I claim the ornamental design for a 3D signal emitter for projector, as shown and described.
FIG. 1 is a front perspective view of a 3D signal emitter for projector of the present invention;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a first side view thereof;
FIG. 5 is a second side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
Portions of the 3D signal emitter for projector shown in broken lines form no part of the claimed design and are included for the purpose of illustrating the environment. Additionally, the unevenly broken lines in the drawings define the limits of the claimed design.