Light control using a double-stacked liquid crystal cell with enhanced viewing angle–blocking performance

In the future, there will be technological challenges between providing entertainment to passengers and eliminating driver distractions to ensure safety. Viewing angle control technologies for automotive display panels depending on each mode are required to integrate and provide both entertainment and advanced driver assistance system functions because watching videos while driving is regulated in most countries. In automotive display panels, unique electro-optical characteristics are required to control blocking or transmission only from the driver's direction while always being well observed from the passenger's direction. In this study, we developed a viewing angle control technology using double-stacked twisted nematic liquid crystal (TN-LC) films with excellent light-blocking performance only in the driver's direction over wide polar angle ranges in the privacy mode. By configuring the two TN-LC films in ordinary-ray mode and the other in the extraordinary-ray mode, the light could be completely blocked in the privacy mode, whereas it remained well transmitted in the normal mode in a specific left direction. Moreover, using double-stacked TN-LC films, light leakage at high polar angles in the privacy mode can be completely eliminated even without an optical compensation film, which is typically used to eliminate light leakage at high polar angles. Electro-optical films based on polarization optics are potential candidates for accelerating the growth of infotainment in self-driving cars.