Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-Treuhand-Gesellschaft Fuer Elektrische Gluehlampen Mbh

Hans-Werner Goelling

Andreas Genz

Clemens Barthelmes

Dieter Franke

Thomas Dittrich

Jurgen Begemann

Jorn Dierks

Angus Dixon

Metal halide lamp for color applications for high wall loading with a long service life of at least 1500 hours and with a color temperature of over 5000 K: fill comprising at least the following constituents: firing gas, mercury, halogen, as well as indium, thallium, tin, no rare earth element or Na; the fill furthermore contains, as lithium replacement, hafnium, zirconium and tantalum, individually or in combination, the wall loading of the discharge vessel being at least 50 W/cm ; specific output based on die arc length is 50 to 90 W/mm; in particular, the concentration of the metals is as follows: lithium replacements: 0.20-4.0 &mgr;mol/ml; indium 0.3-3.0 &mgr;mol/ml.

Metal halide discharge lamp with a long service life

The invention concerns a high pressure discharge bulb. Such bulbs involve a wo-sided sealed bulb with and without an outer bulb. The bulb is sealed by a pinch on at least one side. It generally has a discharge vessel made of quartz. These bulbs particularly comprise metal halide bulbs, which have a metal halide filling in addition to mercury, but they also include mercury high pressure discharge bulbs or xenon high pressure discharge bulbs. The bulbs are used preferably for optical systems, particularly larly for photo-optical purposes, for example, in head-lights, overhead projectors, and decorative lighting devices. They particularly find application in lighting systems for the stage, film and television. Typical lamp powers are 400 to 2000 W. A discharge lamp pinched on each end has pinches in which the ratio of the total width of each wide side is smaller than or equal to 2.2 times the thickness of the wide side. Tube pieces carrying the base sleeves are formed on the outer ends of the pinches.

High pressure discharge bulb

To optimize operating conditions with respect to overall size of a high-psure discharge lamp having a metal halide fill, the wall thickness (d) in millimeters is selected in accordance with a theoretical optimum relationship of d=1.5+0.1.times..cuberoot.P, in which P is the power rating of the lamp, in watts. The optimal theoretical thickness should not vary by more than .DELTA.d=.+-.0.2.times..sup.d, in millimeters, from the theoretical optimal value, with lower power ratings permitting a thinner wall thickness than higher power ratings. Optimizing the wall thickness improves the color rendition index and the light distribution of the emitted light, as well as decreasing the devitrification of the quartz glass of the discharge vessel.

High-pressure discharge lamp with optimized discharge vessel

To prevent stresses from occurring in lamps in which an electrode system luding, for example, tungsten or molybdenum electrode shafts (4, 12, 22) and current supply leads (15, 26) of, for example, molybdenum, extend into a neck portion (3, 11, 20) of a discharge bulb, a metal foil of high temperature resistant resistant material (6, 16, 17, 18, 29, 32, 33, 34, 35, 36, 37) partially or completely surrounds the metallic portions of the electrode system where it might come into contact with quartz glass during melt sealing of the neck portion of the lamp. The high temperature resistant metal foil is embossed and, preferably of molybdenum with a base thickness of between 0.02 and 0.2 mm, which, when profiled, changes by a factor of between 1.2 to 12 in thickness. Up to two layers of this foil can be wrapped around or placed on the respective metallic portions of the seal, a covering of for example, 1.25 to 1.5 turns about a circular shaft being preferred. Adhesion of quartz glass on the current supply elements themselves thus is prevented and tension-free thermal expansion of the electrode shafts and the current supplies is made possible, and, also, providing for better alignment of the electrode systems than possible in accordance with the prior art.

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Berlin, Germany

Hans-Werner Goelling