Electrowetting Optical Switch for Crosstalk Reduction

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Solution Overview

Problem

In display apparatuses with optical waveguides, the small area of the grating on the display surface leads to easy occurrence of optical crosstalk due to Fraunhofer diffraction, resulting in uneven image brightness, blurring, and display distortion.

Innovation Solution

An optical switch comprising micro-grooves, electrowetting micro-fluids, and driving electrodes is used to control light transmittance. The micro-grooves are formed on a carrier, and the electrowetting micro-fluids are disposed within these grooves, with driving electrodes providing voltages to control the contact angle and thus the light transmittance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a grating with small area is used on the display surface, then the display apparatus can be more compact, but optical crosstalk occurs due to Fraunhofer diffraction resulting in uneven image brightness and display distortion

Engineering Contradiction:
ImprovecompactnessVSAvoidoptical crosstalk
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

An optical switch layer is introduced as an intermediary component between the grating and the display surface. This layer contains microlenses that can dynamically control light transmission, acting as a mediator to prevent optical crosstalk while maintaining the compact grating structure. The microlenses focus or block light paths to eliminate Fraunhofer diffraction effects without requiring a larger grating area.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs electrowetting or liquid crystal technology to dynamically change the optical parameters (transmittance, refractive index) of the optical switch layer. By adjusting these parameters in real-time, the system can control light transmission to prevent optical crosstalk while maintaining the compact form factor, resolving the contradiction between size and optical quality.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If the grating area is increased to reduce optical crosstalk, then display quality improves, but the display apparatus becomes larger and less compact

Engineering Contradiction:
Improveoptical crosstalkVSAvoiddisplay apparatus size
Core Design Contradiction:
Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

Instead of increasing the grating area in the planar dimension, the patent adds a new dimensional layer - the optical switch layer with microlenses positioned above or below the grating. This vertical dimensionality change allows optical crosstalk control without expanding the horizontal display area, maintaining compactness while improving display quality.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If conventional optical switching methods are used, then light transmittance can be controlled, but response time is slow and energy consumption is high

Engineering Contradiction:
Improvelight transmittance controlVSAvoidresponse time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces conventional mechanical or slow electrical optical switching mechanisms with electrowetting or liquid crystal-based switching. These technologies use electrical fields to control the wetting properties or molecular orientation of fluids, enabling fast response times and efficient light transmittance control without mechanical movement, thus reducing both response time and energy consumption.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 optical switch effectively reduces optical crosstalk caused by Fraunhofer diffraction, improving the display effect by ensuring even image brightness and reducing distortion, while also enabling fast response times for dynamic dimming.

Implementation Method 1

electrowetting micro-fluids, and driving electrodes disposed corresponding to the micro-fluids in the micro-grooves, respectively. The driving electrodes are configured to provide voltages to control contact angles of the micro-fluids

Methodology Applied
Scientific EffectElectrowetting: Electrowetting

Data Source

PatentEP4067967B1Optical switch and control method therefor, and display device
Publication Date: 2025.04.09 BOE TECHNOLOGY GROUP CO LTD
  • EP4067967B1 patent drawingFigure 1~3
  • EP4067967B1 patent drawingFigure 4~6
  • EP4067967B1 patent drawingFigure 7~9

AI summary

An optical switch includes a plurality of micro-grooves, a micro-fluid disposed in each micro-groove of the plurality of micro-grooves, and a driving electrode disposed corresponding to the micro-fluid in each micro-groove. The driving electrode is configured to provide a voltage to a corresponding micro-fluid to control light transmittance of a region where the micro-fluid is located.