Actuator Driving Apparatus Lens Carrier Position Detection
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Solution Overview
Problem
Existing camera module actuators face challenges in accurately determining the position of a lens carrier for precise auto-focus and optical image stabilization, as existing methods often require additional position sensors, increasing manufacturing costs and reducing space efficiency.
Innovation Solution
An actuator driving apparatus that includes a detector to apply a reference signal to a driving coil, detect the coil current, and calculate the lens carrier's position based on inductance changes, allowing the driver to output position information for precise actuator control without the need for separate position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional position sensors are used to determine lens carrier position, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The driving coil serves dual functions: it both drives the lens carrier and acts as a position sensor. By detecting changes in coil current and inductance during normal operation, the system determines lens carrier position without requiring separate sensing components, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The driving coil is designed to perform multiple functions simultaneously: it generates electromagnetic force to move the lens carrier and also functions as a position detection sensor. This multi-functionality eliminates the need for dedicated position sensors, reducing both device complexity and manufacturing cost while maintaining accurate position measurement
2Measurement precision
If additional position sensors are installed in the camera module, then measurement precision is improved, but the space efficiency deteriorates
Solution Approach 1:
The existing driving coil structure is utilized for position detection by monitoring its electrical characteristics (current and inductance changes). This self-service approach eliminates the need for additional space-consuming position sensors while maintaining accurate position measurement capability
Solution Approach 2:
The driving coil is designed to simultaneously perform driving and position sensing functions. This multi-functionality allows the system to maintain precise position measurement without adding extra components that would consume valuable space within the compact camera module
3Ease of manufacture
If inductance-based position detection is used, then manufacturing cost is reduced, but measurement precision may be affected by inductance changes
Solution Approach 1:
The system continuously monitors coil current and inductance changes and uses this feedback information to accurately determine lens carrier position. By establishing a relationship between inductance variations and position, the system achieves precise position detection through low-cost electrical measurements without requiring expensive additional sensors
Solution Approach 2:
The system exploits changes in electrical parameters (current and inductance) of the driving coil that naturally occur with lens carrier position changes. By detecting and interpreting these parameter variations, the system achieves accurate position measurement using simple, low-cost electrical sensing rather than expensive mechanical or optical 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 enables accurate and efficient actuator control, reducing manufacturing costs and improving space efficiency by eliminating the need for additional position sensors, while maintaining precise positioning of the lens carrier for improved image capture.
Implementation Method 1
Inductance of the driving coil may be changed depending on the position of the lens carrier
Implementation Method 2
an actuator including a driving coil disposed in the housing to face the magnetic body, the actuator being configured to receive a control signal to move the lens carrier
Data Source
AI summary
An actuator and a camera module including the same are provided. The actuator driving apparatus includes a detector configured to apply a reference signal to a driving coil of an actuator and detect a coil current flowing in the driving coil, a calculator configured to determine a position of a lens carrier based on the coil current, and a driver configured to drive the actuator based on the position of the lens carrier and a position control signal.