Laminating Composite Panes with Switchable Optical Elements

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Solution Overview

Problem

Existing methods for producing composite panes with electrically switchable optical properties often result in inhomogeneous thickness and optical inhomogeneities due to local pressure on the functional elements during the lamination process, leading to suboptimal optical quality.

Innovation Solution

A method involving a first lamination step without the functional element, using a reversibly removable separating film to ensure thermoplastic composite films form a uniform surface, followed by insertion and lamination of the functional element, which compensates for manufacturing tolerances and avoids local pressure points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the functional element is laminated directly between glass panes using conventional methods, then the lamination process can be completed, but local pressure causes deformation of the functional element leading to optical inhomogeneities

Engineering Contradiction:
Improvelamination processVSAvoidhomogeneity of functional element thickness
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The lamination process is divided into two separate steps: first laminating the glass panes with thermoplastic interlayer films without the functional element, then inserting and laminating the functional element separately. This segmentation prevents the functional element from being subjected to local pressure during the initial lamination, thereby avoiding deformation and optical inhomogeneities while still achieving complete lamination.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The glass panes and thermoplastic interlayer films are prepared and preliminarily laminated before the functional element is inserted. This preliminary action creates a prepared structure with uniform thermoplastic layers that will evenly distribute pressure during the subsequent functional element lamination, preventing local pressure points and deformation.

Inventive Principle:
Principle #10Preliminary action

2Ease of manufacture

If thermoplastic interlayer films with thickness variations are used, then the lamination can proceed, but local thickness increases create pressure points on the functional element causing deformation

Engineering Contradiction:
Improvelamination processVSAvoiduniformity of pressure distribution
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The thermoplastic interlayer films are preliminarily laminated to the glass panes before the functional element is inserted. This preliminary lamination allows the thermoplastic material to settle and distribute its thickness variations evenly across the glass surface, creating a more uniform pressure distribution when the functional element is later laminated, thereby reducing local pressure points and deformation.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If the functional element is inserted before lamination, then the complete structure can be laminated in one step, but the functional element is subjected to local pressure causing color changes and inhomogeneous appearance

Engineering Contradiction:
Improvelamination process efficiencyVSAvoidoptical quality of functional element
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The lamination process is segmented into two distinct phases: first laminating the glass panes with thermoplastic interlayer films without the functional element to establish a uniform base structure, then inserting and laminating the functional element separately. This segmentation prioritizes optical quality by preventing pressure-induced deformation, while still maintaining reasonable productivity through an optimized two-step process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent utilizes hydrostatic pressure from the autoclave process that acts globally on the entire cell rather than locally. By separating the lamination steps, the functional element is only subjected to this uniform hydrostatic pressure during the second lamination, avoiding the mechanical local pressure points that would cause deformation and optical inhomogeneities.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 ensures a composite pane with a homogeneous thickness and improved optical quality by preventing local pressure on the functional element, resulting in a more uniform and transparent or opaque state as needed.

Implementation Method 1

the thermoplastic composite films already begin to flow and thus form a uniform surface

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

When an electrical voltage is applied to the surface electrodes, the liquid crystals change their orientation

Methodology Applied
Scientific EffectElectric Field: Electric Field

Implementation Method 3

liquid crystal-based functional elements, also known as liquid crystal elements

Methodology Applied
Scientific EffectLiquid Crystals: Liquid Crystals

Implementation Method 4

The dye adapts its spatial orientation to the preferred orientation of the liquid crystals... allowing the cell to be switched between a transparent state with low turbidity and low tint and an opaque state with low turbidity and high tint

Methodology Applied
Scientific EffectDichroism: Pleochroism

Data Source

PatentEP4164880B1Method for laminating a composite pane comprising a functional element with electrically controlled optical properties
Publication Date: 2024.03.20 SAINT GOBAIN VITRAGE SA
  • EP4164880B1 patent drawingFigure 1A~1C
  • EP4164880B1 patent drawingFigure 2a~2b
  • EP4164880B1 patent drawingFigure 2c~2d

AI summary

A method for producing a laminated pane (1) with a functional element (2) with electrically switchable optical properties, wherein at least a) a first stack of layers is created from, in this sequence, at least - a first pane (7), - a first thermoplastic laminating film (9.1), - at least one separating film (10), - a second thermoplastic laminating film (9.2), - a second pane (8), b) the first stack of layers from step a) is laminated while being heated, c) the first pane (7) with the first thermoplastic laminating film (9.1) is taken off the second pane (8) with the second thermoplastic laminating film (9.2) and the at least one separating film (10) is removed from the stack of layers, d) a functional element (2) comprising an active layer (3) is provided, e) the functional element (2) is placed into the stack of layers, whereby a second stack of layers is formed from at least - a first pane (7), - a first thermoplastic laminating film (9.1), - a functional element (2), - a second thermoplastic laminating film (9.2), - a second pane (8), and f) the second stack of layers is laminated to form a laminated pane (1), wherein the at least one separating film (10) can be detached from the first thermoplastic laminating film (9.1) and the second thermoplastic laminating film (9.2) without leaving any remains.