| 摘要 |
PROBLEM TO BE SOLVED: To provide a reliable circular fluorescent lamp fixture that never reaches abnormal temperatures at the end of its life or the like. SOLUTION: This fixture is a pre-heated type circular fluorescent lamp with a single discharge path formed that is preheated when actuated. A dual circular lamp 200 arranged on the external surface of the fixture main body 100 having a lighting device includes a large circular light-emitting tube 210 of a larger circular diameter and a small circular light-emitting tube 220 of a smaller circular diameter. The lamp includes a lamp socket that acts as an output terminal for a lighting circuit and the lamp socket has four electrodes with two of them on the power supply side and the other two on the non-power supply side. The lamp includes a four-electrode-type socket-receiving section formed at a lamp base section 240. The lamp includes a thermal fuse housed in the lamp base section 240 with the thermal cutout connected in series to a given one electrode of the socket-receiving section. When the lamp socket 120 is mounted in the socket receiving section, four-electrode wiring connection is made, wherein one power-supply-side electrode for the lamp socket 120 and the thermal fuse are connected in series. A combination selecting means 900 permits a connection form and prohibits the other connection forms. |
