Patent ID: 7719173

Claim:
An electrodeless discharge lamp comprising a bulb into which a discharge gas and a mercury which is controlled at a temperature of a coldest spot are filled, a power coupler that generates a high frequency electromagnetic field, and a ferrule for coupling the bulb and the power coupler, wherein: the bulb is configured as a barrel formed of a transparent material having an opening, and a sealing member welded to the opening of the barrel and having a cylindrical cavity; a protrusion formed at an apex of the bulb, which becomes the coldest spot when the lamp is lit in a state in which the ferrule is disposed upward; and a protruding portion formed in a vicinity of a portion of the bulb just above the ferrule so that the vicinity of the portion of the bulb just above the ferrule serves as the coldest spot when the lamp is lit in a state in which the ferrule is disposed downward, the power coupler having spring members which are fitted to an inside cavity of the protruding portion when fitted into the cavity.