Abstract: A back light module is provided. The back light module comprises a frame, a U-shaped lamp tube and a diffusion plate. The U-shaped lamp tube is set inside the frame. The U-shaped lamp has two electrodes that face the bottom section of the frame just underneath the lamp tube. The diffusion plate is also set inside the frame above the U-shaped lamp tube. Since the U-shaped lamp tube forms the light source of the back light module, the number of light tubes is only half of that of the conventional back light module having straight lamp tubes and hence the light energy required to illuminate the module is effectively reduced.