Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Werner Weiss

Manfred Deisenhofer

Gerhard Wagner

Ewald Poesl

Ewald Posl

Manfred Mair

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.

Electric incandescent and discharge lamps having doped quartz glass

Doped quartz glass, and enclosures for electrical apparatus made therefor

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:

Lead oxide-free glass, particularly for use in electric lamps

To provide a melt glass (10) to seal capillary spaces (9) surrounding external current supply leads (8) of molybdenum passing to molybdenum foils (6) in a pinch or press seal (7) of a high temperature, for example incandescent halogen lamp, the melt glass (10) is made of 3-10% Bi.sub.2 O.sub.3, 25%-40% B.sub.2 O.sub.3, remainder PbO. The melt glass has low toxicity and is molybdenum-compatible. An additive of barium oxide, in up to 15% and preferably up to only about 10%, may be added to the PbO. All quantities in mol-percent.

Lamp with low-toxicity, molybdenum-compatible sealing glass

To improve tightness of a pinch or press seal (2a; 13a, 13b) between a modenum foil and quartz or similar hard glass of an electric lamp, typically a halogen incandescent lamp or metal halide discharge lamp, an intermediate melt glass layer in form of a strip is applied to the sealing foil, which has the following main components:

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Stadtbergen, Germany

Werner Weiss