Diffusion plates and diffusion films  are materials used in optical systems, their main function is to make the light more evenly distributed, thereby improving the visual effect of the display device. However, they differ in structure, function, and application.

Diffusion plate:

Diffusion plates are commonly used in straight-down backlight sources where the particles are dispersed between the resin layers. When the light passes through the diffusion layer, it will pass through the two media with different refractive indices, resulting in multiple refraction, reflection and scattering to achieve the effect of optical diffusion.

The role of the diffusion plate includes scattering the luminous flux, allowing the light to be evenly distributed, and sometimes supporting the backlight architecture to protect the optical material underneath from damage.

The larger the beam Angle of the diffusion plate, the lower the illuminance, which may produce a filtering effect, making certain wavelengths of light impenetrable, resulting in color bias. Therefore, the substrate used to make the diffusion plate should be a material with a lower refractive index to reduce the interference of light.

Diffusion film:

The diffused film is mainly used in the backlight light source part of the LCD module. By coating the optical astigmatism particles on the transparent substrate such as PET, the light refracts, reflects and scatters, so as to correct the light into a uniform surface light source.

The role of the diffusion film is to correct the diffusion Angle, increase the light radiation area and reduce the light intensity per unit area, that is, reduce the brightness. It can make the light source into a larger area, better uniformity, chroma stability of the secondary light source.

The physical properties of the diffusion film include tensile strength, elongation, impact strength, tear strength, expansion strength, temperature resistance characteristics, electrical characteristics and UL grade. Key specifications include full light transmittance, fog, and light transmittance at high temperature, high humidity and low temperature.

In summary, the diffusion plate and diffusion film are designed to improve the uniformity and softness of the light source, but they differ in the specific structure, functional parameters and application scenarios. The diffuser plate is usually used in the direct-down backlight system to realize the uniform distribution of light through the scattering of particles. The diffusion film is mainly used in LCD backlight modules to achieve a similar effect by coating astigmatic particles on a transparent substrate