The degree of imperfection was defined as the independent intrinsic index of the degree of degraded contrast ratio for each component. The scattering index of liquid crystal layer gives an effective guideline for reducing light leakage intensity. By using this guideline, we have made an IPS‐Pro LCD with a uniform contrast ratio of 1500:1 within ±16.5° of polar angle.

We investigated light scattering properties of conventional liquid crystal layers by 651.8 nm laser illumination. The intensity of light scattering strongly depended on the incidence angle of illumination. Although the total light intensity changed with the ordinary refractive index n o , the extraordinary refractive index n e , their difference Án, the elastic constant K, and the thickness of the liquid crystal layers d, it was simply proportional to a specific variable S consisting of those values, as S ¼ Án 2 ðn e þ n o Þ 2 d=K.

We investigated the light leakage behaviors homogeneously aligned liquid crystal layers placed between crossed polarizers using a backlight unit with diffused light to reduce the transmittance in the black state in in-plane liquid crystal displays. The light leakage intensity was clearly proportional to a specific variable (S cell ) consisting of the ordinary refractive index n o , the extraordinary refractive index n e , their difference Án, the elastic constant K, and the thickness of the liquid crystal layers d. A high elastic constant and a low Án can result in a low light leakage intensity.