Abstract: A metal halide lamp comprises a light-transmitting discharge vessel having a discharge space portion, a sealed portion, and a pair of electrodes projecting into the discharge space. The discharge vessel is constructed and arranged to have a D/L ratio being in a range of about 0.25 to about 1.5 and a D/L ratio being in a range of about 0.16 to about 1.1, wherein L is an interspace of tips of the electrodes, D is a maximum inner diameter of the discharge vessel, and t is a maximum wall thickness of the discharge space portion. An ionizable filling contains a rare gas and a metal halide including at least sodium (Na) or scandium (Sc) and does not substantially include mercury (Hg). Each of conductive wires is connected electrically to the electrodes extending from the discharge vessel. The metal halide lamp may be used for a metal halide lamp apparatus or a vehicle lighting apparatus.

Abstract: Disclosed is a metal halide discharge lamp which essentially permits disusing mercury. The metal halide discharge lamp comprises a refractory and transparent hermetic vessel, a pair of electrodes fixed to the hermetic vessel, and a discharge medium sealed in the hermetic vessel and containing a first halide, a second halide and a rare gas, the first halide being a halide of a metal which achieves a desired light emission, the second halide having a relatively high vapor pressure, being at least one halide of a metal which is unlikely to emit a visible light compared with the metal of the first halide, and acting as a buffer gas.

Abstract: A metal halide discharge lamp which essentially permits disusing mercury is provided. The metal halide discharge lamp comprises a refractory and transparent hermetic vessel, a pair of electrodes fixed to the hermetic vessel, and a discharge medium sealed in the hermetic vessel and containing a first halide, a second halide, and a rare gas. The first halide is a halide of a metal which achieves a desired light emission. The second halide has a relatively high vapor pressure, being at least one halide of a metal which is unlikely to emit a visible light compared with the metal of the first halide and acts as a buffer gas.

Abstract: A glow starter comprises a discharge vessel, filled with a filling including a rare gas, substantially transmitting ultraviolet rays of about 300 nm or less. A pair of electrodes, which are arranged in the discharge vessel, is adapted and arranged to touch each ether by being heated by a glow discharge. The glow starter may be used for a high pressure discharge lamp, a high pressure discharge lamp apparatus, or a lighting fixture.

Abstract: In order to maintain an ultraviolet-ray intensity of a metal halide lamp for a long period, the present invention provides a high intensity discharge lamp comprising an arc tube having electrodes at its both ends, and a rare gas, mercury, iron, a halogen and silver enclosed in the tube, wherein a gram atom ratio of silver to iron is 0.05 to 0.2. The present invention also provides a high intensity discharge lamp comprising an arc tube having electrodes at its both ends, and a rare gas, mecury, iron, a halogen, tin and silver enclosed in the tube, wherein ([Fe]+[Sn])/[J]<0.5 and (2[Fe]+2[Sn]+[Ag])/[J]>1, where [Fe], [Sn], ]Ag] and [J] are, respectively, gram atoms of iron, tin, silver and the halogen.

Abstract: A high pressure metal vapor discharge lamp including an arc tube having at least a main electrode at each end thereof, a fill sealed in the arc tube, including mercury, metal halide and starting gases selected from the group consisting of Ar, Kr and Xe, a radioactive source material, impregnated with a radioactive substance having a half-life less than 1.times.10.sup.4 years, sealed in the arc tube and a circuit including a conventional low voltage mercury lamp ballast and a glow starter for starting the arc tube.

Abstract: A high pressure metal vapor discharge lamp including an arc tube having opposed ends at which are provided respective main electrodes and a fill including mercury and a starting gas, a radioactive source material including a radioactive substance having a half-life less than 1.times.10.sup.4 years sealed in the arc tube, an outer tube enclosing the arc tube and a circuit for starting the arc tube.

Abstract: In a metal halide lamp including a luminous sealed tube which is equipped with a pair of discharge electrodes and has an inonizable inert gas and mercury sealed therein, the luminous sealed tube further includes, in addition to tin halide (exclusive of tin fluoride), calcium halide (exclusive of calcium fluoride) or strontium halide (exclusive of strontium fluoride) or their mixture. The metal halide lamp shows a high color rendering property.

Abstract: A metal halide lamp comprising a luminous sealed tube, a pair of electrodes housed in the luminous tube and rare gas, mercury and metal halide sealed in the luminous tube, characterized in that boron or a boron compound is sealed in the luminous sealed tube in such a manner as not to contact the surfaces of the electrodes. The metal halide lamp is advantageous in that the electrodes are prevented from corrosion and that the blackening with time of the inner wall of the luminous tube is suppressed.