Fluid Lens Gravity Sag Compensation via Spatial Membrane Variation
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Solution Overview
Problem
Conventional fluid lenses face issues with gravity sag due to hydrostatic pressure gradients, leading to undesirable variations in optical power with height, and membrane instability due to fluid penetration, which affects performance and requires repeated calibration or replacement.
Innovation Solution
The development of adjustable fluid lenses with a pre-strained flexible membrane that encloses a fluid, featuring a spatial variation in membrane parameters such as thickness, tension, and cross-linking to counteract gravity sag, and the use of polymer additives to prevent fluid penetration and maintain optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform membrane is used in fluid lenses, then the manufacturing process is simple, but gravity sag occurs due to hydrostatic pressure gradients causing optical power variations with height
Solution Approach 1:
The patent applies local quality by creating a non-uniform membrane with spatially varying thickness or tension properties. Specifically, the membrane is designed with greater thickness or higher tension in the lower portion to counteract the hydrostatic pressure gradient, thereby compensating for gravity sag and maintaining optical power uniformity across different heights in the fluid lens.
Solution Approach 2:
The patent employs parameter changes by modifying the membrane's physical parameters (thickness, tension) as a function of position. The membrane thickness or tension is varied systematically to compensate for the pressure distribution in the fluid, transforming a uniform membrane design into a graded structure that actively counteracts gravitational effects on optical performance.
2Device complexity
If a uniform membrane is used in fluid lenses, then the device structure is simple, but membrane instability occurs due to fluid penetration requiring repeated calibration or replacement
Solution Approach 1:
The patent applies local quality by implementing a non-uniform membrane structure with spatially varying properties. This graded membrane design not only addresses optical uniformity but also enhances structural stability by distributing mechanical stresses more effectively and reducing fluid penetration through regions of higher thickness or cross-linking density in the lower portion where pressure is greatest.
Solution Approach 2:
The patent employs composite materials by combining the base membrane material with additional components such as cross-linked polymer networks or reinforcement layers. This composite structure provides both the mechanical strength needed to prevent fluid penetration and the tailored spatial properties required for gravity sag compensation, thereby improving membrane reliability without excessive complexity.
3Manufacturing precision
If spatial variation in membrane parameters is implemented to counteract gravity sag, then optical uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by systematically varying membrane thickness or tension as a controlled function of position. This approach allows for predictable compensation of gravity sag effects while using manufacturing techniques that can implement graded structures, balancing optical uniformity requirements with fabrication feasibility through methodical parameter optimization.
4Reliability
If spatial variation in membrane parameters is implemented to counteract gravity sag, then lens performance stability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform membrane with spatially varying thickness or tension properties. Specifically, the membrane is designed with greater thickness or higher tension in the lower portion to counteract the hydrostatic pressure gradient, thereby compensating for gravity sag and maintaining optical power uniformity across different heights in the fluid lens.
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 solution effectively reduces or eliminates gravity sag, maintains optical uniformity across the field of view, and enhances the stability and reproducibility of fluid lenses by compensating for hydrostatic pressure variations and preventing membrane degradation from fluid penetration.
Implementation Method 1
gravity sag due to hydrostatic pressure gradients
Implementation Method 2
pre-strained flexible membrane
Implementation Method 3
membrane instability due to fluid penetration
Data Source
AI summary
Examples include a device including a fluid lens having a membrane, a substrate, and a fluid at least partially enclosed between the membrane and the substrate. The membrane may have a spatial variation in at least one membrane parameter along a particular direction, that may compensate for gravity sag in the membrane of the fluid lens when the device is worn by a user. Examples also include related methods and systems.