Multi-Layer Flexure Assembly for Stable OIS Image Sensor Motion
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Solution Overview
Problem
Small form factor cameras face challenges in achieving high image quality with minimal parasitic motion in degrees of freedom other than the optical axis, and existing autofocus and optical image stabilization mechanisms are not optimized for compactness and efficiency.
Innovation Solution
A multi-layer flexure assembly with separated layers of flexure arms, spacer elements, and flexure stabilizers provides greater stiffness along the optical axis while allowing movement in orthogonal directions, enabling efficient autofocus and optical image stabilization with a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a single layer of flexure arms is used, then the device complexity is reduced, but the stiffness along the optical axis is insufficient and parasitic motion increases
Solution Approach 1:
The patent transitions from a single-layer flexure arm structure to a multi-layer stacked structure, adding the vertical dimension (Z-axis) to the traditional planar arrangement. Multiple layers of flexure arms are stacked along the optical axis direction, with each layer separated by spacer elements. This dimensional transformation increases the moment of inertia and stiffness along the optical axis without significantly increasing the lateral footprint, thereby reducing parasitic motion while maintaining compactness.
Solution Approach 2:
The patent implements a nested configuration where multiple layers of flexure arms are stacked within a compact vertical space. Each layer is nested above or below the previous layer, separated by thin spacer elements. This nesting approach allows the system to achieve high stiffness along the optical axis by concentrating multiple structural layers in a small vertical envelope, effectively solving the contradiction between stability and device complexity.
2Volume of moving object
If the camera form factor is reduced, then the portability is improved, but the image quality and control of parasitic motion deteriorate
Solution Approach 1:
The patent resolves the form factor versus image quality contradiction by stacking flexure arm layers vertically along the optical axis. This approach achieves high stiffness and precision control in a compact lateral footprint, allowing small form factor cameras to maintain high image quality by controlling parasitic motion through the multi-layer structure's enhanced mechanical properties.
Solution Approach 2:
The patent uses thin spacer elements to separate and maintain the structural integrity of multiple flexure arm layers. These thin film-like spacers enable the compact vertical stacking of layers while maintaining the flexibility needed for autofocus and optical image stabilization operations, thus achieving high precision in a compact form factor.
3Strength
If multiple layers of flexure arms are used, then the stiffness along the optical axis is improved, but the device complexity increases
Solution Approach 1:
The patent addresses the stiffness versus complexity contradiction by exploiting the vertical dimension. Multiple layers of flexure arms are stacked along the optical axis, with each layer contributing to the overall stiffness through its moment of inertia. The stacked configuration achieves high stiffness along the optical axis while maintaining a compact lateral footprint, and the modular layer-by-layer construction actually simplifies the manufacturing process compared to creating a single complex monolithic structure.
Data Source
Figure 1A~1C
Figure 1D
Figure 2
AI summary
Some embodiments may include a multi-layer flexure that may be used in an optical image stabilization voice coil motor (OIS VCM) actuator of a camera. The multi-layer flexure module may include a dynamic platform and a static platform along with multiple layers of flexure arms that mechanically connect the dynamic platform to the static platform. In some examples, the multi-layer flexure may include electrical traces configured to convey signals from the dynamic platform to the static platform. The electrical traces may be routed from the dynamic platform to the static platform via the flexure arms. In some embodiments, a multi-layer flexure may have a greater stiffness in a Z-direction aligning with an optical axis of a camera and may have a lower stiffness in X and Y directions corresponding to optical image stabilization directions of an OIS VCM actuator.