| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a long-life coiled filament for electric bulb. <P>SOLUTION: Assuming a basic filament wound to the predetermined total number of turns at a predetermined pitch over the overall length, a filament 1 is formed which comprises a both-end close winding parts 5 of one-end close winding parts 5a, 5b formed by winding both ends closely to the same number of turns at the same winding pitch and a center loose winding part 10 formed by winding a center part loosely according to the winding pitch and overall length of the basic filament. The filament 1 is characterized in that the number of turns of the center loose winding part 10 is larger than 75% and less than 100% of the total number of turns, and the value obtained by dividing the winding pitch of the center looses winding part 10 by the winding pitch of the basic filament is 1.03-1.045. <P>COPYRIGHT: (C)2013,JPO&INPIT |
