical functions into a single integrated phase difference film structure. The three optically anisotropic layers (X, Y, and Z) are laminated together with specific retardation relationships to achieve both circular polarization and oblique viewing angle compensation in one component, rather than requiring separate films.

The patent controls specific optical parameters of each layer to achieve the desired effect. Layer X has in-plane retardation of 20-90 nm (positive) or -20 to -90 nm (negative), layer Y has retardation of 50-120 nm with twisted liquid crystal compounds, and layer Z has retardation of 70-190 nm. By precisely controlling these parameter ranges and the parallel alignment of slow axes between layers X and Y, the structure minimizes tint changes without excessive complexity.