SMA Camera Actuation With Capacitive Position Sensing

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Solution Overview

Problem

Conventional voice coil motor (VCM) technology is difficult to apply to micro-scale camera devices requiring low power consumption and high-resolution, multifunctional actuators for cellular phone cameras, particularly for autofocus, shutter shaking prevention, and zooming, and there is a need for improved temperature compensation and reliable conductive connections in such devices.

Innovation Solution

A camera device with a simple structure using a shape memory alloy member for movement and rotation, coupled with position sensing units and a controller to accurately detect movement and rotation, minimizing magnetic interference and reducing power consumption, and enhancing temperature compensation and conductive connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If voice coil motor (VCM) technology is used in conventional camera devices, then actuation functions are achieved, but power consumption increases and application to micro-scale devices becomes difficult

Engineering Contradiction:

Improvepower consumptionVSAvoiddifficulty of application to micro-scale

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent replaces the electromagnetic VCM system with a shape memory alloy (SMA) based actuation system. The SMA member undergoes phase transformation under electrical heating to produce mechanical displacement, eliminating the need for complex electromagnetic components in micro-scale devices while reducing power consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes temperature as a control parameter to induce phase transformation in the shape memory alloy member. By applying electrical current to heat the SMA and then allowing it to cool, the system achieves bidirectional actuation without requiring complex mechanical structures, thus reducing power consumption and enabling micro-scale integration.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If conventional position sensing is used, then movement detection is achieved, but magnetic interference occurs and detection accuracy decreases

Engineering Contradiction:

Improvedetection accuracyVSAvoidmagnetic interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces magnetic field-based position sensors with a capacitive sensing system. The position sensing unit detects displacement through changes in capacitance between sensing electrodes and reference electrodes, eliminating magnetic interference while maintaining high detection accuracy for the SMA actuator's position.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If shape memory alloy member is used for actuation, then power consumption is reduced and device size is minimized, but temperature compensation and conductive connection reliability become critical challenges

Engineering Contradiction:

Improvepower consumptionVSAvoidconductive connection reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements a feedback control system where the controller monitors the position of the SMA actuator using the capacitive position sensing unit and adjusts the heating current accordingly. This closed-loop control ensures precise actuation while protecting against overheating and connection failures, thereby improving reliability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent incorporates temperature compensation mechanisms and protective circuitry in advance to prevent conductive connection failures. The system includes over-temperature protection and reliable bonding structures that anticipate and prevent connection issues before they occur, ensuring long-term reliability of the SMA actuator system.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 enables accurate detection of movement and rotation, reduces power consumption, minimizes magnetic interference, and improves temperature compensation and conductive reliability, facilitating smaller device sizes and dual or triple camera devices.

Implementation Method 1

a shape memory alloy member coupled to the fixed unit and the moving unit

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Alloy

Implementation Method 2

Each of the first and third sensors may be a Hall sensor

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS20260012704A1Camera device and optical instrument

Publication Date: 2026.01.08 LG INNOTEK CO LTD

AI summary

A camera device including a fixed unit, a moving unit disposed to be spaced apart from the fixed unit and comprising an image sensor, a shape memory alloy member including a first end coupled to the fixed unit and a second end coupled to the moving unit, and a position sensing unit configured to detect a displacement of the moving unit. A driving signal is supplied to the shape memory alloy member and the moving unit is configured to move in a direction perpendicular to an optical axis due to expansion or contraction of the shape memory alloy member.