The present invention provides a diffusion plate and a direct-type backlight module. By disposing the first groove on the light incident side of the second structure layer of the diffusion plate, disposing the second groove or the third protrusions on the light emitting side of the second structure layer, and the refractive index of the first structure layer, the second structure layer and the third structure layer is sequentially increased, the divergence angles of the incident light can be significantly increased, to achieve uniform backlight brightness. The direct-type backlight module of the present application includes the diffusion plate described above. The mura problem can be solved while reducing the number of the LED lamps and the light mixing distance, so as to realize the low cost and slim design of the direct-type backlight module, and are conducive to the use of the direct-type backlight module in the ultra-thin TV field.
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