Patent ID: 7486008

Claim:
A mask assembly for a Cathode Ray Tube (CRT), comprising: a shadow mask including a plurality of beam passage holes; and a frame including a supporting portion with a pair of long sides and a pair of short sides attached to the shadow mask and a strength maintenance portion bent and arranged from the supporting portion; wherein the frame includes a plurality of reinforcement indentations arranged on a portion of a boundary between the supporting portion and the strength maintenance portion; and wherein at least one of the reinforcement indentations satisfy the following conditions: a ≤ L H 6 , b ≥ L H 3 a ′ ≤ L V 5 , b ′ ≥ 3 10 ⁢ L V wherein a and b respectively represent a distance from the end of the long side to one side and the other side of the reinforcement indentation located on the long side, a′ and b′ respectively represent a distance from the end of the short side to one side and the other side of the reinforcement indentation located on the short side, and LH and LV respectively represent a length of the long side and the short side of the frame.