scholarly journals A Driving System for Fast and Precise Gray-Scale Response Based on Amplitude–Frequency Mixed Modulation in TFT Electrowetting Displays

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 732 ◽  
Author(s):  
Zichuan Yi ◽  
Linwei Liu ◽  
Li Wang ◽  
Wei Li ◽  
Lingling Shui ◽  
...  
Keyword(s):  
Pulse Width Modulation ◽  
Thin Film Transistor ◽  
Response Speed ◽  
Hysteresis Curve ◽  
Driving Voltage ◽  
Gray Scale ◽  
Driving System ◽  
Target Luminance ◽  
Initial Stage ◽  
Relation Model

The gray-scale display which is driven by PWM (pulse width modulation) in TFT (thin film transistor) electrowetting displays (EWDs) has some shortcomings, such as large amplitude of oil oscillation in pixels and slow response speed for displaying gray scale. In this paper, an amplitude–frequency mixed modulation driving system is proposed to improve the response speed of driving gray scale and enhance the oil stability when the gray scale is displayed. In the initial stage of the driving process, the oil is driven by a high voltage to close to the target luminance, and the driving voltage is then decreased to stabilize the oil. The electrowetting hysteresis curve was used to calculate the relation model between the driving voltage and the luminance of the pixel in the system, and the driving voltage value of the pixel at each driving stage was then set to make the oil precisely and rapidly stabilize at the target luminance value. In the output driving platform, the amplitude–frequency mixed modulation is realized based on the source IC, which was used to realize digital-to-analog conversion. An 8 inch EWD was tested using an Admesy colorimeter, and the experimental results show that the pixel response time is reduced by 70% and the gray-scale oscillation is reduced by 80%.

scholarly journals Line of Sight Correction of High-Speed Liquid Crystal Using Overdriving Technology

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1477
Author(s):  
Hongyang Guo ◽  
Qing Li ◽  
Yangjie Xu ◽  
Yongmei Huang ◽  
Shengping Du
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
High Speed ◽  
Pulse Width Modulation ◽  
Response Speed ◽  
Line Of Sight ◽  
Processing Unit ◽  
Driving Voltage ◽  
Light Modulator ◽  
Central Processing

In the line of sight correction system, the response time of the liquid crystal spatial light modulator under the normal driving voltage is too long to affect system performance. On the issues, an overdriving method based on a Field-Programmable Gate Array (FPGA) is established. The principle of the overdrive is to use a higher voltage difference to achieve a faster response speed of liquid crystal. In this scheme, the overdriving look-up table is used to seek the response time of the quantized phase, and the liquid crystal electrode is driven by Pulse–Width Modulation (PWM). All the processes are performed in FPGA, which releases the central processing unit (CPU) memory and responds faster. Adequate simulations and experiments are introduced to demonstrate the proposed method. The overdriving experiment shows that the rising response time is reduced from 530 ms to 34 ms, and the falling time is from 360 ms to 38 ms under the overdriving voltage. Typical light tracks are imitated to evaluate the performance of the line of sight correction platform. Results show that using the overdrive the −3 dB rejection frequency was increased from 1.1 Hz to 2.6 Hz. The suppression ability of the overdrive is about −20 dB at 0.1 Hz, however the normal-driving suppression ability is only about −13 dB.

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.

scholarly journals Dynamic Takagi-Sugeno Model for the Control of Ultrasonic Motor

2011 ◽  
Vol 2011 ◽  
pp. 1-9
Author(s):  
Shi Jingzhuo ◽  
Lv Lin ◽  
Zhang Yu
Keyword(s):  
Experimental Data ◽  
Fuzzy Model ◽  
Calculated Data ◽  
Fuzzy Reasoning ◽  
Ultrasonic Motor ◽  
Driving Voltage ◽  
Driving System ◽  
Position Controller ◽  
Sugeno Model ◽  
Takagi Sugeno

Model of ultrasonic motor is the foundation of the design of ultrasonic motor's speed and position controller. A two-input and one-output dynamic Takagi-Sugeno model of ultrasonic motor driving system is worked out using fuzzy reasoning modeling method in this paper. Many fuzzy reasoning modeling methods are sensitive to the initial values and easy to fall into local minimum, and have a large amount of calculation. In order to overcome these defects, equalized universe method is used in this paper to get clusters centers and obtain fuzzy clustering membership functions, and then, the unknown parameters of the conclusions of fuzzy rules are identified using least-square method. Different experimental data that are tested with different operational conditions are used to examine the validity of the fuzzy model. Comparison between experimental data and calculated data of the model indicates that the model can well describe the nonlinear characteristics among the frequency, amplitude of driving voltage and rotating speed. The proposed fuzzy model can be used to analyze the performance of ultrasonic motor driving system, and also can be used to design the speed and position controller of ultrasonic motor.

scholarly journals Electrochemical Coupled Analysis of a Micro Piezo-Driven Focusing Mechanism

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 216 ◽  
Author(s):  
Chong Li ◽  
Kang Liang ◽  
Wei Zhong ◽  
Jiwen Fang ◽  
Lining Sun ◽  
...  
Keyword(s):  
Electromechanical Coupling ◽  
Response Speed ◽  
Coupled Analysis ◽  
Maximum Output ◽  
Driving Voltage ◽  
Matlab Simulation ◽  
Output Performance ◽  
Output Force ◽  
Drive Theory ◽  
Output Characteristics

In order to improve the response speed and output force of the camera focusing mechanism, the authors proposed a novelty micro focusing mechanism based on piezoelectric driving, which has the characteristics of rapid response, high precision positioning and large displacement focusing. In this paper, the operating principle of the proposed focusing mechanism is presented. Using the piezoelectric output characteristic, the movable tooth drive theory and the screw drive theory, the electromechanical coupling mechanical model and equations of the piezoelectric focusing mechanism are established. Through MATLAB simulation, the output characteristics of the piezoelectric focusing mechanism are calculated. The results indicate that the maximum thrust force of the lens and the maximum output torque of the movable tooth drive for the piezoelectric focusing mechanism are 562.5 N and 1.16 Nm, respectively. Furthermore, the driving voltage directly affects the output performance of the piezoelectric focusing mechanism. These results can be utilized both to optimize the dimensions and improve the overall performance of the piezo-driven focusing mechanism.

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.

Research on Control System of Gearless Permanent Magnet Synchronous Traction Elevator

2011 ◽  
Vol 383-390 ◽  
pp. 5945-5950
Author(s):  
Yan Hu ◽  
Zhen Guang ◽  
Xiao Yu Wang
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Permanent Magnet ◽  
Pulse Width ◽  
Pulse Width Modulation ◽  
Control Method ◽  
Modulation Method ◽  
Driving System ◽  
Simulation Results ◽  
The Mathematical Model

A driving system for gearless traction machine plays an very important role in controlling elevator’s running. And its performances have a direct effect on the elevator’s performance. On the basic of the mathematical model of the gearless permanent magnetic synchronous machine (PMSM), id=0 vector control method and space vector pulse width modulation method are used in the control system. Then making a simulation on the system designed by MATLAB/SIMULINK. The simulation results show that the control method is feasible.

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