We claim the ornamental design for a pencil sharpener, as shown and described.
FIG. 1 is a first perspective view of a pencil sharpener showing our new design;
FIG. 2 is a second perspective view of the pencil sharpener of FIG. 1;
FIG. 3 is a front elevational view of the pencil sharpener of FIG. 1;
FIG. 4 is a rear elevational view of the pencil sharpener of FIG. 1;
FIG. 5 is a right side elevational view of the pencil sharpener of FIG. 1; and,
FIG. 6 is a left side elevational view of the pencil sharpener of FIG. 1.
The broken lines in FIGS. 1-3 showing features on the front and the inside edges of the drawer and the opening into which the drawer goes show parts of the design that form no part of the claim.