Display device and driving method thereof

A display device comprising:

• a flat display unit configured to output a planar image;
• a hologram generation unit configured to output a hologram image;
• a controller configured to acquire the holographic image with respect to the planar image;
• an upper plate;
• a lower plate separated and arranged having a predetermined space from the upper plate;
• a connector configured to connect one side of the upper plate and to one side of the lower plate;
• an image projector arranged at an end of the connector and configured to project the at least the portion of the planar image;
• a mirror arranged on the upper plate and configured to reflect the planar image to the lower plate;
• and
• a scanning screen arranged on the lower plate and configured to project the image reflected from the mirror to the predetermined space between the upper plate and the lower plate to display the holographic image,
• wherein the scanning screen rotates about a rotation axis perpendicular to a surface of the lower plate,
• wherein a protrusion is formed at one side of the upper plate and projected downward from the upper plate,
• wherein the protrusion of the upper plate includes a first surface facing the image projector and a second surface opposite the first surface, and
• wherein an angle θ1 between the first surface of the protrusion and a lower surface of the upper plate differ from an angle θ2 between the second surface of the protrusion and the lower surface of the upper plate.