Glazing Variable Light Diffusion Absorbers

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Solution Overview

Problem

Switchable glazings with diffusing layers suffer from significant disadvantages, including luminous halos in the diffusing state and degraded appearance in the transparent state due to diffuse light reflection, which affect their hiding power and optical properties.

Innovation Solution

Incorporating visible light absorbing elements on either side of the diffusing layer to attenuate diffuse reflection, thereby reducing the residual diffuse reflection and improving the optical properties in both the transparent and diffusing states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a diffusing layer is used to achieve switching between transparent and diffusing states, then the hiding power in the diffusing state is improved, but a luminous halo appears and image sharpness deteriorates

Engineering Contradiction:
Improvehiding powerVSAvoidimage sharpness
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

Absorbing elements are introduced as intermediary components between the light path and the diffusing layer to selectively absorb stray light and luminous halo without interfering with the primary optical function of the diffusing layer. This mediator approach allows the diffusing layer to maintain its hiding power while the absorbing elements clean up the unwanted optical artifacts.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful luminous halo and diffuse reflection are extracted and removed from the optical system by introducing absorbing elements that selectively target and eliminate these unwanted light components, separating the desired diffusing function from the unwanted halo effect.

Inventive Principle:
Principle #2Taking out (Extraction)

2Object-affected harmful factors

If a diffusing layer with large diffusion angles is used to improve hiding power, then the capacity to prevent vision through the glazing is improved, but a white veil appears and appearance degrades

Engineering Contradiction:
Improvehiding powerVSAvoidappearance quality
Core Design Contradiction:
Object-affected harmful factorsVSIllumination intensity

Solution Approach 1:

The absorbing elements convert the harmful effect of diffuse reflection (white veil) into a beneficial outcome by selectively absorbing the stray light that causes the veil, while allowing the primary transmitted light to pass through. The harmful diffuse reflection is transformed into a controlled absorption process that improves overall appearance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Different regions of the optical system are given different properties: the diffusing layer maintains its wide diffusion angle capability for hiding power, while the absorbing elements are strategically positioned to provide localized absorption of stray light, creating a spatially differentiated optical system where each component performs its specialized function.

Inventive Principle:
Principle #3Local quality

3Use of energy by moving object

If the switching voltage is reduced to lower energy consumption, then the use of energy is improved, but the transparency quality and image sharpness deteriorate

Engineering Contradiction:
Improveenergy consumptionVSAvoidimage sharpness
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

Absorbing elements serve as intermediaries that compensate for the reduced optical performance at lower voltages by absorbing the increased stray light and halo effects that become more prominent when the liquid crystal alignment is less perfect at lower switching voltages.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Illumination intensity

If absorbing elements are added to reduce diffuse reflection, then the optical properties are improved, but the device complexity increases

Engineering Contradiction:
Improveoptical propertiesVSAvoidstructure complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The absorbing elements are implemented as thin film coatings rather than bulky discrete components, maintaining the compact structure of the glazing while providing the necessary light absorption function. This film-based approach minimizes the increase in device complexity.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The absorbing elements are integrated into the existing glazing structure by applying them as coatings on the substrate surfaces, merging the absorption function with the existing structural components rather than adding separate discrete elements, thereby minimizing structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 addition of absorbing elements significantly reduces diffuse reflection, enhancing the glazing's optical performance by minimizing the luminous halo and maintaining transparency, even at lower applied voltages, thus improving the glazing's hiding power and image sharpness.

Implementation Method 1

a diffusing layer capable of diffusing the incident light at diffusion angles greater than the critical angle of total internal reflection at the interface between the substrate and the air

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

Incorporating visible light absorbing elements on either side of the diffusing layer to attenuate diffuse reflection

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP2915005B1Glazing comprising a variable light diffusion system and a pair of absorbers
Publication Date: 2020.09.16 SAINT GOBAIN VITRAGE SA
  • EP2915005B1 patent drawingFigure 1~2
  • EP2915005B1 patent drawingFigure 3~4
  • EP2915005B1 patent drawingFigure 5~6

AI summary

The invention concerns a glazing comprising a substrate coated with a variable light diffusion system switching between a transparent state and a translucent state comprising a diffusing layer able to diffuse incident light at diffusion angles greater than the critical angle of total internal reflection at the interface between the substrate and the air and at least one pair of visible light absorbers separated from each other at least by the diffusing layer. The invention also concerns the use of said glazing as a projection or rear projection screen.