Curved Optical Device Thermoforming Gap Control

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Solution Overview

Problem

Existing methods face challenges in manufacturing optical devices with doubly curved surfaces, particularly in maintaining a controlled gap between curved surfaces for encapsulating fluid materials, which is crucial for achieving desired optical properties such as light transmission control.

Innovation Solution

A thermoforming process using a single rigid curved mold to shape flexible substrates with a controlled gap, applying heat and force to conform them to the mold shape, and using fluid pressure or vacuum to maintain the curvature and gap distance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a pair of opposed molds are used to thermoform a cell, then the cell can be formed with controlled gap, but the device complexity increases and manufacturing precision deteriorates

Engineering Contradiction:
Improvegap controlVSAvoidmold configuration
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention extracts one mold from the opposed mold pair, using only a single rigid mold surface to form the curved substrates. The fixture holds the substrates in place while the single mold provides the necessary shaping, eliminating the complexity of coordinating two opposed molds while maintaining gap control through the fixture's positioning features.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention separates the functions of shaping and gap control into distinct components: the single rigid mold provides the curved shape, while the fixture with positioning pins or registration features maintains the controlled gap between substrates. This segmentation allows each component to be optimized independently.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If multiple layers are affixed to a doubly curved surface, then additional optical functionality is achieved, but the manufacturing precision deteriorates due to difficulty in maintaining controlled gaps

Engineering Contradiction:
Improveoptical functionalityVSAvoidgap consistency
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention performs preliminary action by pre-assembling the cell with multiple layers and spacers in the fixture before thermoforming. The spacers are positioned in advance to define the gap, and the layers are assembled in the correct configuration before the substrates are curved, ensuring precise gap maintenance throughout the forming process.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If spacers are used to maintain gap distance between curved surfaces, then the controlled gap is achieved, but the manufacturing precision deteriorates due to alignment difficulties

Engineering Contradiction:
Improvegap distanceVSAvoidalignment process
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention introduces registration features as intermediaries between the substrates and the fixture. These features (such as pins, tabs, or alignment marks) automatically position the substrates and spacers in the correct relative locations, eliminating the need for manual alignment and ensuring consistent gap distances without complex adjustment procedures.

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 process allows for the production of optical devices with consistent optical properties by maintaining the controlled gap and curvature, enabling efficient light transmission and reflection control, and is adaptable to various substrate materials and curvatures.

Implementation Method 1

applying heat and force to said substrates and conforming said substrates to said mold surface

Methodology Applied
Scientific EffectThermal softening: Melting

Implementation Method 2

conforming said substrates to said mold surface so that said substrates permanently retain the curved mold shape

Methodology Applied
Scientific EffectPlastic deformation: Deformation

Implementation Method 3

said force comprises application of a fluid pressure or a vacuum or a combination thereof

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 4

said force comprises application of a fluid pressure or a vacuum or a combination thereof

Methodology Applied
Scientific EffectVacuum: Vacuum

Data Source

PatentEP2144747B1Method of making a curved optical device
Publication Date: 2014.07.30 ALPHAMICRON INC
  • EP2144747B1 patent drawingFigure 1
  • EP2144747B1 patent drawingFigure 2
  • EP2144747B1 patent drawingFigure 3~4

AI summary

A method of constructing a curved optical device includes assembling of at least one cell having opposed flexible substrates with a controlled distance therebetween to form a gap adapted to receive a fluid. The process continues by holding only a portion of the cell in a fixture, positioning a curved mold surface proximal the cell and heating at least one of the curved mold surface and cell. Next, the cell is conformed to the mold surface so that the cell substantially retains the curved shape when the heat and the mold surface are removed.