Louver Surface Roughness for Head-Mounted Display Light Control
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Solution Overview
Problem
Existing louvers in head-mounted displays fail to effectively block external light and stray light while minimizing loss and disturbance of display light, leading to issues such as ghost images and reduced image quality.
Innovation Solution
A louver design featuring a light blocking portion with distinct surface roughness on its surfaces, where the surface roughness of one surface is larger than the other, integrated with a transparent base portion, to optimize light blocking and transmission properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a louver with uniform surface roughness is used, then the manufacturing process is simple, but external light and stray light are not effectively blocked while display light is lost and disturbed
Solution Approach 1:
The louver employs different surface roughness values on different surfaces of the light blocking portion. The first surface (facing display light) has a lower roughness (Ra ≤ 20 nm) to minimize scattering of display light, while the second surface (facing external light) has a higher roughness (Ra > 20 nm) to effectively scatter and block external light and stray light. This local differentiation of surface properties resolves the contradiction between blocking harmful light and preserving useful display light.
2Object-affected harmful factors
If the surface roughness of the light blocking portion is increased to block external light, then external light blocking improves, but display light scattering increases causing image quality degradation
Solution Approach 1:
The patent applies different surface roughness characteristics to different surfaces of the light blocking portion. The surface facing display light maintains low roughness (Ra ≤ 20 nm) to preserve image quality by minimizing scattering, while the surface facing external light has high roughness (Ra > 20 nm) to block external light. This local quality differentiation allows the system to achieve both external light blocking and high image quality simultaneously.
3Object-affected harmful factors
If a light blocking material is used to block external light, then external light blocking improves, but the louver cannot transmit display light effectively
Solution Approach 1:
The louver uses a transparent base portion with light blocking portions having different surface roughness on different surfaces. The first surface (facing display light) has low roughness (Ra ≤ 20 nm) to allow effective display light transmission with minimal scattering, while the second surface (facing external light) has high roughness (Ra > 20 nm) to block external light. This local differentiation enables the light blocking material to simultaneously block external light and transmit display light effectively.
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 louver effectively blocks external light, reduces ghost images, and maintains high image quality by minimizing reflection and scattering of display light, ensuring clear and bright images.
Implementation Method 1
The light blocking portion is formed in the base portion, being made of a light blocking material
Implementation Method 2
A surface roughness of the first surface is larger than a surface roughness of the second surface
Implementation Method 3
a base portion made of a transparent material
Implementation Method 4
A surface roughness of the first surface is larger than a surface roughness of the second surface
Data Source
AI summary
A louver includes a light blocking portion having a first surface and a second surface and a base portion made of a transparent material. The light blocking portion is formed in the base portion, being made of a light blocking material. The second surface is a surface that is in contact with the transparent material and that is located on an outer-edge side of the base portion. The first surface is a surface that is in contact with the transparent material and that is opposite to the second surface. A surface roughness of the first surface is larger than a surface roughness of the second surface.