Patent-treuhand-gesellschaft F. Elektrische Gluehlampen Mbh

Ngk Insulators, Inc.

Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Patent-treuhand-gesellschaft Fuer Elektrische Gluehlampen Mbh

Juergen Heider

Stefan Juengst

Achim Gosslar

Roland Huettinger

Koichiro Maekawa

Osamu Asano

Ulrich Henger

Stefan Kotter

Hartmuth Bastian

Peter Wahrendorff

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

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

A vacuum-tight seal, particularly for an arc tube or discharge vessel for a metal halide or sodium high-pressure discharge lamp, is made by forming the arc tube of transparent ceramic, typically Al.sub.2 O.sub.3, having two open ends, into which connecting plugs (3), with central openings, are sealed. Open metal tubes (4) fitting into the openings of the plugs (3) are then vacuum-tightly sintered therein. An electrode system (5, 10, 10'), forming a subassembly with a current supply lead or lead-through (6, 11, 14, 15, 20, 24) is provided, having an outer diameter fitting into the metal tube. After mounting one of the electrode systems and lead-through into the metal tube (4), and welding the lead-through to the metal tube, the vessel can be evacuated through the still open tube (4) at the other end, supplied with suitable fill substances and an ignition gas, such as argon or xenon, and the second electrode system then introduced, and welded, for example by a laser, to the outer end of the other metal tube (4). The arrangement permits use of molybdenum tubes, molybdenum lead-throughs, in Al.sub.2 O.sub.3 ceramic, in spite of different thermal coefficients of expansion. Preferably, the metal tube extends beyond the end face of the vessel and/or sealing plug (3), to permit free access during the welding step and reduce heat transfer into the interior of the arc tube or discharge vessel (1).

Method of making a vacuum-tight seal between a ceramic and a metal part,

To provide an effective seal for a metal-halide discharge lamp having a ceramic discharge vessel (4), the seal is formed in multiple parts, in which a first part, adjacent the interior or discharge side of the vessel, includes a melt component (14a) which is highly resistant to attack by metal halides within the fill of the lamp. It may contain only 0-12%, by weight, of SiO.sub.2 and has a high melting point, in the order of between 1500.degree.-1700.degree. C. The melt-in region remote from the discharge side is melt-sealed by a vitreous composition (14b), devoid of pores, voids, bubbles, fissures or cracks, to form an effective, vacuum-tight seal, and protected from attack by the metal halides by the mechanically less stable seal in the first zone. The second composition has a much lower melting point, for example in the order of between 1200.degree.-1400.degree. C., and has 20-40% SiO.sub.2. Preferably, and for ease of manufacture, the capillary gap in which the melt seal is formed decreases in dimension towards the discharge side, so that an effective capillary seal can be formed at the higher melting point temperature before the second, lower melting point temperature seal is made.

Metal-halide discharge lamp with ceramic discharge vessel, and method of

The discharge or arc tube chamber of a low-power high-pressure discharge lamp is, in one single step, sealed and shaped by mold or form-blowing by using pinch or press jaws (30, 31) which have concave hollows (34) formed therein to clearly define the shape of the discharge vessel, and hence of the discharge or arc tube chamber, to permit reproducible results with little variation between individual lamps to be made in a single manufacturing step. Additionally, an inclined ramp-like surface can be formed at the narrow sides (14) of the pinch seal extending towards the walls (11) of the discharge chamber (3) to thereby eliminate pockets beneath the electrodes. Preferably, the electrode shafts diverge with respect to the optical axis (A) of the lamp to increase the electrode spacing, and thus permit operation at a lower operating pressure, with respect to prior art lamps.

Single-ended low-power discharge lamp, and method of its manufacture

Method for producing a metal-halide discharge lamp with a ceramic

The high-pressure lamp has a fill including a metal halide of two groups, which the first group is a first rare earth halide of dysprosium, thulium and optionally holmium, and a second group of rare earth halide, namely cerium, neodymium, praseodymium, lanthanum; and an alkali metal halide, such as sodium halide and/or cesium halide, preferably iodide or bromide of sodium and/or cesium. The lamp has a high proportion of light radiation in the red range of the color spectrum to provide substantially improved color rendering indices, particularly in the Ra.sub.8 region, thereby providing better color balance, without loss of lifetime.

Light balance compensated mercury vapor and halogen high-pressure

A double-ended, double-sided pinch seal discharge lamp has pinch seals at posite ends of a discharge vessel, in which the broad side surfaces of the pinch seal, retaining a molybdenum foil (8) is formed with lateral constrictions or indentations (16) located at the transition zone between the pinch seal and the bulbous or discharge vessel portion (3). Preferably, excess glass material from the side surfaces or ribs (14) formed on the side surfaces of the pinch or press seal is squeezed, in the transition zone, towards the bulb or central region (3) during the pinch sealing process to form reinforcement ribs (17), thereby strengthening the transition zone between the pinch seal (5) and the bulb portion (3) of the lamp.

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Munich, Germany

Juergen Heider