A display device and a method for using the display device are provided. The display device includes a display panel, a grating panel over the display panel, and a distance adjusting mechanism for adjusting a distance between the display panel and the grating panel to provide an adjustable optimum viewing distance of the display device. The distance adjusting mechanism includes a first electromagnetic unit configured with the grating panel and a second electromagnetic unit configured under the display panel. Electric current flowing through each of the first electromagnetic unit and the second electromagnetic unit is controlled to allow the grating panel to move towards or away from the display panel.