The present invention discloses a light source device applied to a display module. The light source device produces an emission light field which forms a light field shape when projected in a normal direction onto a planar surface substantially parallel to a placement plane of the light source device. The light field shape includes a light field center, more than three intense light regions, and more than three dim light regions. The intense light regions and the dim light regions are alternately disposed, and radially arranged around the light field center. A light brightness at a predetermined distance from the light field center in the dim light region is less than 90% of a light brightness at the predetermined distance from the light field center in the intense light region.