METHOD FOR IMPROVING VIBRATION RESISTANCE OF SHADOW MASK, INCLUDING STEPS OF DISPOSING SHADOW MASK IN CLOSED VESSEL, INTRODUCING MIXTURE GAS OF NITROGEN AND OXYGEN INTO CLOSED VESSEL, AND PERFORMING HEAT TREATMENT

摘要

PURPOSE: A method is provided to prevent degradation of color purity by preventing vibrations of a shadow mask caused due to impact applied from an external source. CONSTITUTION: A method comprises a first step of disposing a shadow mask(6,7) in a closed vessel; a second step of permitting a mixture gas of nitrogen and oxygen to flow into the closed vessel; and a third step of performing a heat treatment by raising the internal temperature of the closed vessel. The shadow mask in the first step has a plurality of holes(8,9) for passage of electron beams(10) emitted from an electron gun(11), and is passed through a process for forming a curvature.