Color Shift Reduction of Liquid Crystal Displays by Controlling Light Distribution Using a Micro-Lens Array Film

A new optical film is proposed to reduce angular color shifts of liquid crystal displays (LCDs). The film is composed of microstructures to induce the angular light mixing by deflection and reflection at the microstructure surfaces. A simulation scheme was developed to predict color shifts based on geometrical optics, and applied to design and optimize the microstructures. Among various microstructures studied, parallel grooves with parabolic cross sections were found to be the most efficient in redistributing light. Experimental verification by the UV micro-imprinting method were conducted to show the new film design can reduce the angular shifts by 50% or more for 13 primary and secondary colors of a super-patterned vertical alignment (S-PVA) LCD, and greatly reduce the grey inversion of twisted nematic (TN) LCDs as well.