Projection Substrate Resist Thickness for Uniform HMD Viewing
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Solution Overview
Problem
Head-mounted display devices face a challenge in increasing the viewing angle without causing luminance non-uniformity.
Innovation Solution
A projection substrate is designed with a transparent glass plate and a diffraction grating positioned between the glass plate and the second surface, where the thickness of the resist film between the grooves and the glass plate is determined based on the wavelength of diffracted light, allowing for efficient light transmission and image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the viewing angle is increased in head-mounted display devices, then the observable image range is improved, but luminance non-uniformity occurs
Solution Approach 1:
The patent applies local quality by varying the thickness of the resist film in different regions of the diffraction grating. Specifically, the resist film thickness is adjusted according to the local position to compensate for luminance non-uniformity that occurs when increasing the viewing angle. This allows different parts of the optical system to have optimized properties for their specific function, resolving the contradiction between wide viewing angle and uniform luminance distribution.
Solution Approach 2:
The patent employs parameter changes by modifying the resist film thickness parameter in the diffraction grating structure. By changing this physical parameter locally across the grating, the patent optimizes light diffraction characteristics to maintain uniform luminance while enabling larger viewing angles. This directly addresses the technical contradiction by adjusting a key structural parameter to balance both requirements.
2Use of energy by moving object
If a diffraction grating is positioned closer to the second surface than the glass plate, then light transmission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the resist film thickness according to a predetermined pattern or formula. This controlled variation in the thickness parameter enables the diffraction grating to achieve optimal light transmission efficiency while the systematic approach to thickness control makes the manufacturing process more predictable and precise, thereby addressing both the energy efficiency and manufacturing precision requirements.
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 suppresses luminance non-uniformity while maintaining a large viewing angle, ensuring a more uniform and enhanced image projection experience.
Implementation Method 1
a diffraction grating that i) is provided between the first surface and the second surface, positioned closer to the second surface than the glass plate and ii) has a plurality of grooves formed by a resist so that the light corresponding to the image propagates while being diffracted
Data Source
AI summary
This projection substrate is for causing an image to be projected onto a second surface on the opposite side of a first surface while causing at least a portion of light of a specific wavelength range incident on the first surface to be transmitted through the second surface, the projection substrate having a transparent glass plate that is provided on the first surface side, and a diffraction grating that is provided on the second surface side with respect to the glass plate and that has a plurality of grooves formed with a resist so that light corresponding to the image propagates while being diffracted, wherein the thickness of a resist film between the bottom surface of the grooves and the glass plate is determined on the basis of the wavelength of light diffracted in the grooves.