Liquid Crystal Display Technology Research Articles

Development of Additively Manufactured Embedded Ceramic Temperature Sensors via Vat Photopolymerization

Current additive manufacturing (AM) techniques and methods, such as liquid-crystal display (LCD) vat photopolymerization, offer a wide variety of surface-sensing solutions, but customizable internal sensing is both scarce in presence and narrow in scope. In this work, a fabrication process for novel customizable embedded ceramic temperature sensors is investigated. The fabrication techniques and materials are evaluated, followed by extensive characterization via spectral analysis and thermomechanical testing. The findings indicate that LCD-manufactured ceramic sensors exhibit promising sensing properties, including strong linear thermal sensitivity of 0.23% per °C, with an R2 of at least 0.97, and mechanical strength, with a hardness of 570 HV, making them suitable for adverse environmental conditions. This research not only advances the field of AM for sensor development but also highlights the potential of LCD technology in rapidly producing reliable and efficient ceramic temperature sensors.

On the Feasibility of an LCD-Based Real-Time Converter for Ionizing Radiation Imaging.

Here we present the cascade converter (CC), which provides real-time imaging of ionizing radiation (IoR) distribution. It was designed and manufactured with the simplest architecture, utilizing liquid crystal display (LCD) technology. Based on two merged substrates with transparent electrodes, armed with functional layers, with the cell filled with nematic liquid crystal, a display-like, IoR-stimulated CC was achieved. The CC comprises low-absorbing polymer substrates (made of polyethylene terephthalate-PET) armed with a transparent ITO electrode covered with a thin semipermeable membrane of polymer (biphenylperfluorocyclobutyl: BP-PFCB) doped with functional nanoparticles (NPs) of Lu2O3:Eu. This stack was covered with a photoconductive layer of α-Se and finally with a thin polyimide (PI) layer for liquid crystal alignment. The opposite substrate was made of LCD-type glass with ITO and polyimide aligning layers. Both substrates form a cell with a twisted structure of nematic liquid crystal (TN) driven with an effective electric field Eeff. An effective electric field driving TN structure is generated with a sum of (1) a bias voltage VBIAS applied to ITO transparent electrodes and (2) the photogenerated additional voltage VXray induced between ITO and α-Se layers with a NPs-doped BP-PFCB polymer layer in-between. The IoR (here, X-ray) conversion into real imaging of the IoR distribution was achieved in the following stages: (1) conversion of IoR distribution into non-ionizing red light emitted with functional NPs, (2) transformation of red light into an electric charge distributed in a layer of the photoconductive α-Se, which is what results in the generation of distributed voltage VXray, and (3) a voltage-mediated, distributed switching of the TN structure observed with the naked eye. The presented imaging device is characterized by a simple structure and a simple manufacturing process, with the potential for use as a portable element of IoR detection and as a dosimeter.

P‐178: Improve the response time of LCD and expand applications at low temperature

With the requirements for applications in extremely cold environments, LCD (Liquid Crystal Display) technology, limited by the properties of liquid crystal materials, exhibits poor image quality, especially when displaying rapidly changing images at low temperatures. Therefore, improving the response time at low temperatures is a key issue. In this paper, we have designed a heating circuit for the LCD. This circuit is controlled by an internal sensor, which improves the LCD's performance at low temperatures. Experimental results show that the internal sensor can provide feedback within a range of ‐50℃ to 150℃. The Gray‐ to‐Gray (GtoG) response time can reach 100ms at ‐40℃, greatly enhancing the competitiveness of LCD technology.

Assessment of the Development Performance of Additive Manufacturing VPP Parts Using Digital Light Processing (DLP) and Liquid Crystal Display (LCD) Technologies

Non-metallic additive manufacturing technology has seen a substantial improvement in the precision of the parts it produces. Its capability to achieve complex geometries and very small dimensions makes it suitable for integration into strategic industrial sectors, such as aeronautics and medicine. Among additive manufacturing technologies, resin development processes demonstrate enhanced precision when compared to other methods, like filament printing. This study conducts a comparative analysis between digital light processing (DLP) and liquid crystal display (LCD) photopolymerization processes to assess the performance of the technologies and how process parameters affect the accuracy of the resulting parts. The research evaluates the impact of the discretization process used during the digital model export, determining the optimal mesh size and then analyzing the geometric deviations that occur by altering various operating parameters of the process. Statistical methods will be employed to identify the most significant parameters in the manufacturing process. Among other aspects, the precision of manufacturing technologies regarding the movement axis has also been evaluated. Regarding the minimum size of the features that can be fabricated, DLP technology has surpassed LCD technology, successfully producing features as small as 200 µm, compared to 500 µm for LCD technology.

Application of Liquid Crystal Display Technologies to Dye-Sensitized Solar Cell

Application of Liquid Crystal Display Technologies to Dye-Sensitized Solar Cell

E-book with Animation Playing Capability Based on Liquid Crystal Display Technology

E-book with Animation Playing Capability Based on Liquid Crystal Display Technology

Studying the combined effect of layer thickness and solid loading percentage for improving the compressive strength of 3D printed β-TCP scaffold by LCD technique

Customized 3D printed bio-ceramic scaffolds with complex shapes can be fabricated by Liquid Crystal Display (LCD) technology. In this study we investigated the combined effect of the solid loading percentage of the β-Tricalcium phosphate (β-TCP) bio-ceramic powder and the 3D printing layer thickness on the compressive strength of the 3D printed bio-ceramic scaffolds using LCD technique. Three different high solid loadings (40, 60 and 80 vol%) of β-TCP were mixed with resin in the presence of Oleic acid prior to the 3D printing. The β-TCP:resin slurry was used to fabricate scaffolds by using three different layer thicknesses (50 μm, 100 μm and 150 μm). The 3D printed green scaffolds were thermally debinded at 530 °C for 8 h and sintered at 1000 °C for 6 h based on the TGA and DSC thermal analysis of the β-TCP-resin slurry. The x-ray diffraction (XRD) and the Fourier transform infrared (FTIR) spectroscopy analysis confirmed that the β-TCP structure is preserved after scaffold fabrication. The Scanning Electron Microscopy (SEM) analysis showed the surface morphology of the scaffolds with internal pores, micro porosity, and localized delamination. The main finding of the results suggests that decreasing the layer thickness and the solid loading will enhance the compressive strength of the scaffold. Maximum compressive strength attained was (0.19 ± 0.01 MPa) for scaffolds with 40 % solid loadings, layer thickness of 50 μm and porosity 83.49 %. These results demonstrate the potential of using the low-cost LCD 3D printing in fabricating a customized porous β-TCP scaffolds for bone tissue engineering.

Synthesis and characterization of functional thermoresponsive photoactive copolymers and study of their thermal and photoluminescence properties

ABSTRACT Poly(N-isopropyl acrylamide-co-disperse yellow 7 methacrylate) (PNIPAM) copolymers were synthesized by radical polymerization of N-isopropyl acrylamide with disperse yellow 7 methacrylate using 2,2/-Azo-bis-isobutyronitrile (AIBN) as an initiator. N-isopropyl acrylamide is a thermoresponsive monomer, and disperse yellow 7 methacrylate is a photoactive monomer. The synthesized photoactive and thermoresponsive copolymers were characterized by FTIR, NMR, and UV-Vis spectrophotometer with a temperature variation. A proton NMR signal at 8.16 ppm is observed for aromatic protons surrounded by an azo (-N=N-) group. The peak that appeared at 4.0 ppm is due to the CH-CONH group. The amide group proton of CONH appeared at 8.16 ppm. The molecular weights of homopolymers (like PNIPAM and PDY7MA) and their copolymers (PNIPDY) were observed to be 104 and 103 Da, respectively. The optical band gaps for synthesized copolymers, PNIPDY-1B, PNIPDY-2B, and PNIPDY-3B, are 2.98 eV, 2.95 eV, and 2.91 eV, respectively. The multiple emission spectra were observed at 407 nm, 428 nm, and 460 nm for the excitation energy of 365 nm due to the n-π* and π-π* transitions of the azobenzene chromophore. Thermal properties were also studied using TGA analysis. Stimuli-responsive polymers are widely used in optoelectronics and photonics, such as optical switching, optical information storage devices, liquid crystal display technology, and diffractive optical elements.

Prediction of Cellular Structure Mechanical Properties with the Geometry of Triply Periodic Minimal Surfaces (TPMS).

The paper investigates the physical and mechanical properties of structures with the geometry of triply periodic minimal surfaces (TPMS). Test samples were made from polyamide using SLS (selective laser sintering) 3D printing technology, from polylactide using FDM (Fused deposition modeling) 3D printing technology, and from a photopolymer based on acrylates using LCD (liquid crystal display) technology; samples were made in the form of a cube with edge size 30 mm. The strength and energy-absorbing properties of TPMS-based cellular samples have been determined. To analyze the features of the geometry of the samples, the skeletal graph method was used. It is shown that this approach makes it possible to predict the physical and mechanical characteristics of products with TPMS geometry.

3‐2: Integration of Dye‐Sensitized Solar Cell and Liquid Crystal Display Technologies.

We introduce the dye‐sensitized solar cell (DSSC) integrated by the Liquid Crystal Display (LCD) technology, which called LC‐LH (Liquid and Crystal ‐ Light Harvesting). We show that LC‐LH is a device that achieves both low cost and high conversion efficiency, and could enable further expansion of the market.

88‐1: E‐book with Animation Playing Capability Based on Liquid Crystal Display Technology

Electronic ink (E‐ink) displays have become increasingly popular in e‐books due to their paper‐like appearance, readability in direct sunlight, low power consumption, and flexible sizing. However, the slow switching speed of bistable LCDs and E‐ink limits their ability to play animations. This paper proposes a novel method for fabricating fast‐ switching bistable liquid crystal displays capable of playing animations. The research is based on a new type of bistable LCD technology that achieves lower driving voltages than existing E‐ink displays. The research team has significant experience developing bistable displays and has invented many new technologies in their laboratory. The proposed technology combines the benefits of bistable displays with the ability to play animations, a significant advancement in display technology.

Pixelated Photonic Crystals

Photonic crystals can prevent or allow light of certain frequencies to propagate in distinct directions in anomalous and useful ways for use as waveguides, laser cavities, and topological light propagation. However, there exist limited approaches for fundamental reconfiguration of photonic crystals, such as changing the unit cell to various and on‐demand geometries and symmetries. This work introduces the concept of pixelated 2D photonic crystals where the variability of the dielectric profile is achieved by a pixelated matrix of the material. Specifically, the cross sections of dielectric cylindrical pillars distributed in a photonic crystal lattice are replaced with pixelated circles using different resolutions and the corresponding band diagrams are calculated. The comparison to the band diagrams of the original structure shows that the original—and today typically used—cylindrical design can be well approximated by as few as square switchable pixels while retaining less than change in the photonic band structure. Experimental realization of switchable pixelation is proposed based on the liquid crystal display (LCD) technology with high birefringence materials. More generally, the demonstrated approach to reconfigurable 2D photonic crystal based on switchable pixels can enable realization of diverse fundamentally reconfigurable advanced optical materials.

Survey of Mura Defect Detection in Liquid Crystal Displays Based on Machine Vision

Liquid crystal display (LCD) is a display device based on liquid crystal electro-optic effect, and LCDs have gradually appeared and have become an indispensable part of people’s lives. In the development of LCD technology, the detection of Mura defects is a key concern in the manufacturing process. The Mura defect is a kind of display defect with low contrast and an irregular shape. This study first explains the mechanism of Mura defects in the LCD manufacturing process and classifies typical Mura defects. Then, three main purposes for the defect detection of LCDs are compared, and the advantages and disadvantages are conducted. Following that, this research examines reviews the linked literature on image preprocessing, feature extraction, dimension reduction, and classifiers of Mura defects. Finally, the future development trend and research direction of Mura defect detection based on machine vision can be drawn by this study.

Physical Properties of Thermally Crosslinked Fluorinated Polyimide and Its Application to a Liquid Crystal Alignment Layer.

This study demonstrated the use of a thermally crosslinked polyimide (PI) for the liquid crystal (LC) alignment layer of an LC display (LCD) cell. Polyamic acid was prepared using 4,4′-oxydianiline (ODA) and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The 6FDA−ODA-based polyimide (PI) prepared by the thermal cyclic dehydration of the polyamic acid (PAA) was soluble in various polar solvents. After forming a thin film by mixing trifunctional epoxide [4-(oxiran-2-ylmethoxy)-N,N-bis(oxiran-2-ylmethyl)aniline] with the 6FDA−ODA-based PAA, it was confirmed that thermal curing at −110 °C caused an epoxy ring opening reaction, which could result in the formation of a networked polyimide not soluble in tetrahydrofuran. The crosslinked PI film showed a higher rigidity than the neat PI films, as measured by the elastic modulus. Furthermore, based on a dynamic mechanical analysis of the neat PI and crosslinked PI films, the glass transition temperatures (Tgs) were 217 and 339 °C, respectively, which provided further evidence of the formation of crosslinking by the addition of the epoxy reagent. After mechanical rubbing using these two PI films, an LC cell was fabricated using an anisotropic PI film as an LC alignment film. LC cells with crosslinked PI layers showed a high voltage holding ratio and low residual direct current voltage. This suggests that the crosslinked PI has good potential for use as an LC alignment layer material in advanced LCD technologies that require high performance and reliability.

P‐12.11: Researching on Wide Color Gamut of TV Products

Liquid crystal display technology is widely used because of its advantages of light weight, environmental protection and high performance. Compared with the emerging organic light‐emitting display, the color performance of liquid crystal display needs to be further improved. Increasing color saturation, displaying bright pictures and pursuing more realistic picture quality is a trend of the development of liquid crystal display technology.

Building a Display Field Leader: SKL's Journey

Building a Display Field Leader: SKL's Journey

P‐115: Contrast Ratio Analysis and Improvement of Transparent Waveguide Liquid Crystal Display

In recent years, the transparent waveguide liquid crystal display (WLCD) technology attracted a lot of attention for the high transmittance. To further improve the display performance, the contrast ratio was systematically optimized in this work. A coarse‐grained model based on Mie scattering was established to perform the limiting theoretical analysis of the contrast ratio of polymer‐stabilized liquid crystal devices. To improve the contrast ratio, we tried different material formulations and optimized the UV polymerization process, and also applied light shielding layer to suppress metal lines reflection. Finally, the contrast ratio can reach to 18:1. With these improvements and the advantage on transmittance, it is believed that the WLCD technology will be applied in various intelligent IoT systems in the near future.

Birth of the Innovative Overdrive Technology for Liquid Crystal: Paving the Way for Practical Use of LCD Televisions

This article describes our experience developing innovative display technologies with the aim of providing hints for researchers to break away from conventional wisdom. In the 1990s, we focused mainly on liquid crystal display (LCD) technologies for creating and developing the new flat-panel TV market, despite claims that the motion blur problem for LCD TVs could not be solved without materials featuring ultrafast response times. We then discovered that motion blur is not due to a binary response, as was commonly believed at the time, but rather a drastically degraded gray-level response and decreased driving voltage due to electrostatic capacity change according to dynamic rotation of liquid crystal molecules. On the basis of a novel image-lag mechanism, we invented the overdrive method to emphasize the voltage applied to the liquid crystal for only a certain period according to change in picture brightness for high-speed response LCD TVs. This overdrive technology is now a de facto standard technology for LCD TVs, though the time-to-market exceeded 13 years. This article describes why so much time was required and how many issues were resolved to realize this revolutionary innovation.

(Invited) Material Development and Equipment Improvement for 3D Gel Printing Using a Commercially-Available Stereolithography Printer

Hydrogels are known as a soft and water-rich material, and they are widely applied in the medical and industrial fields. On the other hand, when a liquid material is poured into a mold to make a gel, it is generally difficult to form a complicated shape due to the shape restriction included in the mold. To overcome this challenge, we have independently developed the 3D gel printer "SWIM-ER". This gel printing can make very complex structures that is unable to create by the hydrogel molding process. The our previous works includes soft robots for teaching, research, and surgical simulation and applications of 3D-printed organ models in hydrogel.However, it should be pointed out that due to the high economic cost, this printer is not popular. This study proposes an inexpensive gel printing technology using a commercially available stereolithography 3D printer equipped with liquid crystal display (LCD) or digital light processing (DLP) technology for UV irradiation. The price of a commercial 3D printer for general use ($500) is much cheaper than the price of a 3D gel printer. We have confirmed that our proposed method can perform three-dimensional modeling of gel by photopolymerization reaction under excitation of 405 nm. Figure 1

Preparation and Characterization of Semi-Alicyclic Polyimide Resins and the Derived Alignment Layers for Liquid Crystal Display Technology.

Uniform alignment of rigid-rod liquid crystal (LC) molecules under applied voltage is critical for achievement of high-quality display for thin-film transistor-driven liquid crystal display devices (TFT-LCDs). The polymeric components that can induce the alignment of randomly aligned LC molecules are called alignment layers (ALs). In the current work, a series of organo-soluble polyimide (SPI) ALs were designed and prepared from an alicyclic dianhydride, hydrogenated 3,3′,4,4′-biphenyltetracarboxylic dianhydride (HBPDA), and various aromatic diamines, including 4,4′-methylenedianiline (MDA) for SPI-1, 4,4′-aminodianiline (NDA) for SPI-2, 3,3′,5,5′-tetramethyl-4,4′-diaminodiphenylmethane (TMMDA) for SPI-3, and 3,3′-diethyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane (DMDEDA) for SPI-4. The derived SPI resins were all soluble in N-methyl-2-pyrrolidone (NMP). Four SPI alignment agents with the solid content of 6 wt.% were prepared by dissolving the SPI resins in the mixed solvent of NMP and butyl cellulose (BC) (NMP/BC = 80:20, weight ratio). Liquid crystal minicells were successfully fabricated using the developed SPI varnishes as the LC molecule alignment components. The SPI ALs showed good alignment ability for the LC molecules with the pretilt angles in the range of 1.58°–1.97°. The LC minicells exhibited good optoelectronic characteristics with voltage holding ratio (VHR) values higher than 96%. The good alignment ability of the SPI ALs is mainly attributed to the good comprehensive properties of the SPI layers, including high volume resistivity, high degree of imidization at the processing temperature (230 °C), good rubbing resistance, good thermal stability with glass transition temperatures (Tgs) higher than 260 °C, and excellent optical transparency with the transmittance higher than 97% at the wavelength of 550 nm.