Process for producing an electric lamp with outer bulb

A process for producing an electric lamp with outer bulb and with an inner vessel, in particular a discharge vessel, arranged therein, in which the following process steps are used:

• a) providing a hollow body made from glass which defines an interior volume and has at least one opening;
• b) supplying the hollow body or tube with at least one current bushing system which projects into the volume from the outside via the opening, the current bushing system being an electrode system which comprises at least an electrode, a foil and a supply conductor;
• c) evacuating and filling the internal volume;
• d) heating and deforming the hollow body at the open end, so that a sealing part which surrounds a central part of the current bushing system in a gastight manner, and an extension part, which includes an outer part of the current bushing system, are formed, with a lateral opening remaining in the extension part formed in this way to act as a pumping hole;
• e) fitting over a second hollow body made from glass, being a tube made from glass of relatively large dimension, the dimension of the second hollow body being such that the second hollow body covers the internal volume, the sealing region and a certain part of the extension part, being a region amounting to from 10 to 60% of the length of the extension part, with the pumping hole also being enclosed in the covered region;
• f) guiding the open end of the second hollow body, via a contact zone, onto the extension part, sealing the second hollow body along the contact zone to the extension part, in order to form an outer bulb, so that gastight contact is produced in the region of the extension part at least at the end of the contact zone, with the pumping hole located inside the contact zone;
• g) evacuating and filling the volume which extends between the inner vessel and outer bulb via the pumping hole and the open end of the extension part;
• h) closing the outer bulb in the region of the contact zone by heating at least a part of the contact zone and subsequently guiding this part of the contact zone onto the adjacent part of the inner vessel.