Camera Module Lens Barrel Position Detection Using Inductance Sensing
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Solution Overview
Problem
The challenge lies in miniaturizing camera modules while maintaining precise autofocusing and optical image stabilization, as reduced actuator sizes lead to decreased driving force and sensor sensitivity, making it difficult to achieve both miniaturization and performance improvement.
Innovation Solution
The camera module incorporates a first position sensor with 1-1-th and 1-2-th sensing coils, and a second position sensor with a second and third sensing coil, utilizing inductance changes to detect lens barrel positions in multiple directions, and a processor to calculate accurate positions by adjusting inductance values, enabling precise control and compensation for disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of actuators is reduced for miniaturization, then the camera module size is reduced, but the driving force and sensor sensitivity are reduced
Solution Approach 1:
The patent changes the parameter of inductance measurement by using multiple sensing coils with different orientations and calculating position based on inductance changes rather than direct force measurement. This allows the miniaturized actuator to maintain sufficient driving force while enabling precise position detection through electromagnetic field interactions.
Solution Approach 2:
The patent replaces direct mechanical position sensing with electromagnetic inductance-based sensing. By using sensing coils that detect inductance changes caused by lens barrel movement, the system achieves precise position measurement without requiring additional mechanical sensors that would increase size or reduce sensitivity.
2Volume of moving object
If the size of actuators is reduced for miniaturization, then the camera module size is reduced, but the sensor sensitivity is reduced
Solution Approach 1:
The patent segments the position detection function into multiple sensing coils oriented in different directions. Each coil detects inductance changes in its specific orientation, and the processor combines these segmented measurements to achieve comprehensive three-dimensional position detection with high sensitivity despite the miniaturized actuator size.
Solution Approach 2:
The patent adds the dimension of inductance measurement to traditional mechanical position sensing. By measuring inductance changes in multiple directions through differently oriented sensing coils, the system achieves enhanced position detection sensitivity that overcomes the limitations of miniaturization.
3Measurement precision
If multiple sensing coils are used to detect position in multiple directions, then position detection accuracy is improved, but device complexity is increased
Solution Approach 1:
The patent makes the sensing coils multi-functional by using them for both position detection and actuator feedback. The same sensing coils that detect position in different directions also serve as part of the actuator system, reducing overall device complexity while maintaining high position detection accuracy through electromagnetic field interactions.
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 the miniaturization of camera modules while maintaining sufficient driving force and precise position measurement of the lens barrel, effectively addressing the trade-off between size reduction and performance.
Implementation Method 1
a first position sensor configured to detect a position of a lens barrel in a first direction and including a 1-1-th sensing coil and a 1-2-th sensing coil having respective inductances that change as the lens barrel moves in the first direction
Implementation Method 2
a focusing actuator configured to move the lens barrel in the first direction and including a first magnet configured to move in the first direction together with the lens barrel, and a first coil disposed to face the first magnet
Data Source
AI summary
A camera module includes a first position sensor configured to detect a position of a lens barrel in a first direction and including a 1-1-th sensing coil and a 1-2-th sensing coil having respective inductances that change as the lens barrel moves in the first direction; and a second position sensor including a second sensing coil having an inductance that changes as the lens barrel moves in a second direction, and a third sensing coil having an inductance that changes as the lens barrel moves in a third direction, wherein the second position sensor is configured to detect a position of the lens barrel in the second direction and a position of the lens barrel in the third direction by adding or subtracting a reference inductance to or from the inductance of the second sensing coil and the inductance of the third sensing coil.