| 摘要 |
PURPOSE:To obtain a long-livedness, with a sputtering being small, by making a wire distance of a thin wire in a tubular bulb coil filament,which is formed by loosely winding a high melting-point metal thin wire around a high melting- point metal core wire, to be smaller than the wire diameter of the core wire. CONSTITUTION:A tubular bulb coil filament used in a fluourescent lamp or the like is formed by loosely winding a thin wire 12 of tungsten or the like around a core wire 11 of tungsten or the like, as a primary coil 1, and more winding it as a secondary coil 2. Then, when a diameter of the core wire 11, a diameter of the thin wire 12, a wire distance of the thin wire 12, and a diameter of the secondary coil 2 are respectively d, ds, s, and D, the wire distance s is made smaller than the wire diameter d of the core wire 11, with a limitation of 1.0<=d/s<=1.5. Moreover, when an emitter is filled between the thin wire 12 and the core wire 11, the emitter exposed area is reduced. There fore, with a spattering being small, consumption of the emitter can be reduced to obtain its long-livedness. |
