Camera Actuator Yoke Structure for Long-Stroke Lens Motion
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Solution Overview
Problem
Existing camera devices face challenges in providing a long stroke for auto focusing (AF) and zooming functions while minimizing magnetic field interference between facing magnets, coils, and Hall sensors, especially in ultra-slim and high-resolution camera applications.
Innovation Solution
The camera device incorporates a driving unit with a yoke structure that reduces magnetic field interference, allowing for a long stroke movement by increasing the number of driving coils and improving positional linearity through multiple Hall sensors. Additionally, a blocking member is placed in the coil to protect the Hall sensor from magnetic forces, and protrusions are used to reduce impact between the lens assembly and the housing, preventing lens damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the number of driving coils is increased to provide long stroke for AF and zooming, then the moving distance is improved, but magnetic field interference between adjacent magnets and coils increases
Solution Approach 1:
The camera actuator divides the driving function into multiple independent driving units, each with its own coil and magnet. This segmentation allows each unit to operate with smaller magnetic fields while collectively achieving long stroke movement, thereby reducing magnetic field interference between adjacent components.
Solution Approach 2:
A magnetic shield is introduced as an intermediary component between adjacent magnets and coils to block and redirect magnetic field lines. This mediator prevents direct magnetic field interference between neighboring driving units while allowing the system to maintain multiple coils for long stroke operation.
2Volume of moving object
If magnets are disposed close to each other for compact design, then the device size is reduced, but magnetic field interference between OIS magnet and AF/zoom magnet increases
Solution Approach 1:
Magnetic shields are positioned between the OIS magnet and AF/zoom magnets to act as intermediaries that block magnetic field lines. This allows the magnets to be disposed close together for compact device size while preventing harmful magnetic field interference between them.
Solution Approach 2:
The magnetic shield provides localized magnetic field management in specific regions where magnets are disposed close to each other. By applying magnetic shielding only in critical interference zones rather than throughout the entire device, the design achieves compact size while selectively reducing interference where needed.
3Length of moving object
If the lens assembly moves in long stroke direction for improved performance, then the moving distance is increased, but the lens is shocked and broken by impact
Solution Approach 1:
A protrusion is provided on the lens assembly that extends in the long stroke moving direction. This protrusion acts as a beforehand cushioning element that makes contact with the housing before the lens assembly can travel its full stroke distance, thereby preventing impact and potential breakage while still allowing substantial movement range.
4Measurement precision
If Hall sensors are used to detect position for accurate measurement, then the positional linearity is improved, but the sensor performance is degraded by magnetic force of the coil
Solution Approach 1:
A magnetic shield is positioned between the coil and the Hall sensor to act as an intermediary that blocks magnetic field lines from the coil. This allows the Hall sensor to accurately detect position with high linearity while the magnetic shield prevents the coil's magnetic force from degrading sensor performance.
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 camera devices to achieve a long stroke movement for AF and zooming functions while minimizing magnetic field interference, improving positional accuracy, and reducing the risk of lens damage due to impact.
Implementation Method 1
a first driving unit configured to move the lens assembly, wherein the first driving unit includes a first coil and a first magnet facing the first coil
Implementation Method 2
improving positional linearity through multiple Hall sensors
Data Source
AI summary
Embodiments of the present disclosure disclose a camera device including a housing, a first bobbin configured to move in an optical axis direction with respect to the housing, and a first driving unit configured to move the first bobbin, wherein the first driving unit includes a first coil and a first magnet facing the first coil, the camera device includes a first yoke which is coupled to the first bobbin and on which the first magnet is disposed, the first yoke includes a bottom portion and a side plate portion disposed on a side surface of the bottom portion, and the first magnet is surrounded by the bottom portion and the side plate portion.