Folded Camera OIS Using Dual-Axis VCM Prism Rotation
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Solution Overview
Problem
Compact digital cameras with folded optics face challenges in achieving large optical image stabilization (OIS) movements without introducing point of view (POV) aberrations, requiring large actuators and complex corrections, and often include dual cameras with scanning zoom cameras that increase complexity.
Innovation Solution
A folded camera module comprising an optical prism for folding light from a first optical path toward a second optical path that is substantially orthogonal to the first optical path, a lens with a lens optical axis along the second optical path, an image sensor, a module frame with specific dimensions, and a voice coil motor (VCM) actuator for rotating the optical prism around two axes to perform OIS by more than ±1 degrees in each direction, with minimal distances between the prism and the frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large FOV movement is required for OIS in folded cameras, then image stabilization performance is improved, but actuator size and camera module complexity increase
Solution Approach 1:
The patent combines the OIS actuator functions for both yaw and pitch directions into a single integrated voice coil motor assembly. The first and second voice coil motors are mounted on the same actuator housing and work together to rotate the optical element holder, eliminating the need for separate actuators and reducing overall system complexity while achieving the required large stroke OIS performance
Solution Approach 2:
The patent utilizes the folded optical path geometry to achieve large angular FOV movement within a compact linear space. By folding the optical path at approximately 45 degrees using the optical element, the system can produce large angular displacements (±1 degree or more) without requiring proportionally large linear actuator travel, thus maintaining compactness while improving stabilization performance
2Device complexity
If a single VCM is used to rotate the optical prism around two axes, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces complex mechanical rotation mechanisms with electromagnetic voice coil motors to achieve precise rotational control. The voice coil motors provide controlled electromagnetic forces that can accurately position the optical element holder around both yaw and pitch axes, reducing the need for precision mechanical components such as gears, bearings, and linkages while maintaining high positioning accuracy
Solution Approach 2:
The patent introduces an optical element holder as an intermediary component that interfaces between the single integrated actuator system and the optical element. This holder provides a stable mounting platform with precise attachment points, allowing the voice coil motors to effectively control the optical element's orientation without requiring direct precision mounting of the element itself to the moving parts
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 large stroke OIS with minimal POV aberrations, using a compact and cost-effective design that minimizes distances between the optical prism and the module frame, allowing for efficient stabilization without increasing camera complexity.
Implementation Method 1
a first voice coil motor (VCM) included in a folded camera module, and operational to rotate a optical element holder around a first rotation axis and around a second rotation axis
Data Source
AI summary
Folded camera modules, comprising: an optical path folding element (OPFE) for folding light from a first optical path toward a second optical path that is substantially orthogonal to the first optical path; a lens with a lens optical axis along the second optical path and an effective focal length in the range of 5-40 mm; an image sensor; a module frame with an inner wall pointing towards the OPFE and having a module height HM, a module length LM and a module width WM; and an OPFE actuator for rotating the OPFE around a first rotation axis and around a second rotation axis that is perpendicular to the first rotation axis to perform optical image stabilization (OIS) by more than ±1 degrees around respectively, a first OIA direction and a second OIS direction, wherein a minimum distance YMin between the OPFE and the inner wall of the module frame in an extreme rotation OPFE position measured along a direction parallel to the second optical path fulfills YMin≤2 mm, wherein YMin/LM≤0.075, wherein a minimum distance XMIN between the OPFE and the inner wall of the module frame in an extreme rotation OPFE position measured along a direction perpendicular to both the first optical path and the second optical path fulfills XMin≤3 mm, and wherein XMin/WM≤0.25.