Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Walter Kiele

Bernd Lewandowski

Andreas Genz

Dieter Franke

Alexander Dobrusskin

Manfred Deisenhofer

Alfred Langer

Joern Dierks

Juergen Begemann

Jurgen Reichardt

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 20 .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%, by weight, 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.

Method of making a quartz glass tube having a reduced ultraviolet

Double-ended high-pressure discharge lamp

To maintain a predetermined design color temperature throughout the lifet of a metal halide high-pressure discharge lamp, particularly suitable for illumination of theaters, film or television studios, the discharge vessel of the high-pressure lamp, typically made of quartz glass, contains a fill which, besides mercury, has a noble gas, cesium and dysprosium halide and a nickel halide. Optionally, gadolinium halide may be used. Per cubic centimeter of volume of the discharge vessel, 0.03 to 3 mg dysprosium, 0.002 to 0.5 mg nickel, and, optionally, 0.002 to 0.1 mg gadolinium are suitable. Suitable halogens for the halides are iodine and bromium, preferably in a mol relationship between 0.2 and 1.5. The metals, nickel and gadolinium limit the color temperature drop-off over the average lifetime of the lamp to at the most 1 K per operating hour of the lamp.

High-pressure metal halide discharge lamp with a fill containing nickel

To provide a high-pressure lamp capable of carrying lamp currents of 100 eres and higher, an essentially rotation-symmetrical discharge space (2) has two cylindrical necks (3, 4) melt-sealed thereto. Each one of the necks is formed of at least two telescoped hollow cylindrical quartz glass tubes (19, 27) which, with sealing foils circumferentially located within the neck, are all gas-tightly melt-sealed together. The sealing foils, typically of molybdenum, are electrically connected to a molybdenum disk (7, 8), for example by being welded to the circumference thereof which, in turn, is soldered to an end portion of an electrode shaft (5, 6), typically of tungsten, which extends into the discharge space of the discharge vessel. During manufacture, the inner quartz glass tube (27) is formed with a ring-shaped expansion or distention (23) which is melt-sealed to the inner wall of the outer glass tube (19), to permit flushing of the space between the glass tubes and where the sealing foils are located, for example flushing with argon, and subsequent melt-sealing with a vacuum of 20 mbar argon, while introducing 1 bar air pressure into the interior of the inner tube. After the neck structure is gas-tightly sealed together, the enlargement or distention together with an adjacent portion of the neck structure, is severed.

High-pressure, high-power discharge lamp, and method of its manufacture

To increase the power output of a high-pressure metal halide discharge lamp aving a fill of mercury and at least one noble gas, and rare-earth halides which include at least one of: holmium; dysprosium, preferably present, each, of from 0.01 to 2.4 mg/cm.sup.3 of the discharge vessel, a gadolinium halide, present of from 0.01 to 2.3 mg/cm.sup.3 of the discharge vessel is additionally included in the fill. The discharge vessel is made of quartz, the electrodes of tungsten, and, in an example, a lamp operating at 12 kW, with 380 V power supply at 65 A is obtainable, the light output being comparable to that of daylight based on CIE standard D 60, with a color temperature of 6000.degree. K. so that an overall color temperature of about 5600.degree. K. is obtainable when the lamp is installed in a customary fixture, for example used in theatrical, film or television illumination application. The preferred halogens are bromium and/or iodine, in which the halogen is present in excess over the rare-earth - halide stoichiometric relationship. The specific arc power obtainable is between 1000 to 5000 W/cm, with a wall loading of between 50 to 120 W/cm.sup.2.

High-power, high-pressure metal halide discharge lamp with improved

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Munich, Germany

Walter Kiele