A display device comprises a backlight (6) and a light modulating layer (5) such as an LCD device. The backlight (6) can be controlled to operate as a single homogenous light source for producing 2D images or a series of narrow parallel light sources for producing 3D images. Preferably, the backlight (6) is an OLED device and the 2D/3D mode switching is achieved by selectively energising all or a subset of parallel control electrodes (11) of the OLED device.