Folded Optics Camera with VCM Actuator for Image Stabilization
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Solution Overview
Problem
Small form factor cameras in mobile devices face challenges in achieving high-resolution imaging with optical image stabilization and autofocus, as existing mechanisms often result in unwanted motion and image quality issues due to translational and rotational vibrations.
Innovation Solution
A folded optics camera arrangement incorporating voice coil motor actuators and horizontal suspension wires, which allow motion along the optical axis for autofocus and optical image stabilization while restricting motion orthogonal to the axis, thereby minimizing image distortion and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional autofocus and optical image stabilization mechanisms are used in small form factor cameras, then focus adjustment and motion compensation functions are achieved, but translational and rotational vibrations cause unwanted motion and image quality degradation
Solution Approach 1:
The camera system is divided into separate functional modules: a lens assembly that can move independently along the optical axis for autofocus, and a prism assembly that remains relatively stable for optical image stabilization. This segmentation allows independent control of focus adjustment and motion compensation functions, reducing unwanted motion coupling between different components.
Solution Approach 2:
A movable prism assembly acts as an intermediary element between the lens and the image sensor. The prism can be independently actuated to compensate for rotational vibrations and stabilize the optical path, while the lens assembly handles focus adjustment. This intermediary structure prevents direct transmission of unwanted motions to the image sensor.
2Volume of moving object
If the camera module size is reduced for mobile device integration, then form factor requirements are met, but the effectiveness of optical image stabilization and autofocus mechanisms is compromised
Solution Approach 1:
The patent utilizes the folded optics configuration where the optical path is folded back on itself using prisms, effectively using the depth dimension (z-axis) to achieve a compact footprint. The lens assembly moves along the optical axis in a folded path, and the movable prism assembly compensates for motions in multiple dimensions, maintaining stabilization effectiveness while reducing the overall camera module volume.
Solution Approach 2:
The camera module employs a nested arrangement where the movable prism assembly is positioned within the optical path between the lens and image sensor. The prism assembly can be nested within the folded optical structure, allowing multiple functional elements to occupy overlapping spatial volumes and reducing the overall camera module size while maintaining full functionality.
3Reliability
If lens movement is allowed in all directions for comprehensive stabilization, then motion compensation is improved, but lens skew relative to the image sensor increases and image quality deteriorates
Solution Approach 1:
The patent implements directional selectivity in motion compensation: the lens assembly is constrained to move primarily along the optical axis (x-direction) for autofocus, while the movable prism assembly handles compensation for rotational vibrations in perpendicular directions (y and z directions). This local specialization of motion freedom maintains lens alignment precision while achieving comprehensive motion compensation through coordinated action of different components.
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 effectively stabilizes the camera lens system, reducing unwanted motion and maintaining image quality by allowing controlled movement along the optical axis while preventing motion that could skew the lens relative to the image sensor, thus enhancing the performance of small form factor cameras in mobile devices.
Implementation Method 1
voice coil motor actuators
Implementation Method 2
suspension springs that allow motion of the lens carrier in the carrier frame in a first direction along the optical axis, but prevent motion of the lens carrier relative to the carrier frame in directions orthogonal to the optical axis
Data Source
AI summary
Various embodiments include a camera with a folded optics arrangement and include a voice coil motor (VCM) actuator assembly to provide autofocus (AF) and/or optical image stabilization (OIS) movement. The camera with folded optics and the associated VCM actuator assembly have a first rotational normal mode of free vibration such that lenses of the camera rotate about an optical axis of the camera such that the rotational motion in the first rotational mode of free vibration is invisible from a perspective of an image sensor of the camera.