ELECTRODELESS DISCHARGE LAMP AND ILLUMINATOR COMPRISING IT

摘要

An electrodeless discharge lamp producing a constant light output regardless of the fixing direction. The electrodeless discharge lamp (1) comprises a bulb (10) encapsulating discharge gas and mercury being controlled at the temperature of the coolest point, a power coupler (20) generating a high frequency electromagnetic field, and a base (15) for coupling the bulb and the power coupler. The bulb consists of a translucent spherical container (14) having an opening, and a sealing member (11) being welded to the opening of the spherical container and having a tubular cavity (5). A protrusion (4) formed at the top of the bulb becomes the coolest point when the lamp is lighted while directing the base upward. A projection (17) is formed at the bulb neck (19). Consequently, the bulb neck becomes the coolest point when the lamp is lighted while directing the base downward.