Mura-compensable direct-lit mini-LED backlight module
The disclosure provides a mura-compensable direct-lit Mini-LED backlight module, including a PCB substrate, a reflective cover, and an optical diaphragm group which are sequentially arranged from bottom to top. The optical diaphragm group includes at least one diffusion diaphragm, and a plurality of microlens structures are arranged on a light emission side and/or a light incidence side of the diffusion diaphragm to form a microlens structure surface. In the backlight module provided by the disclosure, light is subjected to multiple reflections between the reflective cover and the diffusion diaphragm, thus improving the light emitting uniformity along the diffusion diaphragm.
1. A mura-compensable direct-lit Mini-LED backlight module, comprising a PCB substrate with a plurality of Mini-LED light sources mounted on a surface, a reflective cover provided with a plurality of reflector cup structures with upper and lower openings, and an optical diaphragm group, wherein
the PCB substrate, the reflective cover and the optical diaphragm group are sequentially arranged from bottom to top, and the Mini-LED light sources are arranged corresponding to the reflector cup structures on the reflective cover and penetrate through the lower openings of the reflector cup structures;
the optical diaphragm group comprises at least one diffusion diaphragm; and
a plurality of microlens structures are arranged on a light emission side and/or a light incidence side of the diffusion diaphragm to form a microlens structure surface;
wherein the microlens structures are recessed toward inside of the diffusion diaphragm to form recessed cavities on a surface of the diffusion diaphragm;
wherein the optical diaphragm group further comprises at least one transflective diaphragm, a reflectivity corresponding to light incident from a light incidence side of the transflective diaphragm at incident angles of 10°, 30° and 50° is R10, R30 and R50 respectively, and the transflective diaphragm satisfies R10>R30>R50.
2. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein the transflective diaphragm includes a transmissive layer, resin layers and a reflective layer sequentially arranged, and the resin layers are formed by laminating more than 11 thermoplastic resin layers, and a difference between refractive indices of adjacent thermoplastic resin layers is 0.01 or above in a thickness direction of the transflective diaphragm.
3. The mura-compensable direct-lit Mini-LED backlight module according to claim 2 , wherein the resin layers comprise resin layers A and resin layers B, and the resin layers A and the resin layers B are alternately compounded to form the transflective diaphragm.
4. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein a side surface, facing the transflective diaphragm, of the diffusion diaphragm is provided with the microlens structures.
5. The mura-compensable direct-lit Mini-LED backlight module according to claim 4 , wherein the transflective diaphragm is attached to the microlens structure surface of the diffusion diaphragm to realize composition of the transflective diaphragm and the diffusion diaphragm.
6. The mura-compensable direct-lit Mini-LED backlight module according to claim 4 , wherein the microlens structures are arranged on the light emission side of the diffusion diaphragm so as to form the microlens structure surface on the light emission side of the diffusion diaphragm.
7. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein the optical diaphragm group is attached to a top of the reflective cover, so that the optical diaphragm group seals the upper openings of the reflector cup structures.
8. The mura-compensable direct-lit Mini-LED backlight module according to claim 7 , wherein
in the optical diaphragm group, the diffusion diaphragm is used as a bottom diaphragm, and
a distance H between a light incidence side surface of the bottom diaphragm and an upper surface of the PCB substrate is equal to a thickness T of the reflective cover.
9. The mura-compensable direct-lit Mini-LED backlight module according to claim 8 , wherein the transflective diaphragm satisfies that an average reflectivity for blue light is greater than 40%, or an average reflectivity for red light and green light is greater than 70%.
10. The mura-compensable direct-lit Mini-LED backlight module according to claim 9 , wherein
the optical diaphragm group further comprises a diffusion sheet and a quantum dot film, the Mini-LED light sources are blue light sources, the transflective diaphragm comprises a first transflective diaphragm and a second transflective diaphragm, and the diffusion diaphragm, the first transflective diaphragm, the diffusion sheet, the second transflective diaphragm and the quantum dot film are sequentially laminated from bottom to top; and
the average reflectivity of the first transflective diaphragm for blue light is greater than 40%, and the average reflectivity of the second transflective diaphragm for red light and green light is greater than 70%.
11. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein
a bottom diaphragm of the optical diaphragm group is the transflective diaphragm, the reflective cover, and the transflective diaphragm and the diffusion diaphragm are sequentially attached from bottom to top so that the transflective diaphragm seals the upper openings of the reflector cup structures.
12. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein a distance between a lower surface of the optical diaphragm group and the Mini-LED light sources is H, and a minimum pitch between adjacent Mini-LED light sources is P, H:P=1:1-1:7.
13. The mura-compensable direct-lit Mini-LED backlight module according to claim 1 , wherein
the microlens structures are subjected to periodic distribution corresponding to the reflector cup structures, and
the periodic distribution refers to that a plurality of microlens structures located right above the upper opening of each reflector cup structure form a microlens structure group, and the microlens structure group is used as a repeating unit of the periodic distribution.
14. The mura-compensable direct-lit Mini-LED backlight module according to claim 13 , wherein
each microlens structure group corresponds to the Mini-LED light source arranged in its corresponding reflector cup structure; and
in the microlens structure group, with an optical axis of its corresponding Mini-LED light source as a central axis, distribution density of the microlens structures decreases in a radiation manner.
15. The mura-compensable direct-lit Mini-LED backlight module according to claim 13 , wherein
each microlens structure group corresponds to the Mini-LED light source arranged in its corresponding reflector cup structure; and
in the microlens structure group, with an optical axis of its corresponding Mini-LED light source as a central axis, a slope of a concave inclined surface of each microlens structure increases as a distance between the microlens structure and the central axis decreases.
16. The mura-compensable direct-lit Mini-LED backlight module according to claim 13 , wherein the light incidence side and the light emission side of the diffusion diaphragm are both provided with the microlens structures.
17. The mura-compensable direct-lit Mini-LED backlight module according to claim 16 , wherein
each microlens structure group corresponds to the Mini-LED light source arranged in its corresponding reflector cup structure; and
in the microlens structure group, with an optical axis of its corresponding Mini-LED light source as a central axis, sizes of the microlens structures increase as a distance between the microlens structures and the central axis decreases, so that a thin film structure whose edges are thicker than middle is formed in a region of the diffusion diaphragm where the microlens structure group is located.