Liquid Crystal Display Research Articles

Ultra high-speed 3D shape measurement technology for specular surfaces based on μPMD

Phase measuring deflectometry (PMD) has been extensively applied to measure specular surfaces due to its non-contact, high-precision, full-field measurement capabilities. Liquid crystal display (LCD) screen is the most common structured light source in PMD. However, the response time of liquid crystal molecules limits its frame rate to around 100 frames per second (fps). Therefore, it is quite difficult for traditional PMD to measure rapidly moving surfaces. This paper proposes a 3D dynamic sensing technique, microsecond-PMD (µPMD) based on the high-frame-rate sinusoidal fringe display (HSFD). In the proposed method, the switching time for each fringe pattern display is at a sub-microsecond level, enabling high-speed fringe acquisition with kHz-level area array detection or 100kHz-level line array scanning. The HSFD method uses a specially designed LED array and two-step optical expansion. The high-speed switching characteristic of LED sources is utilized to allow a superfast display rate. Moreover, the superior sinusoidal property can be achieved by the combination of the specially designed discrete sinusoidal LED array, the light-diffracting effect of orthogonal gratings, and the filtering effect of the light diffuser. The mechanism and analytic model of fringe generation are thoroughly analyzed and discussed in this work. Furthermore, the swarm optimization algorithm and corresponding weighted fringe quality evaluation function are presented to obtain the optimal fringes. To the best of our knowledge, the proposed µPMD, for the first time, achieved a superfast fringe acquisition rate of 4000fps with sub-micrometer precision in three-dimensional (3D) reconstruction for specular surfaces. We envision this proposal to be broadly implemented for real-time monitoring in manufacturing.

Dimension compensation of printed master molds by a desktop LCD 3D printer for high-precision microfluidic applications.

Recent advances in low-cost liquid crystal display (LCD) 3D printing have popularized its use in creating microfluidic master molds and complete devices. However, the quality and precision of these fabrications often fall short of the rigorous standards required for advanced microfluidic applications. This study introduces a novel approach to enhance the dimensional accuracy of microchannels produced using a desktop LCD 3D printer. We propose a method for dimension compensation, optimize the printing parameters, and provide a straightforward post-treatment technique to ensure high-quality curing of polydimethylsiloxane (PDMS) in master molds made from photosensitive resin. Our investigation assesses the precision of 3D printing across three different scales of square cross-section microchannels by measuring their widths and heights, leading to the determination of optimal printing parameters that minimize dimensional errors. The dimensional errors are further reduced by introducing a series of dimension compensation factors, which correct the nominal dimensions of the microchannels by using the compensation factors in 3D printing. The dimensional accuracy is significantly improved after compensation even in fabricating complex microchannels of triangular cross-sections. Finally, a spiral channel of trapezoidal-like cross-section with tilted edges is fabricated for microfluidic application, and highly efficient particle separation is realized in the channel. The proposed method provides new insights for utilizing desktop LCD 3D printers to achieve high-accuracy microstructures necessary for advanced microfluidic applications.

Development of a Frugal Onboard Tire Pressure Monitoring Control System

Tires, the bridge between vehicles and roads, play an unparalleled role in both performance and safety. In everyday use, the tire health is often neglected, with factors such as tread depth, inflation pressure, and tire damage overlooked by most users, leading to ∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document}30% of cars in developed nations, operating with underinflated tires, a situation exacerbated in developing nations. Hence, innovations such as tire Pressure Monitoring Systems have become imperative. The objective of the current work is to develop an economical, direct, on-board tire pressure monitor for automotive tire health upkeep. This is achieved through the integration of a pressure sensor and transmitter with an Arduino, and wireless transmission of the data to the dashboard display. While the initial model, tested on a bicycle, effectively displayed tire pressure on the handlebar-mounted LCD screen with an accompanying LED indicating deviations from the standard pressure, the current design has lot of scope for improvement by the utilization of a wireless technologies for the pressure sensors for continuous monitoring of tire pressures in a range of vehicles from two-wheelers to heavy vehicles.

Design of wireless charging system for E-Vehicle

To address the dual problems of fuel reliance and air pollution, this study describes the design of a wireless ground to vehicle charging system powered by solar energy and specifically designed for electric vehicle (EV) charging stations. As the number of electric vehicles on the road steadily rises, they present a viable way to cut travel expenses by switching from conventional fuel to electricity, which is a more economical and sustainable option. With the introduction of a wireless EV charging system, this creative solution does away with the need for external power sources and permits continuous charging without interfering with driving. Utilizing solar power, the charging system incorporates solar panels, batteries, circuit regulators, boost converters, receiver and transmitter copper coils, AC/DC converters, microcontrollers (such as ATmega), LCD screens, and circuit regulators. This study describes a technique that shows that charging electric cars while driving is feasible and eliminates the need to stop. This technology for wireless solar electric vehicle charging presents a forward-thinking approach to sustainable mobility by providing a workable solution that can be easily included in the road infrastructure. For the wireless charging, in addition, various coil designs are suggested.

Implementation of Solar Panels as an Alternative to Electric Power Used in WiFi-based Freezer Box Temperature Monitoring System (Case Study of NN Frozen Food Wajak)

A freezer box temperature monitoring system using solar panels as alternative power is an important technology to ensure the quality of stored products. This research develops a WiFi-based temperature monitoring system that uses a DS18B20 temperature sensor, a PZEM-004T digital sensor, and an ESP8266 module to read and send real-time data to a website platform. Data is collected through a temperature sensor connected to the ESP8266 microcontroller, then displayed on the LCD screen and uploaded to the server for further monitoring via WiFi connection. The results show that this system successfully maintains the freezer box temperature at optimal conditions with an average temperature value of -24.82°C and a temperature range ranging from -28.81°C to -19.63°C. The voltage values are in the range of 197.10 V - 218.70 V, current between 0.02 A - 1.03 A, and power between 158 W - 186.80 W.

Machine-learning-based sampling inspection under OQC capacity for real-time quality monitoring in the TFT-LCD industry

ABSTRACT In the thin film transistor-liquid crystal display (TFT-LCD) industry, the competition is fierce, and the external failure cost is high. To improve the quality of released products, sampling inspection under outgoing quality control (OQC) is conducted before products are released. Owing to the variety and complexity of inspection items, the task must be carried out manually while realising automation is difficult. Traditional random sampling inspection is limited by sampling quantity, manpower, and material resources. To effectively improve acceptable quality levels, this paper proposes a quality predictive monitoring framework tailored to the production and inspection characteristics of the TFT-LCD industry. This framework includes real-time automatic quality monitoring based on an optimal machine learning prediction model with two-phase feature creation, and it also addresses OQC inspection capacity constraints. Experimental results show the prediction performance based on proposed model is better than the traditional random sampling process. In practice, superior average outgoing quality improves by more than 70% at the same sampling level. In addition, the features of the process can be further controlled and managed based on the prediction model to monitor the key parameters in real time and respond to abnormalities quickly, thereby further improving the quality of released products.

Transition metal-catalyzed C(sp2/sp3)-H α-fluoroalkenylation from gem-(bromo/di)fluoroalkenes to monofluoroalkenes: scope, mechanisms, and synthetic applications.

Organofluorines have a broad range of industrial applications, such as pharmaceuticals, liquid crystal displays (LCDs), solar cells, textiles, and construction coatings, and are used in peptidomimetics, surfactants, refrigerants, anesthetics, and agrochemicals. Among them are versatile monofluoroalkenes that play a crucial role in medicinal and synthetic chemistry. The synthetic strategies for this class of molecules are limited, and prior efforts frequently suffered from poor atom- and step-economies. As a surrogate pathway for traditional cross-coupling transformations, transition metal (TM)-catalyzed C-H direct α-fluoroalkenylation overcomes these obstacles and provides straightforward techniques to access monofluoroalkenes. Nevertheless, substrate scope is still a challenge for catalysis, where gem-bromofluoroalkene synthons are applicable with electronically biased substrates such as azoles, while gem-difluoroalkene-based strategies are limited to substrates containing N-based directing groups. Herein, we review the cutting-edge fluoroalkenylation research for direct synthesis of monofluoroalkenes achieved during the last decade (2013-2023). This review is divided into two main parts: the first part discusses TM-catalyzed direct α-fluoroalkenylation via the merging of C-H activation and C(sp2)-Br cleavage strategies using gem-bromofluoroalkenes, and the second part describes the same reaction, albeit with C(sp2)-F cleavage of highly explored gem-difluoroolefins. Our review surveys all previously reported monofluoroalkenes in this research area, including their preparation techniques, stereoselectivity, and yield percentages. Furthermore, optimal conditions, reactant scope, mechanistic investigations, synthetic applications, benefits, and drawbacks of each presented methodology are critically discussed.

Base-Mediated Chemodivergent [4 + 1] and [2 + 1] Cycloadditions of N-Alkylpyridiniums and Enones.

Divergent synthesis of structurally different products from the same kinds of starting materials is highly synthetically useful but very challenging. Herein, we reported a base-mediated chemodivergent [4 + 1] and [2 + 1] cycloaddition of N-alkylpyridinium and enone under mild conditions, leading to furan-fused bicycles with high diastereoselectivity and spirobicycles, respectively, from moderate to high yields. N-Alkylpyridinium salts were modular nucleophilic transfer reagents and C1 synthons, which underwent tandem Michael addition to the α,β-unsaturated ketones and cyclization under the base conditions. Late-stage derivatization of 4-propyldicyclohexylanone from an important industrial raw of liquid crystal display (LCD) screens was realized. In vitro, compound 3f exhibited good activities against human colon cancer cells (HCT116) with IC50 values in 9.82 ± 0.27 μM. Further biological evaluations investigated the mechanism of the effective inhibition of cell growth, including apoptosis ratio detection, cell cycle analysis, and migration capacity of HCT116 cells. In apoptosis effect studies, complex 3f increased the percentage of apoptotic HCT116 cells to 26.8% (15 μM).

Fast-response liquid crystal display device with trapezoidal pixel electrodes

ABSTRACT A fast response liquid crystal display (LCD) with trapezoidal pixel electrodes is proposed. The trapezoidal shape of the pixel electrode generates a slanted electric field, eliminating the need for a non-zero pre-tilt angle to prevent random domain formation in the LC. Additionally, the absence of a pre-tilt angle enhances viewing angles. During operation, LC molecules can form virtual walls, increasing anchoring energy and improving response time. At 38% transmittance, the response time is 5.1 ms, while at 60% transmittance, it increases to 8.3 ms. With a circular polariser, the device achieves a contrast ratio of 200:1 and a viewing cone of approximately 18°. Consequently, the trapezoidal pixel electrode FFS cell is suitable for fast LCDs used in automotive displays and digital signage. Its narrow viewing angles with a circular polariser also make it ideal for personal privacy displays and certain mobile displays.

3D‐Printed Highly Porous Functional Materials for the Efficient Removal of Adenovirus

AbstractHierarchical porous acrylate‐based materials are highly interesting as 3D filter materials, such as for virus removal from suspensions. Here, the synthesis of highly porous monolithic 3D materials by polymerization‐induced phase separation in liquid crystal display (LCD) based 3D printing is presented for the efficient removal of human adenovirus type 5. The hierarchical porosity can be tuned via the variation of the photocurable resin composition (i.e., inherent porosity) and the computer‐aided design (i.e., “printed” porosity; microchannels). 3D polymer structures with highly intricate geometries and structural features ranging from ≈20 nm up to cm can be achieved, which can be used for effective virus removal in a laboratory‐scale flow‐through approach. Combined focused ion beam/scanning electron microscopy tomography and mercury porosimetry provide detailed information on the inherent pore size, pore size distribution, and pore interconnectivity, which is key for the performance of such functional 3D materials. Polymers with a theoretical void volume of 75% show virus capture with a removal efficiency of ≈70% of the adenovirus. Polymers with the same theoretical void volume and macroscopic design but a more hydrophobic nature captured only ≈33%. An optimized adenovirus retention of 98% is achieved by adjusting the microchannels of the tunable inserts.

The Development of a Novel Nitrate Portable Measurement System Based on a UV Paired Diode-Photodiode.

Nitrates can cause severe ecological imbalances in aquatic ecosystems, with considerable consequences for human health. Therefore, monitoring this inorganic form of nitrogen is essential for any water quality management structure. This research was conducted to develop a novel Nitrate Portable Measurement System (NPMS) to monitor nitrate concentrations in water samples. NPMS is a reagent-free ultraviolet system developed using low-cost electronic components. Its operation principle is based on the Beer-Lambert law for measuring nitrate concentrations in water samples through light absorption in the spectral range of 295-315 nm. The system is equipped with a ready-to-use ultraviolet sensor, light emission diode (LED), op-amp, microcontroller, liquid crystal display, quartz cuvette, temperature sensor, and battery. All the components are assembled in a 3D-printed enclosure box, which allows a very compact self-contained equipment with high portability, enabling field and near-real-time measurements. The proposed methodology and the developed instrument were used to analyze multiple nitrate standard solutions. The performance was evaluated in comparison to the Nicolet Evolution 300, a classical UV-Vis spectrophotometer. The results demonstrate a strong correlation between the retrieved measurements by both instruments within the investigated spectral band and for concentrations above 5 mg NO3-/L.

Enhanced optical bistability of energy saving viologen-based electrochromic display with a commercial phenol-based epoxy resin

A highly bistable viologen-based electrochromic display was successfully developed by using a simple strategy with cheap commercial phenol-based epoxy. By adding epoxy, phenol species can contribute a dual effect, in which they can play as electron shuttles to facilitate fast coloration of ECDs and stabilize the long bistability of ECDs through the proton-coupled electron transfer (PCET) mechanism during coloration state. With the use of epoxy, CPHEV2+/E exhibits an improvement of maximum ΔT, which is 78.6 % at 596 nm compared to 53 % for that of ECD without epoxy. The ECD with added epoxy can hold the colored state up to 50 h after applying a voltage of −2.5 V for 15 s compared with ECD without epoxy which is 22 min. Notably, the color state undergoes decomposition to 10 % of its initial value after 3.5 h without any extra power supply. The 3D-printed rose flower ECD was successfully demonstrated using digital light processing (DLP) with good dimensional accuracy and resolution.

The role of sub-regional electrostatic spinning nanofiber loaded with WO3 nanoparticle in modulating electro-optic performance and stepwise display of polymer dispersed liquid crystal

ABSTRACT The advancement of multi-functional displays with outstanding electro-optical properties is particularly essential at present. However, conventional integral all-area driven transparent displays are gradually failing to meet current demands. Herein, sub-regional electrostatic spinning of nanofibers as a novel fabrication method was introduced into polymer-dispersed liquid crystal (PDLC) to achieve stepwise display in concert with loaded WO3 nanoparticles, addressing the aforementioned drawback. The use of nanofibers played a crucial role in ensuring fine dispersion of nanoparticles, resulting in a reduction of the saturation voltage of the PDLC film from 28.9 V to 19.7 V and an increase in contrast ratio from 105.7 to 194.3. Meanwhile, experimental findings and theoretical considerations have revealed that variations in microscopic pore size can significantly influence the electro-optical behaviour of PDLC film. Next, the stepwise PDLC film was prepared by electrostatically spinning nanofibers onto half of the LC cell region, leading to different voltage-transmittance responses between the two regions. Consequently, under appropriate driving voltages, the PDLC film can realise three different optical states: total scatter, half-transparency, and total transparency. In addition, the PDLC film exhibited excellent anti-thermal ageing performance, allowing it to excel in various advanced display applications.

Sustained release of 3D printed bupropion hydrochloride tablets bearing Braille imprints for the visually impaired

3D printing has been introduced as a novel approach for the design of personalized dosage forms and support patient groups with special needs that require additional assistance for enhanced medication adherence. In this study liquid crystal display (LCD) is introduced for the development of sustained release bupropion.HCl printed tablets. The optimization of printing hydrogel inks was combined with the display of Braille patterns on the tablet surface for blind or visually impaired patients. Due to the high printing accuracy, the Braille patterns could be verified by blind patients and provide the required information. Further characterization revealed the presence of BUP in amorphous state within the photopolymerized resins. The selection of poly(ethylene glycol) (PEG)-diacrylate (PEGDA) of different molecular weights and the presence of surfactants or solubilizers disrupted the resin photopolymerization, thus controlling the BUP dissolution rates. A small batch scale-up study demonstrated the capacity of LCD to print rapidly a notable number of tablets within 24 min.

Perception-Driven Soft-Edge Occlusion for Optical See-Through Head-Mounted Displays.

Systems with occlusion capabilities, such as those used in vision augmentation, image processing, and optical see-through head-mounted display (OST-HMD), have gained popularity. Achieving precise (hard-edge) occlusion in these systems is challenging, often requiring complex optical designs and bulky volumes. On the other hand, utilizing a single transparent liquid crystal display (LCD) is a simple approach to create occlusion masks. However, the generated mask will appear defocused (soft-edge) resulting in insufficient blocking or occlusion leakage. In our work, we delve into the perception of soft-edge occlusion by the human visual system and present a preference-based optimal expansion method that minimizes perceived occlusion leakage. In a user study involving 20 participants, we made a noteworthy observation that the human eye perceives a sharper edge blur of the occlusion mask when individuals see through it and gaze at a far distance, in contrast to the camera system's observation. Moreover, our study revealed significant individual differences in the perception of soft-edge masks in human vision when focusing. These differences may lead to varying degrees of demand for mask size among individuals. Our evaluation demonstrates that our method successfully accounts for individual differences and achieves optimal masking effects at arbitrary distances and pupil sizes.

Photoluminescence and Electroluminescence Confocal Imaging of an OLED

In recent years organic light-emitting diodes (OLEDs) have become one of the leading technologies for full-colour display panels in high-end smartphones and televisions. This rapid growth in use has occurred because OLEDs offer an all-around superior performance to liquid crystal displays (LCDs). For example, they are thinner, lighter, more flexible, less power consumptive, and brighter.When new OLEDs are developed, the optoelectronic properties of individual components and the complete device can be characterised using photoluminescence (PL) and electroluminescence (EL) spectroscopy. In this poster presentation, we use a confocal Raman microscope to characterise and spatially resolve the optoelectronic properties of a fabricated OLED device with four imaging modalities: PL, EL, time-resolved PL (TRPL), and time-resolved EL (TREL). Using a confocal microscope to characterise an OLED's spectral and time-resolved properties provides much greater detail than bulk measurements. Figure 1

Preliminary analysis on the characteristics of stamps by 3D printing and their stamped impression

The development of 3D printing technology has brought new risks and challenges to stamp impression identification. To prevent potential risks, a total of 45 stamps were printed using three types of 3D printers: fused deposition molding (FDM) printer, stereo lithography (SLA) printer, and liquid crystal display (LCD)-based SLA 3D printer, including 6 stamps replicated using LCD-based SLA 3D printer. A preliminary study was conducted on the printed stamps and stamped impressions, and the results showed that stamp are influenced by various factors such as printer type, printing material, the technology level of the producer, mold parameters such as font, size, printing parameters, slicing direction, and polishing process, etc., resulting in significant differences in characteristics. However, there are some obviously common characteristics such as missing of strokes, exposure of white and mottled phenomenon in the impression stamped by the 3D produced stamp. The impression of stamp replicated with an LCD 3D printer can be easily identified since it is difficult to achieve consistency with the real impression in detail characteristics.

Optimizing the separation process for improved zirconia molding through liquid crystal display 3D printing

Mask stereolithography 3D printing for zirconia ceramics has attracted increasing attention in the industrial manufacturing due to their advantages of complex shapes, precisely controlled internal structures and fine surface effects. However, high refractive index and expensive equipment cost have always affected its development. Herein, we combine liquid crystal display (LCD) light curing 3D printing with zirconia molding, which is free from environmental and price limitations. In the conventional method of operation, the cured layer is bonded to the bottom and cannot be manufactured. We put forward a strategy for optimizing separation process and investigate the mechanism of the separation process in depth for high-quality zirconia ceramics LCD 3D printing. The results show that the controlled adjustment of the surface free energy can achieve a great reduction in the separation force, which enabled the successful printing of zirconia ceramics based on LCD. The effect of physical properties of the separation membrane on the separation process was studied and the solid content and 3D printing parameters of ceramic paste were optimized. When the solid content is 72.5 wt%, high quality zirconia ceramic parts with flexural strength of 255 MPa and relative density of 98.1 % can be obtained. This work provides new ideas for the convenient customization of zirconia ceramics in many fields.

3D-Printed Melatonin Tablets with Braille Motifs for the Visually Impaired.

An innovative approach for creating customized dosage forms and supporting patient populations with specific requirements who need additional support to improve drug adherence is 3D printing. This work introduces liquid crystal display (LCD) 3D printing as a means of developing melatonin (MLT) tablets. For patients who are blind or visually challenged, Braille patterns were displayed on the tablet surface in addition to the optimization of printing hydrogel inks. Owing to the great printing accuracy, blind patients could validate the Braille patterns that provided the required information. Upon further examination MLT was found to be present in the photopolymerized resins in an amorphous state. The choice of poly(ethylene glycol)-diacrylate (PEGDA) with varying molecular weights and the inclusion of surfactants or solubilizers interfered with the photopolymerization of the resin, hence controlling the rates of MLT dissolution towards the sought sustained release. Nuclear magnetic resonance (NMR) analysis showed that photopolymerization of the PEGDA resins in the printed dosage forms has taken place. A small batch scale-up investigation showed that LCDs could print a significant number of tablets quickly-about twenty-four minutes.

Internet of things-based rice field irrigation evaporation monitoring system

The urgency for efficient irrigation in Indonesia’s agriculture sector, particularly in paddy fields, is evident. However, existing methods for monitoring water levels are antiquated, often requiring manual measurements with a ruler. This research introduces a comprehensive “monitoring system for light intensity and water temperature as an analysis of evaporation for rice irrigation based on the internet of things”. The system integrates various sensors an anemometer for wind speed, an ultrasonic sensor for water level, a DS18B20 waterproof sensor for water temperature, and a GY-8511 sensor for sunlight intensity. All data are collected by an Arduino Mega controller, connected to an ESP32 for transmitting the readings to the Blynk app and an I2C 20×4 liquid crystal display (LCD) screen. The control mechanism employs a closed-loop system with a direct current (DC) motor actuator to operate the water gate, which can also be manually controlled via a cellphone. The system effectively meets daily evapotranspiration requirements of 1.44 mm, with optimal conditions yielding water levels of 3 cm, water temperatures of 38.53 °C, sunlight intensity of 4.59 mW/cm², and wind speed of 0.21 m/s.