Diffraction Grating Layer for Head-Mounted Display Emission Area

The patent applies a diffraction-grating layer on the encapsulation substrate that introduces a new dimensional aspect to light manipulation. The diffraction grating creates multiple diffraction orders (zeroth, first, second orders) that spread light in different directions, effectively increasing the perceived emission area in the angular dimension. This allows the display to maintain high image quality in head-mounted displays by distributing light across multiple angular paths, thereby reducing the screen door effect without compromising the emission area.

The patent modifies the optical parameters of the system by introducing a diffraction-grating layer with specific periodic structures. The grating period and depth are carefully controlled to optimize the diffraction efficiency and angular distribution of light. By changing these parameters, the system achieves broader light distribution that reduces the screen door effect while maintaining adequate brightness and emission area for the display.

The patent merges the diffraction-grating layer with the encapsulation substrate, integrating the optical function directly into an existing structural component. Rather than adding a separate, complex optical system, the grating structure is formed on or within the encapsulation substrate that already protects the OLED. This merging approach reduces overall device complexity while achieving the desired light distribution effect to eliminate the screen door effect.

The patent replaces complex mechanical or optical systems with a simpler diffractive optical element. Instead of using multiple lenses, mirrors, or moving parts to control light distribution, the system uses a static diffraction-grating layer that passively manipulates light through its periodic structure. This substitution dramatically reduces mechanical complexity while maintaining the ability to control light angular distribution and reduce the screen door effect.