Three dimension display device and controlling method thereof

A three dimension (3D) display device, comprising a display panel for displaying an image and a gratin g structure cooperating with the display panel to provide a 3D display effect, wherein the grating structure comprises a plurality of gratings capable of being switched between a transparent state and a nontransparent state, and

• the 3D display device further comprises:
• an eye tracking unit configured to acquire positions of eyes of a viewer;
• and
• a control unit connected to the eye tracking unit and configured to control the gratings to be switched between the transparent state and the nontransparent state in accordance with the positions of the eyes of the viewer, to enable a left eye of the viewer to view a first view displayed on the display panel through the grating structure and enable a right eye of the viewer to view a second view displayed on the display panel through the grating structure,
• wherein the grating structure consists of a backlight arranged at a rear side of the display panel, the backlight comprises a plurality of light-emitting units arranged separately, and each of the light-emitting units forms the grating in the transparent state when emitting light and forms the grating in the nontransparent state when not emitting light, and
• wherein the control unit further comprises a third controller configured to adjust a size of the light-emitting unit in accordance with a distance between the backlight and the display panel and a distance between a viewer's eyes and the display panel.