Selective internal coating of articles, esp. electric lamp bulbs - by vacuum evapn., using flexible elastomer mask fed through bulb neck

摘要

Mask is for the selective coating of a surface e.g. with Al by vacuum evapn., esp. for masking part of the internal surface of a bulb used for an electric lamp or an electronic tube. The dimension of the mask at 90 degrees to the neck of the bulb is larger than the bore dia. of the bulb neck; and the mask has a structure and texture providing flexibility, so it assumes its natural shape when inside the bulb. The mask is mounted on a support so it can be fed into, and removed from the bulb via the bulb neck. The mask is pref. made at least partly of a homogeneous elastomer; a cellular elastomer with closed cells; and/or an elastomer foil with constant thickness plus a contour and dimensions matching the surface to be shielded. The thickness of the mask may alternatively decrease away from its support, and/or be ribbed. More than one foil may be used to make the mask; and a second mask may be mounted on the support.