Abstract: A high-pressure metal halide discharge lamp includes a sealed light-transmitting discharge vessel, first and second electrodes disposed in the discharge space, and a pair of conductive wires connected to the respective electrodes. The sealed light-transmitting discharge vessel has a pair of seals and envelops a discharge space, which has a gas filling comprising rare gas and metal halides. A first electrode with an emitter disposed in the discharge space at an one side is made of a metal having a high melting point. A second electrode without an emitter disposed in the discharge space at the other side is made of a metal having a high melting point. The pair of conductive wires, which are connected to the respective electrodes, are located in the respective seals and extend from the discharge vessel.

Abstract: A high-pressure metal halide discharge lamp includes a sealed light-transmitting discharge vessel, first and second electrodes disposed in the discharge space, and a pair of conductive wires connected to the respective electrodes. The sealed light-transmitting discharge vessel has a pair of seals and envelops a discharge space, which has a gas filling comprising rare gas and metal halides. A first electrode with an emitter disposed in the discharge space at an one side is made of a metal having a high melting point. A second electrode without an emitter disposed in the discharge space at the other side is made of a metal having a high melting point. The pair of conductive wires, which are connected to the respective electrodes, are located in the respective seals and extend from the discharge vessel.

Abstract: A metal halide lamp comprises a glass tube defining a discharge space and a pair of electrodes provided in the glass tube for generating a discharge therebetween. The metal halide lamp has mercury and halogen fillings comprising bromine and iodine contained in the glass tube. The mol ratio of the bromine to the halogen fillings is 0.3 to 0.7. The metal halide lamp has metal reacting with the halogen and emitting light in the glass tube by the discharge. The metal comprises tin, sodium, thallium and indium. The tin contained in the glass tube is at the amount of 1 to 14 .mu..multidot.mol per 1 cc of discharge space. Each mol ratio of the amount of the sodium, the thallium and the indium to the amount of the tin is not less than 0.2, respectively. The lamp has a color temperature of more than 4000.degree. K. without sacrificing efficiency or color rendition.

Abstract: A single-sealed metal-vapor discharge lamp forms a press sealed portion on one end to seal in a discharge space starting noble gas, light emission metal, and mercury. The discharge lamp has a pair of electrodes with bent portions whose tip ends are bent opposite to each other in the discharge space; a pair of inner metallic foil conductors, to each one end of which the proximal ends of the electrodes are joined; and an arc tube enclosing a pair of internal lead wires, each one end of which is joined to the other end of the inner metallic foil conductors. The electrodes which are arranged approximately parallel in the arc tube. A bend angle .theta. of the bent portions arc is 60.degree..ltoreq..theta..ltoreq.120.degree., and the curvature radius R of the periphery of the bent portions is approximately R.gtoreq.1.2d (where, d is wire diameter of the electrode rod).

Abstract: A metal vapor discharge lamp has a small arc tube of a single end type. The maximum and minimum thicknesses of the wall of the arc tube and the ratio of the minimum thickness to the maximum thickness are set to the values in predetermined ranges. The set thicknesses prevents breakage of the arc tube and deterioration of the lamp characteristics.

Abstract: A single side-sealed metal vapor discharge lamp is disclosed which includes a discharge tube having a sealed section at one end and a discharge region defining envelope at the other end, a pair of metal foils sealed at the sealed section and a pair of electrodes, the discharge region of the discharge tube containing a rare gas for starting and a filled gas containing mercury and light emitting metal. The electrodes are each comprised of a rod connected to the metal foil and a coil of at least one turn mounted on the forward end portion of a bent end portion of the rod, the coils being oppositely spaced apart by a predetermined distance in the discharge region. The coil is formed of a higher melting point material than a surface material of the forward end portion of the bent portion of the rod. With the length from the bent portion to the forward end of the rod indicated by L1, the length of the coil by L2 and the wire diameter of the coil by d, the following inequalities are satisfied: L1.ltoreq.3d and d/2.

Abstract: A single end-sealed type metal vapor discharge lamp includes an arc tube having a bulb made up of a discharge portion defining a discharge region and a sealing portion with a shoulder portion situated adjacent to the discharge portion. A pair of electrodes have a pair of mutually opposite electrode portions on an upper end of each of the pair, the electrodes extending from the sealing portion toward the discharge region. An outer tube encloses the arc tube in which a cross-sectional configuration of the bulb has a point of inflection at a boundary between the discharge portion and the sealing portion. A straight line l connecting a center of one electrode portion to that of the other electrode potion makes an angle of 15.degree.-45.degree. with respect to a straight line L connecting the point of inflection to a midpoint of the straight line l. The shoulder portion is located at a side opposite to that, on which the straight line l exists with the straight line L as a reference.

Abstract: A metal vapor discharge lamp has an envelope formed of a vitreous high temperature resistant material. A pair of electrodes each has a metal rod and an arc supporting electrode. The metal rods are sealed at one end of the envelope. The envelope is filled with a starting gas and a charge. The present invention also includes insulating films formed on the envelope behind the arc supporting electrodes to increase the vapor pressure of the charge, and improve output and the spectral color distribution.

Abstract: An arc tube bulb comprises a sealed portion formed at one end of the bulb and an enclosure portion formed at the other end to surround a discharge space. A pair of metal foils are buried in the sealed portion. A rare gas for start-up, mercury and a metal halide are charged in the discharged space. A pair of electrodes comprise a pair of electrode rods connected to the metal foils and coils disposed at the tips of the rods. These coils are positioned within the discharge space apart from each other and facing each other. The lamp is lit when the value of the input power WL (watt) divided by the inner surface area S (cm.sup.2) of the discharge space falls within the range of between 20 and 70, i.e., 20.ltoreq.WL/S.ltoreq.70. The surface region of the electrode rods is formed of a pure rhenium metal or a rhenium-tungsten alloy.