Mask assembly for cathode ray tube (CRT)

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.