Liquid Lens Diopter Stability via Gas Phase Buffering

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Solution Overview

Problem

Conventional liquid lenses experience deterioration in optical performance due to temperature-induced changes in the volume of liquids, affecting the diopter and overall functionality of camera modules and optical devices.

Innovation Solution

A liquid lens design featuring a cavity with specific dimensions and liquid volumes, including a conductive and non-conductive liquid, is implemented, with electrodes and plates to control the curvature and maintain optical stability despite temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the volume of liquids in the liquid lens is increased to maintain optical performance, then the diopter stability improves, but the temperature-induced volume expansion causes greater curvature changes and deteriorates optical performance

Engineering Contradiction:
Improvediopter stabilityVSAvoidtemperature-induced optical performance deterioration
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical parameters of the system by introducing a compressible gas phase alongside the liquids. This gas phase acts as a buffer that absorbs thermal expansion, allowing the liquid volumes to remain stable despite temperature changes. The parameter change from a closed liquid system to a liquid-gas system resolves the contradiction between maintaining diopter stability and preventing temperature-induced deterioration.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The compressible gas phase serves as an intermediary between the liquids and the external thermal environment. It mediates the thermal expansion effects by providing a compliant volume that can absorb expansion without transmitting stress to the liquid-liquid interface, thereby protecting the optical performance from temperature variations while maintaining liquid volume stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a separate lens-moving apparatus is added to enable auto-focusing and hand-tremor compensation, then the photographing functions improve, but the device complexity and overall size increase

Engineering Contradiction:
Improvephotographing functionsVSAvoidlens-moving apparatus
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The liquid lens serves multiple functions simultaneously: it acts as both the primary imaging lens and the variable focus mechanism through electro-wetting control. By making the lens itself adjustable rather than requiring separate moving parts, the system achieves auto-focusing capability while maintaining simplicity. The same liquid interface that defines the lens curvature can be dynamically controlled to provide both imaging and focus adjustment functions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces mechanical lens-moving apparatus with an electrical control system that directly modifies the liquid lens curvature through electro-wetting. Instead of mechanically moving lenses to achieve focus and stabilization, electrical signals control the interfacial tension between liquids, enabling focus adjustment and hand-tremor compensation without mechanical complexity.

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

3Reliability

If the opening diameter in the cavity is reduced to control liquid volume, then the diopter variation decreases, but the light incidence area is reduced affecting optical performance

Engineering Contradiction:
Improvediopter consistencyVSAvoidlight incidence area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the system configuration by adding a gas phase and adjusting the opening diameter to optimal values. The parameter change from a small opening to a larger opening (1.5-2.5mm) is compensated by the gas phase's ability to control liquid volumes, allowing both adequate light incidence and consistent diopter to be achieved simultaneously.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The compressible gas phase acts as an intermediary that decouples the relationship between opening diameter and liquid volume control. It allows the opening to be larger for better light incidence while the gas absorbs excess liquid expansion, maintaining consistent liquid volumes and diopter values despite the larger opening area.

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

The solution effectively reduces diopter variation and enhances hand-tremor compensation, ensuring consistent light incidence and improved optical performance across temperature changes.

Implementation Method 1

two types of liquids may change in volume depending on temperature

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a method of combining a plurality of lenses and directly moving the combined lenses is used

Methodology Applied
Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentEP3816679B1Liquid lens, camera module, and optical device including the same
Publication Date: 2024.10.09 LG INNOTEK CO LTD
  • EP3816679B1 patent drawingFigure 1
  • EP3816679B1 patent drawingFigure 2
  • EP3816679B1 patent drawingFigure 3

AI summary

One embodiment provides a liquid lens comprising: a first plate having a cavity formed therein for receiving a first conductive liquid and a second nonconductive liquid; a first electrode disposed on the upper part of the first plate; a second electrode disposed on the lower part of the first plate; a second plate disposed on the upper part of the first electrode; and a third plate disposed on the lower part of the second electrode, wherein an opening to the second plate in the cavity has a diameter of 1.6 mm to 1.9 mm and the first plate has a thickness of 0.45 mm to 0.55 mm.