Windshield Heating Coating Uniform Heat Distribution
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Solution Overview
Problem
Heatable windshields with electrically conductive coatings face issues of inhomogeneous heat output distribution due to coating-free zones, leading to local overheating and potential thermal stresses, which complicates the use of dark silver pastes for busbars while maintaining electrical conductivity and aesthetic requirements.
Innovation Solution
A transparent pane design with a continuous electrically conductive coating and strategically placed coating-free zones, using a combination of bright silver pastes for busbars and dark silver pastes for additional electrodes to ensure uniform heat distribution and meet OEM electrical and color requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coating-free zones are introduced to ensure electromagnetic radiation transmission, then communication functionality is improved, but heat distribution uniformity deteriorates
Solution Approach 1:
The patent applies different properties to different regions: the heating coating is removed in specific zones (communication windows) to allow electromagnetic transmission, while retaining coating in other areas for heating. Additionally, busbars are strategically positioned and designed with specific geometries to compensate for the discontinuities caused by coating-free zones, ensuring uniform heat distribution despite the non-uniform structure.
2Power
If busbars are positioned close together to achieve satisfactory heating performance, then heating efficiency is improved, but current path length increases leading to higher resistance
Solution Approach 1:
The patent transitions from a one-dimensional linear busbar arrangement to a two-dimensional distributed network of busbars and heating traces. This allows current to flow through multiple parallel paths and shorter segments, reducing the effective resistance while maintaining close spacing for efficient heating across the windshield surface.
3Illumination intensity
If dark silver pastes are used for additional electrodes to meet aesthetic requirements, then appearance is improved, but electrical conductivity decreases
Solution Approach 1:
The patent changes the compositional parameters of the silver paste to create different formulations: bright silver paste with high silver content (e.g., 90-95%) for busbars requiring high conductivity, and dark silver paste with lower silver content (e.g., 70-85%) for additional electrodes where aesthetics are prioritized. The design compensates for the reduced conductivity in dark paste areas by adjusting trace geometry or increasing trace width.
4Adaptability or versatility
If uncoated zones are created for sensor and electronic device placement, then device integration is improved, but local heating power distribution deteriorates
Solution Approach 1:
The heating system is segmented into multiple independent heating zones separated by coating-free areas for sensors and electronics. Each heating zone is independently controlled through separate busbar connections and heating trace configurations, allowing precise control of heat distribution in each region while accommodating discontinuities caused by embedded devices.
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 more uniform heat output distribution across the windshield, reduces the risk of overheating, and allows the use of dark silver pastes for the additional electrodes, meeting both electrical and aesthetic demands.
Implementation Method 1
applying a supply voltage causes a heating current to flow across a heating field formed between the two busbars
Implementation Method 2
the surface of the first disc, on which the electrically heated coating is arranged, is connected to a second disc over a surface via a thermoplastic intermediate layer
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a transparent panel (1) according to figure 1, comprising at least one heatable, electrically conductive coating (8) that is connected to at least two collection lines (11, 11'), provided for electrically connecting to the two poles of a voltage source, in such a way that, by applying a supply voltage, a heat current flows via a heat field (12) formed between the at least two collection lines, wherein the heat field (12) contains at least one coating-free zone (14) which is bordered by a zone edge (16) of the coating-free zone (14) at least partially formed by the electrically conductive coating (8), and which is at least partially surrounded by at least one additional electrode (15, 15', 15"), wherein the at least one additional electrode (15, 15', 15") is electrically coupled to the collection lines (11, 11') via the heat field (12) of the coating (8), and the at least two collection lines (11, 11') have a light silver colour and the additional electrode has a dark colour. The invention also relates to a production method and a use thereof.