FIG. 1 is a front perspective view of a head-mounted display device;

FIG. 2 is a top, front perspective view thereof;

FIG. 3 is a bottom, front perspective view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear perspective view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a right side elevational view thereof, the left side is a mirror image;

FIG. 9 is a front perspective view thereof, the display portion is positioned on the right; and,

FIG. 10 is a front perspective view thereof, the display portion is positioned upward.

The broken line drawing of a human head in FIG. 1, 9, and 10; the broken line drawing of a cord in FIGS. 1-4, 6-10; and the broken line drawing of the head support in all views are for illustrative purposes only and form no part of the claimed design.