Abstract: An arc tube for a ceramic metal halide lamp includes a hollow first body member (40) that is tapered along a majority of its length to aid in removing the molded component from a pin during assembly. An open end (46) of the first body member has a constant diameter (60) allowing it to be joined to a constant diameter portion (72) of the second body member or end cap (70). The mating constant diameter portions ensure that the hollow first body member can be monolithically joined with the end cap with a reduced level of seal voids.

Abstract: A mercury vapor discharge fluorescent lamp is provided that has a mercury barrier. The mercury barrier is effective to inhibit mercury atoms from absorbing into the glass envelope and amalgamating with sodium atoms in the envelope. The mercury barrier is substantially non-mercury absorptive, both when the lamp is on and when it is off.

Abstract: A process for making an arc tube comprises the steps of sintering an arc tube composition to form the arc tube; annealing the arc tube in a vacuum; and sealing the arc tube with at least one electrode. Preferably, the arc tube annealed according to the present process is a ceramic arc tube. The annealing of the arc tubes in a vacuum preferably occurs at a temperature of between about 1000° C. and 1500° C.

Abstract: A method for forming single element arc tubes is provided. The method includes the use of the lost foam process in combination with ceramic forming processes. First, a polymeric material (20) is formed to define the internal dimensions. The outer dimensions are established with an external mold (40), followed by filling the mold with a suspension (60) that hardens. The outer mold is removed and the part is debindered to melt and remove the inner foam shape, followed by sintering to form a substantially transparent ceramic arc tube (70).

Abstract: A high transmittance polycrystalline alumina arc tube for a metal halide discharge lamp is formed by treating an alumina arc tube material having a few percent of closed porosity in a two step process, which provides a high-transmittance arc tube. An initially porous arc tube is formed by extruding or die pressing individual components of the tube from a mixture which includes powdered alumina, assembling the components into an arc tube body, and then partially sintering the components to seal them together. The two step process includes hot isostatic pressing of the partially sintered arc tube and then chemically polishing the surface of the tube. The first, pressing step involves heating the alumina arc tube in an inert atmosphere, such as argon, at a temperature of 1600 to 1900° C. and a pressure of about 700 to 2100 kg/sq.cm. for from about one to three hours. This reduces porosity in the crystalline structure.

Abstract: A mercury vapor discharge fluorescent lamp is provided that has a mercury barrier. The mercury barrier is effective to inhibit mercury atoms from absorbing into the glass envelope and amalgamating with sodium atoms in the envelope. The mercury barrier is substantially non-mercury absorptive, both when the lamp is on and when it is off.

Abstract: An arc tube for a ceramic metal halide lamp includes a hollow first body member (40) that is tapered along a majority of its length to aid in removing the molded component from a pin during assembly. An open end (46) of the first body member has a constant diameter (60) allowing it to be joined to a constant diameter portion (72) of the second body member or end cap (70). The mating constant diameter portions ensure that the hollow first body member can be monolithically joined with the end cap with a reduced level of seal voids.

Abstract: A high transmittance polycrystalline alumina arc tube for a metal halide discharge lamp is formed by treating an alumina arc tube material having a few percent of closed porosity in a two step process, which provides a high-transmittance arc tube. An initially porous arc tube is formed by extruding or die pressing individual components of the tube from a mixture which includes powdered alumina, assembling the components into an arc tube body, and then partially sintering the components to seal them together. The two step process includes hot isostatic pressing of the partially sintered arc tube and then chemically polishing the surface of the tube. The first, pressing step involves heating the alumina arc tube in an inert atmosphere, such as argon, at a temperature of 1600 to 1900° C. and a pressure of about 700 to 2100 kg/sq.cm. for from about one to three hours. This reduces porosity in the crystalline structure.

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 method of producing a ceramic-metal-halide (CMH) discharge lamp having a monolithic seal between a sapphire (single crystal alumina) arc tube and a polycrystalline alumina end cap. The method includes the steps of providing an arc tube of fully dense sapphire and providing an end cap made of unsintered compressed polycrystalline alumina powder. The end cap is heated until it is presintered to remove organic binder material at a low temperature relative to the sintering temperature. The presintered end cap is placed on an end portion of the arc tube to form an interface therebetween. The assembled presintered end cap and arc tube are then heated to the sintering temperature wherein the end cap is fully sintered onto the arc tube and the sapphire tube grows into the end cap. A monolithic seal is formed at the previous interface between the end cap and the arc tube as the sapphire tube grows into the polycrystalline alumina end cap.

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 method of manufacturing a ceramic arc chamber (420) comprising providing a sintering tray (412) including a plurality of bores (422). The bores (422) having a first diameter upper section (424) and a second narrower diameter lower section (426). Positioning a plurality of ceramic end caps (212) having a main body portion (216), and a leg portion (219) in the bores (422) such that the leg portion (219) passes downwardly through the narrower diameter lower section (426) and the main body portion (216) is retained within the upper section (424). Moreover, the second diameter lower section (426) acts as a shoulder supporting the end cap (210). Next, a ceramic arc tube (214) is positioned within the first diameter upper section (424) and mated with the ceramic end cap (212). A second end cap (210) is mated to a second upper open end of the ceramic arc tube (214) to form an arc tube preform (420). The arc tube preforms (420) are then sintered to join the components via controlled shrinkage.

Abstract: 845 A method of producing a ceramic-metal-halide (CMH) discharge lamp having a monolithic seal between a sapphire (single crystal alumina) arc tube and a polycrystalline alumina end cap. The method includes the steps of providing an arc tube of fully dense sapphire and providing an end cap made of unsintered compressed polycrystalline alumina powder. The end cap is heated until it is presintered to remove organic binder material at a low temperature relative to the sintering temperature. The presintered end cap is placed on an end portion of the arc tube to form an interface therebetween. The assembled presintered end cap and arc tube are then heated to the sintering temperature wherein the end cap is fully sintered onto the arc tube and the sapphire tube grows into the end cap. A monolithic seal is formed at the previous interface between the end cap and the arc tube as the sapphire tube grows into the polycrystalline alumina end cap.

Abstract: A high pressure discharge lamp utilizing an improved ceramic arctube. The arctube has a ceramic central portion, a first ceramic leg extending from one end of the central portion and in some embodiments a second ceramic leg extending from the other end of the central portion. The arctube has reinforcing means where one or both of the legs joins the central portion to reinforce and strengthen the connection between each leg and the central portion. The reinforcing means is preferably seal glass or a layer of seal glass adjacent a ceramic ring.

Abstract: High pressure sodium arc vapor discharge lamps employing an alumina arc tube exhibit less voltage rise and better lumen maintenance over the life of the lamp when the arc tube is coated with an oxide of a metal selected from the group consisting essentially of yttrium, zirconium, hafnium, lanthanum, dysprosium, scandium and mixture thereof.

Abstract: An improved compact, white color and pulse operated high pressure sodium vapor arc discharge lamp employing a radiation sensitive getter RF flashed onto the inner surface of the outer lamp envelope has a ceramic radiation shield interposed between the arc tube and getter.

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: An electrodeless, low pressure gas discharge lamp includes a vitreous envelope containing a discharge medium and being shaped with an external chamber for receiving an electrical excitation circuit. The excitation circuit is effective for exciting the discharge medium to emit light with electromagnetic fields that are generated by the excitation circuit. A circuit is included for supplying electrical power from power mains to the excitation circuit. A transparent, electrically conductive coating is provided atop the vitreous envelope and is electrically connected substantially directly to one of the power mains at any given time. A transparent, electrically insulative coating is disposed atop the electrically conductive coating, and comprises a contiguous, inorganic glass layer. The insulative coating preferably has a minimum coating thickness of at least about 3.1 microns.

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: 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.