Abstract: An arc discharge metal halide lamp for providing visible light comprising an arc discharge vessel which has capillary tubes therein in at least one of which there is a first electrical feedthrough extending through an interior passageway to have an interior end of that electrode positioned in the discharge region opposite the other the interior passageway of the other capillary and an exterior end thereof positioned outside the outer end of that capillary tube but joined to a cermet portion inside that tube. In an intermediate stage of fabricating the lamp, a bonding material ring of limited diameter is provided at the end of the capillary tube about the exterior end. In a completed lamp, the first electrical feedthrough has limited extent joints where its components are joined and, alternatively or in addition, has a limited offset between its components at a joint between them.

Abstract: This invention is about a CMH lamp arc tube seal construction where the feedthrough electrode contains a cermet in such a manner that the said cermet is either not exposed outside the ceramic capillary (which in most cases is polycrystalline alumina, PCA) or if it is exposed to the outside of the arc tube, the part that is exposed has no current carrying function. The invention provides safe ways of assembling the cermet so as to avoid breakage of the said cermet due to mechanical stresses in the electrical connections.

Abstract: An arc discharge metal halide lamp for providing visible light comprising an arc discharge vessel which has capillary tubes therein in at least one of which there is a first electrical feedthrough extending through an interior passageway to have an interior end of that electrode positioned in the discharge region opposite the other the interior passageway of the other capillary and an exterior end thereof positioned outside the outer end of that capillary tube but joined to a cermet portion inside that tube. In an intermediate stage of fabricating the lamp, a bonding material ring of limited diameter is provided at the end of the capillary tube about the exterior end. In a completed lamp, the first electrical feedthrough has limited extent joints where its components are joined and, alternatively or in addition, has a limited offset between its components at a joint between them.

Abstract: This invention is about a CMH lamp arc tube seal construction where the feedthrough electrode contains a cermet in such a manner that the said cermet is either not exposed outside the ceramic capillary (which in most cases is polycrystalline alumina, PCA) or if it is exposed to the outside of the arc tube, the part that is exposed has no current carrying function. The invention provides safe ways of assembling the cermet so as to avoid breakage of the said cermet due to mechanical stresses in the electrical connections.