Transparent Windshield Coating for 14V De-Icing Without Wires
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Solution Overview
Problem
Conventional heatable vehicle windshields face issues such as visible wires affecting aesthetics and reduced solar energy transmission due to increased wire count or wire length, while transparent conductive coatings require higher voltage systems, increasing vehicle complexity and cost.
Innovation Solution
A coated article with a specific thickness of metallic silver layers in a coating stack, ranging between 30 nm and 60 nm, to achieve a sheet resistance suitable for de-icing with a 14v alternator and maintain light transmittance above 70%, reducing wire visibility and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If wire diameter is decreased to reduce visibility, then aesthetic appearance is improved, but the number of wires must be increased which decreases total solar energy transmission
Solution Approach 1:
The patent extracts the heating function from discrete wire elements and implements it through a continuous transparent conductive coating layer. This eliminates the need for multiple individual wires while maintaining the de-icing capability, thereby preserving solar energy transmission without requiring an increased number of wire elements.
Solution Approach 2:
The patent changes the physical form of the heating element from discrete wires with specific diameters to a continuous coating with controlled sheet resistance. By adjusting the coating's electrical properties (sheet resistance between 0.5-2.0 Ω/□), the system achieves effective heating while maintaining optical transparency, resolving the trade-off between visibility and solar energy transmission.
2Reliability
If transparent conductive coating sheet resistance is decreased to improve de-icing capability, then heating effectiveness is improved, but voltage requirements increase system complexity and cost
Solution Approach 1:
The patent optimizes the sheet resistance parameter of the transparent conductive coating to fall within 0.5-2.0 Ω/□, which provides sufficient heating power for de-icing while remaining compatible with standard 14V vehicle electrical systems. This parameter optimization eliminates the need for high-voltage alternators or DC-DC converters, thereby maintaining system simplicity and reducing cost.
Solution Approach 2:
The patent uses transparent conductive coatings that replicate the heating function of traditional wire-heated windshields but with superior optical properties. The coating mimics the electrical heating effect while providing continuous coverage and better compatibility with standard vehicle electrical systems, avoiding the need for complex voltage conversion equipment.
3Reliability
If wire length is increased to maintain power density on larger windshields, then heating effectiveness is maintained, but aesthetic appearance and solar energy transmission are reduced
Solution Approach 1:
The patent transitions from one-dimensional wire heating elements to a two-dimensional continuous coating layer. This dimensional change allows the heating function to be distributed uniformly across the entire windshield surface, eliminating the need for longer wires on larger windshields while maintaining heating effectiveness and preserving solar energy transmission through the transparent coating.
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 effective de-icing capability without visible wires and maintains high light transmittance, addressing aesthetic and cost concerns by optimizing sheet resistance and solar energy transmission.
Implementation Method 1
Passing electric current through a conductor on a laminated vehicle windshield will raise the temperature of the windshield
Implementation Method 2
The coated article is coated with at least one dielectric layer positioned over the substrate, and at least one metallic layer(s)
Data Source
AI summary
A coated article includes a substrate, a first dielectric layer, a first metallic layer, a first primer layer, a second dielectric layer, a second metallic layer, a second primer layer, a third dielectric layer, a third primer layer, a third metallic layer, and a fourth dielectric layer. The total combined thickness of the metallic layers is at least 30 nanometers and no more than 60 nanometers. The article can have a sheet resistance of less than 0.85Ω/□, a visible light reflectance of not more than 10%, and a visible light transmittance of at least 70%.