Vehicle Glazing Busbar Crossover for Uniform Heating

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Solution Overview

Problem

Existing glazings for electric heating in vehicles suffer from uneven heat distribution due to insulating layers covering most of the busbar length, leading to hotspots and inefficient defrosting or demisting.

Innovation Solution

A glazing design featuring a crossover of first and second busbars adjacent to a deletion line, allowing current flow along most of the busbar length for uniform heating, and using deletion lines and zone boundaries to control heat distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating layer covers most of the busbar length, then electrical isolation is improved, but heat distribution deteriorates causing hotspots

Engineering Contradiction:
Improveelectrical isolationVSAvoidheat distribution
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The busbar is segmented into multiple heating zones by deletion lines that divide the conductive coating into separate segments. Each segment can be independently controlled, allowing different temperature distributions across the glazing surface while maintaining electrical isolation through the insulating layer.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The insulating layer is applied selectively only where electrical isolation is needed (between adjacent busbars and at crossover points) rather than covering the entire busbar length. This localized insulation approach maintains uniform heat distribution in areas where the busbar should conduct heat while providing electrical isolation where required.

Inventive Principle:
Principle #3Local quality

2Reliability

If current flows only through contact windows, then electrical isolation is improved, but defrosting speed deteriorates

Engineering Contradiction:
Improveelectrical isolationVSAvoiddefrosting speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The conductive coating is segmented into multiple heating zones by deletion lines, creating independent current paths. This segmentation allows current to flow through multiple parallel paths across the glazing surface, increasing the overall heating efficiency and defrosting speed while maintaining electrical isolation between zones.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The busbar is designed to provide continuous heating along its length by allowing current flow through the conductive coating in multiple zones simultaneously, rather than relying on discrete contact windows. This continuous heating action significantly improves defrosting speed while the insulating layer maintains electrical isolation where needed.

Inventive Principle:
Principle #20Continuity of useful action

3Temperature

If deletion lines divide the conductive coating, then heat distribution is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveheat distributionVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The deletion lines are created using laser processing or chemical etching methods that directly modify the conductive coating material, replacing complex mechanical masking and removal processes. This substitution simplifies manufacturing while achieving precise heat zone segmentation for improved heat distribution.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The conductive coating properties are modified through controlled deletion processes that change the material parameters (conductivity, thickness) in specific patterns. By adjusting the deletion line dimensions, spacing, and depth, optimal heat distribution is achieved while maintaining a relatively simple manufacturing process.

Inventive Principle:
Principle #35Parameter changes

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 glazing achieves improved heat distribution and faster defrosting or demisting compared to conventional designs, while reducing the number of components needed and meeting industrial test requirements.

Implementation Method 1

a conductive coating (2) arranged on a major surface of the glass sheet (1)... first and second busbars (5, 6) arranged spaced from each other and in electrical contact with at least part of the heating area (2')... current flows in a heated coating from the first busbar to the second busbar

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4292396B1Glazing for electric heating, method for manufacturing the same and use of the same
Publication Date: 2025.03.05 PILKINGTON GRP LTD
  • EP4292396B1 patent drawingFigure 1~2
  • EP4292396B1 patent drawingFigure 3~4
  • EP4292396B1 patent drawingFigure 5~6

AI summary

The invention concerns a glazing (10) for electric heating, comprising a glass sheet (1), a conductive coating (2) arranged on the glass sheet (1), a first deletion line (3) in the conductive coating (2) forming a heating area (2'), a second deletion line (4) having a contact with the first deletion line (3) and extending in the heating area (20, first and second busbars (5, 6) at least partly on the heating area (2') adjacent the first deletion line (3), and a crossover (7) of first and second busbars (5, 6) at the contact between first and second deletion lines (3, 4). The invention also concerns a method for manufacturing the glazing and use of the glazing, for example as a window of a vehicle.