Backlight module with a heat dissipation device

A backlight module, comprising:

• a light box, having a bottom and a light-emitting section opposite to the bottom, wherein the bottom has a first surface and a second surface opposite to the first surface, and the first surface is closer to the light-emitting section;
• a plurality of light source sets, disposed on the bottom, wherein each of the light source sets comprises a substrate disposed on the bottom and a plurality of point light sources disposed on the substrate;
• a heat dissipation device, comprising:
• a thermal assembly, including a plurality of covers, wherein each of the covers is disposed on the second surface at a position below one of the light source sets, an air flow channel is formed between each of the covers and the bottom, an end of each of the covers has a first opening, the other end of each of the covers has a second opening, and the second openings are communicated, and wherein a maximum distance between each of the covers corresponding to a central portion of each of the light source sets and the bottom is smaller than a maximum distance between each of the covers corresponding to two end portions of each of the light source sets and the bottom;
• and
• at least one fan, disposed at the thermal assembly, wherein the fan makes air in the air flow channels to flow out from the second openings, or the fan makes the air to flow into the air flow channels from the second openings.