Camera Module Position Control via Coil Impedance Sensing
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Solution Overview
Problem
Existing camera module position control methods, such as those using hall sensors, require additional components and consume significant power, leading to mechanical design limitations, increased material costs, and inefficiencies in autofocusing and optical image stabilization.
Innovation Solution
An apparatus that controls the position of a camera module's lens barrel using a magnetic member and a coil, where a specific frequency component is used in the driving signal to detect the position without the need for a separate sensor, allowing for precise position detection and control without external sensing units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hall sensor and magnet are used for position detection, then position control can be achieved, but additional components increase device complexity and material costs
Solution Approach 1:
The patent combines the driving coil and sensing functions into a single coil structure. The same coil that drives the lens barrel for focusing also serves as the sensor for detecting the lens position, eliminating the need for separate hall sensors and magnets. This merging reduces component count and simplifies the overall device structure while maintaining position detection capability.
Solution Approach 2:
The coil is designed to perform multiple functions: it acts as both an actuator (driving the lens barrel) and a sensor (detecting position through impedance changes). This multi-functionality allows the system to achieve position control without requiring dedicated sensing components, thereby reducing device complexity and material costs.
2Measurement precision
If a hall sensor is used for position detection, then position control can be achieved, but power consumption increases due to bias current and additional circuits
Solution Approach 1:
The system uses the existing coil structure to perform both driving and sensing functions. The coil's own electrical properties (impedance) are utilized for position detection, eliminating the need for separate power-hungry hall sensors and their associated bias currents. The same electromagnetic field used for driving also provides the sensing mechanism, making the system self-sufficient and energy-efficient.
3Measurement precision
If additional circuits are used to correct hall sensor temperature drift, then position accuracy is maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the driving and sensing functions into a single coil, eliminating the need for separate correction circuits. The impedance-based sensing method inherently provides temperature-compensated measurements, as the coil's electrical properties change predictably with temperature and can be calibrated out, reducing manufacturing complexity.
4Measurement precision
If external sensors are used for position detection, then position control can be achieved, but the camera module size increases, limiting miniaturization
Solution Approach 1:
The patent integrates the sensing function into the existing coil structure, eliminating the need for separate external sensors. The coil itself serves as the sensor by detecting changes in its own electrical impedance as the lens barrel moves, thereby maintaining position detection accuracy while minimizing the camera module's overall size and enabling better miniaturization.
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 reduces power consumption, simplifies manufacturing, and enables more efficient miniaturization of camera modules by integrating sensing and driving functions within a single coil, enhancing the stability and precision of autofocusing and optical image stabilization.
Implementation Method 1
a coil disposed opposite to the magnetic member
Implementation Method 2
a position detector configured to detect impedance of the coil using the detection signal and the position confirmation signal
Data Source
AI summary
An apparatus to control a position of a camera module includes a magnetic member, a coil, a driver, a signal extractor, and a position detector. The magnetic member is disposed on a lens barrel of the camera module. The coil is disposed opposite to the magnetic member. The driver is configured to provide a position confirmation signal to the coil. The signal extractor is configured to extract a specific frequency component from a signal of the coil including the position confirmation signal and output a detection signal. The position detector is configured to provide a position signal corresponding to a position of the magnetic member based on the detection signal.