Electrowetting Optical Element Size Reduction via Insulating Film
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Solution Overview
Problem
Existing optical elements using electrowetting phenomena face limitations in reducing size due to unnecessary hydrophilic regions that do not contribute to light transmission, which restricts the miniaturization of the device and complicates the manufacturing process.
Innovation Solution
The optical element design eliminates the need for a hydrophilic film on the second electrode by positioning the first liquid over the second electrode via an insulating film, allowing for a reduced container size and simplified manufacturing by using a first film with higher wettability for the first liquid and a second film with higher wettability for the second liquid, enabling efficient voltage application and light transmission path adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophilic film is formed on the second electrode to position the first liquid, then the first liquid can be positioned over the second electrode, but an unwanted hydrophilic region is created that does not contribute to light transmission and increases device size
Solution Approach 1:
The patent removes the hydrophilic film from the second electrode, extracting the unwanted component that caused the contradiction. The first liquid is repositioned to rest on the insulating film covering the second electrode, eliminating the need for the hydrophilic film and its associated unwanted hydrophilic region, thus reducing device size while maintaining liquid positioning functionality.
Solution Approach 2:
The insulating film serves as an intermediary between the second electrode and the first liquid. Instead of using a hydrophilic film that creates unwanted hydrophilic regions, the insulating film acts as a mediator that allows the first liquid to be positioned over the second electrode without creating non-contributory regions, thereby resolving the contradiction between reliable liquid positioning and compact device size.
2Reliability
If two types of films (water repellent and hydrophilic) are formed on the second electrode to control liquid positioning, then liquid placement is achieved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent eliminates the water repellent film from the second electrode, removing one of the two film types that complicated manufacturing. By repositioning the first liquid to rest on the insulating film, the design achieves reliable liquid positioning without requiring the complex dual-film structure, thus simplifying the manufacturing process.
Solution Approach 2:
The insulating film on the second electrode serves multiple functions: it provides electrical insulation and simultaneously acts as a positioning surface for the first liquid. This multi-functionality replaces the need for separate water repellent and hydrophilic films, achieving reliable liquid positioning while simplifying manufacturing.
3Ease of operation
If the first liquid is positioned over the second electrode via a hydrophilic film, then voltage can be applied to the first liquid, but the hydrophilic region occupies unnecessary area that limits miniaturization
Solution Approach 1:
The patent removes the hydrophilic film that was used to position the first liquid over the second electrode. Instead, the first liquid is positioned directly on the insulating film, which eliminates the unwanted hydrophilic region and allows for device miniaturization while maintaining the capability to apply voltage to the first liquid through the insulating film.
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 design reduces the optical element's size in the direction perpendicular to the light path and simplifies the manufacturing process by eliminating non-contributory hydrophilic regions, enhancing operational speed and cost-effectiveness.
Implementation Method 1
When a voltage is applied to the first liquid 20 from voltage application mean to induce an electrowetting phenomenon, the interface K between the first liquid 20 and the second liquid 22 is deformed
Implementation Method 2
A first film whose wettability to the first liquid is higher than that to the second liquid is formed on the entire inner surface of the first end wall
Data Source
AI summary
An optical element includes a sealed container having a first end wall facing a second end wall in a thickness direction, and a sidewall connecting the first and second end walls; a first polar or conductive liquid encapsulated in the container; a second liquid encapsulated in the container and not mixed with the first liquid so as to form an interface between the first liquid and the second liquid, the first liquid and the second liquid having substantially the same specific gravity and the first liquid having less light transmittance than the second liquid; and a voltage application unit configured to apply a voltage to the first liquid, wherein when a voltage is applied to the first liquid, the interface between the first liquid and the second liquid deforms to form a light transmission path that passes through the first and second end walls and extends in the thickness direction of the container.