The ornamental design for a pop-up display device, as shown and described.
Description:
FIG. 1 shows a front view of an exemplary embodiment of a pop-up display device in a closed position according to the present invention, the rear view is a mirror image thereof; and,
FIG. 2 shows a perspective view of the device in an open position.
The broken lines are shown for illustrative purposes only and form no part of the claimed design.
