Camera Lens SMA Actuator with Low-Friction Plain Bearings
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Solution Overview
Problem
Existing mechanical optical image stabilization (OIS) systems for miniature cameras face challenges in miniaturization due to the use of ball suspensions, which are difficult to assemble and limit size reduction, and plain bearings with high friction are unsuitable for camera lens elements.
Innovation Solution
A shape memory alloy (SMA) actuator arrangement using plain bearings with planar conforming surfaces and SMA actuator wires to move the camera lens element orthogonally, allowing low-friction movement and reducing the overall size by distributing wear across a larger area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ball suspension is used to permit movement of the camera lens element, then good operation performance is achieved, but assembly difficulty increases and miniaturization is limited
Solution Approach 1:
The patent extracts the ball element from the suspension system and replaces it with a plain bearing consisting of a bearing surface on the support structure and a bearing element. This removes the problematic ball component that causes assembly difficulty while maintaining the essential function of permitting movement.
Solution Approach 2:
The patent changes the fundamental parameter of the bearing mechanism from spherical ball contact to planar surface contact. This parameter change transforms the suspension system from one requiring precise ball handling to one using simpler planar surfaces that are easier to manufacture and assemble.
2Reliability
If ball suspension is used to permit movement of the camera lens element, then good operation performance is achieved, but the size of the arrangement increases
Solution Approach 1:
The patent removes the ball component and its associated clearance requirements, replacing it with a compact plain bearing arrangement. This extraction allows for reduced overall size while maintaining the movement function.
Solution Approach 2:
The patent transitions from spherical ball contact to planar surface contact, effectively changing the dimensional characteristics of the bearing interface. This allows for more compact arrangement of components in the available space.
3Volume of moving object
If plain bearing is used to bear the camera lens element, then miniaturization is enabled, but friction increases
Solution Approach 1:
The patent substitutes the mechanical ball suspension system with a plain bearing system that relies on surface contact rather than rolling elements. This mechanical substitution reduces complexity and size while managing friction through the specific design of the bearing surfaces.
Solution Approach 2:
The patent employs materials with appropriate friction characteristics for the plain bearing surfaces. By selecting materials with suitable tribological properties, the friction is controlled to acceptable levels despite the use of plain bearing contact.
4Ease of manufacture
If conventional actuators are used for OIS, then the system is easier to manufacture, but the package size increases
Solution Approach 1:
The patent merges the actuator function with the existing lens barrel structure. The actuator is integrated into the lens assembly rather than being a separate component, which reduces overall package size while maintaining manufacturability through conventional fabrication techniques.
Solution Approach 2:
The actuator components are nested within the lens barrel structure, with the actuator housing formed as part of the lens assembly. This nesting arrangement minimizes the overall package volume while allowing for standard manufacturing processes.
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 SMA actuator arrangement provides effective OIS in miniature cameras by maintaining low friction and stable movement, enabling miniaturization while ensuring reliable operation and reducing wear-related issues.
Implementation Method 1
The shape memory alloy actuator wires are connected between the support structure and the movable element in an arrangement wherein the shape memory alloy actuator wires are arranged, on selective driving, to move the movable element
Implementation Method 2
shape memory alloy actuator arrangement for a camera lens element that provides movement orthogonal to the optical axis
Implementation Method 3
at least one plain bearing that bears the movable element on the support structure, allowing movement of the movable element relative to the support structure orthogonal to the optical axis
Data Source
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AI summary
A shape memory alloy actuator arrangement for a movable element supporting a camera lens assembly comprises plural shape memory alloy actuator wires connected between a support structure and the movable element in an arrangement wherein the shape memory alloy actuator wires are arranged, on selective driving, to move the movable element relative to the support structure in any direction orthogonal to the optical axis of the at least one lens. At least one plain bearing bears the movable element on the support structure, allowing movement of the movable element relative to the support structure orthogonal to the optical axis.