Liquid Lens Autofocus via Shape Memory Alloy Actuation

Solution Overview

Problem

Existing image acquiring devices face challenges in achieving fast and accurate autofocusing, especially for close-up shots due to the physical limitations of traditional lens drive systems, which are costly and occupy significant space, making them unsuitable for distances within 10 cm.

Innovation Solution

An image acquiring device utilizing a liquid lens with a shape-memory-alloy support wire that changes focal distance through pressurization, eliminating the need for a Voice Coil Motor (VCM) drive system, thereby reducing space and manufacturing costs, and allowing stable lens control via current application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a VCM drive system is used to change the shape of a liquid lens, then the liquid lens can be controlled to achieve focusing, but the space required and manufacturing costs increase significantly

Engineering Contradiction:

Improvefocusing controlVSAvoiddrive system space

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent replaces the mechanical VCM drive system with an electrochemical system using shape memory alloy (SMA) wires. The SMA wires change length in response to voltage application, directly actuating the pressurizing member to control the liquid lens shape. This substitution eliminates the need for complex mechanical components, reducing space requirements while maintaining focusing control capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from mechanical force (VCM) to electrical voltage (SMA). By applying voltage to the shape memory alloy wires, they undergo phase transformation and change length, which in turn controls the liquid lens shape. This parameter change enables a more compact design while achieving the same focusing function

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a VCM drive system is used to change the shape of a liquid lens, then the liquid lens can be controlled to achieve focusing, but the manufacturing costs increase

Engineering Contradiction:

Improvefocusing controlVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical VCM drive system with an electrochemical system using shape memory alloy (SMA) wires. The SMA wires change length in response to voltage application, directly actuating the pressurizing member to control the liquid lens shape. This substitution eliminates the need for complex mechanical components, reducing space requirements while maintaining focusing control capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses shape memory alloy wires, which are simpler and less expensive components compared to VCM systems. The SMA wires can be easily manufactured and replaced if needed, providing a cost-effective solution for liquid lens actuation while maintaining the required focusing control functionality

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If a traditional lens translational motion scheme is used, then the lens can be focused, but it cannot achieve close-up shots within 10 cm due to physical limitations

Engineering Contradiction:

Improvefocusing functionVSAvoidclose-up focusing capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent uses a liquid lens whose shape can be dynamically changed by controlling the length of shape memory alloy wires through voltage application. This dynamic shape change capability allows the lens to adjust its focal length continuously, enabling both standard and close-up focusing functions that are not achievable with fixed-structure traditional lenses

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter from mechanical force (VCM) to electrical voltage (SMA). By applying voltage to the shape memory alloy wires, they undergo phase transformation and change length, which in turn controls the liquid lens shape. This parameter change enables a more compact design while achieving the same focusing function

Inventive Principle:

Principle #35Parameter changes

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 solution enables efficient and cost-effective autofocusing for close-up shots by minimizing the volume of the device, reducing power consumption, and correcting errors, while allowing for stable and precise control of the liquid lens.

Implementation Method 1

the support wire includes shape-memory-alloy having a length contracting in response to application of current

Methodology Applied

Scientific EffectShape memory alloy: Shape Memory Alloy

Data Source

PatentUS10911652B2Image acquiring device

Publication Date: 2021.02.02 LG ELECTRONICS INC

AI summary

Disclosed is an image acquiring device, including a liquid lens having a shape changed by pressurization, a membrane provided to one surface of the liquid lens, the membrane forming a pressurization surface, a pressurizing member provided to an outside of the membrane, and a support wire provided across a prescribed region of an outer surface of the pressurizing member, the support wire moving the pressurizing member toward the membrane by contracting by conduction, the support wire moving the pressurizing member toward an opposite side of the membrane by expanding. Accordingly, the present invention solves a problem of a mismatched focus in a close-up photo and minimizes an increasing volume of the image acquiring device.