Magnetic Shape Memory Actuators for Optical Image Stabilization
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Solution Overview
Problem
The incorporation of optical image stabilization (OIS) in portable electronic devices increases power consumption and adds weight due to the need for multiple voice coil motor (VCM) actuators and additional sensor components, which have limitations in holding positions without continuous power and are prone to resonance issues.
Innovation Solution
The use of magnetic shape memory (MSM) actuators, which change dimension in response to magnetic fields, minimizes power consumption and component count by providing opposing forces to stabilize the camera, with measurements of electrical characteristics determining the camera's position and selectively applying power only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple VCM actuators are used to stabilize the camera, then the camera position control capability is improved, but the power consumption increases
Solution Approach 1:
The patent replaces the traditional VCM (voice coil motor) electromagnetic actuation system with a magnetic shape memory alloy (MSMA) based actuation system. The MSMA actuators utilize magnetic field-induced phase transformation to produce mechanical displacement, eliminating the need for continuous electromagnetic power consumption while maintaining camera stabilization capability. This substitution directly addresses the contradiction by providing reliable position control through a mechanism that does not require continuous power input.
Solution Approach 2:
The patent exploits the phase transformation parameter change in magnetic shape memory alloys, where the material transitions between austenite and martensite phases in response to magnetic field strength changes. This phase transformation enables the actuator to achieve discrete position states (locked or unlocked) with minimal power input, resolving the contradiction between maintaining control capability and reducing power consumption.
2Ease of operation
If VCM actuators are used to move the camera portion, then the position adjustment capability is improved, but the ability to hold position without continuous power is worsened
Solution Approach 1:
The patent replaces the VCM continuous electromagnetic field system with a magnetic shape memory alloy system that utilizes superelasticity and phase transformation memory effects. The MSMA actuators can maintain a displaced position indefinitely without power input, as the deformed martensite phase remains stable until a reverse magnetic field or thermal stimulus is applied. This fundamentally resolves the contradiction between position adjustment capability and position holding capability without continuous power.
Solution Approach 2:
The magnetic shape memory alloy actuators are self-locking through their phase transformation characteristics. Once the alloy transforms to the martensite phase and is deformed to a new position, it maintains that position autonomously without requiring external power or active control, effectively serving itself to hold the camera position indefinitely.
3Duration of action of stationary object
If mechanical springs are added to assist VCM actuators in holding position, then the position holding capability is improved, but the device complexity and weight increase
Solution Approach 1:
The patent eliminates the need for mechanical springs by replacing the entire VCM actuation system with magnetic shape memory alloy actuators. The MSMA's inherent phase transformation and superelastic properties provide both the actuation force and the position holding capability that previously required separate spring mechanisms. This substitution reduces device complexity by removing auxiliary components while maintaining position holding capability.
Solution Approach 2:
The magnetic shape memory alloy actuator performs multiple functions simultaneously: it provides the driving force for position adjustment and inherently maintains the position without additional components. The single MSMA actuator replaces both the VCM actuator and the spring support system, demonstrating multi-functionality that reduces overall device complexity.
4Measurement precision
If separate sensor components are added to detect camera position, then the position detection accuracy is improved, but the device complexity and weight increase
Solution Approach 1:
The magnetic shape memory alloy actuator serves dual purposes: it acts as both the actuation mechanism and the position sensor. By monitoring the electrical characteristics (resistance, inductance) of the MSMA actuator, the system can determine the current position state without requiring separate sensor components. This multi-functionality approach maintains position detection accuracy while eliminating additional sensors.
Solution Approach 2:
The MSMA actuator provides self-sensing capability through its inherent electrical property changes during phase transformation. The actuator's own electrical characteristics serve as the sensing signal, eliminating the need for external sensor components and reducing system complexity while maintaining position detection accuracy.
5Duration of action of stationary object
If mechanical springs are used in the OIS system, then the position holding capability is improved, but resonance vibrations occur at specific frequencies
Solution Approach 1:
The patent replaces the mechanical spring system with magnetic shape memory alloy actuators that utilize solid-state phase transformation. The MSMA actuators do not possess the mechanical resonance characteristics inherent in spring-based systems, as they rely on magnetic field-induced phase changes rather than elastic mechanical deformation. This substitution eliminates resonance vibrations while maintaining position holding capability.
Solution Approach 2:
The patent replaces the continuous electromagnetic operation of VCM actuators with magnetic shape memory alloy actuators that operate through phase transformation cycles. The MSMA actuators can be activated intermittently based on stabilization needs, reducing average power consumption while maintaining effective camera position control through the material's memory and superelastic properties.
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 approach reduces power consumption and component count while effectively counteracting camera movements caused by unsteadiness, maintaining position without continuous power and minimizing resonance issues.
Implementation Method 1
Each MSM actuator includes a portion of material that changes a dimension and/or a shape as a result of a molecular level response to a magnetic field
Data Source
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AI summary
Various embodiments are generally directed to techniques for using MSM actuators to minimize the consumption of electric power and/or the quantity of components in implementing OIS in an image capture device. An apparatus may include a camera pivotally mounted within an endpiece of a casing, the camera including an image capture element to capture an image of an object along a line of sight of the image capture element; an actuator of elongate shape coupled to the camera to exert a mechanical force to pivot the camera about an axis, the elongate shape of the actuator extending into a relatively thin and elongate portion of the casing that is coupled to and extends from the endpiece; and a countering movement component to operate the actuator to pivot the camera about the axis in a countering movement to provide OIS to the camera. Other embodiments are described and claimed.