Abstract: The invention relates to a high-pressure discharge lamp comprising a discharge vessel enclosing a discharge space and provided with two main electrodes. Each of the main electrodes is connected to a lead-through element which is enclosed with an intermediate space by a closing part and is connected thereto in a gas-tight manner by means of a sealing joint. According to the invention, the lead-through element is provided with a protuberance reaching as far as the closing part and being present around the whole periphery of the lead-through element. In this manner, a screening of the sealing joint from the discharge space is obtained.

Abstract: The invention relates to a discharge lamp which has a discharge vessel provided with an external auxiliary electrode. The lamp also has a bimetal which in the inoperative condition of the lamp causes the external auxiliary electrode to bear against the discharge vessel. According to the invention the auxiliary electrode is connected to an end of only one bimetallic strip and in the operating condition of the lamp the auxiliary electrode is remote for the greater part from the discharge vessel due to the action of the bimetal. Combined with an operating condition of the lamp in which no hindrance is experienced from the auxiliary electrode.

Abstract: In electric lamps a type of glass is used for the envelope which, in many cases, has a coefficient of expansion which differs considerably from that of the current supply conductors. Therefore, special measures have to be taken to seal the lamp envelope in a vacuum-tight manner around the current supply conductors.The invention provides a simple, vacuum-tight seal of a lamp envelope (1), which seal consists of a metal plug (8, 9, 11) which is sealed both to the glass of the lamp envelope (1) and to the current supply wires (4, 5, 10).The metal plug (8, 9, 11) of 100 parts by weight of a first metal (tin and/or lead) 0.05-1 parts by weight of a second metal (titanium, zirconium, hafnium, niobium, tantalum, and vanadium) has a strong adhering power and a large ductility.

Abstract: The invention relates to an electric lamp having a pinch seal in which a molybdenum foil is incorporated as a current leadthrough conductor. An external current conductor is connected to the foil. As a result of differences in coefficients of expansion, a capillary space is present around the external current conductor, through which space oxidizing gas can reach the molybdenum foil. Oxidation of the foil involves an increase of its volume and results in crack of the pinch seal.In lamps according to the invention a metal plug is provided around the external current conductor, said plug being sealed to said current conductor and to the glass of the pinch seal and sealing the capillary space in a vacuum-tight manner.