Electrodeless low-pressure discharge lamp.

摘要

The invention relates to an electrodeless low-pressure discharge lamp comprising a discharge vessel made from a light-transmitting material and having a bulb portion and a tubular cavity portion sealed in a gas-tight manner, the discharge lamp comprising furthermore an induction coil placed in the cavity portion, and a base member providing for electrical connection with the terminals of the coil and for fixing the lamp and for outer electrical contact where the discharge vessel contains a noble gas fill and additive material and its wall is provided with phosphor-containing coating. The essential feature of the solution according to the invention is that the top surface /10/ of the tubular cavity portion /4/ is formed - over a distance of at least one-third tube radius /r/, beginning at the mantle surface /11/ of the tubular cavity portion /4/ and continuing inwardly towards the lamp axis /t/ - so that the theoretical tangential planes /s/ of the top surface /10/ make an angle / alpha / exceeding 90 degrees with the lamp axis /t/ and the top surface /10/ of the tubular cavity portion /4/ has a rounded juncture with the mantle portion /11/ of the cavity portion /4/.