Electrochromic Device Resistance Gradient Sense Voltage Alignment

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Solution Overview

Problem

Large area electrochromic devices often experience slow and spatially non-uniform switching between lightened and darkened states, known as the 'iris effect', due to voltage drops across transparent conductive coatings.

Innovation Solution

The implementation of electrically conductive layers with gradients in electrical resistance, configured to form a region of maximum local cell potential aligned with a sense voltage pad, to improve switching uniformity and prevent overdriving.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a voltage is applied across transparent conductive coatings in large area electrochromic devices, then the device can switch between lightened and darkened states, but voltage drops cause non-uniform transmissivity (iris effect) across the device

Engineering Contradiction:

Improveswitching uniformityVSAvoidvoltage drop across conductive coatings

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces sense voltage pads at specific locations to locally monitor cell potential. By measuring the potential at these specific points, the system can detect and compensate for voltage drops across different regions of the device, enabling uniform switching control despite the inherent voltage drops in large area devices.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements feedback control by measuring the cell potential at sense voltage pads and using this information to adjust the applied voltage. This feedback mechanism allows the system to compensate for voltage drops and maintain uniform switching across the entire device area, preventing the iris effect.

Inventive Principle:

Principle #23Feedback

2Productivity

If transparent conductive coatings are used to provide electrical contact, then the device achieves optical functionality, but resistivity causes non-uniform voltage distribution and slow switching

Engineering Contradiction:

Improveswitching speedVSAvoidspatial uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent divides the conductive layer into multiple segments by introducing sense voltage pads at different locations. This segmentation allows the system to independently monitor and control voltage distribution across different regions, enabling faster and more uniform switching by identifying and addressing specific areas with higher resistance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the electrical parameters by introducing additional voltage measurement points (sense voltage pads) and adjusting the applied voltage based on measured cell potential. This parameter adjustment compensates for resistivity variations and optimizes switching speed and uniformity across the device.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If voltage is applied to switch electrochromic medium, then optical properties change, but unmonitored areas may be overdriven causing non-uniform transmissivity

Engineering Contradiction:

Improvetransmissivity uniformityVSAvoidoverdriving unmonitored areas

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces sense voltage pads as intermediary measurement points between the voltage source and the electrochromic medium. These pads act as intermediaries that monitor the actual cell potential at critical locations, allowing the system to adjust the applied voltage to prevent overdriving any single area while ensuring uniform transmissivity across the entire device.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach enables more uniform optical properties during switching, preventing unmonitored areas from being overdriven and enhancing the overall performance of electrochromic devices.

Implementation Method 1

When a voltage is applied across these conducting layers the optical properties of a layer or layers in between change. Such optical property changes are typically a modulation of the transmissivity of the visible or the solar subportion of the electromagnetic spectrum.

Methodology Applied

Scientific EffectElectrochromism: Electrochromism

Data Source

PatentUS20250102874A1Electrochromic device with maximum local cell potential aligned with sense voltage

Publication Date: 2025.03.27 SMART WINDOW INC LTD

AI summary

An electrochromic device is provided. The device includes a first transparent substrate, a second transparent substrate, a first electrically conductive layer with a first resistance gradient arranged on an inner surface of the first transparent substrate, a second electrically conductive layer with a second resistance gradient arranged on an inner surface of the second transparent substrate. The device includes a first bus bar in contact with the first electrically conductive layer, a second bus bar in contact with the second electrically conductive layer, a first sense voltage pad arranged on the inner surface of the first transparent substrate configured to measure a local cell potential at a sense voltage measurement position within the electrochromic device, wherein the first and second resistance gradients are configured to form a region comprising a maximum local cell potential approximately coinciding with the sense voltage measurement position.