Electric lamp and discharge devices – With gas or vapor – Having electrode lead-in or electrode support sealed to...
Patent
1991-09-26
1994-04-19
O'Shea, Sandra L.
Electric lamp and discharge devices
With gas or vapor
Having electrode lead-in or electrode support sealed to...
H01J 6136
Patent
active
053048920
DESCRIPTION:
BRIEF SUMMARY
Reference to related patent and application the disclosures of which are hereby incorporated by reference, assigned to the assignee of the present application:
U.S. Pat. No. 4,647,814, Dobrusskin et al.
U.S. Ser. No. 07/766,005, filed Sep. 26, 1991, Lewandowski et al.
U.S. Ser. No. 07/766,451, filed Sep. 26, 1991, Dixon et al., now U.S. Pat. No. 5,200,669.
FIELD OF THE INVENTION
The present invention relates to high-pressure discharge lamps, and more particularly to high-pressure discharge lamps of high power, having lamp currents which may exceed 100 A, for example of 130 A and even more, and to a method to make the lamp. The lamp construction and method may, of course, also be used with lamps of lower power requirements
BACKGROUND
The high-pressure discharge lamps to which the present invention relates, and which are , for instance, shown in the referenced U.S. Pat. No. 4,647,814, Dobrusskin et al., assigned to the assignee of the present application, are particularly suitable for illumination of theater stages, television and motion picture film studios and the like. The light flux should be high and, further, have a color temperature which is similar to daylight, with a very good color rendition index. Such high-pressure discharge lamps have a discharge vessel, retaining a fill which includes metal halides. Prior art lamps of this type provide a light flux of over one million lumens; in a typical lamp, and with an operating current of 65 A and an arc power of 12 kW, a light flux of 1.1. mega lumens can be obtained. The electrodes within the discharge vessel are rod or pin-like and retained in the discharge vessel by being melt-sealed therein, with a molybdenum sealing foil providing a current supply connection for the electrodes.
The requirements for still higher light output and higher power lamps have led to investigations of loading of the current supply connection. To obtain still higher light flux, standard melt seals permit operating currents of at the most 100 A. Higher operating currents lead to excessive heating of the melt, and the molybdenum sealing foils tend to corrode, and separate from the seal. The metal halide fill in the lamp also causes devitrification of the discharge vessel, so that the average lifetime of the lamp is short and becomes economically unsatisfactory.
Other high-pressure discharge lamps of this type having a fill of mercury and a rare gas or of extra-high pressure rare gas are used specifically in the manufacture of electronic components.
THE INVENTION
It is an object to provide a high-pressure discharge lamp which has electrode melt seals which can tolerate operating currents far in excess of 20 A. These seals, further, should be simple in construction and permit ready manufacture.
Briefly, a sealing and connection arrangement is provided between the electrodes within the discharge vessel and an external current supply, which includes two metal disks. One of the metal disks is electrically and mechanically secured to the end region of the electrode and the other metal disk is electrically and mechanically secured to the end region of the current supply lead. At least two, and preferably four elongated sealing foils extend between the first and second disks, secured to the disks, for example, at a circumferential region or at the rims thereof. The melt seal then includes a quartz glass filling within the connection necks of the lamps, which embed the at least two, and preferably four sealing foils connecting the first and second disks. The quartz glass filling, and the necks of the lamps, are melt-sealed together, so that the quartz glass filling forms with the neck portions of the discharge vessel, a solid quartz glass cylinder, in which the sealing foils as well as the two disks are melt-sealed. A plug element, through the electrode shaft passes, is melt-sealed in the neck adjacent the discharge vessel to center the electrode and provide for thermal isolation.
To make such a lamp, in accordance with a feature of the invention, the discharge vessel is formed
REFERENCES:
patent: 3315116 (1967-04-01), Beese
patent: 3675068 (1972-07-01), Strauss
patent: 4647814 (1987-03-01), Dobrusskin et al.
patent: 4959587 (1990-09-01), Schug
Soviet Inventions Illustrated, El Sektion, Woche E 12, 5, May 1982, Derwent ublications Ltd., London, UK.
Begemann Juergen
Dierks Joern
Franke Dieter
Kiele Walter
Lewandowski Bernd
O'Shea Sandra L.
Patent-Treuhand-Gesellschaft fur elektrische Gluhlampen mbH
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