Patent attributes
A backlight module including a light guide plate, a light source, an optical film, a first prism sheet and a second prism sheet is provided. The light guide plate has a light incident surface and a light emitting surface. The light source is disposed on a side of the light incident surface. The optical film is overlapped with the light emitting surface and includes a substrate, a plurality of optical microstructures and a first diffusion structure layer. The optical microstructures are disposed on a light incident side of the substrate. An extending direction of the optical microstructures intersects with the light incident surface. The first diffusion structure layer is disposed on a light emitting side of the substrate and is overlapped with the optical microstructures. The first prism sheet and the second prism sheet are overlapped with the optical film and are positioned on the light emitting side.