Light source module

A light source module comprises a plurality of light emitting units each including a reflection plate, a light extraction plate, a side wall structure, a light source and a diffusion plate. The reflection plate and the light extraction plate are arranged opposite to each other, and the light extraction plate is provided with a plurality of first holes. The side wall structure is interposed between the reflection plate and the light extraction plate, and a first light guiding chamber is formed by the reflection plate, the light extraction plate and the side wall structure, wherein the side wall structure is provided with a plurality of second holes. The light source is disposed inside the first light guiding chamber and close to side wall structure. The diffusion plate is arranged above the light extraction plate, wherein a second light guiding chamber is formed between the light extraction plate and the diffusion plate. According to the invention, the light source module is designed to have a thickness smaller than that of the conventional edge-light light source module. Besides, the generation of dark zones between light zones is prevented.