Production manner of shadow mask and the color picture tube and the invar alloy original plate for this shadow mask which use this and production manner null of this

摘要

PURPOSE: To provide a shadow mask, in which defects in the aperture shape and nonuniformity of aperture diameters are restrained so that the color unevenness does not occur, and a color picture using the same. ;CONSTITUTION: A shadow mask is formed using an Invar original plate manufactured by continuous casting method. The Invar original plate obtained thereby has a smaller amount of nonmetallic inclusions on its surface than at the center, and the cleanliness of the surface as measured by a method specified by JIS G 0555 is 0.01% or less. The cleanliness of the center portion as measured by a method specified by JIG G 0555 is 0.03% or less. A color picture tube is formed using the shadow mask.;COPYRIGHT: (C)1996,JPO