Backlight source, display module and display device

An edge-type backlight source, comprising:

• a back plate, the back plate comprising a bottom plate and a side plate, the side plate and the bottom plate defining an accommodation cavity, the bottom plate being provided with a plurality of concaves depressed toward the accommodation cavity, a reflection layer being arranged on a first surface of the bottom plate used to form the accommodation cavity, a black adhesive layer for filling up the concaves being arranged on a second surface of the bottom plate opposite to the first surface of the bottom plate used to form the accommodation cavity, so as to provide a planar surface;
• a light guide plate injection-molded with the accommodation cavity as a die cavity and arranged within the accommodation cavity in such a manner that the light guide plate is engaged with the back plate in a seamless manner, a light-exiting surface of the light guide plate being arranged opposite to the first surface of the bottom plate used to form the accommodation cavity, a light-entering surface of the light guide plate being arranged close to the light-exiting surface, at least two grooves being formed at a light-entering side of the light guide plate using an injection molding process for forming the light guide plate, each groove extending to the light-exiting surface of the light guide plate;
• a light source comprising at least two light bars arranged within the grooves respectively, each light bar being of a shape adapted to a shape of the groove and having a length equal to a depth of the groove;
• and
• an optical membrane comprising a diffuser, a lower prismatic lens and an upper prismatic lens sequentially arranged on the light-exiting surface of the light guide plate, a transparent adhesive being applied onto a first surface of the upper prismatic lens adjacent to the light guide plate so as to form a first adhesive layer, the optical membrane being fixedly adhered onto the light-exiting surface of the light guide plate through the first adhesive layer, and the upper prismatic lens being configured to fixedly press the light bar into a corresponding groove through the first adhesive layer.