| 摘要 |
<p>An annulus fluorescent lamp (1, 2) comprises two annulus fluorescent tubes formed into shapes having different diameters and disposed substantially concentrically in substantially the same plane. Each of the annulus fluorescent tubes (1, 2) has a first end (4) with an electrode seal portion and a second end (5) without electrodes. The second ends (5) of the annulus fluorescent tubes (1, 2) are communicated with each other via a bridge portion so that a single discharge path is formed inside the plurality of annulus fluorescent tubes (1, 2). The annulus fluorescent lamp also comprises a mouthpiece (14) covering the first and second ends (4, 5) of the annulus fluorescent tubes (1, 2), and a thermal fuse (9) disposed in the mouthpiece (14) and close to the electrode seal portion (4) of the annulus fluorescent tubes (1, 2). The thermal fuse (9) is connected electrically between one of outer lead wires (8) of the electrodes (6) and one of lead terminals (16) fixed to the mouthpiece (14). The thermal fuse (9) is connected thermally to the surface of the annulus fluorescent tubes (1, 2) at a portion close to the electrode seal portion (4) via a silicone resin (13). When the electrode seal portion (4) is overheated in the last period of the lamp life, the thermal fuse (9) cuts off current supply to the annulus fluorescent tubes (1, 2). <IMAGE></p> |
