Heated Windshield Busbar Arrangement for Uniform Heating
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Solution Overview
Problem
Existing windshield heating systems face challenges in achieving uniform heating while maintaining sufficient light transmission and avoiding visual obstructions, leading to non-uniform heating and potential overheating around functional elements, which can affect the quality of thermoplastic interlayers and cause delamination.
Innovation Solution
The solution involves strategically arranging busbars to prioritize heating in main vision zones (A and B) by extending them laterally up to the limits of these zones, allowing for differential voltage application, and using additional busbars under non-heated zones to maintain current distribution continuity, reducing hot spots and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the busbars are positioned at the edges of the windshield, then the heating coverage is maximized, but the distance between busbars increases leading to insufficient power density and slow heating speed
Solution Approach 1:
The busbars are extended from traditional edge-only positioning into the lateral zones of the windshield, utilizing the vertical dimension along the side edges. This dimensional extension reduces the effective distance between power sources and heating zones without compromising edge coverage, thereby increasing power density and heating speed.
2Productivity
If the busbars are moved closer together to increase power density, then heating speed improves, but the busbars encroach into the driver's field of vision creating visual obstructions
Solution Approach 1:
The busbars are strategically positioned to extend into lateral zones that correspond to non-critical viewing areas. This localized positioning provides high power density where needed while preserving light transmission and visual clarity in the driver's primary field of vision, thus resolving the contradiction between heating efficiency and optical performance.
3Power
If the metallic coating thickness is increased to reduce resistance, then heating power increases, but light transmission in the visible range decreases below regulatory requirements
Solution Approach 1:
The heating system is segmented into multiple zones supplied by multiple busbars positioned at edges and lateral areas. This segmentation allows each metallic coating section to be thinner and meet light transmission requirements, while the combined effect of multiple segments provides sufficient total heating power across the entire windshield surface.
4Area of stationary object
If the windshield size is increased to meet modern vehicle requirements, then the heating area increases, but the resistance increases leading to insufficient power and slower heating
Solution Approach 1:
The large windshield surface is divided into multiple heating zones, each served by its own busbar positioned at strategic locations including edges and lateral areas. This segmentation maintains low resistance and adequate power density across the entire large surface area, enabling effective heating of modern oversized windshields.
Solution Approach 2:
Additional busbars are positioned along the lateral edges of the windshield, utilizing the vertical dimension. This dimensional approach provides multiple power injection points across the large surface, reducing overall resistance and enabling adequate power delivery to the entire extended heating area.
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
This arrangement achieves faster heating in critical vision zones while minimizing overheating and maintaining uniform appearance, ensuring efficient power distribution and reducing temperature disparities across the windshield.
Implementation Method 1
The power output is limited by the vehicle's voltage, typically 12-14V... equipped with an electrically conductive grid powered by busbars... equipped with a film electrically powered by busbars to allow uniform heating of the windshield
Data Source
Figure 1
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Figure 4~5
AI summary
The invention relates to a heated laminated windscreen made up of two sheets of glass joined by an inserted sheet, comprising a system of conductive layers covering most of the surface of one glass sheet of the windscreen, said system being electrically powered by busbars at the top (6, 13, 14) and bottom (7) of the windscreen, with windows (2, 3, 4) which are devoid of layers arranged at the top in the middle of the windscreen, and the windscreen including at least one additional busbar arranged laterally on the edges and at the top of the windscreen.