The ornamental design for a filamentbulb, as shown and described.
FIG. 1 is a perspective upper front View of a filament bulb;
FIG. 2 is a front View thereof;
FIG. 3 is a left side View thereof;
FIG. 4 is a rear View thereof;
FIG. 5 is a right side View thereof;
FIG. 6 is a top plan View thereof;
FIG. 7 is a bottom plan View thereof; and,
FIG. 8 is a perspective lower front View thereof.
Disclaimer: The glass plunger surrounding the filament, the lamp holder beneath the filament as well as the screw base are shown in broken lines because they are not part of the claimed design, but are considered necessary to show the environment in which the design is associated.
Secondly, in the center of the filament bulb several groups of vertically oriented LED wires are shown wherein each group contains of one LED wire. Only one group of one LED wire is shown in solid lines. The purpose of showing only one group of one LED wire in solid lines is that the second and any further group of one LED wire are identical to said group of one LED wire that is shown in solid lines. Therefore, any repetition of said group of one LED wire—that is shown in solid lines—is shown in broken lines.