Design correlations for the optical performance of the particle-diffusing bottom diffusers in the LCD backlight unit

Although the bottom diffuser film is one of the key components in the backlight unit in a liquid crystal display, the design equations for the optical performance of the bottom diffuser films were not reported in the literature. In this work, different narrow-size-distributed acrylic-styrene resin particles were mixed with the thermosetting acrylic resins and coated on the transparent poly(ethylene terephthalate) (PET) substrates to form particle-diffusing bottom diffusers with different optical performances. The correlations for the light transmittance and haze of a bottom diffuser as functions of the coating thickness/particle diameter ratio and beads/resin weight ratio were empirically developed as a power law model and an exponential model, respectively. The developed correlations may effectively reduce the time required for bottom diffuser designs in the backlight unit.