Reduction of the parasitic capacitance of a pixel in a horizontal-electric-field type active matrix liquid crystal display

摘要

Two basic types of active matrix LCD substrate assembly (fig.1) are disclosed.
Both employ a planar lower electrode (typically the common electrode, 270) and an upper electrode provided with cut-outs (92) on the AM-substrate (100) to produce a horizontal electric field component (fringe-field switching).
First type: a light shielding layer (220, typically high permittivity) is in direct electrical contact with the common electrode (fig.2). The parasitic capacitance arising between the pixel (191) and common electrodes (220) at the edge of the contact hole (185) is reduced to improve display quality.
Second type: the light shielding layer (20, typically low permittivity) extends over the edge (93) of a cut-out (92) in the upper electrode (mostly the pixel electrode 191) nearest the gate line (121, fig.9). The effect of the fringe field on the LC molecules at the edge is reduced to improve display transmittance.