Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Manfred Deisenhofer

Andreas Genz

Bernd Lewandowski

Werner Weiss

Dieter Meiss

Alfred Langer

Ekkehard Messner

Walter Kiele

Ewald Poesl

Manfred Mair

Jurgen Reichardt

J Urgen Reichardt

Walter Keile

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 barium and boron. The barium/boron 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 be used, optionally together with praseodymium to attenuate the fluorescence. Preferably, barium and boron form a combined doping substance with cerium, in form of a cerium aluminate and metaborate, added to the starting material for the quartz glass, and before the quartz glass is fused from quartz sand or pulverized quartz crystal.

Fluorescence-suppressed quartz glass, and electric lamp with this quartz

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. Preferably, the praseodymium is used as a combined doping with cerium, in form of a cerium-praseodymium aluminate, added to the starting material for the quartz glass, and before the quartz glass is fused from quartz sand or pulverized quartz crystal.

Electric lamp having a fluorescence-suppressed quartz-glass envelope,

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.

Quartz glass with reduced ultraviolet radiation transmissivity, and

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

To reduce the transmissivity of glass, and particularly quartz glass, espally highly thermally loaded quartz glass of discharge lamps or halogen incandescent lamps, a coating or glaze is applied to the bulb and adjacent regions which includes, as an ultraviolet light absorption, a glaze of a mixture of cerium fluoride (CeF.sub.3) and aluminum trioxide (Al.sub.2 O.sub.3) and silicon dioxide (SiO.sub.2), in a relationship, by weight, of about 3:1, preferably about 2:1. The weight relationship of Al.sub.2 O.sub.3 to SiO.sub.2 in the mixture is about 1.7:1. The mixture can be applied in form of an alcohol or alcohol-like suspension, after grinding to a grain size of less than 300 mesh, by spraying, dripping on, painting or the like, subsequent drying for 10 seconds, and firing in a hydrogen/oxygen flame or in an ordinary gas flame for about 2 seconds, while axially rotating the lamp bulb.

Highly thermally loaded electric lamp with reduced UV light emission,

A lead oxide free glass of high electrical resistance, easy workability, that is, low abrasive characteristics, and a thermal coefficient of expansion compatible with electrical current supply leads, has an electrical resistance of 10.sup.12 ohm cm at 250.degree. C., and, basically, the following composition:

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Altenmuenster, Germany

Manfred Deisenhofer