Camera Actuator Coil Layout for Long-Stroke AF and Zoom
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Solution Overview
Problem
Existing camera actuators face challenges in providing a long stroke for auto focusing (AF) and zooming functions due to space constraints, especially in ultra-slim and high-resolution cameras, and suffer from magnetic field interference between OIS and AF/zoom magnets.
Innovation Solution
A camera actuator design featuring a driving unit with overlapping sub-coils and a moving magnet within the coil's range, along with Hall sensors for improved positional linearity and reduced magnet size, allowing for increased moving distance and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the lens size is increased to increase the amount of received light in high pixel density cameras, then the image quality is improved, but the space occupied by the actuator for OIS increases, making it difficult to secure sufficient space for lens tilting or moving
Solution Approach 1:
The patent applies dimensionality change by moving the OIS actuator from a lateral arrangement (around the lens) to an axial arrangement (above the lens assembly). This vertical stacking in the optical axis direction enables the OIS magnet and AF/zoom magnets to be disposed at different positions along the Z-axis, eliminating magnetic field interference while maintaining compact lateral dimensions for ultra-slim camera devices.
2Reliability
If the actuator for OIS is disposed around the lens to enable image stabilization, then the OIS function is achieved, but magnetic field interference occurs between the OIS magnet and AF or zoom magnets due to close proximity
Solution Approach 1:
The patent resolves magnetic field interference by redistributing magnets along the optical axis (Z-axis) dimension. The OIS magnet is positioned above the lens assembly while AF and zoom magnets are positioned at different axial locations, creating sufficient magnetic field separation. This axial arrangement eliminates interference while preserving both OIS and autofocus/zoom functions.
Solution Approach 2:
The patent segments the actuator system into functionally independent modules: an OIS actuator module positioned above the lens assembly and AF/zoom actuator modules positioned at different axial locations. This segmentation allows each magnetic system to operate independently without interference, while the modular structure facilitates flexible spatial arrangement along the optical axis.
3Device complexity
If a conventional single-coil driving unit is used for AF and zooming, then the structure is simple, but the moving distance of the lens assembly is limited due to space constraints in ultra-slim cameras
Solution Approach 1:
The driving coil is segmented into multiple independent coils (first driving coil and second driving coil) that can be actuated separately. This segmentation enables the lens assembly to achieve extended moving distance by sequentially or simultaneously activating different coil segments, overcoming the stroke limitation of conventional single-coil designs while maintaining a compact overall structure suitable for ultra-slim cameras.
Solution Approach 2:
The multi-coil driving unit provides multi-functionality by enabling both AF and zooming operations through coordinated actuation of different coil segments. The same driving unit structure serves multiple functions (focus adjustment and zoom), eliminating the need for separate actuators and maintaining simplicity while achieving extended travel distance.
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
The solution enables a camera actuator with a longer stroke for AF and zooming, enhanced positional accuracy, easier design, reduced manufacturing costs, and minimized magnetic interference, suitable for ultra-slim and high-resolution cameras.
Implementation Method 1
a first driving coil and a first driving magnet facing the first driving coil
Implementation Method 2
improving positional linearity through connection of a plurality of Hall sensors
Data Source
AI summary
Embodiments of the present disclosure disclose a camera device including a housing, a first lens assembly moving in an optical axis direction with respect to the housing, and a first driving unit configured to move the first lens assembly, wherein the first driving unit includes a first driving coil and a first driving magnet facing the first driving coil, the first driving coil includes a first sub-coil and a second sub-coil disposed to overlap each other in the optical axis direction, and a maximum moving distance of the first lens assembly in the optical axis direction is greater than a length of a hollow of the first sub-coil in a short axis direction and smaller than or equal to a length of the hollow of the first sub-coil in the optical axis direction.