The Study of the Mold Monitor and Processes Optimization of the Thin Light Guide Plate

• Main Authors: Ming-Feng Yang, 楊明峰
• Other Authors: Chung-Ching Huang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/77377683100877569797

碩士 === 國立高雄應用科技大學 === 模具工程系碩士班 === 95 === Abstract With the quick developing of photoelectric product, TFT-LCD display has been developed toward the thin shape gradually, and the quality of display is decided by Light-Guide Plate’s shape. The shaping of LGP will usually generate dimension deviation because of melt filling, shrinking, residual stress, and warpage…etc, and these factors cause the shaping of LGP unable to be applied to the optics products. Therefore, the shaping quality of LGP has very important influence on the display. This study is directed against a 6 inches medium size liquid crystal display with 1mm thick LGP, and its plastic is PMMA with proceed injection molding and injection compression molding. It influences the warpage of thin planar LGP to compare the two shaping types. In the thin shaping, melting temperature and pressure change rapidly according to the flow length in the cavity. In this study, mold sensor is applied to monitor the variation of temperature and pressure, and compare with the result of mold flow simulation in order to verify the accuracy of the analysis result. After that, using Taguchi Method to find the main influence factor of warpage and determine the best shaping condition. The result of study showed that the temperature difference and pressure unevenness of the cavity are the main reasons that affect the warpage of LGP. They produce the obvious residue stress in gate to injection molding, and the temperature difference and pressure difference are bigger in near the gate and the end of product. Injection compression molding applies the uniform pressure of closing to exert pressure in an all-round way on the mold wall. By using mold sensor, it is proved that the temperature and pressure detected in the cavity is more uniform. This method can effectively disperse the residual stress near the gate; therefore, the warpage degree of product can be improved obviously.