Abstract: A metal halide lamp in which the radiant efficiency is not adversely affected, in which outstanding color reproducibility is obtained, and which is suitable for a light source of an OHP or a direct projector is achieved, according to the invention, by the fact that, within an arc tube provided with a pair of electrodes, together with mercury and a starting rare gas, halides of dysprosium (Dy), yttrium (Y) and cesium (Cs) are encapsulated with the molar ratio of the encapsulated metals Dy to Y is being fixed in the range of 0.3.ltoreq.Dy/Y.ltoreq.1.0. In this way the green portion to which there is a sensitive visual reaction is reduced, the blue portion increased, and thus the color reproducibility is increased.

Abstract: A metal halide lamp includes a light transmitting container filled with a rare gas, a halide of indium in an amount of 0.1 mg/cc to 1.5 mg/cc, at least one halide of a rare earth element selected from terbium, dysprosium, holmium, erbium, or thulium. The metal halide lamp has an emission spectrum distributed over the visual inspection range, a high luminous efficacy, a high color temperature, and long lifetime.

Abstract: A high performance miniature projection lamp which includes a glass envelope having a pair of opposite neck portions each with a coaxial central opening having a reduced section and an hermetically sealed central chamber having a volume of about 130 mm.sup.3 which contains a fill. The fill includes an argon pressure at room temperature at a range of about 0.5 atmospheres to about 2.0 atmospheres and mercury in an amount in the range of about 5 mg to about 15 mg, and a mixture of metal halide material in an amount from about 50 up to 1000 micrograms. A pair of axially aligned electrodes are positioned at opposite neck portions and separated form each other by a predetermined distance. The electrodes each have a shank portion which each having a coil wrapped around its end.

Abstract: A metal halide headlamp comprising an electrode and a coil wrapping around said electrode to prevent the occurrence of cracks in a sealing portion, in which the diameter d.sub.0 of said electrode, the cross-section S of said electrode including said coil, the inner diameter ID of said coil, the pitch P of said coil, the distance L between an end of said coil and a metal foil, and the amount of metal halides with a NaI-to-ScI.sub.3 ratio are specifically limited. Thereby, the prior art problems, i.e., changes in the lamp characteristics, the degradation of durability, and so on, can be solved.

Abstract: A lamp for providing visible radiation includes tellurium or a tellurium compound in the fill. This substance is present in an amount such that when the fill is excited with sufficient power, substantially all of the radiation resulting from tellurium is emitted at wavelengths exceeding 400 nm. When tellurium is added to a sulfur or selenium based lamp for emitting visible radition, the spectrum is shifted towards the red region.

Abstract: A method wherein the light in a sulfur or selenium lamp is reflected through the fill a multiplicity of times to convert ultraviolet radiation to visible. A light emitting device comprised of an electrodeless envelope which bears a light reflecting covering around a first portion which does not crack due to differential thermal expansion and which has a second portion which comprises a light transmissive aperture.

Abstract: A metal halide gas discharge lamp comprises an arc tube containing a vaporizable metal halide and first and second spaced electrodes. An arrangement for heating the arc tube assists in creating an arc discharge between the first and second electrodes. It comprises a heat source positioned to heat the arc tube, and an electron barrier disposed between the heat source and the arc tube for minimizing accumulation of photoelectrons on an outer surface of the arc tube so as to substantially avoid sodium migration out of the arc tube. A switch deactivates the heat source after the arc tube is heated a desired amount.

Abstract: To increase the radiation output from a discharge lamp having a diaphragm arrangement located between an anode (3) and a heatable cathode (4), the diaphragm arrangement constricts the radiation discharge path along an axis (5, 105) extending through the diaphragm opening and towards the anode (3, 103), and has a dimension along the length of said axis of at least 0.3 mm. The diaphragm arrangement can be formed by a plurality, preferably about 3 diaphragm elements (6, 7, 8), each having diaphragm openings of from between 0.1 to 2 mm, made of sheet metal of a thickness of at least 0.03 mm, and preferably of between 0.1 to 1 mm, and in which the spacing of the diaphragm openings (10, 11, 12) with respect to each other is in the range of about 0.1 to 5 mm, preferably about 0.3 mm; alternatively, the diaphragm arrangement may include one massive diaphragm having an axial thickness of between 1 and 50 mm, preferably between about 1 and 5 mm, and spaced from the anode by between about 0.

Abstract: A light transmitting discharge vessel encloses a discharge space, sealed in a gas-tight manner, in which electrodes connected to current conductors which extend to the exterior are disposed. A filling in the discharge vessel comprises a rare gas, a buffer gas and at least one transition metal halide chosen from the halides of hafnium, zirconium and tantalum. Each of the electrodes comprises an electrode part containing a carbide chosen from the carbides of hafnium, zirconium and tantalum. As a result diffusion of transition metal from the plasma into the electrode is strongly suppressed so that the lamp keeps very good color rendering properties throughout its operation.

Abstract: A lamp for emitting in the visible portion of the spectrum, which utilizes a fill which includes a selenium and/or a sulfur containing substance. The lamp has superior performance characteristics, including long lifetime and excellent color rendition. The bulb may be either electrodeless or electroded, and may contain additives for emphasizing a desired spectral region.

Abstract: A sulfur, selenium, and/or tellurium based lamp for providing visible light. The lamp is operated in a regime for providing high efficacy wherein the ratio of the volume to surface area of the bulb is greater than 0.45 cm, the concentration of the sulfur, selenium, or tellurium is less than 1.75 mg/cc, and the power density is between about 100 watts/cc and 5 watts/cc.

Abstract: High-pressure sodium vapor lamp with high color rendering including, in an arc tube of a light transmitting material formed in a substantially cylindrical shape sealed hermetically at both axial ends, a pair of electrodes disposed internally at both axial ends of the tube and xenon gas of at least 2.5.times.10.sup.4 (Pa) sealed in the tube together with sodium vapor, is so constituted that a lamp voltage upon lighting of the lamp and represented by V (V as a unit), lamp power represented by W (watt), internal diameter of the arc tube represented by .phi. (mm) and distance between the pair of electrodes represented by d (mm) will satisfy the following formulas:2.0.ltoreq.V/d.ltoreq.2.7 (1)and20.ltoreq.W/.phi..ltoreq.

Abstract: The spectral energy characteristic of a discharge lamp is controlled by changing the density of the fill substance. The spectral characteristic can be shifted while substantially maintaining its shape by changing the density of the fill. A sulfur or selenium containing discharge lamp which is operated at a pressure of at least about 1 atmosphere contains a low ionization potential substance in the fill. Characteristics which are improved are one or more of spatial color uniformity, extinguishing characteristics, and bulb starting reliability. Particular substances which are added to the fill are alkalai metal containing substances, III B metal containing substances, and alkaline earth metal containing substances. When light is reflected back into the bulb, the light which is re-emitted is stronger in the higher wavelengths.

Abstract: A metal-halide discharge lamp for photo-optical purposes contains an ionisable fill, comprising mercury, at least one noble gas, at least one halogen, aluminum (Al) and indium (In) as well as gallium (Ga) in addition. By the addition of Ga, typically in the range between 0.02 mg/cm.sup.3 and 1 mg/cm.sup.3, a reduction in the starting voltage is attained, while maintaining an Ra>85 at color temperatures typically between 5000 K and 11000 K.

Abstract: The spectral energy characteristic of a discharge lamp is controlled by changing the density of the fill substance. The spectral characteristic can be shifted while substantially maintaining its shape by changing the density of the fill. A sulfur or selenium containing discharge lamp which is operated at a pressure of at least about 1 atmosphere contains a low ionization potential substance in the fill. Characteristics which are improved are one or more of spatial color uniformity, extinguishing characteristics, and bulb starting reliability. Particular substances which are added to the fill are alkalai metal containing substances, III B metal containing substances, and alkaline earth metal containing substances. When light is reflected back into the bulb, the light which is re-emitted is stronger in the higher wavelengths.

Abstract: A metal halide lamp in which no color shadowing occurs on the light acceptance surface and which at the same time emits with sufficient brightness is achieved according to the invention by encapsulating lutetium halide and one or more of the metal halides from groups A, B and C in an arc tube of a metal halide lamp together with a mercury halide:Group A: dysprosium halide, holmium halide, erbium halide, thulium halideGroup B: cerium halide, praseodymium halide, neodymium halideGroup C: cesium halide.

Abstract: In a quartz glass tube body for high-pressure discharge lamp, the devitrification occurs during lighting, a light flux decreases and finally the useful life ends, where the main cause of this devitrification phenomenon is reaction between a sealed substance and the quartz glass tube body. It is one object of the present invention to attain the longer useful life, for example, of a high-pressure discharge lamp by preventing such a phenomenon. According to the present invention, a coating is made up by forming one or more oxynitride layers of an element chosen from among aluminum, tantalum, niobium, vanadium, chromium, titanium, zirconium, hafnium, yttrium, scandium, magnesium, silicon and lanthanum rare earth elements.

Abstract: A cadmium discharge lamp which can emit line spectra with wavelengths of 214.+-.2 nm with high power is achieved by encapsulating metallic cadmium, in an amount producing a pressure in stationary lighting operation in the range from 2 kPa to 13.7 kPa, together with at least one of the rare gases xenon, krypton, argon and neon, in a temperature-controlled arc tube which is provided with electrodes located adjacently opposite one another, and by operating the lamp such that J/P is in the range from 1.4 to 75, where J is the discharge current in stationary lighting operation in amperes and the P is the cadmium pressure in stationary lighting operation.

Abstract: A sodium containing lamp constructed to include of a fused quartz or fused silica arc chamber wherein the fused quartz and/or fused silica contains less than about 0.05 parts per million sodium. The arc chamber of the invention demonstrates a resistance to sodium diffusion resulting in a longer lived lamp with excellent color maintenance.

Abstract: A metal halide discharge lamp with a coaxial discharge vessel (2) and outer ulb (9) contains a fill of metals with a tendency to diffusion. Their specific content is less than 6 .mu.mols/cm.sup.3. The current supply leads (4, 5) are surrounded, over a large portion of their length, by a sheath (14) that is UV-shielded.

Abstract: An arc tube for a high intensity discharge lamp. The arc tube has a hermetically sealed body formed from a vitreous material subject to devitrification, at least two oppositely disposed electrodes are sealed in the body. An are generating and sustaining medium is provided in the body and operates to produce visible light when an electric current is applied to the electrodes. The are tube has a given color rendering index, and at least a portion of the medium comprises a color correcting component of lithium iodide which contributes no only to the given color rendering index but which also acts as a devitrification agent. The improvement comprises an anti-devitrification component in the medium, the anti-devitrification component having a minimal detrimental effect on the given color rendering index while increasing the life of the are tube.

Abstract: A high pressure sodium lamp is provided. The high pressure sodium lamp includes a discharge lamp vessel to the ends of which a pair of electrodes are respectively connected, a sleeve coupled to at least one end of the discharge lamp vessel and connected to one of the electrodes, a wire frame slidably inserted into the sleeve, and a buffer coil, one end of which is connected with the wire frame and the other end of which is housed inside the sleeve, elastically supporting the discharge lamp vessel.

Abstract: A metal halide lamp includes a discharge vessel with a ceramic wall and a filling which comprises besides mercury and a halogen also Na, Tl and one or several of the elements from the group formed by Sc, Y and lanthanides. The filling also contains Mg to improve lumen maintenance.

Abstract: A metal-halide discharge lamp for photooptical purposes has a small electe spacing of less than 15 mm, preferably 2-8 mm, to provide an essentially pin-point light source, and a fill which contains AlI.sub.3 in an amount between 0.1 and 4.5 mg/cm.sup.3. Other filling components may in particular be halides of mercury, indium, thallium or cesium; up to 2 mg/cm.sup.3 of AlBr may be added. The lamp is particularly adapted for combination with a, preferably parabolic, reflector.

Abstract: An optically transparent polycrystalline alumina sintered body consists essentially of alumina, magnesia, yttria and zirconia. The magnesia is present in an amount of about 0.020 wgt. percent, the yttria is present in an amount of about 0.035 wgt. percent, and the zirconia is present in an amount of about 0.018 wgt. percent. An arc tube for a high pressure sodium lamp made from this composition has greatly increased resistance to sodium loss and concomitant outer jacket darkening, whereby the effective amount of lumen output is increased.

Abstract: A lamp for providing visible radiation includes tellurium or a tellurium compound in the fill. This substance is present in an amount such that when the fill is excited with sufficient power, substantially all of the radiation resulting from tellurium is emitted at wavelengths exceeding 400 nm. When tellurium is added to a sulfur or selenium based lamp for emitting visible radiation, the spectrum is shifted towards the red region.

Abstract: Low pressure sodium lamp color output is shifted from yellow to a fuller spectral range of visible light (white) by effective simultaneous excitation of sodium and a mercury additive. This is made possible principally by controlling the vapor constituents and the excitation arrangement.

Abstract: A lamp for providing visible light which utilizes a fill containing selenium and/or sulfur, or compounds of these substances. The lamp is excited such that the excited fill emits radiation from elemental selenium and/or elemental sulfur which is in a continuous band principally within the visible range.

Abstract: An emission device which operates a cadmium lamp with a light intensity sufficient for used in industrial applications is achieved by an emission device having a cadmium lamp with a fluorescent tube within which a cathode and an anode are space a small distance apart and a buffer gas for easier initiation of luminous operation and metallic cadmium in an amount per unit volume of the fluorescent tube of 1.times.10.sup.-4 g/cm.sup.3 to 3.times.10.sup.-3 g/cm.sup.3 are encapsulated, and a power source device for supplying an electrical input between the cathode and the anode in an electrical input range from 0.5 kW to 5.0 kW with the condition:6.03+2.79 W.ltoreq.r.ltoreq.40being satisfied, where the electrical input of the power source device into the cadmium lamp in steady-state luminous operation is W (kW) and the maximum inside radius of the fluorescent tube is r (mm).

Abstract: A cadmium rare gas discharge lamp of the short arc type that has a high power of the spectra in a wavelength range of 210 nm to 230 nm and a stable lamp voltage in lighting operation for a long period. An arc tube 1 is provided within which are disposed opposed, spaced apart electrodes 2, 3 and thermal insulation films 6, 7. A rare gas is encapsulated together with metal cadmium and a quartz glass is used for the material of the arc tube whose OH radical has a weight content of no more than 200 ppm. Electrodes 4 and 5 are spaced apart no more than 10 mm, so that with a lamp current at least 20 amperes, an arc of the electrode-stable type is formed and radiant light of Cd ions obtained. For the encapsulated rare gas, in one embodiment at least one of the rare gases neon, argon or krypton, are used and are encapsulated at a gas pressure of 35 kPa to 2.5 MPa at a standard temperature of 25.degree. C. The arc tube 1 is formed of quartz glass, electrodes 2 and 3 are placed opposite one another.

Abstract: In a metal halide lamp container 1 sealed with mercury and rare gas, GdX.sub.3, LuX.sub.3, and CsX where halogen is iodine, bromine, or their mixture are sealed in a total weight of 1 mg/cc or more, with the weight of CsX defined within a range of 15% or more to 50% or less of the total halides, and the weight ratio of GdX.sub.3 and LuX.sub.3 is set in a range of 0.1.ltoreq.GdX.sub.3 /LuX.sub.3 .ltoreq.10. In addition to GdX.sub.3, LuX.sub.3, and CsX, at least one of thallium halide and dysprosium halide is added. Or DyX.sub.3, LuX.sub.3, NdX.sub.3, and CsX where halogen is iodine, bromine or their mixture are sealed in the specified total weight, with the weight ratio of CsX defined in the above range.

Abstract: The method of conducting a lighting operation of a metallic vapour discharge lamp, to maintain a suitable arc tube temperature, even if the lamp is operated at an input power higher than 160 W/cm of lighting length. A metallic vapour discharge lamp, in which mercury, rare gas, iron and halogen are encapsulated wherein an arc tube is used and which is operated with an internal pressure of 0.5 to 10 psi, an input power of higher than 160 W/cm of lighting length and within a heater having an air injection cooling system. The lamp characteristics are D.ltoreq.28 and simultaneously P/D.ltoreq.14, where the arc tube external diameter is designated D (mm) and the input power/cm of lighting length is designated P (W/m).

Abstract: A metal halide discharge lamp operated from a D.C. power source, which is suitable for an optical light source, has a quartz arc tube. Anode and cathode electrodes are disposed in the arc tube. The gap length between electrodes is so short that the metal halide discharge lamp functions as a point light source. The arc tube contains an inert gas, mercury and metal halide additives including metal bromine. By utilizing the catephoresis effects, the transformation of silica (SiO.sub.2) of the arc tube to cristobalite or the formation of an opaque substance on the arc tube is prevented. Atomic percent of bromine to halogen contained in the arc tube is about 60% to 90% and a wall load developed in the arc tube is substantially greater than 40 W/cm.sup.2.

Abstract: A high intensity metal halide arc discharge lamp, such as an electrodeless lamp wherein RF energy is inductively coupled to the arc discharge, contains a halide of neodymium alone or in combination with other metals such as one or more rare earth metals, Na, Cs and is essentially mercury free (i.e., <1 mg per cc of arc chamber volume).

Abstract: A cadmium/inert gas discharge lamp of the short arc type, which suppresses an unnecessary emission upstream and downstream of the necessary emission spectra in a wavelength range of 210 to 230 nm, achieves a high efficiency of the emission spectra in the range 210 to 230 nm and can be used in very satisfactory manner for industrial applications. Also, a highly efficient projection exposure device through the incorporation of a cadmium/rare gas discharge lamp of the short arc type having good emission spectrum characteristics in the wavelength range 210 to 230 nm, which can transmit in projecting manner fine image patterns with a large depth of focus. The cadmium/rare gas discharge lamp of the short arc type is arranged within a temperature-regulated quartz bulb, and is provided with a pair of adjacently facing electrodes, together with inert gas selected from xenon, krypton, argon, neon or mixtures of them.

Abstract: To provide a sealed through arrangement for electrical leads through a ceramic end plug, suitable for discharge lamps of between about 50 to 250 W power rating, the lead-through (9) is made of a material having a thermal coefficient of expansion which is substantially less than that of a ceramic sealing plug (10), for example of tungsten, molybdenum or rhenium, but so small that the individual, actual expansion of the ceramic material will not cause separation from the metal, and/or a glass melt, ceramic melt or sintar connection therewith. The electrical connection is formed by at least two, and preferably more than two, thin wires or pins (23) having a diameter, each, of up to only about 0.25 mm, and preferably less. Each of the wires, then, will carry currents in the tenths ampere ranges, sufficient for operation of the lamp, and passed through melt-sealed capillary openings in the ceramic sealing plug (10).

Abstract: A metal halide lamp includes a quartz sealed tube having a pair of electrodes using tungsten as the base material. Argon gas, mercury, at least one kind of rare earth metal (e.g., dysprosium, holmium, thulium, neodymium, and erbium), bromine, iodine, and an alkali metal, e.g., cesium, are contained in the sealed tube. The total number of moles of bromine and iodine in the sealed tube is in excess of the number of moles of the rare earth metal. Accordingly, tungsten which is liberated from the electrode during electric discharge can be captured mainly by iodine. A reaction between silicon dioxide, which is a constituent component of the sealed tube, and tungsten is prevented, thereby preventing blackening of the tube wall of the sealed tube.

Abstract: Silver metal and nickel silicide are added to the fill of an electrodeless high intensity metal halide discharge lamp, which includes at least one metal iodide as a fill ingredient, for controlling the iodine vapor level therein. The nickel silicide acts to getter oxygen which has been introduced into the arc tube during lamp processing, thereby avoiding oxidation of the metal iodide portion of the fill and a concomitant release of free iodine into the arc tube. The silver acts to getter free iodine available from the metal iodide(s) of the fill as metal diffuses into the quartz arc tube wall, forming silver iodide (AgI). The combination of silver and nickel silicide acts to control the iodine level below an arc instability threshold to promote and maintain arc stability. In addition, neither silver nor nickel silicide attack the quartz arc tube wall. Lamp performance and lamp life are thus substantially improved.

Abstract: The invention relates to a high-pressure sodium discharge lamp provided with a discharge vessel (3) with a ceramic wall (3a) of aluminum oxide in which at least Na as an ionizable filling component, a rare gas and Al (20) are present. According to the invention, the Al is provided near the wall of the discharge vessel in a location which reaches a temperature of at least 1000 K in the operational condition of the lamp.

Abstract: A high power lamp which utilzes a lamp fill containing sulfur or selenium, or compounds of these substances. An electrodeless lamp utilizing such a fill at a pressure at least as high as 1 atmosphere is excited at a power density in excess of 50 watts/cc. An arc lamp utilizing the fill at a pressure at least as high as 1 atmosphere is excited at a power density of at least 60 watts/cm.

Abstract: An arc tube of fused silica for a metal halide arc discharge lamp including a fill for the arc tube comprised of a sodium halide, at least one additional metal halide, and an inert starting gas, the arc tube including a tube of fused silica having an inner wall defining an arc chamber, the inner wall of the tube having provided thereon a metal silicate coating which is vitreous and light-transmissive, and which is comprised of a silicate of at least one metal selected from the group consisting essentially of scandium, yttrium, and a rare earth element, and preferably which is the same metal as that of the at least one additional metal halide. Protection of the fused silica arc tube with the metal silicate coating reduces loss of the metallic portion of the fill by diffusion or reaction and corresponding buildup of free halogen in the arc tube.

Abstract: In a metallic vapor discharge lamp, in whose arc tube provided with electrodes are encapsulated together with mercury and inert gas, whose quantity is adequate for maintaining arc discharges, an adequate quantity of iron and an adequate quantity of a metal, in which at least one of the metals tin, magnesium, bismuth, thallium, cadmium or manganese is selected, together with halogen, as a result of the fact that the encapsulated halogen at least contains bromine, whose weight ratio to the total halogen is 0.26%, the adhesion of iron to the inside of the arc tube is prevented and consequently a radiation intensity of the ultraviolet rays effective for curing paints or inks is maintained over a long period of time.

Abstract: The high-pressure discharge lamp has a filling in a discharge vessel (1) which includes a rare gas and a metal compound (2) chosen from hafnium halides and zirconium halides. The halide evaporates and discomposes to form incandescent, condensed metal particles. The lamp may be electrodeless and may in addition contain a buffer gas as a component of its filling. Alternatively, the lamp may have internal electrodes (13) and contain mercury (12) as a buffer gas. The lamp has favorable light generating properties, in particular a good color rendering, and in addition may have a very high luminous efficacy.

Abstract: An electrodeless discharge lamp comprising an arc tube constructed of a light-transmissive material. An exciting structure surrounds the arc tube and is energizable with radio frequency current to develop an arc discharge. A reflective coating of non-conducting insulating material is disposed on the arc tube wall and is located to reflect light from the arc discharge through the arc tube. The reflective coating and the uncoated portion of the arc tube wall are surrounded by the exciting structure so that light from the arc discharge may reach the reflective coating without blockage by the exciting structure and, following reflection by the coating, travel through the uncoated portion of the arc tube wall.

Abstract: An electrodeless high intensity discharge (HID) lamp arc tube having a stabilized condensate location. The arc tube contains a predetermined location or distortion on the inside surface of the arc tube. The distortion may be a protrusion on the inside surface of the arc tube formed during the arc tube forming process. In operation of the lamp, the non gaseous dose remains condensed substantially in the cold spot region formed by said protrusion so that the arc tube walls remain clear for maximal light output, and the arc tube remains stable and efficacious to substantially higher power than is the case for arc tubes without the distortion.

Abstract: A high intensity electrodeless metal halide arc discharge lamp wherein RF energy is coupled to the arc discharge, contains a halide of praseodymium alone or in combination with other metals such as one or more rare earth metals, Na and Cs and is essentially mercury free (i.e., < 1 mg per cc of arc chamber volume).

Abstract: A high intensity discharge lamp having a fill including at least one rare earth metal iodide has an additional metal component for avoiding a substantial loss of the metal component of the fill and the attendant substantial buildup of free iodine, thereby increasing the useful life of the lamp. During lamp operation, the additional metal component combines with iodine in the vapor phase, forming a relatively stable iodide and thus reducing the total level of free iodine in the lamp. As a result, arc instability is avoided. The additional metal component also emits visible light and hence improves efficacy. Moreover, the additional metal component does not attack the arc tube wall by reducing silica. Suitable additional metal components include indium and thallium.

Abstract: An electrodeless HID lamp having a quartz arc tube having a gas fill contained therein, is energized to a discharge state upon the introduction of a high frequency RF current in close proximity thereto, also includes a starting aid stem which extends from the arc tube. An outer jacket surrounds the arc tube and a portion of the starting aid stem. The outer jacket is pinch sealed at the end from which the starting aid stem extends. This pinch sealing results in the formation of a sealed space between the outer jacket and the arc tube and further allows that, by the gripping of the starting aid stem at the pinch seal region, the arc tube is supported in a fixed non-contacting position within the outer jacket. A sealant material can be applied around the starting aid stem at the pinch seal region to prevent leakage of the sealed space formed within the outer jacket.

Abstract: A coating for the arc tube of a high intensity metal halide discharge lamp includes at least two oxide layers for protecting the arc tube from devitrification, cracking and etching of the arc tube wall and for avoiding arc instability, thereby extending the useful life of the lamp. A first layer of the multi-layer oxide coating is applied directly to the arc tube to provide thermal compatibility in order to avoid cracking during lamp operation. At least one additional layer provides chemical stability of the arc tube wall with respect to the lamp fill. As a result, a substantial loss of the metal portion of the fill and a corresponding substantial buildup of free halogen are avoided, thereby avoiding devitrification and etching of the arc tube wall. Furthermore, for HID lamps including as a fill ingredient a metal, such as sodium, which diffuses into the arc tube wall and causes further devitrification thereof, at least one layer of the multi-layer oxide coating acts as metal-barrier.

Abstract: A scandium halide and alkali metal halide discharge lamp has a chemical fill in the arc tube comprising an inert starting gas, mercury, alkali metal iodides, scandium iodide and platinum metal as an additive for reducing the tendency of the lamps to discolor during operation.