Backlight module

A backlight module comprising:

• a back plate having a supporting surface;
• at least one optical film disposed on the back plate, wherein the supporting surface and the optical film have a gap therebetween;
• a light source disposed at an edge of the supporting surface;
• and
• a plurality of optical microstructures disposed between the supporting surface and the optical film, wherein the light source is adapted to emit a light towards the optical microstructures, and each of the optical microstructures comprises:
• a first transparent structure connected to the supporting surface and having a front end and a rear end opposite to each other, wherein the front end faces toward the light source and has a first concave surface, and the rear end faces away from the light source and has a convex surface;
• and
• a second transparent structure connected to the first transparent structure and located between the first transparent structure and the optical film, wherein the second transparent structure has a front surface and a rear surface opposite to each other, the front surface faces toward the light source and tilts in relative to the supporting surface, and the rear surface faces away from the light source and tilts in relative to the supporting surface.