Miniature Camera Stabilization Using Shape Memory Alloy Actuators
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Solution Overview
Problem
Current optical image stabilization (OIS) techniques in miniature digital cameras of mobile electronic devices face challenges due to size constraints, leading to crop artifacts and loss of resolution, and existing solutions like electronic image stabilization (EIS) and pseudo rotation methods provide insufficient stabilization against both low and high-frequency external movements.
Innovation Solution
A miniature camera gimbal system using shape memory alloy (SMA) actuators is integrated into mobile electronic devices to provide increased stabilization, where SMA actuators are attached between the camera module and the base, and actuation signals are generated to counter rotational movements, allowing for a larger range of motion and improved image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If electronic image stabilization (EIS) is used to stabilize video in miniature digital cameras, then image stabilization is achieved, but crop artifacts and loss of resolution occur
Solution Approach 1:
The patent replaces electronic image stabilization (EIS) with a mechanical optical image stabilization (OIS) system using a voice coil motor to physically move the lens relative to the sensor. This mechanical substitution allows stabilization without cropping the image, thereby maintaining resolution while achieving stability.
Solution Approach 2:
The patent introduces a voice coil motor as an intermediary mechanism between the camera module and the sensor. This intermediary enables precise mechanical adjustment of the lens position to counteract hand movements, providing stabilization without the resolution loss associated with EIS cropping.
2Stability of the object's composition
If a gimbal system is used to provide optical image stabilization, then a large range of motion is achieved, but the device size and cost increase
Solution Approach 1:
The patent extracts the stabilization function from a traditional gimbal system and implements it through a simplified pseudo-rotation mechanism where only the lens moves relative to the sensor. This extraction eliminates the need for a full gimbal structure, reducing device size while maintaining stabilization capability.
Solution Approach 2:
The patent segments the stabilization function into independent lens movement along X and Y axes, controlled separately by voice coil motors. This segmentation allows for a compact implementation without requiring a full mechanical gimbal, achieving range of motion with reduced device volume.
3Volume of moving object
If pseudo rotation with voice coil motor is used for optical image stabilization, then device size is reduced, but the stabilization stroke is limited to 0.8-1.2° at 6 Hz
Solution Approach 1:
The patent implements dynamic control of the voice coil motors to adjust lens position in real-time based on detected hand movements. This dynamic adjustment enables the system to achieve larger effective stabilization stroke beyond the static 0.8-1.2° limitation, while maintaining the compact form factor.
Solution Approach 2:
The patent employs feedback from gyroscopic sensors to detect hand movements and uses this information to control the voice coil motors. This feedback mechanism allows the system to compensate for limitations in stroke by anticipating and pre-positioning the lens to counteract upcoming movements, effectively extending the stabilization capability.
4Device complexity
If current pseudo rotation OIS is used in miniature digital cameras, then device integration is improved, but auto-focus and OIS artifacts appear due to insufficient response to low and high frequency movements
Solution Approach 1:
The patent implements periodic actuation of the voice coil motors at different frequencies to address both low-frequency hand movements and high-frequency vibrations. This multi-frequency periodic action eliminates the insufficient response problem, reducing artifacts while maintaining good integration.
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 actuator-based gimbal system achieves enhanced image stabilization with a larger range of motion, reduced size, and lower power consumption compared to traditional pseudo rotation methods, providing better counteraction to external movements and maintaining lens and sensor alignment.
Implementation Method 1
The digital camera includes shape memory alloy (SMA) actuator(s) that are attached between the base and the camera module. An electrical interconnect directs actuating signal(s) from a gimbal driver of the electronic device to the SMA actuator(s) to rotate the camera module.
Data Source
AI summary
An electronic device includes a gimbal driver and a digital camera. The digital camera includes suspension member(s) attached to a base. The digital camera includes a camera module supported by the suspension member(s). The camera module includes: (i) a lens that focuses an image; and (ii) a sensor attached to the lens and that detects the focused image. Shape memory alloy (SMA) actuator(s) are attached between the base and the camera module. The gimbal driver generates actuating signal(s) in response to movement of the base to stabilize the image. An electrical interconnect directs the actuating signal(s) from the gimbal driver to the SMA actuator(s) to rotate the camera module.