A Combined Pulse Driving Waveform With Rising Gradient for Improving the Aperture Ratio of Electrowetting Displays

Tian, Lixia; Bai, Peng

doi:10.3389/fphy.2021.709151

Cited by 11 publications

(9 citation statements)

References 30 publications

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“…When the driving voltage exceeds the threshold voltage, the oil film ruptures at its thinnest part. The Coatings 2023, 13, 935 4 of 14 ruptured oil film shrinks along the pixel wall, and the surface area of the shrunken oil film can be calculated using Equation (4) [36]:…”

Section: Oil Film Splittingmentioning

confidence: 99%

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

Long

Wang

et al. 2023

Coatings

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An electrowetting display (EWD) is a new reflective display device with the advantages of paper display, high reflectivity, and fast response times. However, the display performance of EWDs has been restricted by oil film splitting and luminance oscillation. Therefore, a new driving waveform based on a falling slope function and a high-voltage, square-wave reset signal is proposed to solve these defects. It consists of a shrinkage stage and a stabilizing stage. First, the oil film of a pixel can be quickly ruptured by applying a falling slope function during the shrinkage stage according to the oil film-splitting theory. Then, a direct current (DC) voltage is applied to promote the complete fusion of the dispersed oil films by analyzing the voltage characteristic curves of EWDs. Finally, a high-voltage, square-wave reset signal is applied during the stabilizing stage to reduce luminance oscillations and suppress oil film backflow. Experimental results show that the average luminance was increased by 6.5% compared with a PWM driving waveform. The display stability of EWDs was improved by 89.1% compared with a driving waveform with a rising gradient.

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Section: Oil Film Splittingmentioning

confidence: 99%

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

Long

Wang

et al. 2023

Coatings

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“…As shown in Figure 12a, four different driving waveforms were used to compare performance with the proposed driving waveform. The four driving waveforms include a combined pulse waveform [20], an exponential function waveform with a reset stage [32], a linear function waveform [19], and an exponential function waveform [33]. In order to control the variable, the duration of the oil shrinking stage in all driving waveforms was set to 180 ms, and the maximum driving voltage V max was set to 30 V. The initial voltage of both the linear function waveform and the exponential function waveform with a reset signal was set to 16 V. luminance oscillations, which could not maintain a stable luminance value.…”

Section: Performance Of the Proposed Waveformmentioning

confidence: 99%

“…However, the response time of EWDs was correspondingly increased. In order to solve this problem, a combined pulse driving waveform was proposed [20]. During the rising stage, the voltage was driven from the threshold voltage to a maximum voltage, which effectively shorten the response time.…”

Section: Introductionmentioning

confidence: 99%

Toward Suppressing Oil Backflow Based on a Combined Driving Waveform for Electrowetting Displays

Long

Zhang

et al. 2022

Micromachines

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Electrowetting display (EWD) is a new type of paper-like reflective display based on colored oil, which has gradually become one of the most potential electronic papers with low power consumption, fast response, and full color. However, oil backflow can occur in EWDs, which makes it difficult to maintain a stable aperture ratio. In order to improve the stability of the aperture ratio of EWDs, a new driving waveform was proposed based on analyzing the phenomenon of oil backflow. The driving waveform was composed of a shrinking stage and a driving stage. Firstly, a threshold voltage of oil splitting was calculated by analyzing the luminance curve of EWDs, which were driven by different direct current (DC) voltages. Then, an exponential function waveform, which increased from the threshold voltage, was applied to suppress oil splitting. Finally, a periodic signal combined with a reset signal with a DC signal was applied during the driving stage to maintain a stable aperture ratio display. Experimental results showed that the charge trapping effect could be effectively prevented by the proposed driving waveform. Compared with an exponential function waveform, the average luminance value was increased by 28.29%, and the grayscale stability was increased by 13.76%. Compared to a linear function waveform, the aperture ratio was increased by 10.44% and the response time was reduced by 20.27%.

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“…Hsieh et al studied the optoelectronic performance of ink contact angles by deriving pixel hydrodynamic behavior from a Maxwell stress tensor and the flow phase field of the water-oil layer [5]. Using an electrochemical point of view, Rivas et al, found that the degree of contact angle deformation could be controlled by increasing the solvation energy difference, in order to suppress the contact angle saturation phenomenon under an applied electric field [6]- [11]. Under the electrostatic force characteristics of capillary electric fluid of ink droplets, the charge on the three-phase contact wire constantly accumulates to produce a certain electrostatic force, which makes the capillary tension change, thus changing the contact Angle of the ink and leading to the hysteresis of the contact Angle [12]- [16].…”

Section: Introductionmentioning

confidence: 99%

Research on Suitable Viscosity and Driving Waveform of Chromatic Electrowetting with Good Photoelectric Characteristics

Chen¹,

Lin²,

Mei³

et al. 2023

Preprint

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This paper proposes a kind of periodic complex ramp pulse driving waveform in the electrowetting display system with suitable viscosity ink. Firstly, considering the fluid-motion characteristics of different viscosity inks, the relationship between the contact angle and viscosity of inks in the liquid-oil-solid three-phase contact display system is calculated to obtain the suitable viscosity range and driving voltage range. Secondly, the physical model of ink motion with different viscosity is established by COMSOL simulation. Then, During the ink shrinkage movement after applying voltage, the change of the meniscus height at the oil-liquid interface is calculated. Finally, the appropriate viscosity range of the ink movement is verified and obtained based on the meniscus height. On this basis, after applying the driving voltage of different amplitude and frequency respectively, the ink movement situation is observed to design a suitable driving waveform. The results show that when the viscosity of ink fluid is between 0.005 and 0.015Pa·s, the higher the voltage amplitude and the lower the frequency, the higher the meniscus height of ink shrinkage, which is consistent with the characteristics of magenta ink tested in the experiment. Experimental tests show that the driving waveform designed in this paper can not only suppress the phenomenon of oil film splitting, backflow and contact angle saturation hysteresis, but also improve the ink response speed and pixel aperture ratio, in which the aperture ratio is increased to 68.69%. This research is of great significance to optimize the structure of fluid material and the design of driving in electrowetting display.

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A Combined Pulse Driving Waveform With Rising Gradient for Improving the Aperture Ratio of Electrowetting Displays

Cited by 11 publications

References 30 publications

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

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

Toward Suppressing Oil Backflow Based on a Combined Driving Waveform for Electrowetting Displays

Research on Suitable Viscosity and Driving Waveform of Chromatic Electrowetting with Good Photoelectric Characteristics

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