The structural feature of the backlight type is that a flat surface light source is set on the entire back of the liquid crystal display device. This overall backlight source can be a continuous and uniform surface light source, such as EL or flat fluorescent lamp; it can also be a uniform background light source composed of a large number of point light sources connected into a piece or a point light source and a reflector, such as a dot matrix LED or incandescent backlight source.
(Figure 1: LCD Direct-backlight structure)
The structural feature of edge-lit backlight is that a linear or point-shaped light source is set on the back side of the liquid crystal display device, and then through a special light guide plate and a light homogenizer, it forms a uniform background light that is the same size as the liquid crystal display window and close to the liquid crystal display surface. Edge-lit backlights can generally be made very thin, and the backlight brightness can be made uniform. At the same time, because the light is placed on the side, the effect of the heat from the bulb on the liquid crystal display can be reduced. However, its light source utilization rate is lower than that of backlit backlights, only 40%~50%.
(Figure 2: Schematic diagram of edge-lit backlight structure)