| 摘要 |
PROBLEM TO BE SOLVED: To provide a filament having a structure capable of stabilizing formation of bright spot at lighting of a hot-cathode fluorescent lamp and, as a result, is capable of stably prolonging the lifetime of the hot-cathode fluorescent lamp. SOLUTION: In a double coil filament 5, the pitch of a primary winding coil 11 at a coated region 21 of electron-emitting substance 19 is made large, in a region 21A including the center part of the filament 5 and made small in regions 21Ba, 21Bb on its both sides. In a triple coil filament 23, the pitch for the secondary winding coil 31 at the coated region 39 of the electron-emitting substance 37 is made large, in a region 39A that includes the central part of the filament 23 and made small in regions 39Ba, 39Bb on both sides. In a stick coil filament 41, the pitch of the secondary winding coil 49 at the coated region 55 of the electron-emitting substance 53 is made large in a region, including the central part of the filament 41 and made small in regions 55Ba, 55Bb at both sides. COPYRIGHT: (C)2009,JPO&INPIT
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