U.S. Philips Corporation

Jan A Stoffels

Peter Arend Seinen

Christoffel Wijenberg

Andreas S Geven

Max L Renardus

Willem J Van Den Hoek

Cornelis A Jacobs

Jan Margareta Peeraer

Aldegondus W Jansen

Denise Kl Vandeperre

Harald R Dielis

A metal halide lamp provided with an outer bulb having a volume V.sub.bu in which a discharge vessel with a volume V.sub.ob and having a ceramic wall is arranged, which vessel contains mercury, at least one halide, and also a rare gas having a filling pressure P.sub.ob. The relation P.sub.ob *V.sub.ob /V.sub.bu .ltoreq.6 mbar is satisfied.

Metal halide lamp having specific volume pressure ratio

The invention relates to a high-pressure metal halide lamp provided with a discharge vessel with a ceramic wall enclosing a discharge space. The vessel has a cylindrical portion of internal diameter ID which is closed off at either end by end wall portions which form end faces of the discharge space. At least two electrodes are arranged in the discharge vessel, whose respective tips have an interspacing EA such that ##EQU1## The electrodes have lead-throughs which are enclosed in ceramic closing plugs and are connected thereto in a gastight manner by means of ceramic glazing joints. According to the invention, the rated lamp power is at most 100 W, and an electrode tip lies substantially in the adjacent end face. A closing plug is fastened in the relevant end wall portion in a gastight manner at a distance from the end face.

High-pressure metal halide lamp

A high-pressure sodium discharge lamp provided with a ceramic discharge vessel, in which sodium, mercury and xenon are present, of which the xenon is at a pressure at 300K of at least 26.7 kPa. The sodium and the mercury are present in a weight ratio Na/Hg which is at least 0.075 and at most 0.125. The lamp generates in the operating condition a spectrum, in which at a wavelength of 589.3 nm a self-absorption band is present, which is limited by spectral flanks each flank having a respective maximum. There is a wavelength difference .DELTA..lambda. of at least 3.5 nm and at most 6 nm between the maxima.

High-pressure sodium discharge lamp

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.

High-pressure discharge lamp

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Turnhout, Belgium

Jan A Stoffels