Liquid crystal display having improved retardation film
View Patent ↗A liquid crystal display having improved retardation plate is described. In the liquid crystal display, at least one of two panel plates has a polarizer placed on an outer side which is opposite to a liquid crystal layer and a quarter wavelength retardation plate between a substrate glass and the polarizer. The quarter wavelength retardation plate is composed of two retardation films including a half wavelength and a quarter wavelength retardation film. A slow axis of a half λ film which is adjacent to the polarizer makes an angle of Θ 1 with a transmissive axis of the polarizer and that of a quarter λ film which is adjacent to the substrate glass makes an angle of Θ 2 where Θ 2 =2×Θ 1 ±45 degree. The retardation films are single-axial films. The specific angle Θ 1 is one of degree values (15, 75, 105, and 165). In a transmissive type liquid crystal display, a structure of the other panel plate is similar to that of one panel plate and combination to the values (Θ 1, Θ2, Θ3, Θ4 ) is one selected from the group consisting of combinations (15, 75, 165, 105), (75, 15, 105, 165), (105, 165, 75, 15), and (165, 105, 15, 75).
1. A reflective liquid crystal display comprising:
a first substrate;
a second substrate having a display region;
a liquid crystal layer between the first substrate and the second substrate;
a polarizer placed on an outer side of the first substrate and having a transmissive axis, the outer side being opposite to the liquid crystal layer;
a quarter wavelength retardation plate arranged between the first substrate and the polarizer, the quarter wavelength retardation plate comprising:
a half wavelength retardation film of a predetermined wavelength, wherein a slow axis thereof makes a angle of Θ 1 with the transmissive axis; and
a quarter wavelength retardation film, wherein a slow axis thereof makes a angle of Θ 2 with the transmissive axis in accordance with relation equation of Θ 2 =2×Θ 1 -45 degrees;
at least one pixel disposed in the display region and including a thin film transistor; and
an organic insulating layer covering the pixel,
wherein an effective light path difference Δnd of the liquid crystal layer is equal to a quarter of the predetermined wavelength.
2. The reflective liquid crystal display of claim 1 , wherein a thickness of the liquid crystal layer is controlled by regional thickness of the organic insulating layer.