Reflection Coating for Electrochromic Glazing Angle Stability

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Optical systems with electrochromic devices exhibit undesirable color reflection due to the interface between the electrochromic device and the substrate, which varies with the angle of observation and is affected by layer thickness inhomogeneities, requiring complex lamination and maintenance.

Innovation Solution

An optical system with a chromatic reflection control coating directly on the substrate, controlling the reflected color to be closer to a desired reference color by minimizing chromatic distance variations across different angles and reducing layer thickness inhomogeneities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a reflection modifying layer is interposed between PVB and counter-substrate to control reflected color, then the color in reflection can be modified, but the device complexity and maintenance requirements increase due to complex lamination arrangement

Engineering Contradiction:
Improvecolor controlVSAvoidlamination arrangement
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention extracts the reflection modifying layer from the complex lamination structure and applies it directly to the substrate, eliminating the need for PVB lamination and counter-substrate arrangement. This simplifies the device structure while maintaining the color control function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention segments the optical system into distinct functional layers: the substrate with electrochromic device on one side and the reflection controlling layer on the other. This segmentation allows independent optimization of each component without requiring complex integration through lamination.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If the chromaticity of reflected light is controlled to be closer to reference chromaticity, then color inhomogeneities are reduced, but the coating complexity increases to achieve precise chromatic distance control

Engineering Contradiction:
Improvechromatic uniformityVSAvoidcoating structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention controls the chromaticity of reflected light by adjusting parameters of the reflection controlling layer, such as material composition and thickness, to achieve the desired chromatic distance from reference chromaticity without complex multi-layer structures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies a localized reflection controlling layer with specific optical properties on the substrate surface, providing precise chromatic control only where needed without requiring complex global structural changes.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If the reflected color is controlled to minimize variation with reflection angle, then angular dependence is reduced, but the coating design complexity increases

Engineering Contradiction:
Improveangular chromatic stabilityVSAvoidcoating design
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention applies a reflection controlling layer with properties that provide sufficient chromatic stability across a range of reflection angles without requiring excessive control measures or complex multi-layer designs that would be needed for complete angular independence.

Inventive Principle:
Principle #16Partial or excessive action

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 system achieves controlled and efficient color reflection by ensuring at least 30% of total light intensity is reflected by the coating, reducing color inhomogeneities and angle-dependent variations, without needing complex lamination.

Implementation Method 1

a chromatic reflection control coating (3) formed on the other main face (12) of the substrate (1)... controlling the reflected color to be closer to a desired reference color by minimizing chromatic distance variations across different angles

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

an electrochemical functional device with electrically controllable optical and/or energy properties... between a clear state and a tinted state, in particular transmission, absorption, reflection in certain wavelengths of electromagnetic radiation

Methodology Applied
Scientific EffectElectrochromism: Electrochromism

Data Source

PatentEP4081858B1Optical system with an electrochemical functional device having electrically controllable optical and/or energetic properties and a coating for controlling colour in reflection, and associated processes
Publication Date: 2025.09.10 SAINT GOBAIN VITRAGE SA
  • EP4081858B1 patent drawingFigure 1~2
  • EP4081858B1 patent drawingFigure 3~4
  • EP4081858B1 patent drawingFigure 5~6

AI summary

The invention relates to an optical system (40) comprising: - an optical assembly (50) comprising a glazing-function substrate (1) equipped with two opposite main faces (11, 12) and an electrochemical functional device having electrically controllable optical and/or energetic properties that is formed on one (11) of these two main faces, this optical assembly (50) having an initial colour state with an initial colour value (L*ui; a*ui; b*ui) in reflection at a first angle of refraction (u) on the side of the substrate (1), - a coating (3) that controls colour in reflection, which is formed on the other main face (12) of the substrate, and which forms an external face (41) of said optical system (40), said coating being such that the optical system (40) has a final colour state with a final colour value (L*uf; a*uf; b*uf) in reflection at the first angle of reflection (u), this final colour state being closer than the initial colour state to a reference colour state having a reference colour value (L*uref; a*uref; b*uref) at said first angle of reflection (u), this corresponding to a variation ΔCu in colour distance (Cui, Cuf) between the initial colour value and the reference value, on the one hand, and between the final colour value and the reference colour value, on the other hand, smaller than 0 at said first angle of reflection (u).