Study Of Light Guide Plate Molding

Back light is one of the main parts of Liquid Crystal Display (LCD) and it provide stable light source for LCD. Light Guide Plate (LGP) is the main part of Back Light. The main function of LGP is to control the scattering directions of incident light to transfer linear light source to surface light source, increase luminance and uniformity in displays. In addition, LGP molding technology is an optic dot transfer method by molding.Firstly this thesis introduced LGP light principium and molding technology. Then LGP molding condition was analysed by mold flow soft for this test mold. And molding parameters such as cooling time, mold temperature, barrel temperature, injection rates, injection pressure, packing pressure, packing switching, and packing time were also analysed by mold flow soft. Those gave out effect result on LGP quality. Then Taguchi Quality Engineering Method was adopted for LGP molding experiment design. And actual test was done. The relationship between the qualities and processing parameters was assessed based on the final qualities via both experimental verifications and quality measurements. In conclusions, experimental results had shown that long cooling time could reduce the LGP warpage. High melt resin temperature and high packing pressure and time would increase LGP luminance. The melt temperature is most critical to uniformity of transmittance, but too high melt temperature will cause light dot unevenness shrinkage after molding and decrease uniformity of transmittance. Finally one set parameter was optimized for mass production and this process can improve molding yield from 75% to 90% in normal mass production. And that was good for production cost saving.