RARE GAS FLUORESCENT LAMP

PROBLEM TO BE SOLVED : To provide a fluorescent lamp usable for a backlight source, which has lighting performance that light-emitting by a stable discharge can be maintained in a wide range of dimming, for which a rare gas fluorescent lamp using rare gases including xenon gas as a discharge medium is asked. SOLUTION : A conventional rare gas fluorescent lamp comprises a phosphor coating layer 2 on the inside wall of a transparent airtight vessel 1, a rare gas 3 as a discharge medium enclosed in the vessel 1, an inner electrode 5 on a sealed one-side end, and an external electrode 7 on the outer wall of the transparent airtight vessel 1, whereas the rare gas fluorescent lamp of the present invention has a glass rod made of a transparent dielectric 12 on the top of the inner electrode 5 to eliminate a discharge space, in which a positive column is pinched, and to form a narrow toroidal space. This prevents flicker from occurring, where the flicker is caused by pinching and unstable moving of the positive column, which occur in the space near the inner electrode 5 when the rare gas fluorescent lamp is lit by a PWM dimming control and a dimming rate D becomes close to a MIN.