Requirements for large‐sized high‐resolution TFT‐LCDs

Abstract— A 22‐in. prototype TFT‐LCD with a resolution of 200 pixels per inch and wide‐viewing‐angle capability has been developed and its requirements in terms of screen quality and technology will be discussed. An in‐plane‐switching mode with dual‐domain structure, post‐spacers, and high‐resolution process were implemented to achieve superior front‐of‐screen quality. And, also, in order to improve reliability and productivity, we developed a new injection method for liquid crystals which enabled us to eliminate injection holes.     

Electrical models of TFT‐LCD panels for circuit simulations

Abstract— As thin‐film‐transistor liquid‐crystal‐display (TFT‐LCD) panels become larger and provide higher resolution, the propagation delay of the row and column lines, the voltage modulation of Vcom, and the response time of the liquid crystal affect the display images now more than in the past. It is more important to understand the electrical characteristics of TFT‐LCD panels these days. There are several commercial products that simulate the electrical and optical performance of TFT‐LCDs. Most of the simulators are made for panel designers. However, this research is for circuit, system, and panel designers. It is made in a SPICE and Cadence environment as a commercial circuit‐design tool. For circuit and system designers, it will help to design the circuit around a new driving method. Also, it can be easily modified for every situation. It also gives panel designers design concepts. This paper describes the electrical model of a 15‐in. XGA (1024 × 768) TFT‐LCD panel. The parasitic resistance and capacitance of the panel are obtained by 3‐D simulation of a subpixel. The accuracy of these data is verified by the measured values of an actual panel. The developed panel simulation platform, the equivalent circuit of a 1 5‐in. XGA panel, is simulated by HSPICE. The results of simulation are compared with those of experiment, according to changing the width of the OE signal. The proposed simulation platform for modeling TFT‐LCD panels can be especially applied to large‐sized LCD TVs. It can help panel and circuit designers to verify their ideas without making actual panels and circuits.     

An overview of product issues in wide‐viewing TFT‐LCDs

Abstract— Several TFT‐LCD devices exhibiting high image quality have been developed and commercialized, overcoming the narrow viewing‐angle characteristics of conventional twisted‐nematic (TN) devices. Nevertheless, no single device dominates large‐sized TFT‐LCDs. In this paper, the product issues of existing LC devices related to manufacturing process and performance are discussed.     

Current and future technology of low‐temperature poly‐Si TFT‐LCDs

Abstract— The state of the art of large‐area low‐temperature TFT‐LCDs will be reported in this paper. High‐performance poly‐Si TFTs are expected to realize various applications such as system display where various signal‐processing functions are added to the display. In the past few years, low‐temperature poly‐Si thin‐film‐transistor (LTPS TFT) technology has made great progress, especially in the areas of excimer laser annealing (ELA) of high‐quality poly‐Si film, ion doping for large‐area doping, and high‐quality gate SiO₂ film formation by using the low‐temperature PE‐CVD method. Also, technology trends and possible applications, such as a system displays, will be discussed.     

Optimization of low‐temperature poly‐Si TFT‐LCDs and a large‐scale production line for large glass substrates

Abstract— An update of the progress of inherently low‐temperature poly‐Si (LTPS) technologies, such as ELA, ion doping, and activation in conjunction with chemical vapor deposition (CVD) and photolithography will be given. We will also discuss whether LTPS LCDs will be applied to a large‐scale production line using a large motherglass substrate. It was found that a more‐powerful excimer laser as well as photolithography with higher‐resolution and a more‐precise overlaid arrangement would enable a large‐scale production line handling motherglass of 4th generation size to be constructed in the very near future with reasonable investment and productivity costs.     

Super‐large‐sized TFT‐LCD (55 in.) for HDTV application

Abstract— We have developed the world's largest TFT‐LCD, which has a 55‐in.‐diagonal size. This LCD features a 1920 × 1080 (16:9) resolution for full‐HDTV images, 500‐nit luminance, 72% color gamut, and 12‐msec response time at all gray levels. The size of the panel (55 in.) was determined by the maximum efficiency of our fifth‐generation line (glass size: 1100 × 1250 mm). To overcome the limitation of size in photolithography equipment, a new stitcking‐free technology was applied in both the TFT and color‐filter side. And the super‐IPS mode was used as a wide‐viewing‐angle technology because it is suitable in the fabrication of large panels. In this paper, we present issues on both the fabrication and characteristics of the 55‐in. TFT‐LCD.     

Design of dual‐outputs‐single‐stage a‐Si:H TFT gate driver for high resolution TFT‐LCD application

A new gate driver has been designed and fabricated by amorphous silicon technology. With utilizing the concept of sharing the noise free block in a single stage for gate driver, dual‐outputs signals could be generated in sequence. By increasing the number of output circuit block in proposed gate driver, number of outputs per stage could also be adding that improves the efficiency for area reduction. Besides, using single driving thin‐film‐transistor (TFT) for charging and discharging, the area of circuit is also decreased by diminishing the size of pulling down TFT. Moreover, the proposed gate driver has been successfully demonstrated in a 5.5‐inch Full HD (1080xRGBx1920) TFT‐liquid‐crystal display panel and passed reliability tests of the supporting foundry.     

Development of a 14.1‐in. UXGA TFT‐LCD using LTPS technology

A 14.1‐in. UXGA low‐temperature poly‐Si TFT‐LCD has been developed using p‐MOS technology. Both the peripheral driving circuits and the pixel switches are implemented using only p‐channel TFTs. The device performance for the driving circuits and the panel design issues, such as crosstalk and flicker, were investigated. The image quality required for the notebook‐PC display has been achieved by optimizing the panel design and by improving the device performance. In addition, the redundant gate driving structure has been developed to minimize the degradation of the panel yield.     

IGZO‐TFT technology for large‐screen 8K display

We succeeded in G8 factory for mass production of Indium–Gallium–Zink–Oxide thin‐film transistor (IGZO‐TFT) for the first time in the world. The initial TFT process was an etching stop‐type TFT, but now, we are mass producing channel etching‐type TFTs. And, its application range is smartphones, tablets, PCs, monitors, TV, and so on. In particular, because of recent demands for high‐resolution and narrow frame, our IGZO display has been advanced in technology development with gate driver in panel. In this paper, we report development combining low resistance technology and the latest IGZO‐TFT (IGZO5) for large‐screen 8K display.     

A 15‐in. XGA thresholdless antiferroelectric LCD addressed by TFTs and using the quasi‐dc driving method

Abstract— A 15‐in. TFT‐LCD with XGA resolution using thresholdless antiferroelectric liquid crystal (TLAF) has been developed. TLAF materials show V‐shaped switching and enable display of analog gray scale, wide viewing angle, and fast response. However, in the case that high‐resolution TFT‐LCDs using materials with large spontaneous polarization such as TLAF were driven by the conventional method, alternating current (ac) driving, the obtained contrast ratio was limited because of a sharp decline of holding voltage due to the growth of a depolarization field. In order to enhance the contrast ratio, a novel driving method referred to as quasi‐dc driving was proposed. In the quasi‐dc driving, the polarity of the applied voltage to liquid crystals inverts at certain intervals of several seconds. Moreover, the applied voltage and the charging time at the time of polarity inversion are increased more than the intended signals. By this method, the 15‐in. TFT‐LCD using TLAF with high contrast ratio (more than 100:1) and wide viewing angle was realized.     

A new driving method to compensate for row‐line signal‐propagation delays in an AMLCD

Abstract— The row‐line and data‐line that make up of a TFT‐LCD panel can be modeled as a distributed resistance and capacitance network. As TFT‐LCD panels become larger and provide higher resolution, the induced signal propagation delay time from the row and column lines become an appreciable part of the line time. In particular, the row signal‐propagation delay time is traditionally accommodated by waiting for the worst‐case propagation time before the start of a new line. This conventional method, however, reduces the subpixel charging time. A new driving method, Horizontal Line Delay Compensation (H‐LDC), has been implemented and verified to compensate for row‐line propagation delay. The benefit of longer subpixel charging time is of particular interest to large‐area high‐resolution fast‐refresh‐rate LCD TVs.     

Development of 100‐in. TFT‐LCDs for HDTV and public‐information‐display applications

Abstract— LCDs have achieved a full‐high‐definition resolution of 1920 × 1080 (16:9), 600‐nit brightness, 3000:1 dynamic contrast ratio, 92% color gamut, 178° viewing angle, and 5‐msec response time at all gray levels and are targeted for HDTV and public‐information‐display applications. Some unique technologies, such as Cu bus line, advanced wide view polarizer, and wide‐color‐gamut lamp, were applied. A new stitching‐free technology was developed to overcome the size limitation of the photomask in both the TFT and color‐filter processes. The size of the panel (100 in.), based on the wide format (16:9), is determined by the maximum efficiency of the world's first seventh‐generation line (glass size, 1950 × 2250 mm) in LG.Philips LCD's (LPL) Paju display cluster. The issues facing 100‐in. TFT‐LCDs will be discussed.     

Effects of localized warpage and stress on chip‐on‐glass packaging: Induced light‐leakage phenomenon in mid‐sized TFT‐LCD

Abstract— Mura defects become visible in a 13.3‐in. TFT‐LCD using chip‐on‐glass (COG) packaging when the thickness of the glass substrate is decreased from 0.5 to 0.3 mm. Mura, the non‐uniform brightness in LCDs, is caused by COG packaging due to the mismatch of the coefficient of thermal expansion (CTE) and Young's modulus between the glass substrate and the IC‐driver Si chips. In this paper, a 3‐D finite‐element‐analysis (FEA) model, coupled with transient thermal analysis is first established to examine the warpage and stress behavior in the upper‐glass‐plate post‐COG‐package processing for identifying the root causes of the light‐leakage phenomenon. Prior to that, the simulated warpage results are validated by surface‐contour measurement. Data and modeling results show that a low bonding temperature together with a low modulus in novel ACF materials can effectively eliminate Mura. Besides, thinner silicon or a shorter length of Si chips as drivers offers enhanced reduction in the localized warpage, and thus can be a practical and low‐cost solution for eliminating mura defects.     

Impact of sampling domain and number of samples on the accuracy of large‐signal multisine measurement‐based behavioral model

This article evaluates two alternative ways to execute the sampling of modulated data for large‐signal behavioral modeling. We show that the nonlinear metric domain uniform sampling outperforms the time‐domain uniform approach, and examine how the level of improvement depends on the number of samples used for model generation. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

The Relationships among Internal Marketing,Job Satisfaction,Relationship Marketing,Customer Orientation,and Organizational Performance: An Empirical Study of TFT‐LCD Companies in Taiwan

The thin film technology liquid‐crystal displays (TFT‐LCD) industry has become one of the main industries in Taiwan. In this research, we take Taiwanese TFT‐LCD industrial companies as the research objects and try to identify the interrelationships among internal marketing, job satisfaction, relationship marketing, customer orientation, and organizational performance. Although these companies are classified as part of the manufacturing industry, it is suggested that their service components could be the focus of greater attention to enhance the success of their business operations. Analytical results indicate that internal marketing, job satisfaction, and customer orientation have significant influences on relationship marketing as well as the organizational performance of TFT‐LCD manufacturing companies. Therefore, Taiwan TFT‐LCD manufacturing companies need to implement relationship marketing continuously, increase employee job satisfaction, and inspire employees to become more customer oriented in order to increase productivity. © 2012 Wiley Periodicals, Inc.     

A study of electro‐optical characteristics depending on LC pre‐tilt angle and cell gap in a full‐HD LCOS panel

Abstract— The goal of this work is to achieve a better understanding of the electro‐optical characteristics of a VA‐mode full‐HD LCOS panel via simulations and experiments. The optical parameters, such as reflectance, fill factor, and contrast that vary due to the pre‐tilt angle and cell gap, were also studied. Based on the simulations, the optical fill factor was the highest at an angle of 81° and 2.1 μm under the given conditions. The contrast ratio was the highest at an angle of 89° and 2.4 μm. Five different LCOS panels were fabricated; three different angles (85°, 87°, and 89°) at a 2.1‐μm cell gap and two different cell gaps (1.8 and 2.1 μm) at an angle of 87°. The measured reflected light intensity was compared to the calculated reflectance. The simulated and measured contrasts were compared with each other. The simulation results well‐matched the experimental results and the differences were less than a few percentage points. Based on the comparative studies on reflectance and contrast, the test panel under the condition of an 87° angle and 2.1‐μm gap showed the best performance results.     

Global decentralized sampled‐data output feedback stabilization for a class of large‐scale nonlinear systems with sensor and actuator failures

In this paper, we investigate global decentralized sampled‐data output feedback stabilization problem for a class of large‐scale nonlinear systems with time‐varying sensor and actuator failures. The considered systems include unknown time‐varying control coefficients and inherently nonlinear terms. Firstly, coordinate transformations are introduced with suitable scaling gains. Next, a reduced‐order observer is designed to estimate unmeasured states. Then, a decentralized sampled‐data fault‐tolerant control scheme is developed with an allowable sampling period. By constructing an appropriate Lyapunov function, it can be shown that all states of the resulting closed‐loop system are globally uniformly ultimately bounded. Finally, the validity of the proposed control approach is verified by using two examples.     

Driving performance,sleepiness, fatigue,and mental workload throughout the time course of semi‐automated driving—Experimental data from the driving simulator

Automation offers the potential to mitigate or reduce the risks related to driving. There are some new challenges for drivers related to semi‐automated driving. Some of them are associated with suboptimal mental workload or prolonged need for sustained attention. This paper presents the results of an experiment investigating differences in manual driving before and after the automated phase in the scenario simulating a time‐course of semi‐automated driving. Sample size: 52 participants with two experimental sessions each day and night session. The experiment used a driving simulator to create a semi‐automated driving scenario comprising manual driving, the automated phase, and manual driving. The following questionnaires were collected: Karolinska Sleepiness Scale, Take‐Over Readiness Scale (developed for this research project, included in Appendix), Samn–Perelli Fatigue Scale, and NASA‐TLX. Driving performance significantly decreased after the automated phase (e.g., standard deviation of the steering wheel angle was 255.73 before vs. 287.11 after automation) and the effect was more profound during the night. Participants were sleepier and more fatigued after the automated phase, and assessed mental workload as lower. The results of the questionnaires did not correlate with driving performance. The results of the experiment suggest that manual driving could deteriorate after the automated phase, and that driver might not be able to assess their fitness to drive at the moment of take‐over of manual driving.     

A novel lens cap designed for the RGB LEDs installed in an ultra‐thin and directly lit backlight unit of large‐sized LCD TVs

Abstract— The objective of this study is to design a novel cone‐shaped lens cap on LEDs in order to achieve high optical efficiency in an ultra‐thin directly lit RGB LED backlight unit (BLU) for large‐sized LCD TVs. The use of the novel lens cap could play the role of a diffuser, a low light‐efficiency component in a BLU, in order to gain higher efficiency and simultaneously provide satisfactory uniformity in light distribution. The novel cone‐shaped lens is coated with aluminum on the outside surface of the cone for mirroring effects to reflect most of the LED emitted light horizontally and then reflect the light at the BLU boundaries, and then, finally to the output plane. In this way, bright spots on the output plane of the BLU can be avoided, leading to increased uniformity. Simulations were conducted to design and optimize varied aspects of the designed lens and BLU, including the cone angle of the proposed lens and the LED spacing (pitch). To further achieve color balance, a known Genetic Algorithm is used to search for the optimal angular placement of each RGB LED, resulting in better color balance. Finally, a prototype BLU for large‐sized 37‐in. LCD TVs with the proposed lens was built to verify the expected performance.     

Reflective full‐color LCD using low‐temperature polysilicon TFTs in low‐frequency driving: Analysis of image persistence and flicker with scientific CMOS camera

Image persistence and flicker are major issues for low‐frequency driving of LCDs. Detailed investigation of the mechanisms that produce these phenomena, using image analysis with a scientific CMOS camera, enabled us to reduce it to acceptable levels. We successfully developed a 7.0‐in. WUXGA (1200 × RGBW × 1920) reflective color LCD driven by low‐temperature polysilicon TFTs at 1 Hz.