Camera Module Actuator Control with Interference Elimination
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Solution Overview
Problem
Camera modules face inaccuracies in lens control due to the influence of current applied to voice coil motors, leading to difficulties in high-speed autofocus when adjusting focus, especially when the lens is moving.
Innovation Solution
An apparatus and method that utilize a current controller to detect and eliminate interference voltage from the hall voltage, allowing for precise control of the voice coil motor current based on the interference-eliminated hall voltage and control voltage, thereby improving lens positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current is applied to the voice coil motor to move the lens, then the lens can be positioned, but interference voltage is generated in the hall voltage detection, reducing measurement precision
Solution Approach 1:
The patent segments the voltage signals by separating the hall voltage detection circuit from the voice coil motor drive circuit. The hall voltage is detected independently and then the interference voltage generated by the voice coil current is subtracted through signal processing, effectively isolating the pure position signal from the harmful interference.
Solution Approach 2:
The patent introduces an intermediary signal processing mechanism that detects the interference voltage generated by the voice coil motor current and uses it to compensate the hall voltage signal. This intermediary processing step acts as a mediator to eliminate the harmful effect of the interference voltage on the position detection accuracy.
2Speed
If the lens is moved quickly for autofocus, then speed is improved, but positioning accuracy deteriorates due to current interference
Solution Approach 1:
The patent implements a feedback mechanism where the hall sensor continuously monitors the lens position and the current controller uses the interference-eliminated hall voltage to adjust the voice coil motor current in real-time. This feedback loop ensures that even during high-speed autofocus operations, the lens positioning accuracy is maintained by continuously compensating for interference effects.
Solution Approach 2:
The patent performs preliminary action by pre-detecting and eliminating the interference voltage component before it corrupts the position measurement. The current controller proactively compensates for the expected interference based on the applied current, ensuring accurate position detection even during rapid lens movement for autofocus.
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 solution enables precise control of the camera module's lens, enhancing autofocus accuracy and speed by isolating the lens movement from the influence of the current applied to the voice coil motor, resulting in improved image capture capabilities.
Implementation Method 1
a hall sensor for detecting an amount of change in magnetic lines of force generated by a magnet as a hall voltage
Implementation Method 2
a voice coil motor for moving the lens according to a current applied thereto
Data Source
AI summary
An apparatus for controlling an actuator in a camera module is provided. The apparatus includes a position controller for producing a control voltage to move a lens of the camera module, a hall sensor for detecting an amount of change in magnetic lines of force generated by a magnet as a hall voltage, a voice coil motor for moving the lens according to a current applied thereto, and a current controller for using a voltage applied to the voice coil motor to detect an interference voltage created by the current applied to the voice coil motor, for generating an interference-eliminated hall voltage by removing the interference voltage from the hall voltage, and for controlling the current applied to the voice coil motor based on the control voltage and the interference-eliminated hall voltage.