US Patent 7110059 Display device

A metal electrode also serving as a black matrix is so formed as to cover the periphery of an ITO pixel electrode. A region where the pixel electrode and the metal electrode coextend also serves as an auxiliary capacitor. Since the auxiliary capacitor can be formed by using a thin insulating film, it can have a large capacitance. By virtue of the structure in which the black matrix also serves as the auxiliary capacitor, it is not necessary to provide an electrode dedicated to the auxiliary capacitor, thereby preventing reduction in aperture ratio. Further, the black matrix can completely shield a source line and a gate line from light.