Patent ID: 6657689
Filing Date: 2003-12-02
Classification: G02F

Abstract:
A transflective liquid crystal display, comprising:upper and lower substrates facing into and spaced apart from each other, wherein the upper and lower substrates include a plurality of pixel regions that display images; a liquid crystal layer interposed between the upper and lower substrates, wherein the liquid crystal layer has a first adjusted thickness to compensate a residual optical retardation of incident light caused by anchored liquid crystals near an alignment layer when a maximum operation voltage is applied; a first upper retardation film over the upper substrate; a second upper retardation film between the first upper retardation film and the upper substrate, wherein the second upper retardation film has a second adjusted thickness for compensating an optical retardation caused by the liquid crystal layer; an upper polarizer on the first upper retardation film; a transparent common electrode on a surface of the upper substrate facing into the lower substrate; a pixel electrode over the lower substrate, wherein the pixel electrode corresponds to each pixel region, and the pixel electrode is divided into transparent and reflective portions; a second lower retardation film on the other surface of the lower substrate, wherein the second lower retardation film has a third adjusted thickness to compensate a residual optical retardation caused by the liquid crystal layer when a maximum operation voltage is applied, wherein a slow axis of the second lower retardation film is perpendicular to a slow axis of the second upper retardation film; a first lower retardation film under the second lower retardation film, wherein a slow axis of the first lower retardation film is perpendicular to a slow axis of the first upper retardation film; a lower polarizer under the first lower retardation film, wherein a transmissive axis of the lower polarizer is perpendicular to a transmissive axis of the upper polarizer; and a backlight device arranged adjacent to the lower polarizer, wherein the first adjusted thickness is d+d1 in the reflective portion of the liquid crystal layer and 2d+d2 in the transmissive portion of the liquid crystal layer, the first adjusted thickness is calculated from the following equation, T=Sin2&it;2&it;Ï†Sin2&af;[Ï€&CenterDot;Î”&it;â€ƒ&it;n&CenterDot;d1Î»],wherein d is a thickness of the liquid crystal layer in a reflective portion for an optical retardation of &lgr;/4, 2d is a thickness of the liquid crystal layer in a transmissive portion in order for an optical retardation of &lgr;/2d, T is a value of transmittance when a maximum operation voltage is applied, &phgr; is an angle between an optical axis of the liquid crystal layer and a transmissive axis of the polarizer, &Dgr;n is a birefringence of the liquid crystal layer, and d* is a thickness of the liquid crystal layer, d* is d1 or d2, and d1 and d2 are calculated from the above equation, d1 is a first auxiliary thickness of the liquid crystal layer when the residual optical retardation of the light is &ggr; in the reflective portion, d2 is a second auxiliary thickness of the liquid crystal when the residual optical retardation value of the light is &ohgr; in the transmissive portion, and a phase difference between the transmissive and reflective portions is &dgr;=&ohgr;âˆ’&ggr;.