Multilayer Diffraction Panel for Head Mount Display Light Control
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Solution Overview
Problem
Display devices, particularly head mount displays, face challenges in increasing effective light emission area ratio, reducing reflectance, minimizing visual blurring, and improving screen door effect due to limitations in diffraction grating structures and refractive index management.
Innovation Solution
A display device incorporating a diffraction panel with a multilayer structure of refractive layers, where the refractive index of the second layer is higher than the first and third layers, is used to enhance light emission by diffraction, reduce reflectance, and minimize visual blurring, thereby improving the screen door effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a diffraction grating structure is added to increase effective light emission area ratio, then light emission area ratio is improved, but reflectance increases due to external light
Solution Approach 1:
The patent converts the harmful reflectance effect into a beneficial anti-reflection effect by designing the diffraction grating structure to diffract external incident light away from the display surface. The grating equations are configured so that light from specific directions (external light sources) is diffracted at angles that prevent it from reaching the user's eye, effectively turning the reflective property into an anti-reflection mechanism.
Solution Approach 2:
The patent applies different local optical properties to different regions and orientations of the diffraction grating structure. The first and second diffraction gratings have different orientation angles (first angle and second angle respectively), creating directionally selective diffraction patterns that locally optimize light emission while selectively rejecting external light from specific directions.
2Area of moving object
If diffraction grating structures are used to enhance light emission, then light emission area ratio is improved, but visual blurring increases
Solution Approach 1:
The patent employs dynamic optical control by making the diffraction grating structures responsive to viewing angle. The oriented diffraction patterns dynamically adapt the light distribution based on the user's viewing direction, enhancing light emission in the intended viewing zone while suppressing blurring in other directions through angle-dependent diffraction efficiency.
3Illumination intensity
If conventional diffraction grating structures are used, then light emission is enhanced, but screen door effect persists
Solution Approach 1:
The patent transitions from conventional planar diffraction gratings to three-dimensional oriented diffraction patterns with specific spatial orientations. By introducing angular orientation as an additional dimensional parameter (first angle and second angle relative to the normal), the system achieves superior light distribution and eliminates the screen door effect through volumetric light control rather than simple planar diffraction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively increases the light emission area ratio, reduces reflectance, and minimizes visual blurring, leading to an improved screen door effect in head mount displays by optimizing the refractive index and thickness of the diffraction panel layers.
Implementation Method 1
a diffraction panel including a plurality of diffraction patterns disposed on (or in) a path of light emitted from the plurality of display elements
Implementation Method 2
each of the plurality of diffraction patterns comprises a first refractive layer, a second refractive layer disposed on the first refractive layer, and a third refractive layer disposed on the second refractive layer, and a refractive index of the second refractive layer is higher than a refractive index of the first refractive layer and a refractive index of the third refractive layer
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A display device includes a display panel (100) including a substrate (110) and a plurality of display elements (PX1) disposed on the substrate, and a diffraction panel (200) including a plurality of diffraction patterns (210) disposed on a path of light emitted from the plurality of display elements. The plurality of diffraction patterns are disposed in a first direction to have a first period, each of the plurality of diffraction patterns includes a first refractive layer, a second refractive layer disposed on the first refractive layer, and a third refractive layer disposed on the second refractive layer, and a refractive index of the second refractive layer is higher than a refractive index of the first refractive layer and a refractive index of the third refractive layer. The diffraction pattern is for enlarging the field of view.