US Patent 8656859 Mask and mask assembly having the same

A mask assembly includes a frame including an opening part; and unit masks that are disposed on the opening part and having both ends of each of the unit masks supported by the frame in the state where tensile force is applied in one direction, each of the unit masks including: pattern opening parts disposed in the one direction; and a first groove disposed adjacent to the pattern opening parts and between the pattern opening parts and an edge of the unit mask, and formed to be depressed from a surface of the unit mask.