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.

Study of Response Time Depending on Driving Voltage of Liquid Crystal Spatial Light Modulator

2013 ◽  
Vol 50 (9) ◽  
pp. 092302
Author(s):  
Qi Mengjiao ◽  
Wang Qidong ◽  
Mu Quanquan ◽  
Liu Yonggang ◽  
Yao Lishuang ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
Spatial Light Modulator ◽  
Driving Voltage ◽  
Light Modulator

New Optimal Solutions for Real-Time Reconfigurable Periodic Asynchronous Operating System Tasks with Minimizations of Response Time

2012 ◽  
Vol 1 (4) ◽  
pp. 88-131 ◽  
Author(s):  
Hamza Gharsellaoui ◽  
Mohamed Khalgui ◽  
Samir Ben Ahmed
Keyword(s):  
Response Time ◽  
Real Time ◽  
Scheduling Algorithm ◽  
Processing Unit ◽  
Software Faults ◽  
Worst Case ◽  
Agent Based ◽  
Central Processing ◽  
Technical Solutions ◽  
Task Systems

Scheduling tasks is an essential requirement in most real-time and embedded systems, but leads to unwanted central processing unit (CPU) overheads. The authors present a real-time schedulability algorithm for preemptable, asynchronous and periodic reconfigurable task systems with arbitrary relative deadlines, scheduled on a uniprocessor by an optimal scheduling algorithm based on the earliest deadline first (EDF) principles and on the dynamic reconfiguration. A reconfiguration scenario is assumed to be a dynamic automatic operation allowing addition, removal or update of operating system’s (OS) functional asynchronous tasks. When such a scenario is applied to save the system at the occurrence of hardware-software faults, or to improve its performance, some real-time properties can be violated. The authors propose an intelligent agent-based architecture where a software agent is used to satisfy the user requirements and to respect time constraints. The agent dynamically provides precious technical solutions for users when these constraints are not verified, by removing tasks according to predefined heuristic, or by modifying the worst case execution times (WCETs), periods, and deadlines of tasks in order to meet deadlines and to minimize their response time. They implement the agent to support these services which are applied to a Blackberry Bold 9700 and to a Volvo system and present and discuss the results of experiments.

scholarly journals Response Improvement of Liquid Crystal-Loaded NRD Waveguide Type Terahertz Variable Phase Shifter

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 307 ◽  
Author(s):  
Trong Nghia Lang ◽  
Van Bao Bui ◽  
Yo Inoue ◽  
Hiroshi Moritake
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
Phase Change ◽  
Decay Time ◽  
Phase Shifter ◽  
Dielectric Anisotropy ◽  
Driving Voltage ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Waveguide Type

Liquid crystals, which have high dielectric anisotropy even in the terahertz region and are easily controllable for dielectric permittivity by applying an electric field, have become increasingly attractive in recent years. The non-radiative dielectric (NRD) waveguide has a structure in which a dielectric line is sandwiched between two metal plates and by replacing the dielectric part with liquid crystal, a low loss liquid crystal-loaded NRD waveguide type terahertz phase shifter can be obtained. However, since the thickness of the liquid crystal layer is several hundred micrometers, it has a response time of as long as several hundred seconds when the driving voltage is removed. It is necessary to devise improvements for practical application. By inserting two polyethylene terephthalate (PET) films and reducing the thickness of the liquid crystal layer, the decay time was improved well, but the phase change was significantly reduced. In this study, we report improving both decay time and phase change with aligned nanofiber/liquid crystal complex. In addition, we demonstrate liquid crystal-load phase shifter, which has 360° phase change and the response time below one second.

Response Time of a-Si:H Photosensors in Optically Addressed Spatial Light Modulators

1991 ◽  
Vol 219 ◽  
Author(s):  
Garret Moddel ◽  
Pierre R. Barbier
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
Spatial Light Modulator ◽  
Reverse Bias ◽  
Forward Bias ◽  
Spatial Light Modulators ◽  
Photocurrent Response ◽  
Light Modulator ◽  
Double Injection ◽  
Light Modulators

ABSTRACTA successful application for a-Si:H is as the photosensor in a liquid crystal optically addressed spatial light modulator (OASLM). We analyze the response time of an a-Si:H p-i-n photodiode in a “pseudo-OALSM,” in which the liquid crystal is replaced by an equivalent capacitor, under both forward and reverse bias. Under reverse bias the two important effects are the photocurrent response time, and residual trapped charge. Under forward bias the mechanism shifts from double injection regimes to ohmic transport as a function of voltage. We relate these characteristics to the operation of an OASLM.

High-speed analog complex-amplitude liquid-crystal light modulator

1994 ◽  
Vol 19 (16) ◽  
pp. 1228 ◽  
Author(s):  
Gary D. Sharp ◽  
Kristina M. Johnson
Keyword(s):  
Liquid Crystal ◽  
High Speed ◽  
Complex Amplitude ◽  
Light Modulator

scholarly journals Design of an AC Driving Waveform Based on Characteristics of Electrowetting Stability for Electrowetting Displays

2020 ◽  
Vol 8 ◽  
Author(s):  
Linwei Liu ◽  
Zhuoyu Wu ◽  
Li Wang ◽  
Taiyuan Zhang ◽  
Wei Li ◽  
...  
Keyword(s):  
Response Time ◽  
Indium Tin Oxide ◽  
Pulse Width Modulation ◽  
Charge Trapping ◽  
Driving Voltage ◽  
Reverse Voltage ◽  
Dc Voltage ◽  
Voltage Curve ◽  
Voltage Frequency ◽  
Driving Waveform

In traditional electrowetting display (EWD) drivers, direct current (DC) voltage and pulse width modulation are often used, which easily caused an electrowetting charge trapping phenomenon in a hydrophobic insulating layer. Therefore, the driving voltage must be increased for driving EWDs, and oil backflow cannot be solved. Aqueous solutions are often used as polar liquids for EWDs, and the reverse voltage of alternating current (AC) driving can cause chemical reactions between water and indium tin oxide (ITO). So, a driving waveform was proposed, which included a DC waveform and an AC waveform, to separately drive EWDs for oil rupture and open state. Firstly, a DC waveform was used when the oil was broken, and the response time was reduced by designing the DC voltage and duration. Secondly, an AC waveform was used when the oil required to be stable. Oil backflow could be suppressed by the AC waveform. The main parameters of AC waveform include reverse voltage, frequency and duty cycle. The reverse voltage of EWDs could be obtained by voltammetry. The frequency could be obtained by analyzing the rising and falling edges of the capacitance voltage curve. The experimental results showed that the proposed waveform can effectively suppress oil backflow and shorten the response time. The response time was about 86% lower than the conventional driving waveforms, and oil backflow was about 72% slower than the DC driving waveform.

Sign in / Sign up

Export Citation Format

Share Document