Camera Module Position Control via Coil Impedance Peak Detection
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Solution Overview
Problem
Existing camera module designs face challenges in achieving accurate position control for autofocusing and optical image stabilization without using hall sensors, which require additional components, consume excess current, and increase material costs.
Innovation Solution
An apparatus that controls the position of a camera module by using a magnetic member and a coil, where a specific frequency component is included in the position confirmation signal to detect the position of the magnetic member without a separate sensor, utilizing a peak detector to calculate the impedance of the coil and generate a position signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hall sensor and magnet are used for position sensing, then position detection capability is improved, but device complexity and material costs increase due to additional components
Solution Approach 1:
The patent combines the position sensing function with the existing coil structure by detecting impedance changes of the coil itself, eliminating the need for separate hall sensors and magnets. The coil serves dual purposes: driving the magnetic member and sensing its position through impedance variation.
Solution Approach 2:
The system uses the coil's own electrical properties (impedance) to detect position, allowing the existing component to serve both actuation and sensing functions without requiring external sensing components.
2Measurement precision
If a hall sensor is used for position sensing, then position detection capability is improved, but power consumption increases due to bias current and additional circuits
Solution Approach 1:
The coil's electrical impedance naturally varies with position, providing passive sensing without requiring additional power-consuming circuits or bias currents. The sensing is achieved by measuring the coil's own electrical properties.
Solution Approach 2:
The coil performs multiple functions: it drives the magnetic member during normal operation and simultaneously serves as the sensing element for position detection, eliminating the need for separate power-consuming sensing circuits.
3Reliability
If additional circuits are added to correct hall sensor temperature drift, then measurement stability is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The sensing function is merged into the coil's electrical characteristics, which inherently provide temperature-stable impedance measurements without requiring additional compensation circuits or calibration mechanisms.
4Measurement precision
If external hall sensor is implemented, then position detection capability is improved, but current consumption increases due to bias current and amplifier circuits
Solution Approach 1:
The system leverages the coil's inherent electrical properties for sensing, eliminating the need for power-hungry bias currents and amplifier circuits required by external hall sensors.
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 allows for precise position control of the camera module without a hall sensor, reducing power consumption and manufacturing costs, while enabling miniaturization and stable, precise position control for autofocusing and optical image stabilization.
Implementation Method 1
a magnetic member disposed on a lens barrel of the camera module; a coil disposed opposite to the magnetic member
Implementation Method 2
a driver configured to generate to the coil a position confirmation signal including a specific frequency component; a peak detector detect a peak value of the detected signal and output a position signal corresponding to a position of the magnetic member based on the peak value
Data Source
AI summary
An apparatus is provided to control a position of a camera module. The apparatus includes a magnetic member disposed on a lens barrel of the camera module, a coil disposed opposite to the magnetic member, and a driver configured to generate to the coil a position confirmation signal including a specific frequency component. The apparatus also includes a signal extractor configured to extract a detected signal, including the specific frequency component, from a coil signal of the coil, and a peak detector detect a peak value of the detected signal and output a position signal corresponding to a position of the magnetic member based on the peak value.