Camera Module Lens Position Detection via Inductance
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Solution Overview
Problem
Existing camera modules face challenges in precisely detecting the position of a lens module without using a hall sensor, which affects autofocusing and optical image stabilization functions.
Innovation Solution
A sensing unit with a detection target on a side surface of the lens module and multiple sensing coils, along with a calculator that determines displacement in various directions based on changes in inductance, allowing for precise position detection without a hall sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hall sensor is used to detect lens module position, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the detection function from a separate hall sensor and integrates it into the existing coil structure. The coil serves dual purposes: actuation and position detection, eliminating the need for a separate detection sensor and reducing overall device complexity while maintaining measurement precision
Solution Approach 2:
The coil is designed to perform multiple functions: it acts as both the actuator coil for driving the lens module and the sensing coil for detecting its position. This multi-functional design reduces the number of components needed while achieving precise position detection without requiring additional hall sensors
2Measurement precision
If multiple sensing coils are added to detect displacement in multiple directions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The detection system is segmented into multiple sensing coils arranged in specific directions. Each coil pair (e.g., first and second sensing coils in first direction, third and fourth sensing coils in second direction) independently detects displacement in its respective direction, allowing precise multi-directional measurement through modular coil configuration
Solution Approach 2:
The patent extends the detection capability from single-direction to multi-directional by adding sensing coils in different spatial dimensions. By arranging coils in the first direction and second direction perpendicular to each other, the system achieves two-dimensional displacement detection capability
3Ease of manufacture
If inductance-based detection is used instead of hall sensor, then manufacturing cost is reduced, but measurement precision may be affected
Solution Approach 1:
The coil structure serves itself by using its own inductance characteristics for both actuation and detection purposes. The change in inductance directly reflects the position of the lens module, allowing the system to detect position using the same component that performs actuation, thereby reducing cost while maintaining precision through proper signal processing
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
Enables precise detection of the lens module's position, improving autofocusing and optical image stabilization functions while reducing manufacturing costs and enhancing space efficiency by eliminating the need for a separate hall sensor.
Implementation Method 1
one or more sensing coils disposed to face the detection target; and a calculator configured to determine a displacement of the detection target translated in any of an optical axis direction, a first direction perpendicular to the optical axis direction, and a second direction perpendicular to the optical axis direction, based on inductances of the one or more sensing coils
Data Source
AI summary
A sensing unit of a camera module includes a detection target provided on a side surface of a lens module, one or more sensing coils disposed to face the detection target, and a calculator. The calculator may determine a displacement of the detection target translated in any of an optical axis direction, a first direction perpendicular to the optical axis direction, and a second direction perpendicular to the optical axis direction, based on inductances of the one or more sensing coils.