Abstract: Rare-earth halides are shown to be a replacement for scandium halides in mercury-free discharge arc lamps if modifications are made to the prior art lamp design and operating temperatures. The inventive chemical compositions of the discharge medium provide enhanced color rendition index values. In addition, it has been unexpectedly determined that during the operation of the discharge lamps, the rare earth iodides do not react significantly with the fused silica arc tube. Equally as significant, any free iodine, which is so formed, has minimal impact on the efficacy of the lamp compared to the conventional scandium iodide lamps. Therefore, the rare earth iodide-containing lamps provide longer lifetime with superior illumination characteristics than conventional discharge lamps.

Abstract: The fluorescent lamp has a bulb formed by lead-free glass having an ultraviolet ray transmission factor of 40% or less at 300 nm or less, mercury gas and rare gas sealed in the glass bulb, a phosphor layer formed on the inner wall of the glass bulb, and a pair of discharge electrodes for causing discharge in the glass bulb and the lead-free glass contains an ultraviolet ray reduction material for absorbing or reflecting ultraviolet rays generated from the fluorescent lamp and can reduce ultraviolet rays to 40% or less at a wavelength of 300 nm or less.

Abstract: A long life, halogen cycle, incandescent lamp (30) for operation in excess of 85 volts. The lamp comprises a transparent glass envelope (34) having sealed therewithin a tungsten filament (45); a pair of electrical lead-ins (42, 44) connecting the filament and extending exteriorly of the envelope for connection to a supply voltage greater than 100 V; and a fill gas within the envelope, including a halogen, at a pressure of at least three atmospheres. The envelope is constructed of a five component alkaline earth aluminosilicate glass having a composition consisting essentially of, in weight percent from >58 to about 64% SiO2, from about 14 to about 17% Al2O3; from 0 to about 1% B2O3, from 1 to about 6% MgO, from about 6 to about 12% CaO, from about 7 to about 17% BaO and from 0 to about 1.5% ZrO2.

Abstract: A dielectric barrier discharge lamp with a translucent part made of silica glass which contains OH radicals and in which damage of the silica glass by UV radiation can be suppressed and a sufficient amount of UV radiation can be obtained in a dielectric barrier discharge lamp, in which a silica glass discharge vessel is filled with a discharge gas which forms excimer molecules by a dielectric barrier discharge and which is at least partially provided with a translucent part, by the translucent part having a ratio of non-hydrogen bonding OH radicals to the total number of OH radicals which is less than or equal to 0.36.

Abstract: The present invention provides a long-life discharge lamp by removing the causes of lowering the service life of the discharge lamp owing to quartz glass constituting the discharge lamp and a gas sealed therein, and also provides a discharge lamp production method wherein the mixing of impurities affecting the service life of the discharge lamp is prevented. In the discharge lamp the content of hydrogen, oxygen and their compounds existing in the light-emitting portion is such that the maximum intensity of the light-emitting spectral intensities of the above impurities is {fraction (1/1000)} or less of the intensity of the main light-emitting spectrum of the noble gas when glow discharge occurs by supplying a current of 3 mA, and also the content of OH groups included in the quartz glass of the sealing portions is 5 ppm or less by weight.

Abstract: A glass for tungsten halogen lamp glass envelopes, glass filter lenses, and glass filters consisting essentially in terms of weight percent on the oxide basis, of about 50-62% SiO2, 10-17% Al2O3, 0-6% B2O3, 3.6-10% CaO, 0-7.5% MgO, 0.1-0.3% SrO, 2.4-18% BaO, 0-1% ZnO, 1-8% Nd2O3. The glass exhibits the following physical properties: strain point between about 665° C. to about 750° C., coefficient of thermal expansion to the set point of between about 49-59×10−7/° C., liquidus temperature below 1320° C., viscosity at liquidus temperature greater than 2,000 poises, and transmission at 585 nm of between 5-60% for a 1.2 mm thickness. The lamp color temperature for a tungsten halogen lamp containing a glass envelope, a glass filter lens, or a glass filter prepared from the glass composition is increased from about 3 to 7% above a similar glass with no Nd2O3, and the total visible lumen loss is limited to less than about 10%.

Abstract: An SiO2-glass bulb with at least one current lead-in made of a gas-tight composite material, such that the composite material consists of a noble metal with a melting point >1,700° C. and SiO2 and is at least partially coated with a layer of SiO2. The noble metal and the SiO2 are homogeneously distributed in the composite material. The noble metal content of the composite material is ≧10 vol. % to ≦50 vol. %, and the SiO2 coating covers the composite material at least in the region of the connection with the SiO2-glass bulb.

Abstract: An arc tube is formed by polycrystalline alumina so that an average crystal grain diameter of a surface is two to ten times as large as an average crystal grain diameter of an inside including a center line of a thickness and the average crystal grain diameter on the center portion of the thickness is 10 &mgr;m to 100 &mgr;m. As a result, in the arc tube, the total transmittance is 98%, and a linear ray transmittance is 5%.

Abstract: The present invention is directed at a family of glasses capable of absorbing UV radiation and filtering yellow light in the visible region of the spectrum, the family of glasses having a composition consisting essentially, in terms of weight percent on the oxide basis, of: 55-95.7% SiO2, 0-28% B2O3, 0.5-18% Al2O3, 0-4% SrO, 0-13% BaO, 0-13% CaO, 0-8% MgO, 0-7.5% Na2O, 0-9.5% K2O, 0-1.5% Li2O, 0-1.5% Sb2O3, 0.4-4.5% Nd2O3, and 0.1-1% CeO2. Glasses of the present invention are capable of employment as envelopes for tungsten-halogen lamps and other high temperature light sources, as well as sealed-beam incandescent headlights.

Abstract: A method for producing a translucent alumina sintered body comprising the steps of: forming a raw material powder, and sintering the formed product under the condition of hydrogen atmosphere from atmospheric pressure to vacuum at a temperature of from 1600 to 1900° C., wherein the raw material powder is a mixed powder comprising an &agr;-alumina powder (1) which comprises a polyhedral primary particle having substantially no fractured surface, has a BET specific surface area of 1 to 7 m2/g, and has a purity of 99.99% or more, an alumina powder (2) having a BET specific surface area of 5 to 200 m2/g in an amount of 10% by weight or less based on said &agr;-alumina powder, and a sintering agent, and satisfies the following formula: (BET specific surface area of alumina powder (2))−(BET specific surface area of &agr;-alumina powder (1))>2 m2/g.

Abstract: A ceramic arc tube for a metal halide discharge lamp is soaked in a dopant solution. The dopant solution includes a salt of a UV-absorbing additive, such as europium, cerium, or titanium. The salt is converted to the oxide form of the UV-absorbing additive during sintering of the arc tube. Lamps fabricated using the doped arc tubes filter UV from light emitted from the discharge without appreciably absorbing light in the visible range. The UV retained in the lamp causes the lamp to run at a hotter temperature, improving light output.

Abstract: A lead and arsenic free borosilicate glass is provided which is suitable for use in electric arc discharge lamps. The glass is tungsten-sealing and provides desirable protection from ultraviolet radiation. In addition, the glass is suitable for use in glass melters not equipped with bubblers.

Abstract: A long-life, environmentally disposable high pressure sodium lamp comprising: an arc tube capable of withstanding internal wall temperatures of 1250 to 1300° C. and having electrodes sealed therein and being designed for operation at a given wattage; a discharge space within the arc tube and an arc generating and sustaining medium within the discharge space, the medium being mercury-free and containing sodium in an amount of about 0.02 mg to 0.06 mg/watt of designed operation, and xenon at a pressure of 100 to 200 Torr; mounting means supporting the arc tube within a glass outer envelope, the glass outer envelope being lead-free and arsenic-free; and an electrically conductive base closing the outer envelope and containing lead-in wires affixed to the electrodes, the lead-in wires being attached to the base by welding.

Abstract: A TAG, LAG or YbAG anti-corrosion layer of which Si content is 100 ppm or under and total content of Ca and Mg is 200 ppm or under is provided on the internal surface of a tubular YAG base of a discharge envelope. The mean particle size of the anti-corrosion layer is 20 &mgr;m or over, and the mean particle size of the base is 15 &mgr;m or under.

Abstract: A ballast for a mercury-free, metal halide arc lamp having a quartz or fused silica envelope. The ballast provides a square-wave voltage, which substantially reduces or eliminates the re-ignition voltage in the mercury-free, metal halide arc lamp. The ballast reverses the voltage polarity, and reestablishes the arc current in the opposite direction, before the free halogen in the envelope can quench the arc.

Abstract: A metal halide or mercury lamp including an arc tube comprised of a glass composition consisting essentially of at least 90 weight percent SiO.sub.2 and including between about 10 and 1000 parts per million of a trivalent element slected from the group consisting of Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, Unq, Unp, Ga, and mixtures thereof such that the viscosity of the glass composition is greater than 10.sup.14.5 poise at 1100.degree. C.

Abstract: A lead and arsenic free borosilicate glass is provided which is suitable for use in electric arc discharge lamps. The glass is tungsten-sealing and provides desirable protection from ultraviolet radiation. In addition, the glass is resistant to surface scum formation during melting and reduces the amount of batched iron which must be added for UVB protection.

Abstract: A lighting device is provided which comprises an optically non-opaque wall consisting essentially of a polymeric material and defining a portion of an envelope; a light source sealed within the envelope at a pressure of less than one atmosphere absolute; and an electrical driving device in electrical communication with the light source for causing the light source to generate light. According to another aspect of the invention, a lighting device is provided which comprises an optically non-opaque wall consisting essentially of a polymeric material and defining a portion of an envelope; a gas disposed and sealed within the envelope at a pressure of less than one atmosphere absolute, the wall being substantially impermeable by the gas; and an electrical driving device in at least one of electrical and electromagnetic communication with the gas for activating the gas to generate light. Related methods also are disclosed.

Abstract: A universal lead free glass (ULF) has been developed having a high electrical resistivity and mechanical working properties comparable to conventional lead glasses used in the manufacture of electric lamps. The ULF glass may be used to manufacture both low and high wattage electric lamps and in particular to make filament mounts for such applications.

Abstract: The invention relates to a glass composition for electric lamps which glass composition comprises SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, B.sub.2 O.sub.3, BaO and SrO and optionally CaO, MgO, ZnO, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3, TiO.sub.2, MnO.sub.2, Fe.sub.2 O.sub.3 and/or CeO.sub.2. The composition according to the invention has a B.sub.2 O.sub.3 content of 1 to 2.8 mass %, a SrO content of 2.1 to 4.5 mass %, a BaO content of 3 to 6 mass % and of the components being present optionally, the amount of CaO is maximum 1 mass %, that of MgO is maximum 2.4 mass % and that of ZnO is maximum 3 mass %, on the condition that the total amount of SrO and B.sub.2 O.sub.3 is at least 3.6 mass %, the total amount of CaO and MgO is maximum 2.4 mass % and the total amount of MgO and ZnO is maximum 4.5 mass %.

Abstract: The invention provides a lamp reflecting mirror in which sufficient light reflecting characteristic (surface smoothness) can be obtained without application of any undercoat layer and in which heat resisting property, luminous intensity distributing performance (dimensional stability) and form retaining characteristic (material stiffness) at the time of adjustment of the optical axis can be satisfied at the same time. The lamp reflecting mirror is produced by injection molding a composition containing 30 to 50% by weight of polyphenylene sulfide resin, 5 to 30% by weight of calcium silicate whiskers, and 20 to 65% by weight of granular inorganic filler.

Abstract: A novel type of glass having a low sodium content (<0.1 wt. % Na.sub.2 O), which can be used as a bulb glass (10) for "TL" lamps and for compact fluorescent lamps. Said glass is free of the toxic and/or corrosive components PbO, F, As.sub.2 0.sub.3 and Sb.sub.2 0.sub.3. Apart from favorable properties as regards phosphor poisoning and mercury absorption, resulting in a favorable maintenance of the lamp, said glass is characterized by a wide working range W.R. (=T.sub.work -T.sub.soft), so that glass tubing can be readily made of said glass. By virtue of the low liquidus temperature (T.sub.liq), the glass can be drawn into glass tubing which is free of crystals.

Abstract: A glass halogen lamp which exhibits improved short wavelength light transmission and emission having a glass envelope which is made of a glass composition of the aluminosilicate system in which the iron content of the composition is between 10 and 100 ppm. The glass envelope of the lamp may optionally contain an area of reduced wall thickness which further enhances short wavelength light transmission and emission.

Abstract: A high pressure mercury ultraviolet lamp with high dimensional accuracy in which the emitter material during lamp operation is prevented from spraying and being deposited on the wall of the discharge vessel and the UV radiation transmission factor is prevented from being reduced is achieved by the fact that at least one of a group of halides which consists of halides of yttrium, lanthanum, cerium, dysprosium, gadolinium and thorium and at least one of a group of halides which consists of halides of alkali metal elements are filled at a filling ratio in the range from 1:4 to 1:20 to one another as a molar fraction. This also yields the same action as the application of emitter material to the upholding parts of the electrodes. Furthermore, high dimensional accuracy can be ensured by the measure by which the discharge vessel is made of a translucent ceramic, such as YAG.

Abstract: The subject-matter of the invention is a glass composition, which is suitable for use in electric lamps, comprising SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, SrO, B.sub.2 O.sub.3, and optionally CaO, MgO, TiO.sub.2, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3, Fe.sub.2 O.sub.3, MnO.sub.2, ZnO and/or CeO.sub.2. It is characterized in that its SiO.sub.2 content is 65-73 mass %, Al.sub.2 O.sub.3 content is 0.5 to 2.5 mass %, Na.sub.2 O content is 5 to 9 mass %, K.sub.2 O content is 8 to 12 mass %, Li.sub.2 O content is 0.4 to 1.5 mass %, SrO content is 0.5 to 5 mass %, B.sub.2 O.sub.3 content is 2.1 to 5 mass %. Furthermore in addition to the components listed, it optionally also comprises maximum 2.5 mass % CaO, maximum 3.8 mass % MgO, maximum 1 mass % TiO.sub.2, maximum 0.8 mass % P.sub.2 O.sub.5, maximum 0.5 mass % Sb.sub.2 O.sub.3, maximum 0.25 mass % Fe.sub.2 O.sub.3, maximum 0.25 mass % MnO.sub.2, maximum 5 mass % ZnO, and/or maximum 0.8 mass % CeO.sub.

Abstract: The invention relates to a glass composition for electric lamps comprising SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O, K.sub.2 O, Li.sub.2 O, B.sub.2 O.sub.3, BaO, CaO and MgO, in addition optionally SrO, Sb.sub.2 O.sub.3, MnO.sub.2, Fe.sub.2 O.sub.3, and/or CeO.sub.2. The glass composition according to the invention is characterized in that its B.sub.2 O.sub.3 content is 1 to 5 mass %, K.sub.2 O content is 7.2 to 11 mass %, BaO content is 5.5 to 9 mass % and MgO content is 2.1 to 4 mass %, furthermore in addition to the components listed, it optionally also comprises maximum 3.5 mass % ZnO, maximum 1.2 mass % TiO.sub.2 and maximum 0.8 mass % P.sub.2 O.sub.5 with the condition that the total amount of CaO, MgO and ZnO in the composition is at least 5.8 mass %. Stems and bulbs made of the above glass composition and used in electric lamps are also subject matters of the invention.

Abstract: A glowswitch starter according to the invention is provided with a discharge vessel (1) which is closed in a gastight manner and which has a wall (2), with a pair of electrical conductors (3a, 3b) passed through a portion (2b) of the wall of the discharge vessel, and with a bimetal element (4a) in the discharge vessel which is conductively connected to one (3a) of the electrical conductors (3a, 3b), the discharge vessel containing an ionizable filling. The glowswitch starter according to the invention, which is characterized in that at least that portion (2b) of the wall through which the electrical conductors are passed is made from a glass containing at least 5% BaO by weight, has a short ignition delay time.

Abstract: An electrodeless metal vapor discharge lamp having an airtight arc tube formed with a light transmitting material of metal oxide and containing as sealed therein luminescent substances containing at least one or more of rare earth metallic halide, further includes a promoting substance which renders a halogen cycle occurring adjacent to inner wall surface of the arc tube to be more easily promoted, so as to prevent lamp starting voltage from raising up.

Abstract: This invention involves a new type of feedthrough-plug member for metal halide HID lamp using PCA envelopes. The construction of the lamp housing consists of a PCA envelope and specially designed axially graded alumina-metal cermet multi-layers to eliminate cracking in cermet or PCA due to thermal stresses arising from thermal expansion mismatch. The fills are metal halides such as Na--Sc--I, rare earth halides, Hg, Sn, and inert gases. The PCA vessel and directly sealed cermet-feedthrough assemblies allow the metal halide lamps to operate at high wall temperatures with better lumen output, color temperature, and CRI.

Abstract: A metal halide lamp has an outer envelope (3, 23) of quartz glass which sounds a discharge vessel (2, 22) of quartz glass. The discharge vessel (2, 22) gas-tightly retains an ionizable fill which includes sodium. In order to avoid loss of sodium from the discharge vessel (2, 22) due to UV radiation impinging upon current supply wires (8, 9, 28, 29) extending from the discharge vessel (2, 22) within and into the outer envelope (3, 23), the quartz glass of the outer envelope is doped with materials absorbing UV radiation, preferably cerium aluminate and titanium oxide; the outer envelope is spaced from the discharge vessel by at most 5 mm, the sodium content in the ionizable fill is at most 0.7 mg.sup.3 of the discharge volume, and the space within the outer envelope is evacuated.

Abstract: An optically translucent polycrystalline alumina sintered body consists essentially of alumina, magnesia, terbia and, optionally, yttria. The magnesia is present in an amount of about 0.020 wgt. percent and the terbia is present in an amount of from about 0.005 to 0.060 wgt. percent. The yttria is present in an amount up to about 0.035 wgt. percent.

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: The invention relates to a high-pressure discharge lamp with an outer bulb urrounding the discharge vessel, and to a process for producing a high-pressure discharge lamp. The outer bulb (1) comprises a glass that has a low viscosity and in particular a lower softening temperature than the quartz glass of the discharge vessel (2), and is melted directly onto the ends (5a, 5b) of the discharge vessel (2), which is sealed on both ends. As the glass for the outer bulb, a quartz glass doped with viscosity-lowering additives, in particular alkaline-earth metal borates, is used, while the discharge vessel comprises undoped quartz glass. In addition, the quartz glass of the outer bulb is preferably doped with rare earth metal additives that absorb UV radiation.

Abstract: A solid state method of converting a polycrystalline ceramic body to a single crystal body includes the steps of doping the polycrystalline ceramic material with a conversion-enhancing dopant and then heating the polycrystalline body at a selected temperature for a selected time sufficient to convert the polycrystalline body to a single crystal. The selected temperature is less than the melting temperature of the polycrystalline material and greater than about one-half the melting temperature of the material. In the conversion of polycrystalline alumina to single crystal alumina (sapphire), examples of conversion-enhancing dopants include cations having a +3 valence, such as chromium, gallium, and titanium.

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: Soft quartz glass having low viscosity and a low thermal coefficient of expansion, high electrical insulation capability and free from release of contaminants, when used as a bulb of an incandescent lamp or as an envelope in an arc vessel of a discharge lamp, is a quartz glass made of ultra-pure quartz (SiO.sub.2), for example having a purity of 99.99 mol-%, doped with stoichiometric compounds of alkaline earth oxides with boron oxide, optionally also with a small quantity of Al.sub.2 O.sub.3 in an overall quantity of the doping substance of between about 0.05% to 0.8%, by weight.

Abstract: In a lamp main body in a discharge lamp provided in a lighting apparatus of an edge-lighting type which is used as a back-lighting section of a liquid crystal display apparatus, refractive indexes are distributed such that a light emitted from an inner space traveling in the lamp main body can be guided to a specific direction. In other words, the lamp main body is divided into a plurality of portions and the portions are formed such that refractive indexes become gradually smaller from a light converging side towards a back surface side which is opposite to the light converging side. With this arrangement, a discharge lamp, which is capable of emitting a light from a surface of the lamp main body to a specific direction, can be obtained. Moreover, when the discharge lamp is used, efficiency of utilization of a light is improved, thereby making it possible to obtain a lighting apparatus with high surface brightness and low power consumption.

Abstract: A good discharge lamp which can emit light with wavelengths in the range of 220 nm in an amount sufficient for industrial applications and at the same time can adequately maintain a transmission factor of the radiant light and emits neither water nor hydrogen or the like during luminous operation is achieved by the fact that, in a discharge lamp in which a pair of electrodes are located adjacent to one another encapsulated within a quartz glass fluorescent tube together with mercury and an inert gas, the quartz glass contains an OH radical concentration of a weight of in the range of 300 to 800 ppm. Furthermore, the content of metallic impurities in the quartz glass is limited to a weight less than or equal to 1 ppm.

Abstract: To eliminate radiation from the mercury high-pressure discharge lamp of wlengths below 365 nm, the lamp includes a discharge vessel of quartz glass which is doped with vanadium in a quantity of up to about only 250 ppm, by weight, with respect to 1 mm of wall thickness of the quartz glass. This absorbed radiation also heats the quartz glass, so that the outside wall temperature of the vessel can be maintained between about 400.degree. and 950.degree. C. The effect can be enhanced by adding, additionally, titanium and/or tin to provide metal ions to the doping substance, in an overall quantity of up to 500 ppm, by weight. Alternatively, the quartz glass can be coated with TiO.sub.2 or SnO.sub.2. Suitable wall thicknesses for the discharge vessel are between 1 and 5 mm, and the fill therein is preferably mercury in a quantity of between 0.5 and 15 mg/cm.sup.3 and xenon with a cold fill pressure of 0.1 to 2.5 bar. Electrode spacing of the lamp is preferably between 2 and 5 mm.

Abstract: A glass composition, particularly well suited for use in constructing sodium containing lamp envelopes. The glass composition is comprised of silica doped with yttrium and/or cesium, preferably in combination aluminum.

Abstract: An optically translucent polycrystalline alumina sintered body consists essentially of alumina, magnesia, terbia and, optionally, yttria. The magnesia is present in an amount of about 0.020 wgt. percent and the terbia is present in an amount of from about 0.005 to 0.060 wgt. percent. The yttria is present in an amount up to about 0.035 wgt. percent.

Abstract: A ceramic discharge vessel (6) for a high-pressure discharge lamp (1) made from a sintered body of optically translucent polycrystalline alumina ceramic which is doped with only 100-800 ppm MgO, only 200-1200 ppm ZrO.sub.2 and only 10-300 ppm Y.sub.2 O.sub.3 (by weight). This improves the loading capacity and operating characteristics of the vessel and of the lamp.

Abstract: An arc tube for an electrodeless metal halide discharge lamp has an arc chamber fabricated from a material selected from the group consisting of magnesia-doped polycrystalline alumina, silicon dioxide doped polycrystalline alumina and mono-crystalline alumina. The arc chamber is tubular and has at least one end and has a given outside diameter. At least one end cap closes the at least one end of the arc chamber, the end cap being formed from magnesia-doped polycrystalline alumina and comprising a substantially cup-shaped member having an inside diameter which is sealed to the outside diameter of the arc chamber by a shrink-fit.

Abstract: The electric lamp has a quartz glass lamp vessel (10) in which an electric element (3, 4) is accommodated. The lamp vessel locally has a light-absorbing, non reflective coating (11, 12). The coating mainly consists of 2 to 10% by weight of glass which is free of lead oxide and has a softening point between 600.degree. and 700.degree. C. Iron 50 to 60% by weight, primarily in metallic form, and manganese oxide, 30 to 55% by weight, are dispersed therein.

Abstract: A low breakdown voltage gas discharge device includes an envelope filled with an appropriately selected working substance. Two main electrodes are sealed in a vacuum-tight manner inside the envelope, and are separated by a predetermined distance. A supplemental electrode extends between the main electrodes along the direction of the electrical discharge, and has its geometrical and electrical parameters satisfy the following equation:S=I.sub.d /C,where S is the surface area of the supplemental electrode and depends on the distance between the main electrodes, I.sub.d is the current flowing in the supplemental electrode during normal glow discharge, and C is a constant characterizing the current I.sub.d, the composition of the supplemental electrode, and the type and pressure of the working substance. The supplemental electrode is connected to an AC or DC power source via a switch, so that the supplemental electrode always acts as a preparatory glow discharge cathode.

Abstract: To inhibit, or at least sharply attenuate, fluorescence of a quartz-glass velope (10) surrounding a light source (11), such as a halogen incandescent lamp, a high-pressure discharge lamp, or the like, when the quartz glass is subjected to ultraviolet (UV) radiation from the light source, and has been doped with a UV radiation absorbing material, typically a cerium, or cerium-titanium doping, the quartz-glass envelope is additionally doped with praseodymium or a praseodymium compound, such as praseodymium oxide or praseodymium aluminate. The pure praseodymium in the doping is, preferably, present in quantities of between about 0.008 and 1.25%, by weight, with reference to the undoped quartz glass. Barium metaborate can also be used, preferably together with praseodymium to attenuate the fluorescence.

Abstract: Ultraviolet (UV) radiation in the UV-C and UV-B bands, which is particularly dangerous, is absorbed and filtered by quartz glass doped with between 0.065% and 3.25%, and preferably between 0.065% and 1.3% by weight, of cerium metal, or cerium as such. Preferably, the cerium is added to quartz sand and/or rock crystal, in form of a fine-grained powder of up to 2 0 .mu.m grain size, in form of cerium aluminate (CeAlO.sub.3), present in up to about 5% by weight, and preferably up to about 2%, and melted together in a single step. The quartz glass so obtained is particularly suitable for a metal halide discharge lamp, e.g. as an outer envelope (1), or as the discharge vessel (27) itself, or for halogen incandescent lamps, to form the quartz-glass light bulb or an envelope therefor. A small quantity of titanium oxide, up to about 0.05%, may be added as a further doping agent to the melt to further improve the UV absorption in the B and C bands.

Abstract: Fused quartz containing europium oxide, titanium dioxide and cerium oxide has been found to be effective for absorbing UV radiation while transmitting visible light radiation. Uses for this material include lamp envelopes and shrouds for halogen-incandescent lamps and metal halide arc discharge lamps which emit both UV and visible light radiation.

Abstract: An electric arc discharge lamp has an arc discharge light source which emits both visible light radiation and UV radiation enclosed within a borosilicate, outer glass envelope. The envelope has a transmission of greater than 90% at a wavelength of 425 nm and a transmission of not more than 40% of UV radiation at 320 nm; 8% of UV radiation at 300 nm; and 0.5% of UV radiation at 290 nm. The borosilicate glass comprises, in weight percent: from about 3.89% Na.sub.2 O; about 1.5% K.sub.2 O; from 0.0% to about 0.15% Li.sub.2 O; about 17% B.sub.2 O.sub.3 ; about 1.4% Al.sub.2 O.sub.3 ; about 0.6% CaO; about 0.35% MgO; about 0.13% Fe.sub.2 O.sub.3 ; and the balance SiO.sub.2.

Abstract: An electric lamp has a light source which has an envelope of doped quartz glass. The quartz glass including silicon, cerium, titanium, europium and aluminium in oxidic form. Cerium accounts for 0.1-0.2, titanium for 0.01-0.04, europium for 0.03-0.2 and aluminium for at most 0.8 at % of the cationogenous elements. The aluminium/europium atomic ratio lies in the region from 3 to 8. The doped quartz glass is at least substantially transparent to visible radiation and at least substantially impervious to UV radiation.