Holographic Light Guide Intensity Distribution for HUD Streak Reduction
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Solution Overview
Problem
Conventional head-up display systems using light guides with volume hologram diffraction gratings suffer from image quality issues due to varying propagation angles and intensity distributions, leading to bright or dark streaks when image light is projected onto a display medium, which reduces visibility.
Innovation Solution
A light guide system incorporating holographic optical elements with intensity distributions where the intensity is lower at the end portions than the intermediate portions, and multiple holographic optical elements arranged in specific directions to diffract and emit image light in a way that suppresses overlap and noise, improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If volume hologram diffraction gratings are used in conventional head-up display systems, then image light can be diffracted and projected onto the display medium, but bright or dark streaks appear due to varying propagation angles and intensity distributions, reducing image quality
Solution Approach 1:
The patent applies local quality by making the diffraction efficiency spatially non-uniform across the holographic optical element. Specifically, the diffraction efficiency is designed to be higher in the intermediate portion and lower in the end portions of the intensity distribution, which compensates for the natural intensity profile and suppresses the formation of bright or dark streaks in the projected image.
Solution Approach 2:
The patent changes the diffraction efficiency parameter across different regions of the holographic optical element. By adjusting the diffraction efficiency to have a specific intensity distribution pattern (higher in intermediate portions, lower in end portions), the system optimizes the light distribution to eliminate streaks while maintaining overall image quality.
2Illumination intensity
If multiple holographic optical elements are arranged to diffract image light, then image quality can be improved by suppressing overlap and noise, but the device complexity increases
Solution Approach 1:
The patent segments the holographic optical functionality into multiple discrete holographic optical elements arranged in a specific sequence. Each element contributes to the overall image formation process by diffracting light in a controlled manner, allowing the system to suppress overlap and noise while maintaining manageable complexity through modular design.
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 proposed solution enhances image quality by reducing bright and dark streaks, resulting in improved visibility and clarity of projected images on the display medium.
Implementation Method 1
a holographic optical element that receives image light emitted from an image light emitter... in an intensity distribution of the image light diffracted by and emitted from the holographic optical element
Data Source
AI summary
A light guide includes: a holographic optical element that receives image light emitted from an image light emitter; and a light guide member that includes the holographic optical element. In an intensity distribution of the image light diffracted by and emitted from the holographic optical element, intensity is smaller in an end portion of the intensity distribution than in an intermediate portion of the intensity distribution.