Flat panel display device and stereoscopic display device

A stereoscopic display device, wherein the stereoscopic display device comprises a liquid crystal lens grating, a backlight system, and a display panel, the liquid crystal lens grating being arranged on a light exit surface of the display panel;

• the backlight system comprises an LED (light emitting diode) light bar and a back frame, and the back frame carries the LED light bar, and the back frame comprises at least two primary assembling pieces, the at least two primary assembling pieces being joined to form a main frame structure of the back frame, the back frame further comprising positioning walls, the positioning walls being mounted to a side wall of at least one of the primary assembling pieces to define a receiving space for receiving the LED light bar;
• wherein the positioning walls comprise a first positioning wall, a second positioning wall, and a third positioning wall, wherein the first positioning wall is mounted to an end of the side wall in a lengthwise direction;
• the second positioning wall and the third positioning wall are spaced from each other in a width direction of the side wall so as to define the receiving space between the second and third positioning walls, the receiving space having an end closed by the first positioning wall and an opposite end that is open and receives entry of the LED light bar to slidably move in and along the receiving space until being stopped by the first positioning wall.