Patent ID: 8222817
Filing Date: 2012-07-17
Classification: H01J

Abstract:
1. An arc tube for a discharge bulb comprising: an electrode assembly that includes an electrode bar and a molybdenum foil, wherein an overlapping portion of an end portion of the electrode bar and a molybdenum foil is joined by spot welding; a pinch seal portion that seals a part of the electrode assembly, the part including at least the molybdenum foil; and a closed glass bulb, into which a tip of the electrode bar protrudes, the closed glass bulb forming a discharge light-emitting portion, wherein a size of a recess, which is a weld mark, in the molybdenum foil on a side opposite to a joint portion, at which the molybdenum foil and the electrode bar are joined with each other, is within a range from 0.07 mm