For Flat Panel Display Research Articles

Beneficiation and classification of ITO concentrate from waste LCD panel for industrial-scale indium extraction.

Currently, more than 55% of global indium production is consumed for indium tin oxide (ITO) production because of its excellent display properties mainly driven by demand for flat panel displays (FPDs) or LCDs. At the end of life, the waste LCD flows to the e-waste stream, accounts for 12.5% of the global e-waste, and is forecasted to be increasing progressively. These waste LCDs are potential wealth for indium that poses a threat to the environment. The volume of waste LCD generation is a global as well as national concern from a waste management perspective. Techno-economical recycling of this waste can be a panacea to the challenges associated with the lack of commercial technology and extensive research. Hence, a mass production capable of beneficiation and classification of ITO concentrate from waste LCD panels has been investigated. The mechanical beneficiation process for waste LCDs consists of five steps of operation, i.e., (i) size reduction by shredding by jaw milling, (ii) further size reduction to feed for ball milling, (iii) ball milling, (iv) classification to enrich ITO concentrate, and (v) characterization ITO concentrate and confirmation. The bench-scale process developed is intended to integrate with our indigenously developed dismantling plant (which can handle 5000 tons per annum) to handle separated waste LCD glass for indium recovery. Once scaled up, it can be integrated for continuous operation synchronized with the LCD dismantling plant.

Air-knife design for improved drying efficiency in manufacturing flat-panel displays

Abstract With the growing demand for flat-panel displays (FPDs), the size and production conveyance speed of glass are increasing to improve productivity. Improvement of productivity, speed, and efficiency in the drying process used in FPD manufacturing has become an important issue. Therefore, this study aims to improve the drying efficiency by optimizing the primary design variables of an air knife, the most common FPD drying system, through numerical analysis. To optimize the air-knife design, the feasible optimal values were fixed for the slit gap (0.15 mm) and glass gap (1.5 mm), and the optimized dimensions were determined by considering the nonsymmetric distance (0.5 mm) and installation angle (15°) of the end geometry of the air knife channel. The optimized air-knife design improved the drying efficiency by approximately 30% compared to that of the existing system; therefore, it can increase the productivity of the FPD manufacturing process.

Deep-Learning-Enabled Automatic Optical Inspection for Module-Level Defects in LCD

Liquid crystal display (LCD) defects detection on module level is increasingly important for flat-panel displays (FPD) industry to increase the production capacity via machine vision technology. However, it is an overwhelmingly challenging issue due to various difficulties. This article discloses a practical automatic optical inspection (AOI) system consisting of hardware structure and software algorithm to detect module-level defects. The AOI system is the core component to build a distributed integrated inspection system with the help of the Internet of Things (IoT). Starting from the analysis of the challenges encountered in module-level defects inspection, a delicate photograph scheme is proposed to reveal different kinds of defects. In order to robustly work on the module-level defects detection with complex situations, a novel framework based on YOLOV3 detection unit is proposed in this article, including the preprocessing module, detection module, defects definition module, and interferences elimination module. To the best of our knowledge, this is the first work that designs a practical AOI system for module-level defects detection. In order to demonstrate the effectiveness of the proposed method, extensive experiments have been conducted on the manufacturing lines. The evaluation of the detection performance of the AOI system in comparison with a manual scheme indicates that the proposed system is practical for module-level defects detection. Currently, the proposed system has been deployed in a real-world LCD manufacturing line from a major player in the world.

Novel indicators to better monitor the collection and recovery of (critical) raw materials in WEEE: Focus on screens

Currently, in the European Union (EU), e-waste chain performance is assessed by technical indicators that aim to ensure system compliance with collection and recovery targets set by the WEEE Directive. This study proposes indicators to improve WEEE flow monitoring beyond the current overall weight-based approach, including complementary flows and treatment performance. A case study focused on the screen category in France is presented. In 2017, the collection rate of cathode-ray tube screens (CRT) was 68%, while for flat panel display (FPD) generated only 14% was collected. CRT screens have less precious and critical materials than FDP. Thus, elements like cobalt and gold highly concentrated in FPD, have a collection rate two to four times lower than elements such as copper (37%) which represents a high proportion in CRTs. Recycling is the main treatment in France. Nevertheless, the recycling rate per element varies significantly due to the low collection, and also the lack of technology and/or secondary raw materials market. The elements with higher recycling rates are base metals such as copper (28%), followed by precious metals like silver (23%), and gold (13%). Except for palladium, the recycling rate of the critical raw materials targeted in the study ranged from 6% (cobalt) to 0% (e.g. neodymium and indium). The results stress the need for indicators to support the development of WEEE chain from waste management to secondary (critical) raw materials suppliers.

Overhead shuttle design for a flat panel display production line considering the contactless power supply capacity

Abstract The overhead shuttle (OHS) is a widely used automated material handling system (AMHS) for flat panel display (FPD) manufacturing lines. Recently, an OHS using wireless power transfer (WPT) technology, which transfers power remotely from the contactless power supply (CPS) installed in the track, has been widely applied. The OHS with WPT technology is revolutionary because it removes the need for a battery, as the power is continuously transferred while the OHS is in motion. Unlike a conventional battery-powered OHS, the WPT-based OHS does not need to travel to charging stations to recharge the battery, and therefore, delivery efficiency is increased. One of the key design problems in developing a WPT-based OHS system is determining the power distribution in the track. Typically, the track is divided into multiple zones, and the power supply for each zone is determined independently. This decision is critical because it determines the maximum number of OHSs that can be in a zone at the same time. In this paper, we introduce an optimization algorithm to logically determine the power supply in each zone. The critical problem is that the power supply affects the OHS delivery capacity and the total installation cost. We propose an efficient solution algorithm using the monotonicity and primal-dual properties of the optimization model. Two heuristics algorithms are proposed—gradient-search and genetic-algorithm-based approaches. The numerical case from an actual system is investigated to cross-validate the proposed algorithms.

Comprehensive review on the development of high mobility in oxide thin film transistors

Oxide materials are one of the most advanced key technology in the thin film transistors (TFTs) for the high-end of device applications. Amorphous oxide semiconductors (AOSs) have leading technique for flat panel display (FPD), active matrix organic light emitting display (AMOLED) and active matrix liquid crystal display (AMLCD) due to their excellent electrical characteristics, such as field effect mobility (μ FE ), subthreshold swing (S.S) and threshold voltage (V th ). Covalent semiconductor like amorphous silicon (a-Si) is attributed to the anti-bonding and bonding states of Si hybridized orbitals. However, AOSs have not grain boundary and excellent performances originated from the unique characteristics of AOS which is the direct orbital overlap between s orbitals of neighboring metal cations. High mobility oxide TFTs have gained attractive attention during the last few years and today in display industries. It is progressively developed to increase the mobility either by exploring various oxide semiconductors or by adopting new TFT structures. Mobility of oxide thin film transistor has been rapidly increased from single digit to higher than 100 cm2/V·s in a decade. In this review, we discuss on the comprehensive review on the mobility of oxide TFTs in a decade and propose bandgap engineering and novel structure to enhance the electrical characteristics of oxide TFTs.

A Novel Quality Assessment Method forFlat Panel Display Defects

This paper presents a novel quality assessment method for flat panel display (FPD) defects, often called Muras, that employs the characteristics of the human visual system (HVS). Given a Mura image, the brightness difference between the Mura and its surrounding region is first adjusted to reflect the HVS’s property of background-adaptive perception. Then, the resulting adjusted Mura image is further processed using multiscale defect saliency acquisition (MDSA) to obtain a final Mura image with human perception characteristics. In the experiments, the quality scores of Mura test images are measured using the conventional and proposed methods. The results demonstrate that the quality of Mura evaluated by the proposed method correlates with the subjective quality to a much higher degree compared with the conventional methods.

Heuristics for the Buffer Allocation Problem with Collision Probability Using Computer Simulation

The standard manufacturing system for Flat Panel Displays (FPDs) consists of a number of pieces of equipment in series. Each piece of equipment usually has a number of buffers to prevent collision between glass substrates. However, in reality, very few of these buffers seem to be used. This means that redundant buffers exist. In order to reduce cost and space necessary for manufacturing, the number of buffers should be minimized with consideration of possible collisions. In this paper, we focus on an in-line system in which each piece of equipment can have any number of buffers. In this in-line system, we present a computer simulation method for the computation of the probability of a collision occurring. Based on this method, we try to find a buffer allocation that achieves the smallest total number of buffers under an arbitrarily specified collision probability. We also implement our proposed method and present some computational results.

ChemInform Abstract: Recent Progress in Low‐Voltage Cathodoluminescent Materials: Synthesis, Improvement and Emission Properties

AbstractReview: 277 refs.

Multi-cusp ion source for doping process of flat panel display manufacturing

We developed a multi-cusp ion source for Nissin ion doping system iG5 which is used in low temperature poly-crystalline silicon processes for flat panel display (FPD) manufacturing. In this ion source, BF3 or PH3 diluted H2 plasmas are produced and large area ribbon ion beams are extracted. In general, ion ratio of B(+) in BF3 plasma is much smaller than BF2 (+) in multi-cusp ion sources. We developed a new method to increase B(+) ratio and obtained mass analyzed B(+) target current of 130 mA. We employed newly improved multi-slot type electrodes for the beam extraction system and obtained stable beams with the uniformity of below 3%. In BF3 plasmas, several undesirable metal fluorides are produced in the plasma chamber and deposited on the electrode system, which cause glitches and poor beam uniformity. We introduce several cleaning methods.

Dry Etching Characteristics of Amorphous Indium-Gallium-Zinc-Oxide Thin Films

Amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) backplane technology is the best candidate for flat panel displays (FPDs). In this paper, a-IGZO TFT structures are described. The effects of etch parameters (rf power, dc-bias voltage and gas pressure) on the etch rate and etch profile are discussed. Three kinds of gas mixtures are compared in the dry etching process of a-IGZO thin films. Lastly, three problems are pointed out that need to be addressed in the dry etching process of a-IGZO TFTs.

Design on general development platform for FPD systems

In this paper, a multi-functional development platform for flat panel display (FPD) development is proposed. With the proposed development platforms, a variety of FPD devices, including organic light-emitting diode (OLED) screens, liquid crystal display (LCD) screens with touchscreens, OLED microdisplay screens, etc., can be directly and instantly connected, examined and utilized. A field-programmable gate array (FPGA) is used in the development system to drive different types of FPD devices, and ARM11 S3C6410 is used as the application processor to provide various services. The development system uses Linux as the system kernel, Qt for Embedded Linux as the UI framework, various system libraries for video and audio services, and a custom-made user engine for fine-polished appearance and behavior. The development platform has been used not only in testing and verification of the FPD devices, but also in building OLED-powered handheld digital devices, shortening the development cycle from OLED devices to mature application products.

Systematic studies on fractal scan model for Flat Panel Display (FPD) controllers

This paper presents the design and logic implementation of the fractal scan algorithm based on the mathematical model of the optimal scan architecture. Through the exploration of the sub-space code sequences and bit code sequences for different grey levels, we deduce the general formulae for the sequences and propose the corresponding logic implementations including the fractal scanning IP core and the general grey-level controller for Flat Panel Display (FPD). The parameterised IP core for various grey levels, embedded in FPD scan controller, can efficiently increase the scan utilisation and imaging quality. This research provides a new engineering way to solve a pressing problem of high resolution FPD technology. [Received 28 January 2010; Revised 7 July 2010; Accepted 18 December 2010]

S1108-3-3 ウェブ搬送時のディフェクト防止法に関する実験的検討([S1108-3]卒業研究コンテスト(3))

Thin, flexible and long materials such as paper, metallic thin film and optical film are called webs. These are the important materials supporting our life. In recent years, the market of the webs is increasing rapidly because of the public demand for Flat Panel Display (FPD), electronic paper and solar cell. Therefore, it is very important to improve the productivity of the web in the manufacturing site. The webs are produced by Roll to Roll producing system, which production method can be continuously produced. On the other hand, the production system may undertake a great loss. Therefore, it is necessary to correctly transport the webs. However, the webs have possibility of defect such as wrinkle and slip because the webs become very thin recently. These defects can be prevented using concave roller. We experimented wrinkle generation using concave roller. As a result, the effectiveness of concave roller is verified experimentally.

Failure analysis of video processor defined as No Fault Found (NFF): Reproduction in system level and advanced analysis technique in IC level

This paper has studied the video processors for Flat Panel Display (FPD) which is defined as No Fault Found (NFF) among field failures. NFF phenomenon of video processor was the initial feature of field failure and showed Composite Video Broadcast Signal (CVBS) noise but it worked properly after some hours. NFF phenomenon has been a rising issue in the field of electronic device and the system recently. Highly Accelerated Life Testing (HALT) method has been used to reproduce field failure symptom. Modulated exciting technique has been applied as stress profile. Through the above, it was possible to reproduce the symptom which is the same as the field failure. Fault isolation and the defect was detected through the Advanced failure analysis method such as backside polishing, PEM, OBIRCH, and SEM. And it explains the defect and suggests the stress factor which can cause the defect.

YAGレーザを用いたSnO2系薄膜パターンの高速加工とその加工メカニズムに関する研究

Nano-second pulsed Nd:YAG laser (1064nm) process on SnO2 system thin films on glass as transparent electrode for Flat Panel Displays(FPD) was investigated in this paper. Mechanism of laser ablation, which is an interaction between material and laser, was studied to approach low energy process for mass production application. It was found that carrier concentration is an important factor influencing the process from energy absorption mechanism of free electron vibration induced by laser. The process needed high carrier concentration for low energy process. Experiments showed threshold of the process was about 4.0x1025m-3 of carrier concentration. However, some showed exception of successful process with even low carrier concentration. Then an additional mechanism that YAG photon (1.16eV) excites electrons trapped at deep level to conductive band was inferred. Deep level was measured by cathode luminescence spectroscopy, and result showed existence of electron at less than 1.16eV. It is understood that SnO2 system thin films absorb laser energy through complex process of free electrons vibration and deep level electrons excitation. Considering the mechanisms, it is the first to achieve 20mJ/mm2 of low energy process. This result leads to high process speed and good prospect of the laser process for mass production application for FPD.

비접촉 전원장치에 적용한 직.병렬 공진 DC/DC 컨버터에 관한 연구

최근 FPD 산업에서 물류이송장비의 전원장치로 비접촉 전원장치에 관한 연구가 활발히 진행되고 있다. 양산 라인에 적용되고 있는 물류장비의 비접촉 전원장치는 주로 직선구간을 왕복하고, 이송대차가 한 대인 경우에 적용하고 있다. 그러나 곡선 구간과 이송대차가 다수인 경우의 물류이송장비에는 적합하지 않다.<BR> 따라서 본 논문은 직ㆍ곡선 구간이 혼용되어진 구조이고, 이송대차가 한 대 이상으로 구동되는 물류이송장비의 비접촉 전원장치 시작품에 적용하였고, 적용된 비접촉 전원장치의 회로 구조는 풀 브릿지 구조를 갖는 직ㆍ병렬 공진 DC/DC 컨버터 회로로 하여 회로해석, 제어방법, 특성평가, 실험을 통한 적용ㆍ가능성에 대한 연구를 행하였다. 또한 비접촉 전원장치의 전체 제어는 1차측 전원공급장치에 일정한 공진전류를 제어하기 위해 듀티 제어를 사용하였고, 2차측 전원공급장치의 출력전압을 일정하게 유지하기 위해 다수의 이송대차가 자체 제어를 하도록 구성하였다. 실제 2대의 이송대차를 제작하여 직ㆍ곡선 구간을 구성하고, 물류이송장비를 운용하여 양호한 특성으로 적용 가능함을 알 수 있었다.

15.4: Tin Oxide Transparent Conductor for PDP

AbstractTin doped Indium Oxide (ITO) is the standard transparent conductor (TC) used for flat panel displays (FPDs). Indium is scarce and expensive; consequently there is mounting pressure to find a less costly replacement for it.

Femto-Second Laser Glass Cutting for Flat Panel Display

A laser glass cutting system using a femto-second laser was evaluated for Flat Panel Display (FPD) glass. A theoretical analysis of the ablation threshold and depth is described using an explicit analytic form. Experiments for clean and deep grooves were performed using a 3W femto-second laser, and the relationships between the input energy and the scribing depth as well as the threshold energy are presented. Mechanical breaking after the scribing process was carried out and the results are compared with a theoretical method. It was found that a two-sided LCD panel glass can be cut clearly using the laser cutting method. The methodology was found to be very effective as a mass-production cutting system.

Change in Microstructure and Mechanical Properties of Deoxidized Low-Phosphorous Copper Processed by Accumulative Roll-Bonding with Annealing

Since a pattern defects "repair" system using a diode pumped solid state laser for Flat Panel Display (FPD) was suggested, a lot of laser systems have been explored and developed for mass-production microfabrication process. A maskless lithography system using 405 nm violet laser and Digital Micromirror Device (DMD) has been developed for PDP and Liquid Crystal Display (LCD) Thin Film Transistor (TFT) photolithography process. In addition, a "Laser Direct Patterning" system for Indium Tin Oxide (ITO) for Plasma Display Panel(PDP) has been evaluated one of the best successful examples for laser application system which is applied for mass-production lines. The "heat" and "solvent" free laser microfabrications process will be widely used because the next-generation flat panel displays, Flexible Display and Organic Light Emitting Diode (OLED) should use plastic substrates and organic materials which are very difficult to process using traditional fabrication methods.