Blended lamp

DETAILED DESCRIPTION What is claimed is: 1.
A blended lamp having an incandescent filament in a halogen atmosphere which is electrically arranged in series with a high-pressure sodium vapor discharge tube, the discharge tube containing mercury and a starting gas in addition to sodium, the percentage by weight "G" of the mercury in the discharge tube being between 91 and 98% of the combined weight of the mercury and the sodium in the discharge tube.
2.
A blended lamp as claimed in claim 1, characterized in that G is 95%.
+-.
0.
5%.




Description:
The invention relates to a blended lamp having an incandescent filament which is electrically arranged in series with a high-pressure sodium discharge tube, the discharge tube containing mercury and a starting gas in addition to sodium, the percentage by weight G of the mercury in the discharge tube exceeding 80% of the combined weight of the mercury and the sodium.
Such a blended lamp has the advantage that it can be connected--like an incandescent lamp--to an electric supply source without the need for an external ballast; the reason being that the filament in the blended lamp also operates as a stabilization ballast for the discharge tube.
A known blended light lamp of the above-mentioned type is, for example, disclosed in the Japanese Patent Application No.
PA-46-32858 (publication number Sho-45083), which was laid open to public inspection on Dec.
23, 1972.
This known lamp has the drawback that the amalgam in the discharge tube has such a composition that G is not more than approximately 83%.
This means that the weight ratio between the mercury and the sodium in the discharge tube is not more than approximately 5.
Consequently, with that known lamp, when fed from an a.
c.
voltage source, the required re-ignition voltage of the discharge tube--at the beginning of each half cycle of the electric supply--is relatively high.
This has the result that the arc voltage of the discharge tube can only be relatively low with respect to the voltage of the a