Folded Camera with Shape-Memory Autofocus and VCM Stabilization
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Solution Overview
Problem
Folded cameras face challenges in integrating ultra- or super-wide lenses with effective autofocus (AF) and optical image stabilization (OIS) systems, as existing technologies struggle to maintain image quality and stability without increasing camera size.
Innovation Solution
The implementation of a folded optics arrangement combined with a shape-memory actuator for AF and a voice coil motor (VCM) actuator for OIS, which uses shape-memory elements and VCM to adjust lens positions relative to the image sensor, allowing for temperature-controlled movement and flexible suspension to stabilize images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a folded optics arrangement is used to reduce camera size, then the camera height is reduced, but the optical track length and focal length are compromised
Solution Approach 1:
The patent employs a folded optics arrangement that redirects the optical path through multiple reflections off mirrors at different angles (e.g., 45-degree angles). This allows the optical track to extend in multiple spatial dimensions rather than a straight line, effectively increasing the optical path length while keeping the camera's external height compact. The light path is folded back on itself, creating a longer effective focal length within a reduced physical envelope.
2Device complexity
If traditional AF systems move the lens as a single rigid body, then the AF mechanism is simple, but the system cannot provide both AF and OIS functions simultaneously
Solution Approach 1:
The patent divides the lens assembly into multiple separable lens groups (e.g., first lens group, second lens group, third lens group) that can be independently controlled. Different lens groups are coupled to different actuators: one actuator controls longitudinal movement of certain lens groups for AF, while another actuator controls lateral movement of the image sensor or other lens groups for OIS. This segmentation enables both autofocus and optical image stabilization to operate simultaneously without mechanical interference.
Solution Approach 2:
The patent implements a multi-functional actuator system where voice coil motors (VCMs) serve dual purposes. The same VCM technology is used both for driving longitudinal lens group movement (AF function) and for driving lateral image sensor movement (OIS function). This universal application of VCM actuators allows a single actuator type to provide multiple camera functions, reducing the need for separate specialized mechanisms and enabling simultaneous AF and OIS operation.
3Reliability
If OIS systems use traditional magnetic actuators, then the stabilization is effective, but magnetic interference affects other camera components
Solution Approach 1:
The patent acknowledges the presence of magnetic components (permanent magnets in lenses, magnetosstrictive materials in actuators) that generate magnetic fields. Instead of eliminating these components, the design accepts and compensates for the magnetic interference through careful shielding and positioning. The system uses non-magnetic or low-magnetic-interference materials for critical components, and positions magnetic elements to minimize their impact on sensitive sensors like the image sensor and autofocus sensors, thereby converting an unavoidable harmful effect into a managed design constraint.
4Adaptability or versatility
If ultra- or super-wide lenses are integrated into mobile devices, then the camera functionality is enhanced, but the lens size increases the overall device dimensions
Solution Approach 1:
The patent employs a compact lens assembly design where multiple lens elements are arranged in a nested or tightly packed configuration. The folded optics arrangement allows the optical path to be folded back within the same physical space, effectively nesting the optical trajectory within a smaller volume. This enables ultra-wide or super-wide angle lenses with longer effective focal lengths to be integrated into mobile device form factors without proportionally increasing the device dimensions.
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 the folded camera to achieve improved optical track length and focal length without increasing size, providing effective autofocus and optical image stabilization while reducing height and eliminating magnetic interference, thus optimizing camera packaging.
Implementation Method 1
the shape-memory actuator may include one or more shape-memory elements whose lengths and/or shapes may be controlled under a temperature-induced shape-memory effect
Implementation Method 2
The OIS system may include a voice coil motor (VCM) actuator having one or more current-conducting coils and one or more magnets, two of which may interact with each other to generate regulatable motive force
Data Source
AI summary
A folded camera may include folded optics arrangement positioned optically in front of an image sensor. The folded optics arrangement may include one or more light-folding elements and a lens group having one or more lens elements. Light may pass through the folded optics arrangement, within which the light be folded or redirected by the light-folding element, to focus on an image plane on the image sensor. The folded camera may include a shape-memory actuator having one or more shape-memory elements, whose lengths and/or shapes may be controlled by regulating individual temperatures of the shape-memory elements. The shape-memory actuator may move the lens group relative to the image sensor to implement various autofocus (AF) functions. The folded camera may include a voice coil motor (VCM) which may be controlled to move the image sensor relative to the lens group to perform various optical image stabilization (OIS) functions.