Optical efficiency modulation of vertical alignment liquid crystal displays with transparent shielding and storage electrode

Abstract

A high-transmittance vertical alignment liquid crystal display (VA-LCD) using a transparent shielding and storage electrode (TSS) design is proposed. The aperture ratio of the proposed four domain TSS pixel with size of 52 × 156 μm improves approximately by 40% over the conventional pixel due to the shielding and storage metal electrode can be replaced by TSS electrode. Experimental results shown that the transmittance of TSS designed panel with 3.2 μm cell gap is 35% higher than that with conventional pixel design, whereas it is only enhanced by 21% when the cell gap is 2.6 μm. The liquid crystal dynamics simulation results revealed that both the effective birefringence and the azimuthally controlled director profile of the liquid crystal layer decreases with TSS pixel design, and these adverse impacts are magnified as the cell gap decreases. This is due to that the introduction of TSS common electrode not only weakens the vertical electric field but also affects the horizontal electric field of liquid crystal layer, which leads to a greater loss of optical efficiency under lower cell gap, resulting in the worse transmittance promotion. The proposed method is expected to be advantageously employed in enhancing transmittance of VA-LCDs for power saving.