A High Contrast and High Brightness Reflective LCD with an Internal Diffusive Reflector

Abstract

We have developed a high contrast and high brightness reflective LCD with an internal diffusive reflector(IDR). The IDR is used in a single-polarizer configuration using mixed-mode twisted nematic(MTN)effect. The diffusive reflector, with proper design, is effective in yielding a bright reflective-image under collimated ambient light. The MTN mode is adopted for its high contrast and large tolerance to cell gap variation. The test cell shows contrast ratio over 40:1, response time less than 20 ms and reflectivity of 22%(when combined with micro color filters)relative to a Lambertian standard white, measured at display's normal direction under -30゜ collimated illumination.