Selectively Reflecting Layer for HUD Color Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current head-up display systems face challenges in achieving high visible light transmittance and accurate color reproduction, particularly in displaying white, due to the configuration of light reflection layers which often result in decreased visible light transmittance.
Innovation Solution
A projection image-displaying member with a selectively reflecting layer that wavelength-selectively reflects light, featuring a maximum reflectivity in the 700 to 850 nm range and multiple peaks in the 470 to 700 nm range, including a cholesteric liquid crystal layer and a retardation layer, to enhance visible light transmittance and color reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light reflection layers are used to achieve wavelength-selective reflection, then color reproduction is improved, but visible light transmittance decreases
Solution Approach 1:
The light reflection layer is divided into multiple sub-layers, each responsible for reflecting specific wavelength ranges. This segmentation allows precise control over which wavelengths are reflected and which are transmitted, enabling accurate color reproduction while maintaining high visible light transmittance by ensuring that the reflected wavelengths do not overlap significantly with the transmitted visible spectrum.
Solution Approach 2:
Different portions of the light reflection layer are designed with different optical properties. The first light reflection layer has a first average refractive index while the second light reflection layer has a second average refractive index, creating local variations in optical characteristics. This allows each region to optimize its reflection characteristics for specific colors while maintaining overall transparency.
2Measurement precision
If the reflectivity of the selectively reflecting layer is increased to improve color saturation, then color reproduction is improved, but visible light transmittance decreases
Solution Approach 1:
The patent applies partial action by having the light reflection layer reflect only specific portions of the spectrum (infrared and ultraviolet) rather than all wavelengths. The reflectivity is optimized for non-visible wavelengths while maintaining high transmittance for visible wavelengths, achieving color saturation through selective reflection rather than broad-spectrum reflection.
Solution Approach 2:
The patent changes the refractive index parameters of the light reflection layer materials to optimize the balance between reflection and transmission. By carefully selecting materials with specific refractive indices and controlling the thickness of the layer, the patent achieves high color saturation through precise control of the reflection characteristics at specific wavelengths while maintaining overall transparency.
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 provides a head-up display system with high visible light transmittance and improved color reproduction, specifically for white tones, by optimizing the reflectivity characteristics of the selectively reflecting layer, preventing a yellowish tint and enhancing the brightness of the displayed image.
Implementation Method 1
a selectively reflecting layer that wavelength-selectively reflects light
Implementation Method 2
including a cholesteric liquid crystal layer
Implementation Method 3
and a retardation layer
Data Source
AI summary
There are provided a projection image-displaying member, a windshield glass, and a head-up display system in which both high visible light transmittance and good tint of a screen image displayed are achieved. The projection image-displaying member has a selectively reflecting layer that wavelength-selectively reflects light. The selectively reflecting layer has a maximum reflectivity in a wavelength range of 700 to 850 nm at an incidence angle of 5° and has a peak with a reflectivity of 15% or more in a wavelength range of 470 to 540 nm. The selectively reflecting layer further has two or more peaks of reflectivity in a wavelength range of 540 to 700 nm.