HUD Glass Coating Stack for Brighter, Sharper Display Images
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Solution Overview
Problem
Conventional head up display glasses have low brightness and vague image due to limited reflectivity of reflective coatings, resulting in poor display effects.
Innovation Solution
A head up display glass with an enhanced reflection coating and transparent conducting coating, each with specific reflectivity for P-polarized light, allowing for increased reflectivity and improved image sharpness by superimposing primary and secondary images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective coating is applied to the head up display glass, then the display function is enabled, but the reflectivity is limited to ensure transmittance meets national standards, resulting in low brightness and vague images
Solution Approach 1:
The patent divides the reflective coating into multiple separate layers (transparent conducting coating and enhanced reflection coating) with distinct functions. The transparent conducting coating provides base reflectivity while maintaining transmittance, and the enhanced reflection coating adds additional reflectivity for P-polarized light. This segmentation allows each layer to be optimized independently, resolving the contradiction between brightness enhancement and transmittance compliance.
Solution Approach 2:
The patent uses composite material structures including multiple dielectric layers, metal layers, and coatings with different optical properties. The combination of transparent conducting oxide layers, metal layers (silver, aluminum, or their alloys), and dielectric layers creates a composite coating system that achieves high reflectivity for P-polarized light while maintaining overall transmittance within national standards, thereby improving image brightness without sacrificing compliance.
2Illumination intensity
If the reflectivity of the coating is increased to improve image brightness, then the display effect is enhanced, but the transmittance decreases below national standards
Solution Approach 1:
The patent applies local quality by making the coating properties position-dependent and function-specific. The transparent conducting coating is optimized for general transparency and base reflectivity, while the enhanced reflection coating is specifically designed to reflect P-polarized light at certain angles. This local optimization allows the glass to have high reflectivity where needed (for display brightness) while maintaining adequate transmittance overall (meeting national standards).
Solution Approach 2:
The patent changes optical parameters of the coatings by controlling the thickness, material composition, and optical constants of each layer. By adjusting parameters such as the thickness of transparent conducting oxide layers (e.g., ITO, IZO), metal layer thickness (5-20 nm), and dielectric layer properties, the patent achieves a balance where P-polarized light reflectivity is enhanced for bright display images while total light transmittance remains within national standards.
3Manufacturing precision
If a multi-layer coating structure is used to enhance reflectivity, then the image sharpness and brightness are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the complex coating system into modular layers that can be applied sequentially using standard industrial coating techniques. Each layer (transparent conducting oxide, metal, dielectric) has a specific thickness range and function, allowing for controlled deposition processes. This segmentation enables precise control over the optical properties of each layer, achieving sharp image display through constructive interference effects, while the modular structure facilitates manufacturing by breaking down the complex coating process into manageable steps.
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
Enhances display brightness and sharpness by increasing the reflectivity of P-polarized light, improving the overall display effect and enabling augmented reality applications.
Implementation Method 1
The transparent conducting coating has a reflectivity for P-polarized light not less than 6%
Implementation Method 2
The enhanced reflection coating has a reflectivity for P-polarized light not less than 10%
Implementation Method 3
The high refractive-index layer has a refractive index not less than 1.8
Data Source
AI summary
A head up display glass and a head up display system are provided. The head up display glass includes an outer glass sheet, an inner glass sheet, an intermediate layer, a transparent conducting coating, and an enhanced reflection coating. The outer glass sheet has a first surface and a second surface opposite the first surface. The inner glass sheet has a third surface and a fourth surface opposite the third surface. The second surface faces the third surface. The intermediate layer is disposed between the second surface and the third surface. The transparent conducting coating is disposed on the second surface or the third surface. The enhanced reflection coating is disposed on the fourth surface. The transparent conducting coating has a reflectivity for P-polarized light not less than 6%. The enhanced reflection coating has a reflectivity for P-polarized light not less than 10%.