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

## TL;DR

This paper uses simulation to study how oil viscosity affects the hysteresis effect in electrowetting displays, which impacts grayscale control and display performance.

## Contribution

The study introduces a simulation model to analyze the influence of oil viscosity on the hysteresis effect in electrowetting displays.

## Key findings

- Higher oil viscosity increases the maximum hysteresis difference in electrowetting displays.
- Oil viscosity has little effect on the maximum aperture ratio of EWDs.
- Both pixel-on and pixel-off response times increase with higher oil viscosity.

## Abstract

As the most promising new reflective display technology, electrowetting displays (EWDs) have the advantages of a simple structure, fast response, high contrast, and rich colors. However, due to the hysteresis effect, the grayscales of EWDs 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 the hysteresis effect was studied based on the proposed simulation model. Firstly, the cause of the hysteresis effect was analyzed through the hysteresis curve of an EWD. Then, based on the 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 the hysteresis effect in an EWD pixel cell was studied. We observed that the maximum hysteresis difference in the hysteresis effect increased with the increase in oil viscosity and decreased with the decrease in 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 in oil viscosity.