U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

Klaus Scholler

Manfred Westemeyer

Godfried Maria Manders

Helmut Tiesler-Wittig

Bram Visser

A gas-discharge lamp () is described having an inner envelope () comprising a discharge vessel () and two tubular sections () arranged on the discharge vessel, having two electrodes () that project from the tubular sections () into the discharge vessel () and that, to enable them to be supplied with power, are electrically connected to respective electrical conductors () that extend through the associated tubular sections () and that are enclosed in the tubular sections () with a gastight seal along a sealing section (). The lamp () has an outer envelope () that is connected at each of its ends to respective ones of the tubular sections () of the inner envelope () and that surrounds the discharge vessel () while leaving an outer cavity () between itself () and the discharge vessel (). Arranged on the outside of the inner envelope (), at least in a region or regions, is a conductive coating () that is conductively connected, inside the outer envelope (), to one () of the electrical conductors. Also described is a corresponding method of producing a gas-discharge lamp ().

Gas-discharge lamp

A lamp has a metal layer to prevent light escaping in an undesired direction. A sealed envelope wall encloses an interior space in which an electrical element is arranged. The wall is partly coated by the metal layer, preferably at a lamp end opposite a lamp cap. A light diffusing or absorbing layer over a side of the metal layer facing the interior space prevents light reflection back into the interior space. For use as a vehicle headlamp, the metal layer may be silvery as viewed from the outside so that it is not noticeable.

Electric lamp with an anti-reflecting layer

The capped high-pressure discharge lamp suitable for use in a vehicle headlight has a discharge vessel which is surrounded by an outer envelope. Current conductors extend from a respective electrode to a respective contact at a cap in which a first neck-shaped portion of the discharge vessel is secured. A return portion of one current conductor extends along an outside surface of the outer envelope. The outer envelope has a light-absorbing coating in a region near the first neck-shaped portion, at a side which is remote from the return portion. The outer envelope may have band-shaped coatings at either side, aside from the discharge path between the electrodes, at its side which faces the return portion. Stray light in the beam formed by the reflector and the lens of a head-light in which the lamp is used, is obviated. The bands provide for a rectilinear light/dark transition in said beam.

Capped high-pressure discharge lamp

The electric lamp has a quartz glass lamp vessel (10) in which an electric element (3, 4) is accommodated. The lamp vessel locally has a light-absorbing, non reflective coating (11, 12). The coating mainly consists of 2 to 10% by weight of glass which is free of lead oxide and has a softening point between 600.degree. and 700.degree. C. Iron 50 to 60% by weight, primarily in metallic form, and manganese oxide, 30 to 55% by weight, are dispersed therein.

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Nideggen, Germany

Klaus Scholler