Optical Image Stabilization Actuator Positioning
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Solution Overview
Problem
Conventional optical image stabilization (OIS) systems face limitations in motion range and power consumption, leading to instances of actuator 'railing' and increased power usage, especially in handheld devices during camera motion.
Innovation Solution
The implementation of a controller that synchronizes actuator motion with exposure duration, adjusts the camera lens to a gravity-adjusted neutral position, and rebalances auto exposure parameters to reduce power consumption and prevent railing, by shifting the lens between frames to maintain it closer to the neutral position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OIS arrangements operate actuators to compensate for camera motion, then image stabilization performance is improved, but power consumption increases and actuator railing occurs
Solution Approach 1:
The controller determines a desired start position for the lens before image frame acquisition begins, and pre-positions the lens at this location. This preliminary positioning ensures the lens is ready for stable image capture without requiring continuous actuator operation during the entire frame period, thereby reducing power consumption while maintaining stabilization performance.
Solution Approach 2:
The OIS system operates periodically by positioning the lens at desired start positions before each frame acquisition and then relocating to new start positions between frames. This periodic operation allows the actuators to remain idle or operate minimally during frame capture, reducing overall power consumption compared to continuous operation, while still providing effective stabilization through timed interventions.
2Reliability
If actuators operate continuously to compensate for camera motion, then image stabilization is maintained, but instances of actuator railing increase
Solution Approach 1:
The controller calculates and sets the desired start position for the lens before each frame acquisition. By pre-positioning the lens at this calculated location, the system ensures the lens begins each frame capture at an optimal position that prevents the actuator from reaching its motion limits during exposure, thereby eliminating railing issues while maintaining stabilization effectiveness.
Solution Approach 2:
The system uses feedback from accelerometer and gyroscope data to dynamically determine appropriate start positions for the lens. This feedback mechanism allows the controller to anticipate camera motion trends and position the lens proactively within the actuator's safe operating range, preventing railing before it occurs while maintaining effective image stabilization.
3Illumination intensity
If exposure time is increased to improve image quality, then more light is captured, but the time available for lens relocation decreases
Solution Approach 1:
The controller determines desired start positions for the lens before frame acquisition and completes lens relocation to these positions in advance. By performing the positioning action preliminarily, the system ensures the lens is correctly positioned before exposure begins, allowing longer exposure times to be used without compromising the ability to relocate the lens between frames.
Solution Approach 2:
The system performs rapid lens relocation between frames by slewing the lens to new start positions during the brief interval between frame acquisitions. This rushing through the relocation process in a time-efficient manner allows the system to accommodate longer exposure times while still completing necessary lens repositioning, effectively resolving the time conflict between exposure duration and relocation requirements.
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 significantly reduces the frequency of actuator railing and power consumption while maintaining effective image stabilization, ensuring the camera lens remains within the actuator's motion range during exposure periods.
Implementation Method 1
an actuator mechanically coupled with the lens
Implementation Method 2
receive measured accelerometer data relating to camera orientation with respect to a gravitational field
Data Source
AI summary
An optical image stabilization (OIS) of a camera system includes a controller, a lens and an image stabilizing arrangement (ISA), including one or both of an actuator mechanically coupled with the lens. The controller is configured to: (1) receive measured accelerometer data relating to camera orientation with respect to a gravitational field and causes the actuator to locate the lens at a gravity-adjusted neutral position; and/or (2) synchronously relocate, during a time interval that falls at least partially between a first successive frame and a second successive frame, one or both of the camera lens and an image sensor by controlling a slew motion of the camera lens or image sensor, monitor and controls one or more of exposure time, effective readout time, lens relocation time and frame period, and rebalance the auto exposure algorithm such that the exposure time is less than a critical value.