Display Panel Research Articles

56‐1: Invited Paper: Ultra‐high Frame Rate ADS LCDs

In recent years, LCD end‐users are putting forward higher and higher requirements for dynamic picture display realism. With the increase of display panel refresh rate, dynamic picture fidelity has a significant improvement. The extremely high refresh rate has become one of the most important indicators of high‐end display panels, especially for video game usage scenarios. However, the increase in refresh rate is a challenge to the drive capability of LCD semiconductor TFTs (Thin Film Transistor), the response time of liquid crystal, and the transmission of high‐frequency signals, resulting in the maximum refresh rate of high‐refresh‐rate displays currently on the market still at 240 ~ 300 Hz. In this paper, we solve the display distortion due to low charging ratio at ultra‐high refresh rate by improving GOA（Gate Driver on Array） driver circuit and applying high stability and high mobility bilayer oxide semiconductor technology. At the same time, the 1ms GTG (Gray to Gray) response time is achieved by testing and optimizing the pixel slit angle and cell gap of ADS (Advanced Super Dimension Switch) LCD, ensuring no image trailing at refresh rates up to 600 Hz. Then the anti‐electromagnetic interference ability of high‐speed signal is improved by high‐speed signal transmission quality enhancement technology. Through the application of the above technologies, we have developed the ultra‐high refresh rate IT display panel products such as 600Hz frame rate FHD NB LCD and 500 Hz FHD MNT LCD. And the 16.0” WUXGA 600Hz ADS LCD achieves the highest CMR 9000 rating in VESA latest dynamic picture CMR certification.

6‐4: Deep Learning for Classification of Repairable Defects in Display Panels Using Multi‐Modal Data

This paper uses Deep Learning to classify if a display panel with defects in the manufacturing line can be repaired. Both tabular data and images are fused together to make predictions, with separate feature extraction undertaken for each of the modalities. The model's predictions achieve high Average Precision as well as robust Precision values in the high Recall regions, which makes it practical for deployment. We also demonstrate superior results with multi‐modal data compared to only tabular data.

7‐3: A New Line‐by‐Line SWEEP Signal Generation Method for PWM Driving MicroLED TFT Pixel Circuit

This paper proposes a novel method to generate a SWEEP signal line‐by‐line for PWM driving microLED pixel circuit. The proposed method generates a SWEEP signal based on the linearly increasing voltage of the capacitor by flowing a constant current to the horizontal line parasitic capacitive load. The constant current is supplied by the sweep generation (SG) circuit in each line. Since the SG circuit utilizes the existing SCAN signals for the pixel circuit, additional SCAN or clock signals are not required. By using the proposed method, an individual SWEEP signal for each line can be generated without a significant increase in operational complexity in the display panel.

47‐2: Photosensitive characteristics and application of photosensitive device based on TFT process

A glass‐based TFT (thin film transistor circuit) module with ambient light detection function was designed and manufactured on the display panel, and the photoelectric characteristics of TFT photosensitive devices were measured and obtained. After the data analysis and processing, the photoelectric characteristic curves with good linearity were obtained. After algorithmically optimizing the intrinsic data, the thin‐film transistor photosensitive element achieved the same photoelectric characteristic as the silicon‐based photosensitive element. Measurements of the photoelectric characteristics of the TFT photosensitive device showed that the photoelectric performance of the sensor is repeatable and relatively undetermined. The photoelectric characteristics demonstrate the corresponding relationship of multiple direction functions. Different products show different current values under the same illumination, but the overall photoelectric characteristics still maintain the trend of multiple direction functions. In the experiment, 200 TFT photosensitive device units were connected into a set of photosensitive elements array, and placed under the ambient illumination of 0~30000 LUX. The output current range of the photosensitive array after parallel connection is 0~200 mA. The results indicate that the photoelectric characteristic of TFT photosensitive device has linear relationship after effective data processing and algorithm computing. After testing with different products, the device characterizes the ambient light with less than 5% accuracy. Therefore, the glass‐based TFT module with ambient light detection function can accurately reflect the data of ambient light, realizing the practicability of the photosensitive device based on TFT technology.

14‐1: An Automatic Panel Design Using AI‐Based Design Optimization and Standard Design

The display panel design consists of active area, data pad, gate pad, cell, and glass part. The design sequentially follows the process of plan, optimization, and drawing. We've developed a panel design automation platform to automatically complete all the process with AI‐based design optimization and drawing on the basis of standard panel design.

P‐102: Explainable AI Approach for MOD Outliers in FAB to MOD Process

Display panels manufactured in the FAB process are assembled with various films and components in the module (MOD) process, and their final quality is a result of accumulated the quality of hundreds of preceding processes. Due to these limitations, it is hard to analyze the cause of MOD's outliers relevant to the FAB process and much time and money are consumed to maintain the cause process to eliminate MOD outliers. Therefore, we propose a new explainable AI (XAI) approach to detect and improve the module process's outliers by finding the correlation between FAB and MOD in this paper. The proposed approach was verified for MOD outlier cases in the real world's OLED development and manufacturing process. As a result, it confirmed 96.8% of the average accuracy for classifications. This approach presents the FAB factor that caused MOD's outliers based on the correlation between the MOD and the FAB.

74‐4: Spherical Forming‐A Test Method for Stretchability of Flexible OLED from 2D Plane to 3D Surface†

3D curved shape display with non‐zero Gaussian curvature can only be adapted by a stretchable display panel. Other displays are almost impossible to achieve, even if they are flexible. In this work, we designed a stretchable stacking structure and a 3D deformation process to realize the dome‐shape samples, with reference to the commercial 3D‐shape displays. And a blue‐light 3D scanning method was applied to measure the length change and area change of the dome‐shape samples. The measurement method covered in this paper can be a promising candidate for a standard method of measuring 3D deformation of stretchable displays.

14‐3: Drop Resistance Optimization Through Post‐Hoc Analysis of Chemically Strengthened Glass

In the market of the mobile cover glass, the development of chemically strengthened glass is focused on the drop resistance improvement. The cover glass which protects the display panel is a typical brittle material that the micro cracks tends to be occurred underneath a glass surface by physical impacts. The micro cracks tends to be propagated by tensile stress and it is known as a general procedures on glass breakage. In purpose of the cover glass strength improvement, compressive stress is applied to the glass surface using chemical strengthening method by ion exchange. However, since the central area of the glass is relatively subjected to tensile stress, the glass is instantly broken when the propagated cracks are reached on the tensile stress exerted area. The glass specifications have been managed for maintaining the strength using parameters of compressive stress (CS), depth of compression (DOC), and central tension (CT). However, there was no method to judge the most effective factor for impact drop resistance. In order to solve this problem, we developed a machine learning program for cover glass that can predict the breakage height based on stress and mapped evaluation data based on the measured stress profile data and the actual drop breakage simulated evaluation. Especially, eXplainable AI (XAI) method is used to identify the effective factors on drop breakage height. And the test and measurement data were applied to various chemically strengthened glass for analysis.In this study, it was possible to predict the drop breakage height only by measuring the stress profile of chemically strengthened glass. The feature value of chemically strengthened that has the most effect on the drop breakage resistance on rough surfaces was identified to be stress value at 30um in the case of alkali aluminosilicate glass. And it was proved that the drop breakage height was improved by 25% only by increasing the compressive stress at 30um depth.

Multicolour LED Scrolling Display

Abstract: Size of the display board can be increased row wise and column wise without making any changes in the LED's are a fantastic way to illuminate any kind of sign, be it lettering or panels. LED Dot-Matrix Displays are a common sight nowadays on streets, malls, buildings, parks and other public places. It is a way of visual information where large LCD and other display become too much expensive. The commonly seen displays are single colour or having 2 or 3 colours But here multi coloured LED display is being introduced .This project provides an efficient and scalable approach to LED Dot Matrix displays. The system is comprised of a tricolor dot matrix display panel with an interface circuit to a computer. It also comprises an executive program that runs on the computer for the display control of characters, decorative pattern or messages on the display panel. A multi colour LED Indoor Advertising Display can be used by companies to advertise even in bright day-light conditions. The display board displays any character entered from the host computer which is interfaced using USB to a microcontroller that initializes the led driver. The advantage of this project is that circuitry since display board is the repetition of a small independent module.

Optical compensation schemes for elimination of off-axis color difference in a light control film based on dichroic dyes

We report optical compensation schemes for eliminating off-axis light leakage and color differences when a dichroic dye-based light control film is applied to a display panel. When a vertically aligned dichroic dye (VA-Dye) film without an optical compensation film is applied to the display panel, the light emitted from the display panel can be completely blocked on the upward and downward sides because the absorption axes of the dichroic dye molecules and top polarizer are perpendicular to each other. However, light leakage occurred in the diagonal direction because of the deviation in the angle between the absorption axes. To eliminate off-axis light leakage and off-axis color differences, we present three approaches for optical compensation. First, we optimized the positive biaxial + B plate by controlling its Nz value such that the off-axis color difference could be significantly reduced. Next, we employed optical compensation films using + B/negative C (-C) and positive A (+A)/positive C (+C) configurations. These designed configurations using commercially available films exhibited a significant reduced off-axis color difference as well as the elimination of light leakage in oblique directions when the VA-Dye film was applied to the display panel.

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Perceptually-guided Dual-mode Virtual Reality System For Motion-adaptive Display.

An ideal Virtual reality (VR) device should simultaneously provide retina-level resolution, wide field-of-view (FOV), and high refresh rate display, thereby bringing users into a deeply immersive virtual world. However, directly providing such high-quality display poses great challenges for display panel fabrication, real-time rendering, and data transfer. To address this issue, we introduce a dual-mode virtual reality system based on the spatio-temporal perception characteristics of human vision. The proposed VR system has a novel optical architecture. It can switch display modes according to the user's perceptual requirements for different display scenes to adaptively adjust the display spatial and temporal resolution based on a given display budget, thus providing users with the optimal visual perception quality. In this work, a complete design pipeline for the dual-mode VR optical system is proposed, and a bench-top prototype is built with only off-the-shelf hardware and components to verify its capability. Compared to the conventional VR system, our proposed scheme is more efficient and flexible in utilizing the display budget, and this work is expected to facilitate the development of the VR device based on the human visual system.

Study on the Film-Forming Mechanism of Polymer-Metal Oxide Composite Ink Systems Containing Different Polymer Molecules.

A printable, flexible display panel is an important trend in the field of information display, which requires better mechanical and electrical properties of device materials. Polymer-metal oxide composite materials are promising in the functional layer of a thin-film transistor (TFT) and can be sufficiently fabricated by polymer-metal salt solution systems through the sol-gel process. For the development of polymer-metal oxide composite ink, it is necessary to study the film-forming mechanism of the composite film during solidification, which is an important reference in ink component design. However, the evolution of the composite structure is quite complex, which brings a challenge to characterization and analyzation. We applied a series of characterization methods to study the film-forming process of composite ink from sol to gel and to solid, and an emerging testing technology, nano-infrared spectroscopy (nano-IR), was applied to characterize the gel film. The research conclusion showed that the type of functional group can significantly affect the morphology of the initial particle and can finally determine the microstructure of the composite film. The study provides references for the development of composite ink as well as the characterization method for ink and film with complex composition.

Analytical model for three-dimensional light-field displays based on voxel construction

Three-dimensional light-field displays (3D-LFDs) can provide viewers with glass-free 3D images. The display effect of reconstructed 3D images is closely related to the number of 3D object points that the 3D display system can construct, which can be regarded as the information quantity of the 3D-LFDs. However, the information quantity presented by a 3D-LFD is limited by fixed hardware parameters such as display panels and optical components. It is difficult to present an ideal 3D visual experience with the increase in display depth. In this paper, an analytical model based on voxel construction for 3D-LFDs is proposed, which can estimate the information quantity that a 3D-LFD can reproduce. The variation regularity of information quantity with display depth is analyzed and the influence of hardware parameters on display effect is discussed. With the proposed strategies, the display effect can be improved in a targeted manner without blurring and aliasing by adjusting the hardware parameters in display systems and matching the information quantity at different display depths.

Compliance Level to Food Labelling Regulation for Micro and Small-sized Enterprises Products: A Descriptive Study in Wonosobo District, Indonesia

Food labelling is an effective tool in protecting consumer health with respect to safety and nutrition. Complying with labelling regulations is essential in preventing product recalls. Thus, the objective of this study was to determine the extent of adherence to food labelling regulations by micro and small-sized enterprises (MSEs) in Wonosobo District, in accordance to the existing guidelines. Primary data were collected through a market survey approach, with analysis conducted through purposive sampling in shops, stalls, home industries, markets, and supermarkets. Content analysis was employed to evaluate four categories of processed food: flour/starch-based products, water-based flavored drinks, processed fruit products, and processed grain, nut, and tuber products, totaling 92 products. The compliance level with labelling regulations was evaluated based on the principal display panel, labelling formats, general labelling requirements, and prohibited statements on the label. The results revealed that the compliance level of labelling flour/starch-based products was good, with an average of 75%. In contrast, the average compliance level for water-based flavored drink products was 58%, while the average compliance levels for processed fruit products and processed grain, nut, and tuber products were 54 and 59%, respectively, indicating a lower level of compliance compared to flour/starch-based products.

P‐4.1: Analysis and Application of the Peel Strength of the Foam Tape on Display Panel

In order to solve the problem of peel between display panel and backlight module in new display products such as four-sided borderless display and curved display, in this paper, the peel strength of foam tape was studied through experiment and simulation, and the peel stress strength of the foam tape was established to guide product design. Firstly, the peel stress of foam tape was obtained by peel strength experiment of foam tape samples. Then, the simulation model was established by using finite element software, and the load weight corresponding to the tilt experiment of the 27-inch four-sided borderless display was calculated. Finally, the accuracy of the simulation model was verified by the tilt experiment of 27-inch display, and the peel stress strength of the foam tape was established. The peel stress was about 1.94×10 -2 MPa. Based on the peel stress strength, the minimum width of foam tape for 23.8-inch four-sided borderless display was 1.5 mm. The display passed the 60 ℃/90% RH HTHHS 500 hours experiment, meeting the product quality requirements. This method can guide the size design of foam tape for new display products such as four-sided borderless display and curved display, and enhance the ultimate design competitiveness of products.

2.1: Invited Paper: Grid Pattern Image Sticking Compensation Method for MLED Splicing Screen

COG (Chip On Class) based MLED (Mini‐LED) Splicing Screen has an advantage of ultra low current, but suffers the problem that its red light luminescent efficiency is drastically hindered by high temperature of screen. MLED splicing screen consists of multiple display panels, the display panel sticks partially to its background frame with margin. As a result, the speed of heat diffusion difference between the panel margin area and the central area results in grid pattern image sticking. The central area looks cyan because it has a higher temperature, but the margin area looks white because of its lower temperature. To prevent grid image sticking problem and improve the visual quality of splicing screen, we propose a novel method to dynamically estimate the compensation ratio for red channel and apply this compensation ratio to acquire chroma uniformity. Our method is implemented in FPGA to achieve realtime performance. Experimental results validate the effectiveness of the proposed method.

50.6: Establishing of the Device‐independent Mura Simulation and Quantitative Evaluation Dataset

There is a need to establish a novel dataset for the development of better Mura quantitative evaluation method. Our proposed Mura simulation and quantitative evaluation (MSQE) dataset consists of Mura simulation images and the corresponding quantitative evaluation values. For the Mura simulation images, the images are described in CIE 1931 XYZ space instead of traditional RGB space to achieve device‐independent on any display panels. For the quantitative evaluation values, the unique subjective quantitative evaluation value for each simulation image is obtained by subjective experiments conducted by different researchers, different observers, and on different panels, so that the uncertainty can be minimized by statistical analysis. The number of samples are growing with more simulation images and corresponding evaluation values being added into the dataset, so that more actual Mura patterns can be included into the dataset. Our proposed MSQE dataset makes it easier to improve the performance of Mura quantitative evaluation.

40.3: Polarization‐dependent Binocular Waveguide Display with Patterned Cholesteric Liquid Crystal Optics

We demonstrate a polarization-dependent binocular waveguide display for augmented reality. Two polarization volume lenses (PVLs) are used to collimate and couple the light emitted from a single display panel into the waveguide, and two polarization volume gratings (PVGs) are used to couple the light out to the human eyes. With the proposed design, different high-quality images can be independently produced in the two eyes.

P‐7.7: Static Fatigue Fragment Life Analysis and Application of Curved Display Panel

In order to ensure the service life of the curved display panel, it is necessary to test and analyze the fatigue fragment life distribution of the curved display panel to predict the fragment rate of the product, and design the proof test scheme and life reliability test scheme. First of all, this paper has carried out Weibull test by 300pcs OC (open cell) samples of 27‐inch R1000 curved product. The Weibull life distribution parameters of the samples were obtained by fitting the test data (shape parameter k=0.337, size parameter λ= 1.86×108). Then, according to the requirement of customer (8000ppm fragment rate in 3 years), the proof test stress (σp=81.2 MPa) was calculated, and the life distribution model after proof test and zero failure reliability algorithm were derived. Finally, based on 90% confidence level (1‐α), life reliability test time (TL) and the number of samples (N), calculated the life reli ability test stress (σL=62.7 MPa) by reliability algorithm and life acceleration formula, determined the test scheme {TL, N, σL} and successfully passed the test verification. The static fatigue fragment life analysis method in this paper can accurately evaluate the fragments of curved display panel, guide the design and development of curved products, and effectively improve the reliability of curved display.