Influence of Oil Viscosity on Hysteresis Effect in Electrowetting Displays Based on Simulation

As the most potential new reflective display technology, electrowetting display (EWD) has the advantages of simple structure, fast response, high contrast and rich colors. However, due to the hysteresis effect, gray-scales of EWD cannot be accurately controlled, which seriously restricts the industrialization process of this technology. In this paper, the oil movement process in an EWD pixel cell was simulated, and the influence of oil viscosity on hysteresis effect was studied based on the proposed simulation model. Firstly, the cause of hysteresis effect was analyzed through hysteresis curve of EWD. Then, based on COMSOL Multiphysics simulation environment, the oil movement process in an EWD pixel cell was simulated by coupling the phase field of laminar two-phase flow and electrostatic field. Finally, based on the simulation model, the influence of oil viscosity on hysteresis effect in an EWD pixel cell was studied. The experimental results showed that the maximum hysteresis difference of hysteresis effect increased with the increase of oil viscosity, and decreased with the decrease of oil viscosity. The oil viscosity had little effect on the maximum aperture ratio of EWD. The pixel on response time and pixel off response time increased with the increase of oil viscosity.