Abstract: Metal halide lamp with ceramic discharge vessel having electrodes with spacing EA, internal diameter Di, and EA/Di>5. Ionizable filling comprises NaI and CeI.sub.3, and a coldest spot temperature of 1100-1500 K is achieved.

Abstract: An electrode-less high pressure discharge lamp has a lamp vessel which is surrounded by an electric coil having turns. End portions of the coil are electrically connected to current conductors. The turns of the coil are supported by aluminium nitride, which is in thermal contact with the current conductors. There is a good heat transfer from the coil to the conductors, keeping the coil relatively cool and efficient. The coil screens the lamp vessel to a small extent only, thereby improving the lamp efficacy.

Abstract: The high-pressure discharge lamp has around the discharge vessel an inner sheath of quartz glass and an outer sheath of aluminosilicate glass. An interference filter reflecting UV radiation is present between the discharge vessel and the outer sheath. The light emitted by the lamp thus satisfies the conventional standards regarding radiation for lamps operated in open luminaires.

Abstract: The high-pressure discharge lamp has an ionizable filling containing mercury, rare gas, dysprosium halide and a second halide chosen from the halides of Tl, Ce, Pr, Nd, Sm and Gd. The lamp has a comparatively low color temperature and a good color rendition, especially also of the color of the skin. The lamp may be used, for example, as a studio lamp for the illumination of indoor scenes.

Abstract: An electrodeless low-pressure discharge lamp comprising a lamp vessel (1) sealed in a vacuum-tight manner and filled at least with a metal vapor and a rare gas, the lamp being provided also with a cylindrical core (2) of magnetic material, such as ferrite, a winding (4) arranged to surround the core (2) and an electrical supply unit connected thereto for producing during operation of the lamp an electrical field in the lamp vessel (1). The supply unit is located in a thin-walled metal housing (8) provided in a wall portion (9) of synthetic material, which is partly of conical shape and is provided at its end with an Edison lamp cap (10), and the core (2) accommodates a rod-shaped or tubular body (11) of thermally conducting material connected to the housing (8). In order to improve the ignition properties of the lamp, an electrical insulator (12) is provided between the end of the body (11) and the wall of the housing (8).

Abstract: The invention relates to starting and supplying a low-pressure discharge lamp which comprises two electrodes between which a main discharge path is formed, a shunt path being electrically in parallel with at least a portion of said main discharge path.In accordance with the invention the lamp is started by means of a glow-discharge starter which is shunted by a VDR the threshold voltage of which is lower than a value determined by the geometry of the shunt path, and is higher than the minimum voltage for starting a discharge in the main discharge path. The discharge then only starts in the main discharge path.

Abstract: A high pressure discharge lamp comprising a discharge vessel in which an electrode comprising a resistive element is present, said resistive element consisting of two parallel arranged branches having substantially the same electrical resistance. With such an electrode construction it is achieved that the starting point of the discharge on the electrode is stabilized.

Abstract: The invention relates to a glow-discharge starter (10) having a bimetallic electrode (11) and a rare gas.According to the invention the glow-discharge starter also comprises a reversible getter (13) which, when the temperature increases, gives off a gas and, when the temperature decreases, absorbs the gas and the value of the gas pressure also determines the electric conductivity of the glow-discharge starter.A glow-discharge starter is thereby obtained in which undesired breakdown of the glow-discharge starter can be prevented by controlling the gettering temperature.

Abstract: In a blended lamp, an incandescent filament and a high-pressure discharge tube are arranged electrically in series. The filament forms part of a halogen incandescent lamp and the discharge tube contains a sodium amalgam which is very high in mercury. A relatively high lumen per Watt-value is thereby combined with an acceptable color of the light.

Abstract: The invention relates to a high-pressure sodium vapor discharge lamp comprising a discharge tube containing sodium and xenon.In accordance with the invention the inside diameter of the discharge tube is below 5 mm and greater than 1 mm. In addition the xenon pressure is relatively high in the operating condition of the lamp which -- together with a pressure of the sodium in a given range -- can result in a high luminous efficacy of the lamp.