Patent ID: 6215237
Filing Date: 2001-04-10
Classification: H01J

Abstract:
A color cathode ray tube comprising:an envelope including a substantially rectangular panel having an inner surface on which a phosphor screen is formed;a-substantially rectangular shadow mask provided in the envelope and opposing the phosphor screen; andan electron gun arranged in the envelope, for emitting an electron beam to the phosphor screen through the shadow mask;the shadow mask including a substantially rectangular mask body having a main surface portion opposed to the phosphor screen and provided with a number of electron beam apertures, and a substantially rectangular mask frame having side walls attached to the mask body and being in contact with a peripheral portion of the mask body,the mask frame including a long axis and a short axis perpendicular to each other and perpendicularly crossing a tube axis, and the side walls of the mask frame including a pair of long side walls extending in parallel with the long axis and a pair of short side walls extending in parallel with the short axis,at least one of the long and short side walls having beads, each formed by projecting a part of each side wall of the mask frame, a length of the beads in a direction perpendicular of the tube axis being set in a range of 55% to 80% of a length to the at least one of the long and short side walls in the direction of the long axis, and a width of the beads in a direction of the tube axis being set in a range of 40% to 75% of a maximum width of the at least one of the long and short side walls in the direction of the tube axis so that, when stresses are applied to the mask frame, unbalance between bending of the long sides and bending of the short sides of the mask frame is improved and deformation amounts of the long and short side walls are substantially equalized to each other.