Transparent Pane Conductive Coating Oxidation Protection
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Solution Overview
Problem
Existing transparent electrically conductive coatings for vehicle windshields face challenges in achieving high specific heating power while maintaining optical properties and crystallinity, often requiring additional blocking layers that negatively impact conductivity and increasing production costs due to the need for voltage conversion and potential oxidation during the bending process.
Innovation Solution
A transparent pane with a multi-layer coating structure comprising optically high-index materials, smoothing layers with non-crystalline oxides, and getter materials like niobium, titanium, and zinc oxide, which protects the conductive layers from oxidation and enhances crystallinity, allowing for reduced surface resistance and high transmission without the need for additional blocking layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of silver layers is increased to reduce sheet resistance, then conductivity is improved, but optical properties (transmission and color effects) deteriorate
Solution Approach 1:
The patent divides the single thick silver layer into multiple thinner silver layers separated by dielectric layers. This segmentation allows the total silver content to be distributed in a way that maintains conductivity while improving optical properties. Each thin silver layer contributes to conductivity, while the dielectric layers between them prevent excessive light absorption and maintain transmission.
Solution Approach 2:
The patent creates a composite structure combining multiple silver layers with dielectric layers (such as silicon nitride, silicon oxide, or zinc oxide). This composite material approach allows optimization of both electrical and optical properties by combining the high conductivity of silver with the optical transparency and insulating properties of dielectric materials.
2Reliability
If a blocking layer is added to prevent oxidation during heat treatment, then oxidation protection is improved, but crystallinity of the silver-containing layer deteriorates
Solution Approach 1:
The patent introduces dielectric layers as intermediary layers between the silver layers and the environment. These dielectric layers serve as protective barriers that prevent oxidation during heat treatment and bending processes, while being deposited in a way that does not interfere with the crystallization of silver layers. The dielectric layers are applied after silver layer deposition, allowing silver crystallinity to develop without contamination.
3Power
If voltage conversion from 14V to 40V is implemented to achieve sufficient heating power, then specific heating power is improved, but device complexity and energy losses increase
Solution Approach 1:
The patent changes the electrical parameter of sheet resistance by using multiple silver layers with optimized thickness and configuration. By reducing the sheet resistance through this structural parameter change, the system can achieve sufficient heating power at the standard 14V vehicle electrical system voltage, eliminating the need for voltage conversion equipment and associated energy losses.
4Reliability
If the number of silver layers is increased to reduce sheet resistance, then conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple deposition steps into an integrated manufacturing process where silver layers and dielectric layers are deposited in sequence using vacuum deposition techniques. The process merges the functionality of multiple layers into a single coating operation, reducing manufacturing complexity despite the increased number of layers. The dielectric layers serve dual purposes of electrical insulation and optical management.
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 achieves a high specific heating power with improved conductivity and optical neutrality, meeting legal requirements for vehicle glazing while simplifying production and avoiding oxidation issues during bending.
Implementation Method 1
the lower matching layer and/or the upper matching layer comprises a getter material from the group consisting of niobium, titanium, barium, magnesium, tantalum, zirconium, thorium, palladium, platinum and alloys thereof, distributed homogeneously throughout the layer cross-section
Implementation Method 2
The specific heat output P of an electrically heatable coating with a sheet resistance R square, an operating voltage U and a distance h between two busbars can be calculated using the formula P = U2/(R square *h2)
Implementation Method 3
each functional layer has at least one layer of optically high-index material with a refractive index greater than or equal to 2.1
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a transparent pane comprising at least one transparent substrate (1) and at least one an electrically conductive coating (2) on at least one surface of the transparent substrate (1). The electrically conductive coating (2) has at least two functional layers (3) arranged one on top of another and each functional layer (3) comprises at least: one layer of optically highly refractive material (4) with an index of refraction greater than or equal to 2.1; a smoothing layer (5) containing at least one non-crystalline oxide above the layer of optically highly refractive material (4); a lower adapting layer (6) above the smoothing layer (5); an electrically conductive layer (7) above the lower adapting layer (6); and an upper adapting layer (8) above the electrically conductive layer (7). The lower adapting layer (6) and/or the upper adapting layer (8) contain a getter material (10), distributed homogeneously over the entire layer cross-section, from the group consisting of niobium, titanium, barium, magnesium, tantalum, zirconium, thorium, palladium, platinum and alloys thereof. At least one lower adapting layer (6) and/or upper adapting layer (8) containing the getter material (10) is in direct contact with the electrically conductive layer (7).