scholarly journals Driving Waveform Design of Electrophoretic Display Based on Optimized Particle Activation for a Rapid Response Speed

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 498
Author(s):  
Wenyao He ◽  
Zichuan Yi ◽  
Shitao Shen ◽  
Zhenyu Huang ◽  
Linwei Liu ◽  
...  
Keyword(s):  
Inflection Point ◽  
Response Speed ◽  
Waveform Design ◽  
Testing Device ◽  
Activity Phase ◽  
Particle Activation ◽  
Two Phases ◽  
Motion Characteristics ◽  
Driving Waveform ◽  
Brightness Curve

Electrophoretic displays (EPDs) have excellent paper-like display features, but their response speed is as long as hundreds of milliseconds. This is particularly important when optimizing the driving waveform for improving the response speed. Hence, a driving waveform design based on the optimization of particle activation was proposed by analyzing the electrophoresis performance of particles in EPD pixels. The particle activation in the driving waveform was divided into two phases: the improving particle activity phase and the uniform reference grayscale phase. First, according to the motion characteristics of particles in improving the particle activity phase, the real-time EPD brightness value can be obtained by an optical testing device. Secondly, the derivative of the EPD brightness curve was used to obtain the inflection point, and the inflection point was used as the duration of improving particle activity phase. Thirdly, the brightness curve of the uniform reference grayscale phase was studied to set the driving duration for obtaining a white reference grayscale. Finally, a set of four-level grayscale driving waveform was designed and validated in a commercial E-ink EPD. The experimental results showed that the proposed driving waveform can cause a reduction by 180 ms in improving particle activity phase and 120 ms in uniform reference grayscale phase effectively, and a unified reference grayscale can be achieved in uniform reference grayscale phase at the same time.

scholarly journals A Separated Reset Waveform Design for Suppressing Oil Backflow in Active Matrix Electrowetting Displays

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 491
Author(s):  
Linwei Liu ◽  
Pengfei Bai ◽  
Zichuan Yi ◽  
Guofu Zhou
Keyword(s):  
Experimental Data ◽  
Dielectric Layer ◽  
Waveform Design ◽  
Second Phase ◽  
Active Matrix ◽  
Two Phases ◽  
Back Stage ◽  
A Charge ◽  
Electric Field Force ◽  
Driving Waveform

The electrowetting display (EWD) is a kind of reflective paper-like display. Flicker and grayscale distortion are caused by oil backflow, which is one of the important factors restricting the wide application of EWDs. The charge embedding caused by the electric field force in the dielectric layer is the cause of oil backflow. To suppress oil backflow, a separated reset waveform based on the study of oil movement is proposed in this paper. The driving waveform is divided into two parts: a reset waveform and a grayscale waveform. The reset waveform generated by a reset circuit can be used to output various voltages. The grayscale waveform is set as a traditional PWM waveform. The reset waveform is composed of a charge-releasing stage and oil-moving back stage. Two phases are contained in the charge releasing stage. The overdriving voltage is used during the first phase to reverse the voltage of all pixels. The trapped charges can then be released from the dielectric layer during the second phase. A higher voltage is used during the oil-moving back stage to drive the oil faster in the pixel. By comparing the experimental data, the oil backflow time is extended 761 times by the reset waveform. The four grayscales can be maintained by the reset waveform after driving for 300 s.

scholarly journals Aperture Ratio Improvement by Optimizing the Voltage Slope and Reverse Pulse in the Driving Waveform for Electrowetting Displays

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 862 ◽  
Author(s):  
Zichuan Yi ◽  
Wenyong Feng ◽  
Li Wang ◽  
Liming Liu ◽  
Yue Lin ◽  
...  
Keyword(s):  
Inflection Point ◽  
Charge Trapping ◽  
Response Speed ◽  
Driving Voltage ◽  
Hysteresis Characteristic ◽  
Aperture Ratio ◽  
Dynamic Display ◽  
Capacitance Voltage ◽  
Reverse Pulse ◽  
Driving Waveform

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.

scholarly journals Driving Waveform Design of Electrowetting Displays Based on an Exponential Function for a Stable Grayscale and a Short Driving Time

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 313 ◽  
Author(s):  
Zichuan Yi ◽  
Zhenyu Huang ◽  
Shufa Lai ◽  
Wenyao He ◽  
Li Wang ◽  
...  
Keyword(s):  
Time Constant ◽  
Exponential Function ◽  
Waveform Design ◽  
Hysteresis Curve ◽  
Optimal Time ◽  
Driving Voltage ◽  
Aperture Ratio ◽  
Driving Time ◽  
Long Time ◽  
Driving Waveform

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.

Designing the Plasma Vertical Position Control System in the KTM Tokamak

Vestnik MEI ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 32-38
Author(s):  
Sergey V. Kotov ◽  
◽  
Vadim M. Pavlov ◽  
Denis B. Zarva ◽  
◽  
...  
Keyword(s):  
Control System ◽  
Power Supply ◽  
Position Control ◽  
Response Speed ◽  
Feedback System ◽  
Vertical Position ◽  
In Series ◽  
Motion Characteristics ◽  
Fast Control ◽  
Position Control System

The Tokamak KTM plant with the aspect ratio of A = 2 and a plasma current of around 750 kA, which is being put into operation in Kurchatov (Kazakhstan), will be able to produce heat loads on the tested samples of materials that are characteristic of the ITER plant, and owing to additional HF heating the plasma pulse duration will reach about 4 s. One of the stages of this work involves studies aimed at obtaining an efficient plasma vertical position control system. The system includes special fast control windings located between the toroidal winding and the inner chamber, and also a fast-acting power supply with feedback. Currently, the tokamak inner chamber with all main systems and windings has been assembled, and a plasma discharge with duration of about 100 ms has been obtained in the limiter configuration. To support operation of the plasma vertical position control system, an own power supply has been designed and assembled, which consists of a thyristor rectifier connected in series with a controlled voltage inverter on IGBT transistors, which has a significant margin in power and response speed. Preliminary computation experiments were carried out in the MATLAB environment, which have confirmed the adequacy of the selected power supply and the system for discharging the energy stored in the windings to the water-cooled ballast resistance. With the remaining tokamak systems having sequentially been put into operation and the first experimental data on plasma motion characteristics in the divertor configuration having become available, it is planned to carry out a series of program experiments aimed at developing and optimizing the feedback system controller algorithm in the power supply of the KTM tokamak fast control windings.

An Electrophoretic Display Driving Waveform Design for Reducing a Flicker and a Driving Time Based on the Fusion Optimization of Driving Stages

2021 ◽  
Vol 16 (3) ◽  
pp. 351-356
Author(s):  
Li Wang ◽  
Yi-Fan Zhang ◽  
Ji-Tao Zhang ◽  
Qi-Ming Wan ◽  
Peng-Chang Ma
Keyword(s):  
Waveform Design ◽  
Experimental Results ◽  
Gray Scale ◽  
High Quality ◽  
Look Up Table ◽  
Driving Time ◽  
Electrophoretic Display ◽  
Human Eyes ◽  
Driving Waveform ◽  
Main Factor

The speed of updating an image is very important for an electrophoretic display (EPD) application, but the flicker which can be produced among the process of updating an image is a main factor of affecting reading comfort for human eyes. In this paper, a new driving waveform, which was based on DC balance, was proposed to reduce the number of flicker and decrease the driving time for updating an image. Firstly, we studied properties of particles in the EPD, and the stages in the driving waveform were fused according to the driving properties of the particles. Secondly, an accurate reference was formed in the driving waveform for writing a new image, and the particle activity was guaranteed at the same time. Lastly, the driving waveform was downloaded to a real EPD waveform look-up table and the performance was compared with traditional driving waveforms. Experimental results showed that the proposed driving waveform could reduce flicker effectively and shorten the driving time by 25%, and an accurate white reference gray scale was obtained for displaying high quality images.

An adaptive generation method for electrophoretic display driving waveform design

2016 ◽  
Vol 24 (11) ◽  
pp. 676-685
Author(s):  
Fei-Bo Duan ◽  
Peng-Fei Bai ◽  
Alex Henzen ◽  
Ling-Ling Shui ◽  
Biao Tang ◽  
...  
Keyword(s):  
Waveform Design ◽  
Electrophoretic Display ◽  
Driving Waveform

scholarly journals Design of Driving Waveform Based on Overdriving Voltage for Shortening Response Time in Electrowetting Displays

2021 ◽  
Vol 9 ◽  
Author(s):  
Wenjun Zeng ◽  
Zichuan Yi ◽  
Yiming Zhao ◽  
Weibo Zeng ◽  
Simin Ma ◽  
...  
Keyword(s):  
Response Time ◽  
Physical Model ◽  
Performance Testing ◽  
Charge Trapping ◽  
Response Speed ◽  
Fast Response ◽  
Optimal Performance ◽  
Experimental Results ◽  
Target Luminance ◽  
Driving Waveform

A fast response speed of a pixel is important for electrowetting displays (EWDs). However, traditional driving waveforms of EWDs have the disadvantage of long response time. So, a driving waveform, which based on overdriving voltages and charge trapping theory, was proposed in this paper to shorten the response time of EWDs. The driving waveform was composed of an overdriving stage and a driving stage. Firstly, a simplified physical model was introduced to analyze the influence of driving voltages on the response time. Then, an overdriving voltage was applied in the overdriving stage to increase the respond speed of oil, and a target voltage was applied in the driving stage to obtain a target luminance. In addition, the effect of different overdriving voltages and overdriving time values on the response time was analyzed by charge trapping theory to achieve an optimal performance. Finally, the driving waveform was imported into an EWD for performance testing. Experimental results showed that the response time of the EWD can be shortened by 29.27% compared with a PWM driving waveform.

scholarly journals Design Method of Equivalent Driving Waveform Based on Electrowetting Response Characteristics

2021 ◽  
Vol 9 ◽  
Author(s):  
Lixia Tian ◽  
Hao Li
Keyword(s):  
Contact Angle ◽  
Design Method ◽  
Contact Angle Hysteresis ◽  
Response Speed ◽  
Hysteresis Effect ◽  
Hysteresis Phenomenon ◽  
Driving Voltage ◽  
Interface Tension ◽  
Response Characteristics ◽  
Driving Waveform

As a new reflective display technology, electrowetting displays (EWDs) have many important characteristics, such as high reflectivity, low power consumption, and paper-like display. However, the contact angle hysteresis, which is the inconsistency between the advancing contact angle and the receding contact angle of oil droplet movement, seriously affects the response speed of EWDs in the driving process. According to the hysteresis phenomenon of contact angle in an oil switch motion with the action of interface tension, the brightness curve of EWDs in the process of pixel switching by different driving voltages was tested in this paper, and driving voltage was changed from 30 to 100 V at the same time. Then, in order to reduce the influence of the hysteresis effect, an equivalent driving waveform design method with overdriving voltage was proposed, and the overvoltage was set to 100 V according to the hysteresis effect and driving characteristic of EWDs. Experimental results showed that the response rising time of EWDs was reduced to 21 ms by using the proposed driving waveform, and the response performance of EWDs can be effectively improved.

scholarly journals Driving Waveform Design Based on Driving Process Fusion and Black Reference Gray Scale for Electrophoretic Displays

2021 ◽  
Vol 9 ◽  
Author(s):  
Li Wang ◽  
Pengchang Ma ◽  
Jitao Zhang ◽  
Qiming Wan
Keyword(s):  
Waveform Design ◽  
Low Power Consumption ◽  
Gray Scale ◽  
Strong Light ◽  
Ultra Low Power ◽  
Second Stage ◽  
Driving Time ◽  
Display Technology ◽  
Two Stages ◽  
Driving Waveform

An electrophoretic display (EPD) is a kind of paper display technology, which has the advantages of ultra-low power consumption and readability under strong light. However, in an EPD-driving process, four stages are needed to finish the driving of a pixel erase original images, reset to black state, clear-to-white state, and write a new image. A white reference gray scale can be obtained before writing a new image, and this driving process may take too long for the comfort of reading. In this article, an EPD-driving waveform, which takes the black state as the reference gray, is proposed to reduce the driving time. In addition, the rules of direct current (DC) balance are also followed to prevent the charge from getting trapped in the driving backplane. The driving process is fused and there are two stages in the driving waveform: reset to black state and write the next image. First, the EPD is written to a stable black state according to the original gray scale driving waveform and the black state is used as the reference gray for the next image. Second, the new image is written by the second stage of the new driving waveform. The experimental results show that the proposed driving waveform has a better performance. Compared with the traditional driving waveform which has four stages, the driving time of the new driving waveform is reduced by nearly 50%.

Study on driving waveform design process for multi-nozzle piezoelectric printhead in material-jetting 3D printing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yih-Lin Cheng ◽  
Tzu-Wei Tseng
Keyword(s):  
3D Printing ◽  
Design Process ◽  
High Speed ◽  
Hold Time ◽  
Maximum Velocity ◽  
Waveform Design ◽  
Droplet Velocity ◽  
Content Type ◽  
Satellite Drops ◽  
Driving Waveform

Purpose Material-jetting (MJ) three-dimensional (3D) printing processes are competitive due to their printing resolution and printing speed. Driving waveform design of piezoelectric printhead in MJ would affect droplet formation and performance, but there are very limited studies on it besides patents and know-hows by commercial manufacturers. Therefore, in this research, the waveform design process to efficiently attain suitable parameters for a multi-nozzle piezoelectric printhead was studied. Therefore, this research aims to study the waveform design process to efficiently attain suitable parameters for a multi-nozzle piezoelectric printhead. Design/methodology/approach Ricoh’s Gen4L printhead was adopted. A high-speed camera captured pictures of jetted droplets and droplet velocity was calculated. The waveforms included single-, double- and triple-pulse trapezoidal patterns. The effects of parameters were investigated and the suitable ones were determined based on the avoidance of satellite drops and preference of higher droplet velocity. Findings In a single-pulse waveform, an increase of fill time (Tf) decreased the droplet velocity. The maximum velocity happened at the same pulse width, the sum of fill time and hold time (Tf + Th). In double- and triple-pulse, a voltage difference (Vd) above zero in the holding stage was adopted except the last pulse to avoid satellite drops. Suitable parameters for the selected resin were obtained and the time-saving design process was established. Research limitations/implications Based on the effects of parameters and observed data trends, suggested procedures to determine suitable parameters were proposed with fewer experiments. Practical implications This study has verified the feasibility of suggested design procedures on another resin. The required number of trials was reduced significantly. Originality/value This research investigated the process of driving waveform design for the multi-nozzle piezoelectric printhead. The suggested procedures of finding suitable waveform parameters can reduce experimental trials and will be applicable to other MJ 3D printers when new materials are introduced.

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