A plasma display panel has a first substrate, plural pairs of display electrodes, a second substrate, and plural data electrodes. In a medium that recordsplays back data including video data and control information, the control information includes information for accessing a specific portion of the video data. A current flowing through an inductor is estimated from the terminal voltage of the capacitor. The actuating member is structured to move radially inward of the mode switching member from the initial position toward the rotation axis of the mode switching member with respect to the mode switching member. The tread adjustment mechanism allows the coordinated movement of all the treads to a desired rise height, and allows the positioning of the first tread directly on a supporting surface when it is in a fully lowered position.