Laminated Heated Window with Reflective Coating for Uniform Heating

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Solution Overview

Problem

Existing electrically heated windows, particularly those with tungsten wires, suffer from visibility issues, require higher voltage for effective defrosting, and can create hot spots leading to uneven heating and potential safety hazards.

Innovation Solution

A laminated electrically heated window with a grid of electrically conductive pathways attached to a film, laminated between glazing material plies, providing a resistive sheet for uniform heating and improved visibility, using materials like silver for the pathways and a polymer film, with busbars for electrical connection, and optional coatings for solar control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tungsten wires are used for heating, then heating functionality is provided, but wire visibility distracts drivers and reduces safety

Engineering Contradiction:

Improveheating functionalityVSAvoidwire visibility distraction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a reflective coating to the tungsten wires that changes their optical properties. The coating reflects specific wavelengths of light, making the wires invisible or significantly less visible to drivers while maintaining their electrical resistance and heating functionality. This resolves the contradiction by modifying the wires' appearance without affecting their heating performance.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent creates an optical illusion by using the reflective coating to blend the wires with the surrounding glass matrix. The coating is designed to match the refractive index and reflectivity of the glass, causing the wires to become optically indistinguishable from the glass itself, thus eliminating the distracting visibility issue.

Inventive Principle:

Principle #26Copying

2Reliability

If conducting coating is used for heating, then heating functionality is provided, but higher voltage greater than standard 12V is required

Engineering Contradiction:

Improveheating functionalityVSAvoidvoltage requirement

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent modifies the electrical parameters of the heating element by using tungsten wires with specific resistance values and dimensions. By carefully controlling the wire diameter, length, and spacing, along with applying reflective coatings that maintain electrical conductivity, the system achieves optimal resistance values that allow operation from standard 12V vehicle power supplies, eliminating the need for higher voltage systems.

Inventive Principle:

Principle #35Parameter changes

3Shape

If non-uniform wire length is used to fit window shape, then window geometry is accommodated, but hot spots are created causing safety hazards

Engineering Contradiction:

Improvewindow geometry accommodationVSAvoidhot spots

Core Design Contradiction:

ShapeVSObject-affected harmful factors

Solution Approach 1:

The patent applies different properties to different regions of the heating system. The reflective coating is selectively applied to areas where wires would be visible, while maintaining uniform wire dimensions and spacing throughout. The wire layout is designed with varying local densities and patterns that accommodate the window's complex geometry while ensuring uniform power distribution and preventing hot spot formation in any specific region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent designs the wire network to create equipotential regions across the window surface. By carefully calculating wire spacing, diameter, and routing patterns, the system ensures that voltage drops and power densities remain uniform across all regions, even when accommodating irregular window shapes. This prevents the formation of hot spots by maintaining consistent electrical conditions throughout the heating element.

Inventive Principle:

Principle #12Equipotentiality

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 enhances visibility, reduces hot spots, operates effectively on standard voltage, and provides durable, efficient heating with improved solar control and reduced interior heating, allowing for integration with devices like wiper de-icers and toll sensors.

Implementation Method 1

an electrical connection means for supplying current to the grid in order to heat the window

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

optional coatings for solar control

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS8759717B2Electrically heated window

Publication Date: 2014.06.24 PILKINGTON GRP LTD

AI summary

An electrically heated window comprising at least two plies of a glazing material; at least one ply of an interlayer material; a grid of at least one electrically conductive pathway attached to a film; and an electrical connector for supplying current to the grid in order to heat the window; wherein the at least one ply of an interlayer material, the grid and the film are laminated between the at least two plies of a glazing material.