U.S. Philips Corporation

Cornelis H Van Bommel

Gustaaf A Wesselink

Hendrik Roelofs

Low-pressure sodium vapor discharge lamp comprising a hollow inner member surrounded by an outer member, the wall of at least one of the members having grooves and the members of that portion, located between the grooves, extending to or to near the wall of the other member and a discharge space being formed wherein a discharge path, folded by means of the grooves, is present, the portions located between the grooves and facing the wall of the other member and extending to or to near the wall of the other member being provided with intervening portions extending in parallel with that wall.

Low-pressure sodium vapor discharge lamp

Low-pressure mercury vapor discharge lamps of the fluorescent type are known which comprise two nesting glass members so grooved as to provide between their nesting surfaces a circuitous ('folded') discharge path between two electrodes, the length of the discharge path being considerably greater than the physical distance between the electrodes. The whole surface of each glass member is coated with luminescent material with the result that, when the lamp is in use, the portions of the members not surrounding the discharge appear dark due to their poor light transmissibility. According to the invention, these portions of the two members are not coated with luminescent material and thus act as windows for light generated in the luminescent layers facing the lamp axis. Preferably, a fluted reflector is provided inside the lamp.

Low-pressure mercury vapor discharge lamp with luminescent coatings on

Low-pressure discharge lamp having a discharge space, limited by an elongate lamp vessel, electrodes at one end of the vessel in the discharge space between which electrodes a discharge takes place during operation of the lamp. The lamp vessel has partitions to divide the discharge space into each extending substantially in the length of the discharge vessel which chambers communicate with one another via at least one opening. The chambers are sequentially passed through by the discharge, the opening between at least two chambers being at least partly wedge-shaped, the minimum width being located nearest to an electrode whose discharge path extends itself after ignition.

Growing community of inventors

Eindhoven, Netherlands

Cornelis H Van Bommel