U.S. Philips Corporation

Leo M Sprengers

Rolf E De Man

Jan De Ridder

Jozef I Peeters

A low-pressure sodium vapor discharge lamp provided with a discharge tube having an electrical lead-through conductor extending through the wall of the discharge tube to an internal lamp electrode. The lead-through is enveloped by a protective glass layer having a double bead construction. The layer portion facing the electrode is borate glass and is thinner than a second portion within the discharge tube wall which is lime glass. The lead-through construction thus obtained has a high resistance to sodium in the discharge tube and also to mechanical forces.

Low-pressure sodium vapor discharge lamp with protective glass layer on

An arrangement including a frequency converter (4) and a discharge lamp (10) connected thereto wherein the frequency converter (4) is of a type whose output frequency is at least 80 kHz, while the lamp is a low-pressure sodium vapor discharge lamp. This lamp supply system provides a high luminous efficacy for the lamp.

Arrangement including a metal vapor discharge tube provided with at

Low-pressure sodium vapor discharge lamp. The lamp comprises a cylindrical discharge tube and an outer bulb enveloping this tube. The outer bulb has a transparent layer which reflects infrared radiation. According to the invention the resistance per square of the infrared reflecting layer is approximately 5 ohm. A luminous efficacy of 100 lumen per watt can be obtained at a lamp power of 8 watts. The lamp is particularly suitable for security lighting.

Low-pressure sodium vapor discharge lamp

The invention relates to a low-pressure sodium-vapour discharge lamp which contains an excess of sodium. According to the invention the discharge tube contains a capillary connecting duct extending from a pool of liquid sodium. The provision of the capillary connecting duct prevents the power consumption of the lamp from increasing during the life of the lamp.

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Eindhoven, Netherlands

Leo M Sprengers