Patent ID: 8702465

Claim:
A method of making an electrodeless incandescent bulb, the method comprising the steps of: providing a bulb enclosure of quartz glass; forming an adjacent neck having a bore less than a transverse internal dimension of the bulb enclosure either: integrally with the bulb enclosure in a tube integral therewith or in a branch tube opening into the bulb enclosure; forming a further neck remote from the adjacent neck, either in the integral tube or the branch tube; preparing the bulb for sealing by performing the following steps in direct sequence: inserting at least one pellet of excitable material, either in the integral tube or the branch tube between the further neck and the adjacent neck or all the way into the bulb enclosure through the adjacent neck, evacuating the bulb enclosure via the integral tube or the branch tube, heating, either: the integral tube or the branch tube where the or each pellet is between the further neck and the adjacent neck or the bulb enclosure where the or each pellet is in it to drive off volatile impurity from the excitable material, the impurity being evacuated and allowing the excitable material to condense, either: in the integral tube or the branch tube on the further neck side of the adjacent neck or in the bulb enclosure and filling the bulb tube with inert gas, after evacuation and prior to sealing; preliminarily sealing the bulb at the further neck; and finally sealing the bulb at the adjacent neck.