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

摘要

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.