SMA Actuated Lens Arrangement for Compact Tele-Angle Camera
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Solution Overview
Problem
Current Voice Coil Motor (VCM) based actuation systems in tele-angle cameras face challenges in implementing autofocus (AF) and optical image stabilization (OIS) due to size constraints, limited stroke range, and interference issues, which restrict the design and performance of lens arrangements in smartphones.
Innovation Solution
A lens arrangement using shape-memory alloy (SMA) members as actuators to move a reflective element and a movable lens unit, allowing for linear displacement and orthogonal movement, reducing power requirements and interference, while enabling high force generation and stability, and allowing for a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If VCM based actuation systems are used for AF and OIS, then autofocus and optical image stabilization functions can be achieved, but the size of the actuator becomes large due to poor force generation capacity for long AF stroke length
Solution Approach 1:
The patent replaces the traditional VCM (Voice Coil Motor) based actuation system with a shape memory alloy (SMA) based actuation system. The SMA wire utilizes shape memory effect to generate mechanical force, eliminating the need for large VCM actuators. This substitution resolves the contradiction by providing sufficient force generation capacity for long AF stroke length while significantly reducing the actuator size and enabling compact camera module design.
2Length of moving object
If VCM based actuation systems are used, then autofocus and OIS functions can be implemented, but the stroke range is limited making it difficult to achieve longer focal length requirements
Solution Approach 1:
The patent changes the actuation mechanism from VCM to SMA wire, which fundamentally alters the stroke range characteristics. The SMA wire can be designed with appropriate wire length and coil structure to achieve the required stroke length for long focal length cameras. This parameter change enables the actuator to provide sufficient stroke range for tele-angle cameras while maintaining compact form factor.
3Stability of the object's composition
If K-factor of suspension springs is reduced to achieve lower resonance, then posture stability improves, but settling time increases and dynamic performance deteriorates
Solution Approach 1:
The patent replaces the traditional suspension spring system with a direct rigid mounting system for the optical element. This eliminates the need for suspension springs with specific K-factors, thereby avoiding the trade-off between resonance reduction and settling time. The rigid mounting provides both stability and fast response without the compromising effects of spring-based suspension.
4Force
If actuator structure is added around horizontally moving optics, then AF and OIS functions can be achieved, but the effective lens diameter is reduced requiring larger sensor size
Solution Approach 1:
The patent moves the actuation mechanism from a horizontal arrangement (which would surround the optics and reduce effective lens diameter) to a vertical arrangement where the SMA wire acts on the optical element from above. This dimensional change allows the actuator to be positioned outside the optical path, preserving the full effective lens diameter while still providing the required AF and OIS functions.
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 SMA-based actuation system enhances stability, reduces resonance, and allows for efficient autofocus and image stabilization, enabling a compact and cost-effective design that accommodates larger lenses and reduces the overall camera unit length.
Implementation Method 1
at least the first actuator or the second actuator comprises a shape-memory alloy member
Implementation Method 2
a reflective element configured to fold the path of light from a first optical path to a second optical path that is at an angle with the first optical path
Data Source
Figure 1~3
Figure 4~8
AI summary
A lens arrangement (1) with a reflective element (2) for folding the path of light orthogonally from a first optical path (10) to a second optical path (20) and with a movable lens unit (4). The movable lens unit (4) is provided with one or more optical lenses arranged along a first optical axis (11) along said first optical path (10). A movable reflective element (2) folds the incoming light and provides OIS correction.