Type Of Liquid Crystal Display Research Articles

Reflective blue phase liquid crystal display with triangular dielectric layer

ABSTRACT We propose a reflective blue-phase liquid-crystal display (LCD) with triangular dielectric layers and a diffuse reflector electrode. The triangular dielectric layers with a high dielectric coefficient on the top and bottom indium tin oxide glass substrates are equivalent to the conductive plates, forming a corrugated electrode structure. This type of reflective blue-phase LCD based on planar electrode and diffuse mirror electrode can offer relatively high reflectance (~74.5%) and low operation voltage (9.2 Vrms) compared to most other devices due to its fairly strong and uniform horizontal electric field component along the whole blue-phase liquid crystal bulk. This design has the advantages of fast response time, easy manufacturing process, a high resolution and full-colour capability. It is a promising future high-quality reflective full-colour microdisplay.

Study of the Operational Properties of Bistable Smectic-A Liquid Crystal Displays

Abstract Nowadays liquid crystal display (LCD) is an integral part of humans’ everyday life. High demand for new and innovative LCD products force LCD industry to develop and implement new types of LCDs. Bistable smectic-A (SmA) LCD is one of the most promising devices for smart glass applications due to long-term bistability, low haze at clear state, low transmittance at scatter state and low power consumption. The study describes the most relevant conclusions obtained from frequency response testing and electric current measurements of bistable SmA LCD samples. Bistable LCDs have two states: opaque (light scattering state) and focal conic (transparent state). Switching between clear and scatter states and vice versa is a frequency dependant process. The conducted research on bistable SmA LC frequency response provides important knowledge about operation principles of the smart glass devices.

Color‐by‐Blue QD‐Emissive LCD Enabled by Replacing RGB Color Filters with Narrow‐Band GR InP/ZnSeS/ZnS QD Films

AbstractColor‐by‐blue quantum dot (QD)‐emissive liquid‐crystal displays (LCDs) with eco‐friendly, green, red (GR) InP/ZnSeS/ZnS QD films are introduced to overcome the disadvantages of conventional color‐by‐white color filter (CF)‐assisted LCDs, such as a narrow viewing angle, low external device efficiency of these types of LCDs, and a restricted color gamut. In this study, the color‐by‐blue InP‐based QD‐emissive LCD consists of a blue (B) light‐emitting diode (LED) and GR InP‐based QD films sandwiched between a light recycling filter and a long‐wavelength pass dichroic filter. The GR InP‐based QDs are synthesized with a high photoluminescence quantum yield (>77%) and narrow bandwidth (<40 nm), which are suitable for display applications. The overall enhancement of InP‐based QD‐emissive LCDs, in this case by the enhanced efficiency of a blue LED backlight transmitted through the LC shutter compared to a white LED backlight and the improved efficiency of the enlarged color gamut, is 2.42 times that of a conventional red, green, and blue (RGB) CF‐LCD with a GR phosphor‐converted (pc)‐LED (a B LED + R K2SiF6:Mn + G β‐SiAlON:Eu phosphor) backlight. Therefore, this considerable enhancement of the external efficiency of a QD‐emissive LCD makes it more feasible as a replacement for conventional RGB CF‐assisted LCDs.

A consumer-grade LCD monitor for precise visual stimulation.

Because they were used for decades to present visual stimuli in psychophysical and psychophysiological studies, cathode ray tubes (CRTs) used to be the gold standard for stimulus presentation in vision research. Recently, as CRTs have become increasingly rare in the market, researchers have started using various types of liquid-crystal display (LCD) monitors as a replacement for CRTs. However, LCDs are typically not cost-effective when used in vision research and often cannot reach the full capacity of a high refresh rate. In this study we measured the temporal and spatial characteristics of a consumer-grade LCD, and the results suggested that a consumer-grade LCD can successfully meet all the technical demands in vision research. The tested LCD, working in a flash style like that of CRTs, demonstrated perfect consistency for initial latencies across locations, yet showed poor spatial uniformity and sluggishness in reaching the requested luminance within the first frame. After these drawbacks were addressed through software corrections, the candidate monitor showed performance comparable or superior to that of CRTs in terms of both spatial and temporal homogeneity. The proposed solution can be used as a replacement for CRTs in vision research.

Effect of Color Temperature on Color Scale Test Patterns in Medical Liquid-crystal Display Monitor

In Japan, medical liquid-crystal display (LCD) and general LCD monitors have color temperatures of 7500 and 6500 K, respectively. The differences in color temperature make it difficult for radiologists to judge whether the same color is being displayed on the monitor. Therefore, the radiologist may overlook lesions. We examined chromaticity on a color scale test pattern to determine the relationships between color temperature (6500-12,500 K) of the medical color LCD monitors, there are three types of fluorescent light and three types of illuminance LCD monitors. As the color temperature of the monitor increased, the variation in chromaticity for grayscale test patterns increased and those variations for the blue scale test patterns decreased in a dark room and at 600 lux. In addition, even if the color temperature of the monitor was changed, the variation in chromaticity showed no change under fluorescent lighting with light bulb color and daylight color. The results of this study will be useful for quality control and quality assurance of medical LCD monitors in terms of illuminance and color temperature of the monitor.

A study on the life of an innovative product using a Bayesian approach

In this paper, the life cycle of an innovative product is divided into three stages, where a nonhomogeneous Poisson process (NHPP) with a power law intensity function is employed to illustrate the entry process of rival firms in a competitive market. The effects of the competitors’ entry on the profits of the incumbent firm are taken into consideration, with an objective of deriving the optimal product life to maximize the incumbent’s profit. Furthermore, a case study of a new type of LCD (liquid–crystal display) TV is empirically investigated to examine the effectiveness of the proposed approach. The results of the posterior analysis suggest that the influence of the competitors’ entry on the optimal product life is overestimated in the prior analysis. The results of sensitivity analyses indicate that the effect of competition of the introduction and growth stages on the optimal product life is greater than that of the maturation stage on the optimal product life, which is subsequently greater than that of the decline stage on the optimal product life.

正規化順位法による解像度や表示色が異なる医用画像表示用液晶ディスプレイの評価

The purposes of this study were to evaluate the image quality of five types of liquid-crystal display (LCD) monitors by utilizing the normalized-rank approach and to investigate the effect of LCD monitor specifications, such as display colors, luminance, and resolution, on the evaluators' ranking. The LCD monitors used in this study were 2, 3 and 5 mega-pixel monochrome LCD monitors, and 2 and 3 mega-pixel color LCD monitors (Eizo Nanao Corporation). All LCD monitors were calibrated to the grayscale standard display function (GSDF) with different maximum luminance (recommended luminance) settings. Also, four kinds of radiographs were used for observer study based on the normalized-rank approach: three adult chest radiographs, three pediatric chest radiographs, three ankle joint radiographs, and four double-contrasted upper gastrointestinal radiographs. Ten radiological technologists participated in the observer study. Monochrome LCD monitors exhibited superior ranking with statistically significant differences (p<0.05) compared to color LCD monitors in all kinds of radiographs. The major difference between monochrome and color monitors was luminance. Therefore, it is considered that the luminance of LCD monitors affects observers' evaluations based on image quality. Moreover, in the case of radiographs that include high frequency image components, the monitor resolution also affects the evaluation. In clinical practice, it is necessary to optimize the luminance and choose appropriate LCD monitors for diagnostic images.

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.

WE-C-304A-10: The Impact of Powering Off On Calibration Status of Liquid Crystal Displays

Purpose: To investigate whether time in a powered off status impacts on the calibration status of two types of liquid crystal displays(LCDs). Method and materials: Two types of LCDs were examined (NEC multisync LCD 1830 [n=6] and Viewsonic 810b [n=8]). A total of 14 displays were examined before calibration, after calibration and after a time powered off. Displays were calibrated using a VeriLum calibration pod and associated software in accordance with the Digital Imaging and Communications in Medicine Part 14: Greyscale Standard Display Function (GSDF) standards. Displays were evaluated in terms of adherence to the GSDF using the Display Index (DI) and Luminance Confornance (LC) ratings obtained within the VeriLum software. Displays were assessed in a pre‐calibrated state and a post‐calibrated state at two separate time intervals. The time period between each assessment and for which monitors were off, was 5 months. Only in the initial assessment stage were the brightness and contrast levels of the displays manipulated to specified VeriLum levels. Minimum luminance was set to the lowest possible level between 0.1 – 1cd/m2 and maximum luminance set as close as possible to 100cd/m2 (82.04cd/m2 – 153.44cd/m2). Results: Statistically significant improvements were noted for both display types across all displays after calibration. After a powered off period calibration was checked and the DI ratings in 5 (36%) and LC ratings in 6 (43%) of the monitors demonstrated reduced performance by at least a single rating. Monitors were then re‐calibrated and performance measured. The DI in 4 (29%) and LC in 9 (64%) of the monitors improved and monitor variance was reduced. However, statistical analysis showed no improvement in performance after re‐calibration in the second stage. Conclusions: Re‐calibration after a powered off period, offers advantages in monitor calibration, performance and uniformity across displays.

Electrically Tunable and Dual-Wavelength Semiconductor Laser with a Liquid Crystal Display

An electrically tunable semiconductor laser with a liquid crystal display (LCD) and a commercially available laser diode is presented. We tested two types of LCD under strong laser light and, on the basis of the results, selected the supertwist-nematic (STN) LCD with a passive matrix. Tuning is achieved up to 5 nm by moving a single stripe pattern displayed on the LCD. The wavelength shifts in 0.553 nm/cell, which agrees well with the calculated resolution derived from the diffraction grating formula. Dual-wavelength oscillation is also achieved up to a wavelength separation of 4.62 nm using the double stripe pattern.

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.

High-resolution monochrome liquid crystal display versus efficient household colour liquid crystal display: comparison of their diagnostic performance with unenhanced CT images in focal liver lesions

This study compared the ability of an efficient household liquid crystal display (LCD) and a medical high-resolution LCD to detect small hepatic lesions on unenhanced computed tomography (CT) images. We obtained the images from 100 subjects who had undergone abdominal CT. They consisted of 41 patients with a single space-occupying lesion (SOL) in the liver and 59 control subjects with no SOL. Independently, five radiologists rated their confidence concerning the presence of hepatic SOLs on a continuous scale from 0 to 1. Receiver-operating characteristic (ROC) analysis was performed using the jackknife method using the program LABMRMC. We evaluated the differences in A(z) based on the 95% confidence intervals. The mean A(z) of the five observers was 0.9594 with the efficient household LCD vs. 0.9335 with the medical high-resolution LCD. The difference was -0.0422, and the 95% confidence interval was -0.1101 to 0.0257 (p=0.2203). There was no significant difference in the A(z) value between the two types of LCDs. The diagnostic performance with the household LCD was comparable to that with the high-resolution LCD, implying that the former type of LCD can be used to diagnose CT images.

Synthesis, Evaluation, and Selection of Parts Design Scheme in Supplier Involved Product Development

Taking into account the supplier involvement in the new product development (NPD), this article focuses on the synthesis evaluation, and selection of the part design scheme in part deployment process. The concepts of performance indicator (PI) and integrated performance indicators (IPI) are introduced to measure the performance of the part design scheme and product design scheme respectively. A two-layer fuzzy synthesis evaluation method is applied to assess the part design scheme in a supplier-involved new product development process. Combining the information of House of Quality (HoQ) and evaluation results of the part design scheme and taking into account the design budget, a 0–1 integer programming model is developed for selection of the parts combinatorial scheme in supplier-involved part deployment processes. A case study with a type of liquid crystal display (LCD) design in an Electronic Appliance Manufacturing Enterprise is also illustrated in the article.

Relative enhancement of near-UV emission from a low-pressure mercury-rare-gas discharge lamp, for an LCD backlighting application

A narrow band near-UV backlight source with application in a new type of liquid crystal display is described. The light source is a pulse driven, mercury-argon gas, low-pressure discharge lamp. Pulse driving and lamp filling conditions are described for a lamp for which the ratio of the radiant outputs at 365 and 254 nm is enhanced considerably compared with the same lamp when it is operated with a conventional ac ballast. Pulsed operation of the lamp is shown also to increase the absolute radiant output of the group of transitions near 365 nm compared with the respective radiant output power from the same lamp when it is operated with ac with the same total input power.

A New Projection Exposure Method Using a Liquid Crystal Display as a Switching Matrix in Place of a Reticle

A new concept of a projection exposure system is proposed. In the new system, a liquid crystal display (LCD) is used in place of a conventional reticle, and arbitrary patterns are introduced on the LCD by a computer keyboard. After investigating what types of LCDs are suitable, and what exposure contrast is obtained, a prototype test exposure bench is manufactured using a LCD panel that is detached from a notebook computer. The bench has a camera lens with F-numbers of 2.8–16 as a projection lens. The LCD dots are of size 263×263 µm2, and each dot includes red, green and blue filter cells. Patterns on the LCD are replicated onto the wafer on a scale of 1/14.3. It is clarified that a maximum contrast of 4.9 is obtained when blue and black designations are used as transparent and opaque cells respectively. Since color LCDs are composed by such red, green and blue cells, the transparent part cannot be stitched in the lateral direction. However, in the longitudinal direction, patterns are stitched quite smoothly, and quasi-arbitrary patterns are replicated successfully.

The process to make a ridge- and fringe-field multidomain structure using a photoimageable polymer for a wide viewing angle liquid crystal display application

Liquid crystal display (LCD) is very important in the computer industry and many other areas. However, the application of LCD is limited by its narrow viewing angle, compared with a cathode ray tube (CRT) display. In this article a new type of LCD [ridge- and fringe field multidomain homeotropic (RFFMH) LCD], is introduced. In RFFMH LCD, a transparent photoimageable polymer resist is applied to build ridges on each pixel to control the liquid crystal pretilt direction. This photolithographic step imparts a wider viewing angle and simpler LCD production process. In this article the detailed process of building the ridge structure is described, and the thermal stability and chemical resistance of this polymer are studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1197–1203, 1999

Viewing‐angle evaluation method for LCDs with gray‐scale images

Abstract— A new evaluation method of viewing‐angle characteristics for liquid‐crystal displays (LCDs) with gray‐scale images has been studied. In this method, reverse images, excessively dark images, and excessively bright images, which are a serious problem while displaying gray‐scale images, are evaluated quantitatively along with the display contrast ratio. The viewing‐angle characteristics of several types of LCDs are compared using this method.

液晶配向膜の合成と特性

Liquid-crystal display (LCD) is a device utilizing the electrooptic property of aligned liquid-crystal (LC), and LC molecules are aligned homogeneously by the alignment film. The most of alignment film now in use industrially is polyimide (PI) thin film which should be rubbed. The required properties for alignment film vary with the types of LCD, however the most important is to give LC molecules planer alignment and suitable pretilt angle. The planer alignment property is supported to be related with the strain of thin film surface by rubbing, and pretilt angle is supported to be related with the physical and chemical properties of thin film surface. The control of surface tension and moleculer structure of thin film surface can be achieved by several moleculer designs of PI, and, by use of these PI for alignment film, the control of pretilt angle can be achieved. This method is very important for the commercial production of STN-mode LCD.

Multicolored Liquid Crystal Displays

Basic principles applicable to color liquid crystal displays (LCDs) are summarized, and various types of color LCDs are reviewed. Among these LCDs, the one with microcolor layers of the three primary colors is most promising for general applicability. The characteristics, problems, and subjects for the future study of this LCD are summarized.