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: In a discharge lamp having a discharge medium sealed in a discharge tube assembly including electrodes for producing a discharge, a nitride layer is formed on a surface of an envelope tube of the discharge tube assembly. The nitride layer is formed by substituting an oxygen component of an oxide constituting the tube wall of the envelope tube with nitrogen, and exhibits a continuous and smooth reduction in nitride content in the direction of depth. This chemically stable nitride layer prevents a reaction between the discharge medium and the tube wall material, and removal or injection of the discharge medium. In addition, since the nitride layer also exhibits a continuous change in thermal expansion coefficient in the direction of depth, the thermal stress is reduced, and cracking, peeling, removal, and the like do not occur.

Abstract: This invention provides an improved layer coated on the outer surface of the envelope of high intensity discharge lamps, halogen lamps and so on. The overcoated layer is provided for preventing glass pieces of the envelope from scattering when the glass envelope is broken. Therefore the improved and strengthened layer comprises a fluorocarbon polymer containing metal oxide grains dispersed therein. The metal oxide grains are dispersed in the fluorocarbon polymer since the overcoated layer is heated at more than 200.degree. C. Further, for the purpose of strengthening the overcoated layer, the overcoated layer has an even density of the metal oxide grains in the fluorocarbon polymer. The even density of the metal oxide grains in the fluorocarbon polymer is obtained only by this invention of the coating method that includes a electrostatic coating step.

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 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: A metal vapor discharge lamp. The metal vapor discharge lamp includes an enclosed discharge tube having a pair of main electrodes mounted at spaced apart locations therein, the discharge tube including a fill of at least a metal vapor and a starting gas, a radiation source including radioactively impregnated ceramic material having a vitrified radioactive outer protection portion and an outer bulb for enclosing the discharge tube and a circuit for electrically generating an arc between the main electrodes.

Abstract: A headlight for a vehicle includes a metal halide lamp and a reflector having a focus and reflecting a light beam, emitted from the lamp, in a forward direction from the front of the vehicle. The lamp has a luminescent tube in which at least sodium is sealed, and positive and negative electrodes. The respective distal ends of the electrodes are located in the luminescent tube and spaced at a predetermined distance from each other. The lamp is positioned so that a straight line connecting the respective distal ends of the electrodes is horizontal and passes through the focus, and so as to meet the following requirement:0.ltoreq.L0/L1.ltoreq.0.4,where L0 is the distance between the focus and the distal end of the negative electrode, and L1 is the distance between the distal ends of the electrodes.

Abstract: A high-pressure metal vapor arc lamp, lit by direct current power supply, which includes an arc tube in which an anode and a cathode are arranged opposite to one another. The cathode includes a cathode shaft and a coil element wound around the cathode shaft. A diameter of a wire of the coil element is fixed within specific values in connection with a diameter of the cathode shaft, a pitch of the coil is fixed in connection with a diameter of the wire of the coil and I.sub.L (discharge current)/d.sub.0.sup.2 (external diameter of the coil) is determined within specific values, whereby an arc spot can be easily moved to the top portion of the cathode even if the arc spot is generated at the base portion of the cathode.

Abstract: A metal halide arc lamp includes a quartz arc tube having a pair of electrode shaft therein. The quartz arc tube which encloses a fill including mercury and metal halide materials is composed of a hollow illuminating portion and a pair of squeezed portions which have an individual elongated space, extending along the electrode shaft, the minimum value of the width, in the direction perpendicular to the electrode shaft, of which is controlled within specific values in connection with a diameter of the electrode shaft to reduce a probability of crack occurrence in the squeezed portion by a pressure produced when the fill is vapored rapidly in the elongated space of the squeezed portion.