U.S. Philips Corporation

Willem Van Benthem

Ernst M Schmidt

Robertus L De Vaan

A low-pressure sodium vapor discharge lamp having a tubular discharge vessel (1) not more than 400 mm long and not more than 20 mm in diameter, which contains anexcess of sodium, helium and at least one of the rare gases neon, argon, krypton and xenon. The object of the invention is to provide a small low-pressure sodium vapor discharge lamp which has a lower power consumption than a similar known lamp. The composition of the rare gas filling present in the discharge vessel is defined by a quadrilateral AB CD in a ternary volume composition diagram PQR shown in FIG. 1, where P represents He, Q represents Ne and/or A and R represents Kr and/or Xe. A denotes a mixture consisting of 80% by volume of He and 20% by volume of Ne, B denotes a mixture consisting of 95% by volume of He and 5% by volume of Kr and/or Xe, C denotes a mixture consisting of 50% by volume of He and 50% by volume of Kr and/or Xe, and D denotes a mixture consisting of 25% by volume of He and 75% by volume of Ne and/or A.

Low-pressure sodium vapor discharge lamp

The invention relates to a low-pressure sodium vapor discharge lamp provided with a U-shaped discharge tube which is enveloped by an outer bulb. The bend of that discharge tube is supported by means of a metal element relative to the outer bulb. In accordance with the invention the bend of the discharge tube is partly passed through a hole in the metal element and bears against two fingers which are part of the metal element.

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Eindhoven, Netherlands

Willem Van Benthem