ONE-BASE LOW-PRESSURE DISCHARGE LAMP, AND METHOD OF MANUFACTURING IT

Two U-shaped inner tubes, each of which have a straight leg which is hermetically sealed about a preheatable electrode, are sealed into the upper, oval reception section of a preshaped flare. The seal also includes the exhaust tube and the lead-in wire pairs supporting the preheatable electrodes and is carried out as a press seal in one single working step. The other legs of the U-shaped inner tubes remain open. The lower, outwardly facing rim of the preshaped flare which is concentric with the longitudinal lamp axis is sealed to an outer envelope whose neck drops off during this sealing process and which surrounds the U-shaped inner tubes and contains a gas and/or metal vapor filling. The inner tubes are preferably coated with a three-line phosphor, and the outer envelope is provided with a light diffusing coating. The single-ended low-pressure discharge lamp may largely be manufactured on conventional machines and may be directly used in place of an incandescent lamp as a compact lamp of low electrical wattage when a starting and operating circuitry is incorporated in a conventional type of base used for incandescent lamps. Also disclosed are methods of manufacture of such a lamp.