| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a coil-like filament for an electric bulb having a long life. <P>SOLUTION: The coil-like filament is constituted of both end densely wound parts, whose both end parts are densely wound with the same number of turns and a winding pitch to make each one as a one end densely wound part, and a center sparsely wound part whose center part is sparsely wound. The number of turns of the both end densely wound parts is 12.5% of the total number of turns of the filament, and the winding pitch of the both end densely wound parts is in a range of 135% to 173%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
