Performance Of Liquid Crystal Display Research Articles

P‐193: Ring‐shaped circular Patch liquid crystal display structure based on fringe field effect

The liquid crystal display (LCD) continues to hold a prominent position in the display industry. These years' key research topic is the fringe field effect, which aims to improve the LCD's performance. A new LCD structure utilizing the fringe field effect has been identified as a promising solution. This structure allows for the control of the electromagnetic field of the liquid crystal cell by regulating the voltage of the ring‐shaped and circular‐patch cell (RCC). This innovative structure is comprised of nematic liquid crystals (LCs) with negative dielectric anisotropy, a two‐electrode system consisting of a ring‐shaped ITO structure on the top layer and a circular patch structure on the bottom layer, and a SiO2 porous structure. Finite element simulation tests have verified the electric field strength, transmittance, and contrast of the cell and the 2x2 matrix structure, meeting the design objectives. This breakthrough has significant potential for application in the display field.

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.

Ultralow Power Consumption Liquid Crystal Display Retaining Superior Image Qualities

AbstractGlobal energy policies have urged power consumption reductions for electronic devices. However, this is inconsistent with the users' need for enhanced device performance. In this work, converse flexoelectricity is used to reduce power consumption while maintaining the superior display image quality of liquid crystal display (LCD). The first 1 Hz‐refresh‐rate and flicker‐free fringe‐field switching (FFS) LCD for a 13.4‐inch laptop are reported. A noticeable brightness deviation is inevitable when driving voltage polarity is altered during low‐frequency driving, which is caused by the flexoelectric effect and voltage‐holding failure. The nature of the converse flexoelectric contribution of mesogenic systems with the optimum flexoelectric coefficients and molecular polarity, and developed materials based on findings is investigated. The quality of static images and videos at 1‐ and 10 Hz refresh rates, respectively, is maintained, and the measured power consumptions are reduced by 83% and 47% compared to that at a 60 Hz refresh rate, and minimal flicker level is measured by −68 dB. It is believed that this will serve as a new paradigm for energy consumption in electronic devices with superior display performance of FFS LCDs.

Temperature dependence of dynamic response of liquid crystal materials

Most properties of liquid crystal (LC) materials will change with the change of temperature, which makes the performance of liquid crystal display (LCD) and other devices change. However, at low temperature, the properties of LC will mutate with the decrease of temperature, which directly leads to the defects of LC devices. This paper makes use of the developed homemade temperature control device to realize the construction of high temperature to low temperature environment, using precision LCR meter (Agilent E4980A) and self-built optical path, combined with LC cell capacitance model and dual-cell model, the dynamic response properties of LC materials with temperature change law was explored. The results show that the decay time τ d of the LC with positive dielectric anisotropy increases from 12.04 ms to 159.7 ms, and the rotational viscosity coefficient γ 1 increases exponentially from 12.04 mPa·s to 1582.45 mPa·s. While τ d of the LC with negative dielectric anisotropy increases from 13.10 ms to 408.1 ms, γ 1 also increases exponentially from 162.73 mPa·s to 7903.69 mPa·s. The conclusions presented in this paper provide some guidance for the improvement of low temperature properties of LC.

Achieving a wide color gamut based on polarization interference filters in a liquid crystal display.

We propose two polarization interference filters (PIF1 and PIF2) used in the backlight unit of a liquid crystal display (LCD) to achieve a wide color gamut. Both PIF1 and PIF2 consist of two polarizers and two 720° super twisted nematic liquid crystal polymer (LCP) layers, where two polarizers are crossed in PIF1, and two polarizers are parallel in PIF2. The PIFs can eliminate unwanted cyan and yellow parts in the output spectrum, which can improve the color gamut of LCD. In our calculation, when the PIF1 is employed in the LCD with normal color filter and QD-LED backlight, the color gamut increases from 107.3% NTSC to 124.6% NTSC, which is 13.7% NTSC larger than that of the LCD with high-performance color filter. When the PIF2 is employed in the LCD with normal color filter and QD-LED backlight, the color gamut of LCD with a normal color filter is improved by 6.8% NTSC larger than that of LCD with high-performance color film, and the transfer efficiency is close to that of the LCD with high-performance color film. We define the color gamut enhancement ratio (CGER) to compare the influence of PIFs and the high-performance color filter on the color gamut enhancement performance of LCD. Compared with the high-performance color filter, the two kinds of PIFs have a higher CGER. The PIFs have a great potential for achieving a wide color gamut.

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.

3.1: Invited Paper: Electrowetting display: Towards full‐color video reflective display

Current mainstream display technologies include liquid crystal displays (LCD), Organic Light‐Emitting Diode (OLED), and electrophoretic paper displays (EPD). The electrowetting display (EWD) is expected to become a new member of the display family due to its fast response speed, paper‐like reflective display. In recent years, technology breakthroughs of electrowetting have been made in EWD. EWD has achieved playing dynamic videos with the comparable performance of LCD and displays print‐level color images. The current EWD has reached the color gamut NTS 50%, refresh time 12ms, and 260000 colors display. The potential applications of EWD including education, mobile terminals, e‐book readers, outdoor billboards, etc. The advantage of EWD will create new markets which are not accessible now.

Fabrication of TiO2-Embedded Polyimide Layer with High Transmittance and Improved Reliability for Liquid Crystal Displays.

Construction of liquid crystal (LC) alignment by introducing polyimide (PI) to indium tin oxide (ITO) electrodes is one of the main methods to realize high-resolution images in liquid crystal displays (LCD). However, the loss of transmittance caused by the difference in refractive index between ITO and PI leads to direct degradation of LCD performance. Thus, we herein fabricated a functional hybrid PI alignment layer that reduces the difference in refractive index and greatly increases the transmittance of the device by introducing inorganic titanium dioxide (TiO2) nanoparticles (NP) to the organic PI. The highly refractive TiO2 NPs were surface-treated with stearic acid comprising long alkyl chains to improve their dispersibility and uniformly dispersed in the PI matrix by simply stirring the mixture. The hybrid PI mixture was spin-coated on the ITO substrate, and the resulting LC cell exhibited excellent electro-optical properties. In addition, the reliability of the LC cells was enhanced by the inclusion of the TiO2 NPs, which was confirmed through the evaluation of voltage holding ratio, residual direct current, and LC cell reliability. Overall, functional hybrid PI can be used in advanced display technology for next-generation LC devices that require high transmittance and reliability.

Emerging Perovskite Nanocrystals-Enhanced Solid-State Lighting and Liquid-Crystal Displays

Recent advances in perovskite nanocrystals-enhanced solid-state lighting (SSL) and liquid-crystal displays (LCDs) are reviewed. We first discuss the development, optical properties, and stability issue of materials, and then we evaluate the performance of SSL and LCDs with perovskite downconverters adopted. In SSL performance evaluation, we investigate the fitting-curve effect in calculations and optimizations where simple Gaussian fitting and precise fitting are compared in detail, and we further optimize for highly efficient, good color-rendering, and human-healthy SSL sources. For LCD performance evaluation, we study the intrinsic tradeoffs between total light efficiency and color gamut coverage. Through optimizations using real line shapes, Rec. 2020 standard coverage as large as 92.8% can be achieved through hybrid integration. Finally, we briefly discuss two future challenges: materials development and device integration. We believe the emerging perovskite nanocrystals are highly promising for next-generation SSL and LCDs.

Advanced liquid crystal displays with supreme image qualities

ABSTRACT‘LCD vs. OLED: who wins?’ is a heated debatable question. Each technology has its own pros and cons. We review recent advances in liquid crystal displays (LCDs) from three performance metrics: response time, contrast ratio, and viewing angle, which determine the final-perceived image quality. To enhance LCD performance, ultra-low viscosity materials, quantum dots, and new device structures have been explored, and their working mechanisms investigated. Another round of LCD innovation is around the corner.

Assessment Tool of Image Quality for Medical Liquid-crystal Displays Using Commercially Available Digital Cameras

We developed a simplified tool for measuring image quality of medical liquid-crystal displays (LCDs) using a commercially available color digital camera. This tool implemented as a plug-in software for ImageJ (open-source image processing program) was designed to compute modulation transfer functions (MTFs) and Wiener spectra (WS) of monochrome and color LCDs from LCD photographed images captured by a camera. The intensities of the red (R), green (G), and blue (B) signals of the unprocessed image data depend on the spectral sensitivity of the image sensor used in the camera. In order to evaluate image quality based on LCD luminance, the plug-in software calibrates the RGB signals from the camera using measured luminance of the LCD and converts them into grayscale signals that correspond to the luminance of the LCD. The MTFs and WS are determined based on the line response from a one-pixel line image and the one-dimensional noise profiles acquired by scanning the uniform image using numerically synthesized slit, respectively. With this plug-in software for ImageJ, we are able to readily compute MTFs and WS of both monochrome and color LCDs from unprocessed image data of cameras. Our simplified tool is helpful to evaluate and understand the physical performance of LCDs for a large number of display users in hospitals and medical centers.

Line‐time optimization technology for ultra‐large and high‐resolution liquid crystal displays

AbstractThis paper proposes a line‐time optimization (LTO) technology for ultra‐large and high‐resolution liquid crystal display (LCD) televisions. Line‐time optimization enables a single‐bank data driver configuration without severe image degradation. When the proposed method is applied to an ultra‐high‐definition (UHD) LCD with a single‐bank data driver scheme, the LCD performance comparable to that of a dual‐bank data driver method can be obtained. The implementation of the proposed method helps in achieving desirable goals such as a reduction in the number of drivers and realization of a much more flexible design of UHD LCDs.

Tailoring the light distribution of liquid crystal display with freeform engineered diffuser.

We propose a versatile design approach of engineered diffuser based on freeform optics that can tailor the light distribution of a liquid crystal display (LCD) to meet different applications. The proposed LCD system consists of a quasi-directional backlight, liquid crystal panel, and an engineered diffuser. It offers high efficiency, wide view, high contrast, as well as low ambient light reflection. For large size LCDs, we design a wide view diffuser to match the light distribution with state-of-the-art organic light emitting diode (OLED) TV. For mobile displays, we design a diffuser to replicate current LCD performance. Our design can also provide flattop light intensity distribution for privacy protection. These exemplary designs prove that our engineered diffuser is versatile for different applications.

液晶显示器广色域技术的研究

To resolve the problem of poor color performance of liquid crystal display,the main factors which affect the color gamut were researched from the principle. The affects of the color filter thickness,LED light source spectrum and quantum dot materials were verified by experiments. The color gamut is increased 8% by thickening the color filter and raised to more than 85% NTSC by changing the LED light source spectrum. By using quantum dot material,the color gamut raises to more than 100% NTSC.

Improvement of the Performance of Liquid Crystal Displays by Doping with Supramolecule‐Protected Metal Nanoparticles

AbstractMetal nanoparticles are now creating a new class of materials that are different from either conventional bulk materials or atoms, giving one of the smallest building blocks of matter. Metal nanoparticles have various properties based on high surface area and quantum size effects. Here we focus on the application of metal nanoparticles to liquid crystal displays, which is providing a new field in science and technology. The doping of nanoparticles into liquid crystal materials induces the modification of almost all of the physical properties of the liquid crystal, causing a reduction in the response time of liquid crystal displays. These techniques may be an alternative approach for improving the properties of liquid crystals other than chemical synthesis.

Comparison of viewing angle and observer performances in different types of liquid-crystal display monitors

It is known that the performance of liquid-crystal display (LCD) monitors, such as the luminance and contrast ratio, is dependent on the viewing angle. Our purpose in this study was to compare the angular performance and the effect on observer performance of different types of LCD monitors. The luminance performance and contrast ratio as a function of viewing angle (-60 degrees to 60 degrees) in each direction for two types of LCD monitors, namely, a general-purpose LCD monitor and one especially designed for medical use, were measured in this study. Furthermore, the observer performance at various viewing angles in the horizontal direction for a medical-grade LCD monitor was investigated by eight observers based on a contrast-detail diagram. The two types of LCD monitors showed notable variations in luminance and contrast ratio as a function of the viewing angle. Acceptable viewing angles in terms of the contrast ratio were much smaller in each direction than those for nominal viewing angles in the specifications provided by the manufacturers, and those for the medical-grade LCD monitor in the horizontal and vertical directions were broader than those of the general-purpose LCD monitor. There was no significant difference in observer performance between 0 degrees and 40 degrees. On the other hand, our results showed a statistically significant difference in observer performance between 0 degrees and 60 degrees.

Wavelength-dependent diffraction patterns from a liquid crystal display

Liquid crystal displays (LCDs) are invaluable for a variety of optical applications, including the encoding of programmable diffractive optical elements. The pixel structure in these devices produces a set of diffracted orders of which the central order is the strongest. In most devices that we have examined, the intensity distribution of the diffraction pattern is independent of the wavelength of the illuminating light. Recently we have been examining the performance of LCDs having very small pixel sizes. We compare results for two devices from the same manufacturer. One of them exhibits the normal behavior. For the other, we find surprisingly strong wavelength dependence. The diffraction pattern varies from having most of the energy in the zero order for long wavelengths to having the energy distributed among 50-60 orders as the wavelength decreases. We attribute this behavior to a phase structure over each pixel. We analyze this behavior using a simple two-dimensional model that qualitatively explains the phenomenon. These results can be viewed in two ways--on the positive side this behavior might lead to optical logic or fan-out applications. On the negative side, there is less intensity available in the normally used zero order.

SU‐GG‐I‐55: Comparison of Viewing Angle Performance and Observer Performance of Different Types of Liquid Crystal Displays

Purpose: Liquid crystal displays (LCDs) have a number of advantages over cathode ray tubes and conventional viewers based on film. However, it is nown that the performance of LCDs varies by viewing angle. The purpose of this study was to compare the angular performance and effects on observer performance in different types of LCDs, namely a general purpose LCD for personal computers and one especially designed for medical use. Method and Materials: Two types of LCDs were used in this study, an in‐plane switching (IPS) technology display especially designed for medical use and a general‐purpose twisted nematic (TN) technology display. We measured the luminance responses and contrast ratios for the two types of LCDs at different viewing angles (−60 degrees to 60 degrees). Furthermore, observer performance at various viewing angles in the horizontal direction for the medical display was also examined by eight observers based on contrast‐detail diagrams. Results: The two types of LCDs showed notable variations in luminance and contrast ratios as a function of the viewing angle. Results obtained in different directions (horizontal, vertical and diagonal directions) indicated different contrast ratios. Acceptable viewing angles in terms of the contrast ratio were much smaller in each direction than those for nominal viewing angles in the specifications provided by the manufacturers. Acceptable viewing angles of the medical‐grade display in the horizontal and vertical directions were broader than those of the general purpose display. There was no significant difference in observer performance between 0 and 40 degrees. On the other hand, our results showed a statistically significant difference in observer performance between 0 and 60 degrees. Conclusion: Contrast ratio and luminance response showed notable variations with different viewing angles and different types of LCD. More importantly, the detection of contrast‐detail materials of the LCD monitor was influenced by viewing angles.

The World of Liquid-Crystal Display TVs—Past, Present, and Future

The full-fledge development for liquid-crystal display (LCD) technologies began aiming to achieve a ldquowall-mounting TVrdquo in the 1960 s. Since then, it has been more than 30 years from the birth of LCD product, the market of LCDs has grown above 10 billion dollars, and in the future, it is expected to further expand at a fast pace. The driving force in the current marketplace will be the original goal, ldquoLCD TVs,rdquo which contribute to drastically improving display performance of LCD and the evolution of LCDs. This paper, therefore, will focus on the LCD-TVs, and describe their history, the state-of-the-art of the technologies, as well as the prospect of their potential in the future.

Competing display technologies for the best image performance

Abstract— Cathode‐ray tubes (CRTs) have been the dominant display technology for years, having the best image performance and low cost. During the last several years, flat‐panel‐display technologies, such as liquid‐crystal displays (LCDs), began to replace the CRT mainly because of its favorable form factor. Today, the image performance of LCDs are equal to that of a CRT, and attractive flat‐display products have become so affordable that they have replaced the CRT from its dominating market position and have obtained the largest market share. In the past, the CRT set the standards for digital imaging technologies, but today, modern image capturing, storage, transport, signal processing, and printing technologies have improved to such high levels that they demand better display technologies and standards. At present, the LCD is at the forefront of this display‐technology evolution. This paper will focus on the latest image‐quality improvements in LCD technology and briefly touch alternatives such as plasma‐display panels (PDP) and microdisplay projection. Special attention will be given to the latest developments in wide‐color‐gamut technologies and methods to reproduce accurate colors within a display device.