Papers by Keyword: TFT-LCD

Abstract: In this paper we present a global approach for the automatic inspection of spot-type defects in TFT-LCD module process. The proposed method is based on a global image reconstruction scheme using the Fourier transform. Since TFT-LCD surface has the statistical and periodic texture, the isotropic spread of frequency components in the power spectrum space forms the shape approximate to a circle. By computing the convolution between the Fourier transform result and a ideal low pass filter (ILPF) , we can remove the TFT-LCD periodic and repetitive patterns using the inverse Fourier transform. In the restored image, the global structurally textured background is eliminated and the spot-type defects are preserved. This converts the difficult defect detection in TFT-LCD images into a simple segmentation problem. The spot-type defects are classified into general point defects and spot Mura defects .The experimental results from point defects and spot Mura defects have shown the efficacy of the proposed method.

Abstract: Anisotropic Conductive Film (ACF) is essential material in LCM (Liquid Crystal Module) process. It is used in bonding process to make the driving circuit conductive. Because the price of TFT-LCD is much lower than before in recent years, the ACF cost has relatively higher ratio in manufacture cost. The conventional long bar ACF cutting unit is changed to short bar ACF cutting unit in new bonding technology. However, the new type machine was not optimized in process and mechanical design. Therefore, the failure rate of new ACF cutting process is much higher than the one of the conventional process. This wastes the material and rework cost is considerably large. How to make the manufacturing cost down effectively and promote the product quality is the concern issue to maintain competition capability for the product. Therefore, the Orthogonal Particle Swarm Optimization is used to analyze the optimal design problem. The ACF cutting yield rate is selected to be objective function for optimization. The quality characteristic function is used in Orthogonal Particle Swarm Optimization. The plasma clean speed, ACF peeling speed and ACF cutter spring setting are selected to study the effect of the yield rate. Results show that the proposed method can provide good solution to improve the ACF cutting process for TFTLCD.

Abstract: With the rapid development of the technology of liquid crystal display, LCDs have become the main stream displays. However, if there are no appropriate ways to recycle the discarded LCDs, the environment will be polluted and the resources will be wasted. TFT-LCD panels mainly consist of the color filter (CF) substrate and the thin film transistor (TFT) substrate which both have a surface covered with indium-tin oxide (ITO). ITO layer contains the metal of indium which is rare, precious and of high value. In view of the difference of the structure and material of the CF substrate and TFT substrate, an efficient and green process has been presented for recycling the indium by means of theoretical analysis and experimental verification. Under heating condition, the sodium hydroxide solution is used to dissolve the color filter of the CF substrate and the ITO layer attached to the color filter can be eliminated quickly and the metal indium can be enriched by filtering solution. By grinding the ITO layer on the TFT substrate with the aid of water-proof sand paper and collecting ITO scraps, indium can also be enriched quickly. The experiments show that the indium content of the CF substrate and TFT substrate are both quite low. Enriching indium on the premise of not dissolving indium is beneficial to the concentrated recovery of indium and is helpful to raise the recycling efficiency and protect the environment.

Abstract: TFT-LCD panel defect detection has been one of the difficulties in this field because of fuzzy defect boundary, low contrast between defects and background, and low detection speed. The structure of TFT-LCD panels and classification are introduced. Through the analysis of panel defect features, current detection methods for the TFT-LCD panel defects are reviewed. The key technologies of feature extraction and defect classification are analyzed in the defect image recognition of TFT-LCD panel. Meanwhile the methods of fuzzy boundary defect segmentation, image subtraction and image filtering are also discussed. Finally, the characteristics and advantages of these detection methods are concluded, and several key issues for the TFT-LCD defect detection have been proposed for future development.

Abstract: With the research on LCD production process, a low cost practical tool was developed to solve the problem of v-line defect detection, and the yield is improved from 95% to 97%. A new method was proposed to repair bright spot with laser without disassembling LCD panel. The repair time is shortened to seven minutes from twelve minutes, and the repair success rate reaches 94.85%.

Abstract: The present Automatic Optical Inspection (AOI) technology can hardly satisfy online inspection requirements for large-scale high-speed, high-precision and high-sensitivity TFT-LCD. First, through studying the working principle of TFT-LCD Defect AOI System, the system architecture for mixed-parallel multi-core computer cluster is proposed to satisfy design requirements. Second, the study focuses on the software framework of AOI system and related key software technology. Finally, the fusion programming model for parallel image processing and its implementation strategy is proposed based on OpenMP, MPI, OpenCV, and Intel Integrated Performance Primitives (IPP).

Abstract: DVB-T system is a hi-tech product that integrated software, hardware, mechanism, optics all-in-one. It includes digital television's decoding, error correction, standard compatible, frequency search, DVD servo system, pick-up trace, DVD data stream decoding, driving for TFT-LCD, lithium battery's charge/discharge control, power supply management, different work mode's switch, complex machine structural design and so on. Needs software, Hardware, Structural engineers' cooperation, every function needs muck complex technology support.

Abstract: Intense global competition and declining profit have caused most Thin Film Transistor - Liquid Crystal Display (TFT-LCD) manufacturers to increase their competitiveness by improving productivity and reducing cycle times. This research developed Automated Scheduling and Dispatching (ASD) system to automatically generate production schedules for multiple color filter fabrication plants in TFT-LCD industry. On the basis of backward scheduling and forward scheduling, ASD was developed to estimate future equipment loading and calculate order due dates according to capacity limits by taking into account the due date and size of orders, as well as the capacity, loading, and yield of fabrication plants. ASD system can assign orders to production lines, plan order release time, and balance equipment loading. Microsoft Visual Basic for Application (VBA) was used to develop ASD system in this research. Preliminary results in a case study demonstrated that ASD can efficiently generate scheduling results. ASD has been partially implemented in the studied color filter fabrication plants. Compared to manual operations for scheduling and dispatching, more than two-third time was saved by using ASD. Further improvement is under study and development.

Abstract: An AutoMod simulation model was constructed for real-world 4.5th-generation (4.5G) Thin Film Transistor - Liquid Crystal Display (TFT-LCD) Color Filter (CF) fabrication plants in this study. The characteristics and data of customer orders, production facility, material handling tools, and warehouse (also called stocker) were collected from real plants. Based on these, a simulation model was developed and validated. As the simulation model was complex and had different parameters representing the operation details in the plants, it is of interest to justify the effects of these parameters to the key performance indicators such as system throughput and equipment utilization. Using fishbone analysis, sensitivity analysis and experimental design, a series of simulation experiments were conducted and the resulting simulation model was representative to the CF plants. On the basis of the simulation model with 3-dimension animation, decision makers can conduct what-if analysis for the evaluation of production control policies such as in-process capacity and tact time without disturbing the operations in the real plant. Better alternatives leading to higher system throughput can be identified in system simulation before its real implementation in the fab.

Abstract: This research proposed Advanced Planning and Scheduling (APS) system to effectively and efficiently balance machine loading for color filter fabrication plants in Thin Film Transistor - Liquid Crystal Display industry. APS uses six modules to estimate future equipment loading and calculate order due dates according to capacity limits by taking into account the due date and size of orders, as well as the capacity, loading, and yield of fabrication plants. These six modules include: Order Priority Module, WIP-Pulling Module, Order Release Module, Material Management Module, Workload Accumulation Module, and Workload Balance Module. A lot’s start processing time at each production step is selected leading to the best workload balance. Simulation and experimental design are used to evaluate the performance of APS. Production manager can use APS to improve color filter fabrication plants’ productivity and competitiveness.