U.S. Philips Corporation

Hendrik Roelofs

Gustaaf A Wesselink

Cornelis H Van Bommel

Jan Hasker

Petrus R Van Ijzendoorn

Gijsbert Johannes Ponsen

Arie Koelewijn

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.

Low-pressure discharge lamp with tortuous discharge path

A low pressure gas discharge lamp having a body present in the discharge vessel which consists of a longitudinal support which extends into the longitudinal direction of the vessel, the support being provided with fibers which are distributed over the space within the discharge vessel and extend substantially transversely from the support.

Low pressure gas discharge lamp having fibers evenly distributed between

A method for manufacturing a low pressure gas discharge lamp having a body present in the discharge vessel which consists of a longitudinal support which extends into the longitudinal direction of the vessel. The support being provided with fibres which are distributed over the space within the discharge vessel and extend substantially transversely from the support.

Method of making a low-pressure gas discharge lamp

The invention relates to a device for operating a low-pressure sodium vapor discharge lamp without a stabilizing ballast. The lamp is provided with a discharge tube having first and second main electrodes opposing a third main electrode. An automatically operating change-over switch occasionally switches the lamp current to either the first or second electrodes. A reservoir of liquid sodium near the first electrode affects sodium vapor pressure in the discharge tube by the switching action.

Discharge lamp operating circuit

Electric lamp having a hermetically sealed gas-filled hard-glass or vitreous-silica lamp envelope provided with a current lead-in which is sealed into a portion of the lamp envelope and comprises a foil mainly consisting of molybdenum and a current supply lead mainly consisting of tungsten which is secured to the foil by a welded joint and extends into the lamp envelope. The welded joint contains iron or an alloy of at least 50% by weight of iron and one or more of the elements scandium, titanium, vanadium, chromium, manganese, cobalt, nickel and copper as the welding agent.

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Eindhoven, Netherlands

Hendrik Roelofs