High intensity discharge lamp with improved crack control and method of manufacture

摘要

A high intensity discharge lamp comprises an arc tube, which encloses an arc chamber. The arc chamber contains a gas fill and the arc tube is terminated by at least one sealed portion. The sealed portions enclose an electrode assembly. The electrode assembly comprises an electrode, a lead-in wire and an electrically conducting foil. The electrode extends into the arc chamber. The lead-in wire extends outward from the sealed portion for providing electric contact with a power supply. The electrically conducting foil connects the lead-in wire and the electrode and provides a sealed electric connection through a sealed portion of the arc tube. At least one of the electrodes is provided with surface irregularities in a region between the foil and the arc chamber in order to control shape and size of cracks in a seal wall surrounding the electrodes.;In the method, an electrode of predetermined geometry and structure is provided with at least one artificial surface irregularity. Subsequently, an electrode assembly comprising said electrode, a seal foil and a lead-in wire is prepared. The electrode assembly is introduced into an arc chamber, the arc chamber is closed with a seal, and the electrode assembly is sealed therein, so that the irregularities of the electrode are formed in a region between the foil and the arc chamber. The electrodes may be provided with artificial surface irregularities also after preparing the electrode assembly.