The LED filament 100 shown in FIG. 6A is bent to form a contour resembling to a circle while being observed from the top view of FIG. 6A. According to the embodiment of FIG. 6A, the LED filament 100 is bent to form a wave shape from side view. The shape of the LED filament 100 is novel and makes the illumination more uniform. In comparison with a LED bulb having multiple LED filaments, single LED filament 100 has less connecting spots. In implementation, single LED filament 100 has only two connecting spots such that the probability of defect soldering or defect mechanical pressing is decreased.
The stem 19 has a stand 19a extending to the center of the bulb shell 12. The stand 19a supports the supporting arms 15. The first end of each of the supporting arms 15 is connected with the stand 19a while the second end of each of the supporting arms 15 is connected with the LED filament 100.
