Toward Suppressing Charge Trapping Based on a Combined Driving Waveform with an AC Reset Signal for Electro-Fluidic Displays

Abstract

Digital microfluidic technology based on the principle of electrowetting is developing rapidly. As an extension of this technology, electro-fluidic displays (EFDs) have gradually become a novel type of display devices, whose grayscales can be displayed by controlling oil film in pixels with a microelectromechanical system (MEMS). Nevertheless, charge trapping can occur during EFDs’ driving process, which will produce the leakage current and seriously affect the performance of EFDs. Thus, an efficient driving waveform was proposed to resolve these defects in EFDs. It consisted of a driving stage and a stabilizing stage. Firstly, the response time of oil film was shortened by applying an overdriving voltage in the driving stage according to the principle of the electrowetting. Then, a direct current (DC) voltage was designed to display a target luminance by analyzing leakage current-voltage curves and a dielectric loss factor. Finally, an alternating current (AC) reset signal was applied in the stabilizing stage to suppress the charge trapping effect. The experiment results indicated that compared with a driving waveform with a reset signal and a combined driving waveform, the average luminance was improved by 3.4% and 9.7%, and the response time was reduced by 29.63% and 51.54%, respectively.

High-Performance Multi-Level Grayscale Conversion by Driving Waveform Optimization in Electrowetting Displays

“…In this experiment, an integrated experimental platform was constructed. The platform consisted of a colorimeter, which could record the EWD’s luminance, and a voltage amplifier, which was used to amplify the driving voltage of driving waveforms [ 13 ]. In the experiment, the EWD used for testing was designed and manufactured by us, as shown in Figure 2 .…”

“…Compared to traditional electrophoretic displays, EWDs based on electrowetting technology had better performance, with the advantages of a fast response speed, wide viewing angle, and excellent readability in daylight [ 2 , 3 , 4 , 5 , 6 ]. However, some shortcomings, such as oil splitting [ 7 , 8 , 9 ], oil backflow [ 10 , 11 ], charge trapping [ 12 , 13 , 14 ], and the hysteresis effect [ 15 , 16 ], have a negative impact on EWD quality. The main reason for these multiple problems was the interaction between the structure of the EWD and its driving mechanism.…”

Design of Multi-DC Overdriving Waveform of Electrowetting Displays for Gray Scale Consistency

“…The pixel could be switched on by voltage driving at and release charges in the insulation layer at to obtain a stable gray scale. This is inspired by Zeng [ 27 ], Long [ 39 ], and Chiu [ 23 ], who decrease the pixel response time and inhibit the oil splitting of EWD based on an overdriving waveform; however, the gain effect of each parameter of the overdriving waveform was not described in detail. Therefore, the related characteristics of our proposed driving waveform need to be further studied.…”

A Driving Waveform with a Narrow Falling and High-Voltage Reset Structure for Improving the Stability of Electrowetting Displays

“…Pixels are the main component of EWDs, and the switching process of a pixel is driven by an applied electric field [15,16]. The electric field sequence is called a driving waveform.…”