Patent ID: 7294035

Claim:
An apparatus for welding a shroud glass tube disposed coaxially with and covering an arc tube body having a substantially centrally and longitudinally displaced discharge emitting portion therein, a first end side of the shroud glass tube welded primarily to a first end side of the arc tube body, said apparatus comprising: an axially rotatable shroud glass tube holding portion that holds the first end side of the shroud glass tube, and maintains communication with a hollow shaft of the shroud glass tube; a relatively rotatable airtight seal coupling between the hollow shaft and a piping passage component configured to maintain a negative pressure at an inner part of the shroud glass tube by discharging air and introducing an inactive gas; a rotating and driving mechanism that rotates the shroud glass tube holding portion; and means for heating a secondary welding portion at the first end side of the shroud glass tube held by the shroud glass tube holding portion, wherein said secondary welding between an outer periphery at a second end side of the arc tube body and the secondary welding portion occurs when the negative pressure is maintained substantially simultaneously with (a) said heating means heating and melting the shroud glass tube and (b) said rotating and driving mechanism rotating the shroud glass tube.