Heated Windshield Control Using Resistance Feedback

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Solution Overview

Problem

Existing vehicle windshield defogging/defrosting systems waste energy by continuing to operate after fog/frost removal, leading to potential overheating and structural issues, particularly in electric vehicles.

Innovation Solution

A closed-loop control system that determines the temperature of the windshield heating element resistance to adjust the duty cycle, eliminating the need for exterior sensors and optimizing power usage by correlating resistance changes with outside glass temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the defogging/defrosting system operates continuously after fog/frost removal, then the windshield remains clear of condensation, but energy is wasted and overheating risks increase

Engineering Contradiction:

Improvewindshield clarityVSAvoidenergy waste

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system uses the conductive medium's resistance as a feedback signal to monitor windshield temperature. When the resistance indicates the windshield has reached the desired temperature (fog/frost removed), the control assembly automatically reduces or stops power delivery, preventing energy waste while maintaining clear visibility.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The conductive medium serves dual functions: it heats the windshield to remove fog/frost and simultaneously acts as a temperature sensor through its resistance changes. This self-service capability eliminates the need for separate sensors and enables automatic control based on the medium's own physical properties.

Inventive Principle:

Principle #25Self-service

2Reliability

If the defogging/defrosting system operates continuously after fog/frost removal, then the windshield remains clear, but overheating and structural damage may occur

Engineering Contradiction:

Improvewindshield clarityVSAvoidoverheating and structural damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The control assembly continuously monitors the conductive medium's resistance, which changes with temperature. When the resistance indicates the windshield has reached the optimal temperature range, the system automatically reduces power delivery, preventing overheating and potential structural damage while maintaining clear visibility.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the power delivery to the conductive medium based on real-time resistance measurements. The duty cycle varies continuously to match the heating requirements, transitioning from high power during frost removal to low or zero power when the windshield is clear, thereby preventing thermal damage.

Inventive Principle:

Principle #15Dynamics

3Loss of energy

If the conductive medium resistance is used to control heating, then energy efficiency is improved, but the system requires precise resistance-temperature correlation

Engineering Contradiction:

Improveenergy efficiencyVSAvoidresistance-temperature correlation

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The conductive medium's inherent resistance changes with temperature are directly utilized as the control signal. The system leverages the natural physical property of the heating element itself rather than requiring external sensors, thereby achieving energy efficiency while using the medium's own resistance characteristics for temperature indication.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system exploits the change in electrical resistance of the conductive medium as a function of temperature. By monitoring resistance variations and correlating them with temperature states, the control assembly can precisely determine when the windshield has reached the desired temperature without requiring additional measurement devices.

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

Efficiently manages power usage by dynamically adjusting the heating cycle based on resistance changes, preventing overheating and maximizing energy efficiency while maintaining clear visibility.

Implementation Method 1

a control assembly operably connected to both the conductive medium and the power source, wherein the control assembly is configured to control a duty cycle that drives the conductive medium to heat the glass panel assembly

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Methodology Applied

Scientific EffectElectrical resistance temperature dependence: Electrical Resistance

Data Source

PatentUS20250280471A1Heated windshield control assembly

Publication Date: 2025.09.04 J B POINDEXTER & CO

AI summary

A glass panel assembly for use in a vehicle having a power source. The assembly includes at least one transparent panel and a defroster assembly. The defroster assembly has a conductive medium disposed adjacent the inner surface of one transparent panel and a controller that is operably connected to both the conductive medium and the power source. The controller determines the resistance of the conductive medium and based on said determination, the controller determines a corresponding temperature of the outer surface of the transparent panel. Based on the determined corresponding temperature of the outer surface of the transparent panel, the controller controls a duty cycle that drives the conductive medium to heat the at least one transparent panel. Optionally, the conductive medium can be eGlass.