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The traditional driving waveform of the electrowetting display (EWD) has many disadvantages, such as the large oscillation of the target grayscale aperture ratio and a long time for achieving grayscale. Therefore, a driving waveform based on the exponential function was proposed in this study. First, the maximum driving voltage value of 30 V was obtained by testing the hysteresis curve of the EWD pixel unit. Secondly, the influence of the time constant on the driving waveform was analyzed, and the optimal time constant of the exponential function was designed by testing the performance of the aperture ratio. Lastly, an EWD panel was used to test the driving effect of the exponential-function-driving waveform. The experimental results showed that a stable grayscale and a short driving time could be realized when the appropriate time constant value was designed for driving EWDs. The aperture ratio oscillation range of the gray scale could be reduced within 0.95%, and the driving time of a stable grayscale was reduced by 30% compared with the traditional driving waveform.

In the Internet of Things environment, the secure transmission of digital images has attracted much attention. To improve the confidentiality, we propose an image cryptosystem adopting a quantum chaotic map and the certain security-enhanced mechanisms. Firstly, we use the good random characteristics of quantum chaotic sequences to enhance security performance. Then, we introduce a plaintext correlation mechanism and a diffusion-permutation-diffusion structure in the cryptosystem. Finally, we verify the cryptosystem on a common secure communication platform. The theoretical and statistical analysis results demonstrate that the cryptosystem has excellent performance and can resist various cryptographic attacks. Moreover, feasibility and effectiveness of the image cryptosystem are verified on the Internet of Things secure communication experimental platform. It proves that the proposed image cryptosystem is a preferred and promising secure communication technology solution. INDEX TERMSSecure communication; image encryption; Internet of Things; quantum chaos I. INTRODUCTION

Electrowetting display (EWD) performance is severely affected by ink distribution and charge trapping in pixel cells. Therefore, a multi structural driving waveform is proposed for improving the aperture ratio of EWDs. In this paper, the hysteresis characteristic (capacitance–voltage, C-V) curve of the EWD pixel is tested and analyzed for obtaining the driving voltage value at the inflection point of the driving waveform. In the composition of driving waveform, a voltage slope is designed for preventing ink dispersion and a reverse pulse is designed for releasing the trapped charge which is caused by hysteresis characteristic. Finally, the frequency and the duty cycle of the driving waveform are optimized for the max aperture ratio by a series of testing. The experimental results show that the proposed driving waveform can improve the ink dispersion behavior, and the aperture ratio of the EWD is about 8% higher than the conventional driving waveform. At the same time, the response speed of the driving waveform can satisfy the dynamic display in EWDs, which provides a new idea for the design of the EWD driving scheme.