Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Peter Arend Seinen

Christoffel Wijenberg

Andreas S Geven

Josephus Theodorus Van Der Eyden

Max L Renardus

Jan A Stoffels

Adrianus Johannes Hendricus Petrus Van Der Pol

Joseph L G Suijker

Elisabeth Onnekes-Van Der Voort

Jeroen Peter Balm

Mark Bolech

Martin F C Willemsen

Engelbertus Cornelius Petrus Vossen

Franciscus H Van Lierop

Hendrik Dreuning

Harald R Dielis

Low-pressure mercury vapor discharge lamp comprising a discharge vessel () having a first and a second end portion (), the discharge vessel () containing mercury and a rare gas, wherein the end portions () each support an electrode () arranged in the discharge vessel () for initiating and maintaining a discharge in the discharge vessel (), wherein an electrode shield () substantially encompasses at least one of the electrodes (), and wherein said electrode shield () comprises an inner wall () and an outer wall (), said walls () being spaced apart.

Low-pressure mercury vapor discharge lamp

A low-pressure mercury-vapor discharge lamp is provided with a discharge vessel and a first and a second end portion ( ). The discharge vessel encloses a discharge space provided with a filling of mercury and an inert gas in a gastight manner. Each end portion ( ) supports an electrode ( ) arranged in the discharge space. An electrode shield ( ) encompasses the electrodes ( ) and, according to the invention, carries an electric current during operation, and is at a temperature &gE;250&deg; C., preferably &gE;450&deg; C., during nominal operation of the discharge lamp. Preferably, a first current supply conductor ( ) electrically contacts a first current divider ( ), which is electrically connected to a second current divider ( &prime;) via a shell-shaped body ( ). Said second current divider ( &prime;) electrically contacts the electrode ( ), which is connected to the second current supply conductor ( &prime;), the electrode shield ( ) is made from stainless steel, in particular a chromium nickel steel. Preferably, the heat dissipation of the electrode shield ( ) during nominal operation ranges between 0.1 and 10 Watts. Preferably, the electrode shield ( ) is made from a ceramic material or carbon. The discharge lamp exhibits a comparatively low mercury consumption.

Low-pressure mercury-vapor discharge lamp having electrode shield carrying direct electric current

The electric lamp has a ceramic lamp vessel ( ) having a filling of rare gas and metal halide. Current conductors ( ) which support electrodes ( ) inside the discharge vessel ( ) enter the discharge vessel ( ) in a gastight manner through a ceramic sealing compound ( ). At least one of the current conductors ( ) has inside the lamp vessel ( ) a first, halogen-resistant part ( ) which is selected from tungsten silicide, molybdenum aluminide, molybdenum boride, pentamolybdenum trisilicide and combinations of at least two of these intermetallic compounds. These compounds have a coefficient of thermal expansion which corresponds to that of the discharge vessel ( ). It is thereby prevented that the discharge vessel starts leaking if the ceramic sealing compound ( ) extends beyond the first part ( ). As a result of their coefficient of thermal expansion, the intermetallic compounds may constitute the second part ( ) of the current conductors ( ) as well, which part ( ) is surrounded by the ceramic sealing compound ( ) in a gastight manner.

Metal halide lamp having halide resistant current conductors

A low-pressure mercury-vapor discharge lamp comprises a discharge vessel ( ) and a first and a second end portion ( ). The discharge vessel ( ) encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner. Each end portion ( ) supports an electrode ( ) arranged in the discharge space. Current supply conductors ( &prime;) extend from the electrodes ( ) through the end portions ( ) so as to project from the discharge vessel ( ). An electrode shield ( ) encompasses at least one of the electrodes ( ). According to the invention, the electrode shield ( ) is mounted on the current supply conductors ( &prime;). Preferably, the electrode shield is clamped to the current supply conductors. The electrode shield is preferably provided with recesses to accommodate the current supply conductors. Preferably, the current supply conductors are flattened at the location where the electrode shield is mounted on the current supply conductors. Preferably, the electrode shield ( ) is made from a ceramic material. The lamp according to the invention can be readily manufactured and exhibits a comparatively low mercury consumption.

Low pressure mercury-vapor discharge lamp with electrode shield mounted on current supply conductors

A high-pressure metal halide discharge lamp having a power rating of at most 100 W is provided with a discharge vessel having a translucent ceramic wall with a thickness d of at least 1.2 mm. In the discharge space enclosed thereby, two electrodes are arranged with their electrode tips at a mutual interspacing EA. The discharge vessel contains an ionizable filling comprising at least Na and a halide.

High-pressure metal halide discharge lamp

Metal halide lamp radiates light with a color temperature T.sub.c of between 3900 K and 4200 K and with a general color rendering index R.sub.a .gtoreq.90. The ionizable metal halide filling comprises between 30 and 50 mole % CaI.sub.2. The lamp has a limited crest factor, and accordingly a long useful life.

Metal halide lamp having specific filling

A high-pressure discharge lamp of the invention includes a ceramic discharge vessel (10) in which a first and a second electrode (40a, 40b) are arranged and which encloses a discharge space (11 ) which is provided with a filling containing a metal halide. The discharge vessel (10) has a central zone (20) between the electrodes (40a, 40b) and a first and a second cylindrical end zone (30a, 30b) which each surround a current supply conductor (50a, 50b) connected to a respective electrode (40a, 40b). At least the first end zone (30a) has a diameter smaller than the smallest diameter of the central zone (20). The current supply conductor (50a) through the first end zone (30a) has a halide resistant portion (51a) which faces the discharge space (11) and a portion (52a) permeable to hydrogen and oxygen and facing away from the discharge space (11). The halide resistant portion (51a) extends through the first end zone (30a) over a distance that is at least the inner diameter D of the first end zone (30a) augmented by 2 mm. Furthermore, the current supply conductor (50b) through the second end zone (30b) has a halide resistant portion (51b) which faces the discharge space (11). The construction allows for a sufficient reduction of the amount of hydrogen and oxygen in the discharge vessel (10), while corrosive attack of the current supply conductors (50a, 50b) by halides is prevented.

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Eindhoven, Netherlands

Peter Arend Seinen