Patent ID: 7291224

Claim:
A method for forming a phosphor screen comprising: placing a substrate in an assembly comprising two plates wherein one plate of said plates is an outermost plate, and both, at least in part having a perforation pattern over a surface area covering an open side of a crucible having a bottom and surrounding side walls containing raw materials, wherein said outermost plate is mounted at a distance farther from said crucible than said cover covering said open side of said crucible, and wherein both plates are mounted versus each other, so that, when viewed through an axis in a direction perpendicular to the bottom of the crucible from a distance to said outermost plate of at least 10 times the distance between said two plates, its contents cannot be observed; heating said crucible to evaporate said raw material; and depositing said evaporated raw material on said substrate further provided with a non-perforated cover as a closing cover.