TFT-LCD Contrast Ratio Improvement by Using Design for Six Sigma Disciplines

The current market demands for thin-film transistor (TFT) liquid crystal display (LCD) is high; however, the LCD televisions still have contrast ratio-related issues. To resolve this, researchers conventionally use trial and error methods for parameter optimization and adjustment. However, this method is slow and can delay the development of new products. Therefore, this study focused on the high contrast ratio of the in-plane switching (IPS) panel. The Define-Measure-Analyze-Design-Verify procedure, comprising the methodology of the Design for Six Sigma, was used to help the researchers enhance the ultra-high contrast ratio of LCD panels. In this study, customer requirements were confirmed, after which the quality function deployment method was used to establish the technical requirements of the enhanced high contrast ratio of LCD. The contradiction matrix of TRIZ was then used to find the corresponding principles and thus propose the design scheme for the LCD contrast ratio. Methodologies, such as design failure modes and effect analysis, Taguchi's parameter design, and reliability tests were used to enhance the ultra-high LCD contrast ratio. After the implementation of an actual case, the ultra-high contrast ratio of LCD panel was enhanced to 1000000:1; the benefits of such an improvement exceeded U.S. $9.5 million. This has also driven market orders for TFT IPS LCD. This study can serve as a reference for product design, product performance enhancement, pilot run yield improvement, and patent applications of LCD panel plants.