Liquid crystal viewing angle controller for unidirectional privacy protection

We propose a viewing angle controller (VAC) for automotive central information display (CID) and co-driver display (CDD). This VAC, when integrated with CID and CDD, provides essential information to both the driver and co-driver while minimising light leakage to the windscreen. It consists of two twisted nematic (TN) liquid crystal (LC) cells and two + C optical compensation films. Under an appropriate voltage, it exhibits low transmittance when the upward viewing angle exceeds 40° (in simulation) and 35° (in experiment), effectively suppressing reflections on the windscreen and thus reducing driving risk. Compared with the latest double-stacked TN-LC film, the proposed VAC maintains higher light transmittance in the normal direction and a lower transmittance in privacy direction, making it suitable for various in-vehicle displays. These results demonstrate that this VAC can be widely applied in automotive displays to enhance driving safety.