| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a filament having high efficiency for converting electric power to visible light.SOLUTION: A base material 1 made of metal is covered with a white scatterer layer 2. The white scatterer layer 2 is formed of white scatterer particles added with a visible light absorbing material. The average particle diameter of the white scatterer particle in a region 21 near the base material 1 is smaller than the average particle diameter thereof in a region 22 distant from the base material 1 in the thickness direction of the white scatterer layer. The white scatterer layer 2 suppresses infrared light radiation of the base material 1. Thereby, a filament having high visible light luminous flux efficiency can be provided. Also, infrared light radiation can be further suppressed by enlarging the average particle diameter in a region near the surface of the white scatterer layer to improve reflectance. Moreover, adhesion between the white scatterer layer and the base material can be increased by making the average particle diameter in the region near the base material smaller than that in the region near the surface of the white scatterer layer. |
