Patent ID: 7751009

Claim:
An array substrate for an in-plane switching mode liquid crystal display device, comprising: a substrate; a thin film transistor on the substrate; a gate line connected to the transistor; a data line crossing the gate line and connected to the transistor, the crossed data line and gate line defining boundaries of a pixel region; a pixel electrode disposed in the pixel region connected to the transistor, the pixel electrode including at least one vertical portion and a plurality of horizontal portions; and a common electrode disposed in the pixel region, the common electrode including at least two vertical portions, a plurality of horizontal portions and at least one auxiliary common electrode portion, wherein the vertical portion of the pixel electrode is disposed between the vertical portions of the common electrode, wherein the horizontal portions of the common electrode cross the vertical portion of the pixel electrode, wherein the vertical portion of the pixel electrode and one of the plurality of horizontal portions of the pixel electrode crossing each other, and one of the two vertical portions of the common electrode and one of the plurality of horizontal portions of the common electrode crossing each other define boundaries of a quadrangular domain, and wherein an in-plane electric field is induced in the domain along a direction which is slanted with respect to the vertical portion of the pixel electrode and the one of the plurality of horizontal portions of the pixel electrode, wherein the auxiliary common electrode portion protrudes from both of said one of the two vertical portions and said one of the plurality of horizontal portions of the common electrode crossing each other toward inside of the domain such that an outer side of the auxiliary common electrode portion, which connects both of said one of the two vertical portions and said one of the plurality of horizontal portions of the common electrode crossing each other, has one of a straight shape and a round shape.