The ornamental design for a diaphragm, as shown and described.
FIG. 1 is a perspective view of a diaphragm showing my new design;
FIG. 2 is a front elevational view thereof.
FIG. 3 is a rear elevational view thereof.
FIG. 4 is a left side elevational view thereof.
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a cross-sectional view thereof, corresponding to 6-6 of FIG. 2.
The diaphragm is symmetrical about a central vertical axial plane Thereof. Hence a right side elevational view of the diaphragm is a mirror image of the left side elevational view thereof.
In addition, the diaphragm is symmetrical about 6-6 of FIG. 2. Hence a bottom plan view of the diaphragm is a mirror image of the top plan view thereof.