Camera Lens Control Mode Switching Under Magnetic Interference
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Solution Overview
Problem
Camera systems, especially those in small mobile devices, face interference from external magnetic or non-magnetic fields, which can cause position sensors to generate incorrect values, leading to improper camera behavior and image stabilization issues.
Innovation Solution
A test is performed at the start of the camera session to detect external interference, and based on the results, the camera switches to a control mode that either uses or bypasses position sensors, employing alternative methods like accelerometers to maintain lens positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors are used to control lens positioning, then measurement precision is improved, but reliability deteriorates in the presence of external magnetic interference
Solution Approach 1:
The system changes the operational parameters of the camera by switching between different control modes (first control mode using position sensors, second control mode bypassing position sensors) based on detected magnetic interference conditions. This allows the system to adapt to varying environmental conditions and maintain reliability while preserving measurement precision when conditions permit
Solution Approach 2:
The control mode of the camera is made dynamic rather than static. The system continuously monitors for magnetic interference and automatically transitions between control modes as needed. This dynamic adaptation allows the camera to maintain reliable operation in changing environmental conditions while utilizing precise sensor-based control when conditions are favorable
2Reliability
If a test is performed to detect external interference, then reliability is improved, but device complexity increases
Solution Approach 1:
The camera system integrates multiple functions into a unified control architecture that can operate in different modes. The same control system that normally processes position sensor data for autofocus and optical image stabilization is extended to also perform magnetic interference detection and mode switching. This multi-functionality approach improves reliability without requiring a completely separate testing subsystem
Solution Approach 2:
The system implements a feedback mechanism where the results of magnetic interference detection are fed back into the control mode selection logic. The controller continuously monitors sensor data, detects signs of magnetic interference, and automatically adjusts the control mode in response. This closed-loop feedback approach ensures reliable operation while keeping the complexity management systematic rather than ad-hoc
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 ensures the camera operates reliably by adjusting its control mode to compensate for external interference, maintaining image quality and user experience even in the presence of magnetic fields or other disturbances.
Implementation Method 1
The autofocus position may be measured using sensors, which may be located on the camera module substrate along an axis of the lens
Implementation Method 2
some cameras may include optical image stabilization (OIS) mechanisms that may sense and react to external excitations or disturbances by adjusting location of the optical lens
Data Source
AI summary
Methods and apparatus are disclosed for selecting a lens control mode for a camera in external magnetic fields or other types of non-magnetic interference. In embodiments, when the camera is activated, a test of a position sensor for the camera lens is performed by moving the camera lens through a range of positions and collecting values from the sensor. In embodiments, the sensor readings are analyzed to determine conditions such as (a) whether the sensor is saturated by an external magnetic field or non-magnetic interference, (b) whether the sensor's readings are within an error margin, and (c) whether a computed position offset for the sensor is valid. Based on the analysis, the camera is placed into a first control mode where movement of the lens is controlled using the position sensor, or a second control mode where lens movement is controlled without the position sensor.