US2020716A - Electric discharge tube - Google Patents

Description

Nov. 12, 1935. G. ZECHER ET AL ELECTRIC DISCHARGE TUBE Original Filed April 15, 1929 INVENTORS ATT RNEY Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE TUBE Gustav Zecher and Johannes Bruiines, Eindhoven, Netherlands, assignors, by mesne assignments, to General Electric Company, a corporation of New York June 14, 1928 1 Claim.

This invention has reference to electric discharge tubes and more particularly to electric glow discharge tubes containing metal vapour, preferably mercury vapour.

The invention has for its object to cause the metal vapour enclosed within the discharge tube to take part intensively in the discharge. For this purpose, according to the invention, a heating element is arranged adjacent to the path of discharge between the electrodes. The discharge tube may contain, in addition to a metal vapour, a gas, preferably a rare gas. Another object of the invention is to lessen the chances of condensed metal vapour forming on the walls of the tube, which is accomplished by reason of the higher and more uniform temperature of operation maintained by the heating element referred to above. I

The heating element is arranged outside the discharge tube within a re-entrant part of the latter.

The wall of the discharge tube may be at least partly of material that is transparent to ultraviolet rays.

Preferably the heating element acts as a current limiting resistance. In some instances it m y be used to entirely replace such a resistance,

thus saving energy.

The arrangement of a heating element adjacent the path of discharge is of great advantage in connection with glow discharge tubes, as a higher metal vapour pressure can thus be attained. In discharge tubes having a discharge of a kind other than a glow discharge, for example a positive column discharge, a sufiicient vapour I pressure can always be ensured by a sufliciently intense current which cannot be resorted to in the case of glow discharge tubes.

The invention will be readily understood by reference to the accompanying drawing in which an embodiment of the invention is diagrammatically illustrated in elevation.

The glow discharge lamp I has two electrodes 1 and 8 helically wound together which are fixed to and taken out of the lamp by two small tubes l3 and I4 at the reentrant part l5 of the discharge tube. The gaseous filling of this lamp contains mercuryvapour which is heated by a heating element l6 that is arranged outside the discharge tube within the re-entrant part l5 and which is connected to the leading-in wires l1 and I8 by which a separate heating current can be supplied.

Three important results follow the use of the heater element described as part of this invention-the electrodes discharge more readily and at a lower impressed voltage; the operation of the tube as a light source is steadied; and finally the carrier vapor for the discharge itself enters more freely and efliciently in the reaction to emit radiation.

This application is a division of co-pending application, Serial Number 355,334, filed April 15, 1929 and granted August 28, 1934; Patent Number 1,971,890.'

What we claim as new and desire to secure by Letters Patent of the United States is:-

A glow discharge lamp comprising a transparent envelope containing helically wound electrodes each concentric to the axis of the envelope, and supporting means for said electrodes provided with a single heater coil carried adjacent the windings of the electrodes and exterior to the envelope for increasing the temperature of the discharge normal to said electrodes, said heater coil being coextensive with said electrodes and the discharge path between said electrodes.

GUSTAV ZECHER. JOHANNES BRUIJNES.

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