Ngk Insulators, Inc.

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Osamu Asano

Stefan Juengst

Juergen Heider

Koichiro Maekawa

Roland Huettinger

Kouichiro Maekawa

Jens Clark

The invention provides a method for producing a polycrystalline transparent sintered alumina body suitable for use in a ceramic envelope for a high intensity discharge lamp, with optimized kinds and amounts of sintering aids. First, adding and mixing, to alumina of a purity of 99.9% or higher, MgO within a range from 0.002 to 0.010 wt. % and La O within a range from 0.005 to 0.020 wt. %, in such a manner that a sum of MgO and La O is 0.030 wt. % or less and that a ratio thereof satisfies a relation 0.2&lE;MgO/La O &lE;0.5. Next, firing a mixture at 900 to 1200&deg; C. and cast molding the fired alumina. Then, after a chelating treatment, sintering the molded alumina for at least 1 hour at 1650 to 1900&deg; C. in a reducing atmosphere under a normal pressure.

Ceramic envelope for high intensity discharge lamp and method for producing polycrystalline transparent sintered alumina body

A ceramic discharge vessel (8) for a high-pressure discharge lamp has a pin-like feedthrough (10) inserted in a plug (11) made from a composite material. The feedthrough (10) has been sintered directly into the plug (11) and is additionally sealed by covering the area, surrounding the feedthrough, of the plug's surface facing away from the discharge volume with a ceramic sealing material (7a).

High-pressure discharge lamp, method of its manufacture, and sealing

Ceramic discharge vessel for a high-pressure discharge lamp, having a

A high pressure discharge lamp having an extended life includes a discharge vessel 8, and a feedthrough 10 extending through a plug 11. A directly sintered connection is formed between the feedthrough 10 and the plug 11 wherein sealing material 7 is provided covering the area surrounding the feedthrough on the outer surface of the plug 11. The plug 11 is formed of a composite material whose thermal expansion coefficient lies between that of the ceramic vessel and of the metal feedthrough.

High pressure discharge lamp including directly sintered feedthrough

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Hashima, Japan

Osamu Asano