Abstract: A compact fused silica, electroded HID lamp for automotive forward lighting, which contains no mercury. The lamps voltage, approximately 40 volts, is developed in this lamp by vaporizing zinc iodide instead of mercury. A compromise between voltage and luminous flux is achieved through the choice of the sodium scandium (Na:Sc) molar ratio, between 4.5:1 and 6:1 and a zinc iodide (ZnI2) dose of 2 to 6 micrograms per cubic millimeter that permits the lamp to operate within the North America, European and Japanese automotive color specifications for white light. The voltage in the lamp can be controlled according to the zinc iodide doping level without seriously impacting the visible spectrum otherwise provided by the other known dopants in the lamp.

Abstract: A compact fused silica, electroded HID lamp for automotive forward lighting, which contains no mercury. The lamps voltage, approximately 40 volts, is developed in this lamp by vaporizing zinc iodide instead of mercury. A compromise between voltage and luminous flux is achieved through the choice of the sodium scandium (Na:Sc) molar ratio, between 4.5:1 and 6:1 and a zinc iodide (ZnI2) dose of 2 to 6 micrograms per cubic millimeter that permits the lamp to operate within the North America, European and Japanese automotive color specifications for white light. The voltage in the lamp can be controlled according to the zinc iodide doping level without seriously impacting the visible spectrum otherwise provided by the other known dopants in the lamp.

Abstract: An electric lamp is provided including a sealed outer glass envelope having an arc tube therein supported from the stem of the outer glass envelope by a support frame. The support frame is attached to the stem by a stem clip to which the support frame is welded. An inert refractory fibrous material is disposed between the stem and the stem clip to provide resiliency and a friction fit therebetween.

Abstract: A metal halide discharge lamp includes an arc tube having a chemical fill, and a pair of electrodes sealed in the arc tube. The electrodes are tungsten and have differing thoria contents. The electrodes with differing thoria contents provide faster starting times than electrodes with equal low thoria contents and eliminate the electrode meltback, voltage increase and lumen loss that is characteristic of electrodes with equal but higher thoria contents. Preferably, one electrode has a thoria content of about 1.5 to 2 weight percent, and the other electrode has a thoria content of about one weight percent or less.

Abstract: A double-enveloped lamp assembly includes a light-source capsule subject to burst on rare occasions, a light-transmissive shield substantially surrounding the light-source capsule for absorbing and dissipating a portion of the energy when the light-source capsule bursts, a mesh of substantially nonconducting fiber for reinforcing the shield, and a light-transmissive outer envelope. The mesh is fabricated of ceramic fibers having sufficient strength to reinforce the shield. Since the fibers are nonconducting, sodium migration is minimized. The ceramic fiber mesh is particularly useful for high wattage lamps where thick-walled outer envelopes are not practical.

Abstract: A double-enveloped lamp having a shield surrounding a light-source capsule within a thick-walled outer envelope so that the lamp may be safely operated without necessity of a protective fixture. In the rare event of a burst of the light-source capsule, the shield absorbs and dissipates a portion of the burst energy sufficient to permit the thick-walled outer envelope to remain intact and contain shards and other internal parts within the lamp. In alternate embodiments, the shield may be reinforced, such as with a wire mesh, or the outer envelope may be reinforced, such as with a polymer coating, or both. A thin-walled capsule may be employed in combination with a shield and thick outer envelope. A lamp in accordance with the invention provides the unexpected benefits of improved luminous efficacy and better color rendering characteristics, since the presence of an optimally positioned shield causes the operation of the light-source capsule to be more nearly isothermal.

Abstract: A low wattage metal halide discharge lamp includes an evacuated envelope wherein is disposed a heat reducing member having an arc tube therein. The heat reducing member and the arc tube have a metal band and outer strap member adjacent one another and adjacent an electrode with the metal band, strap member and electrode all electrically connected to an electrical lead of one polarity whereby sodium losses from the arc tube are reduced.

Abstract: A low wattage metal halide discharge lamp includes an evacuated envelope wherein is disposed a heat reducing member having an arc tube therein. The heat reducing member and the arc tube have a metal band an outer strap member adjacent one another and adjacent an electrode with the metal band, strap member and electrode all electrically connected to an electrical lead of one polarity whereby sodium losses from the arc tube are reduced. Importantly, the evacuated envelope includes a getter and the heat reducing member is in the form of a domed sleeve having an open end directed away from the getters.

Abstract: A line-of-sight arched arc tube of an arc discharge lamp; e.g., a metal halide arc discharge lamp for horizontal operation having an arched upper wall to accommodate the bowing of the arc discharge during full temperature and pressure operation of the lamp and a lower wall of lesser curvature to accommodate the arc discharge during lamp start and warm-up. The curvature of the lower wall is such that there is a straight line-of-sight between the primary electrodes without being impeded by the lower wall of the arc tube and such that temperature profiles over the body of the arc tube are optimized during full temperature and pressure operation of the lamp.

Abstract: A high intensity discharge lamp operable from an AC potential source includes an arc discharge tube having a pair of oppositely disposed main electrodes therein and an associated external starting electrode, all disposed within a sealed envelope having an affixed base with a circuit means including a negative potential blocking device coupling the starting electrode to the AC potential source.

Abstract: A high-pressure metal halide arc discharge lamp having an arc tube with a pair of main electrodes disposed within the tube at opposite ends and a starting electrode located adjacent one of the main electrodes. A tubular sleeve of insulating material, such as quartz, is disposed about the starting electrode, which is recessed within the sleeve but exposed through the open end thereof to the interior atmosphere of the arc tube. Since the starting electrode does not project beyond the open end of the sleeve, conduction between that electrode and the adjacent main electrode is minimized or prevented during normal lamp operation, thereby minimizing or preventing electrolysis.

Abstract: A metal halide arc discharge lamp comprises an arc tube having electrodes at its ends and containing a fill including mercury, a starting gas, elemental scandium and at least about 2.6.times.10.sup.-6 gram atoms of scandium halide and 3.0.times.10.sup.-5 gram atoms of sodium halide per centimeter of arc length.

Abstract: The fill of a tungsten halogen lamp includes an organic halide. After the exhausting, filling and sealing steps, the lamp is heated in a monoxidizing atmosphere to the dissociation temperature of the organic halide prior to lamp finishing.