US 5,352,952 A · High-pressure discharge lamp with ceramic discharge vessel

Abstract

To permit operation of a high-pressure discharge lamp having a metal halide ill at temperatures higher than those acceptable by quartz glass bulbs, the discharge vessel is made of transparent ceramic, thus providing, in operation, better color rendition and higher light output. To eliminate the corrosive effects of attack by the halides on a lead-through connection, the lead-through is made of a solid rod, pin or wire of, preferably, niobium of between 0.5 to 1 mm diameter, passing through a sintered plug (10), in which the niobium lead-through is recessed into the bore from the plug, and the electrode shaft (12) is connected to the lead-through within the recess. The walls of the plugs surrounding the recess thus protect the niobium against corrosive attack, while maintaining the seal throughout its length. Thus, niobium which has a temperature coefficient of expansion close to that of the ceramic can be used. If a glass melt is also used, it is placed at the outer circumference of the plug where the operating temperature is sufficiently low so that the halides in the fill will not degrade the glass melt. To prevent evaporation of niobium during the sintering process, a protective sleeve, for example of ceramic, can be placed over the lead-through at portions where niobium might evaporate from the rod, pin or wire, and also then strengthening the niobium, which has a tendency to become brittle at sintering temperatures.

Claims20

Dependent claims

High-pressure discharge lamp comprising

a ceramic discharge vessel (4) having at least one open end (6, 6');
a ceramic plug (10) formed with an axial bore (14) therethrough, closing off the open end of the vessel and defining, respectively, a discharge side at the interior of the vessel and an outer side opposite said discharge side;
a lead-through passing through said axial bore (14), said lead-through comprising
a solid rod or pin or wire (9, 21) essentially consisting of a metal which has a temperature coefficient of expansion at least approximately similar to the temperature coefficient of expansion of the ceramic material of the ceramic plug (10);
an electrode (13) having an electrode shaft (12), said electrode shaft extending towards said lead-through rod, pin or wire and being electrically and mechanically secured to one end of said lead-through rod, pin or wire at the discharge side of the plug;
and
current connection means (7, 22) connected to the other end of said lead-through rod, pin or wire,
and wherein
the rod, pin or wire (9, 21) is gas-tightly sintered into the bore (14) of the ceramic plug (10, 10') and the rod, pin or wire (9, 21) is recessed into the bore (14) at least at the discharge side of the plug.

6 more elements

High-pressure discharge lamp comprising

a ceramic discharge vessel (4) having at least one open end (6, 6');
a ceramic plug (10) formed with an axial bore (14) therethrough, closing off the open end of the vessel and defining, respectively, a discharge side at the interior of the vessel and an outer side opposite said discharge side;
a lead-through passing through said axial bore (14), said lead-through comprising
a solid rod or pin or wire (9, 21) essentially consisting of a metal which has a temperature coefficient of expansion at least approximately similar to the temperature coefficient of expansion of the ceramic material of the ceramic plug (10);
an electrode (13) having an electrode shaft (12), said electrode shaft extending towards said lead-through rod, pin or wire and being electrically and mechanically secured to one end of said lead-through rod, pin or wire at the discharge side of the plug;
and
current connection means (7, 22) connected to the other end of said lead-through rod, pin or wire,
and wherein
the rod, pin or wire (9, 21) is gas-tightly sintered into the bore (14) of the ceramic plug (10, 10') and the rod, pin or wire (9, 21) is recessed into the bore (14) at least at the discharge side of the plug;
and
wherein said rod, pin or wire (21) is fitted into the bore (14) recessed from both the discharge side as well as the outer side of the plug (10).

8 more elements

Dependencies are inferred from the claim text.

High-pressure discharge lamp with ceramic discharge vessel

Life of this patent

High-pressure discharge lamp with ceramic discharge vessel

Life of this patent

Abstract

Claims20