| 摘要 |
PURPOSE:To eliminate inrregular flickering even after the lighting time is over by keeping the length of a rod type auxiliary electrode extruded in the discharge side from an electrode filament, distance between the end point of auxiliary electrode and the internal wall of a glass bulb and an internal diameter of the bulb in the specified relation. CONSTITUTION:The lead wires 3, 3 are implanted to a stem 2 sealed to the end portion of a glass bulb 1 at which internal surface the phosphorus film is deposited. An electrode filament 4 of tangusten coil is connected to the end portion of these lead wires 3, 3. Moreover, both lead wires 3, 3 are provided with rod type auxiliary electrodes 5, 5 by electrical welding. When, a length of electrode 5 extruded to the discharge side from the center axis of filament 4 is defined as h mm, distance of filament 4 extruded to the external side of lead wire 3 from the end portion 6 as a mm, the electrode 5 is formed within the range, h>=4, 0 <a/h<=0.6. Moreover, the end point 7 of electrode 5 is in the relation 0.2 <=L/D<0.5, when an internal diameter of bulb 1 is defined as D mm, and distance between the end point 7 and internal wall of bulb 1 as L mm. |
