Optical fine-tuning for improving the dark level of a reflective liquid crystal display

Optical fine-tuning was performed to reduce blue light leakage in a conventional reflective LCD and to obtain a reflective LCD with a better contrast ratio. Total light leakage in the dark state was examined by simulation, according to the optical axes of the half-wave plate and LC layer and the central wavelength used in the optical design of the LCD. The contrast ratio of the reflective LCD could be improved by more than fivefold, compared to that of a conventional LCD with a wide-band optical design, when the optical axis angles of the half-wave plate and the LC layer were 75° and 15.68°, respectively, and the central wavelength was 520 nm. Therefore, such optical fine-tuning can be applied to reflective LCDs to increase their contrast ratio.