Non-canting VCM Autofocus via Mechanical Stops
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Solution Overview
Problem
Current camera systems using voice-coil motors (VCMs) for autofocus often suffer from dynamic tilt or canting, which reduces image quality due to imbalances in springs and electromagnetic forces, especially in array cameras where misalignment affects image fusion and calibration.
Innovation Solution
The implementation of mechanical stops and corresponding stop-mates within the camera system's structure to prevent canting by defining multiple focal positions, allowing for precise mechanical alignment of lens housings relative to image sensors, thereby reducing or eliminating tilt and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If voice-coil motors with springs and electromagnets are used to move lens elements for autofocus, then the camera can achieve focusing capability, but the housing may cant or tilt reducing image quality
Solution Approach 1:
A mechanical stop is introduced as an intermediary element between the lens housing and the camera body. This stop acts as a mediator that provides a precise mechanical reference surface, ensuring the lens housing is positioned accurately without canting while still allowing the VCM to perform focusing movements. The mechanical stop thus mediates between the focusing requirement and the anti-canting requirement.
Solution Approach 2:
The patent replaces reliance on purely electromagnetic positioning with a mechanical reference system. Instead of depending solely on the balance between springs and electromagnets, a mechanical stop provides a physical reference that defines the correct lens position, substituting mechanical precision for electromagnetic control precision.
2Reliability
If multiple image sensors and lens collections are used in array cameras to capture multiple images, then high quality final images can be created through image fusion, but even small amounts of cant in any lens collection substantially reduce image quality and affect calibration
Solution Approach 1:
The mechanical stop serves as a common reference intermediary for all lens collections in the array camera. Each lens housing contacts its own mechanical stop, which provides a standardized reference surface. This ensures that all lens collections are positioned consistently relative to their respective image sensors, enabling reliable image fusion while preventing canting that would disrupt calibration.
3Ease of operation
If springs and electromagnets are not in perfect balance, then the system can still move the lens, but this causes loss of focus or misaligned image capture
Solution Approach 1:
The patent substitutes mechanical reference (the stop) for electromagnetic balance precision. Instead of requiring perfectly balanced springs and electromagnets to achieve accurate focus, the mechanical stop provides a physical reference that defines the correct lens position, making the system tolerant of imbalances in the electromagnetic components while maintaining focus accuracy.
4Manufacturing precision
If mechanical stops and stop-mates are implemented to prevent canting, then image quality and alignment are improved, but device complexity increases
Solution Approach 1:
The anti-canting function is segmented into separate mechanical stops for each lens housing rather than requiring a complex overall structure. Each lens collection has its own simple stop and stop-mate pair, dividing the complexity into manageable, identical modules that can be independently implemented and assembled.
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 approach enables higher image quality, faster focusing, lower power consumption, and reduced settling time by mechanically setting focal positions rather than relying solely on electromagnets, effectively addressing the issue of canting and enhancing the performance of VCM-actuated autofocus systems.
Implementation Method 1
A mechanical stop is provided in a camera system effective to prevent cant of a lens housing at a first focal position and at a second focal position
Implementation Method 2
Voice-Coil Motors (VCMs) are a common and conventional mechanism to autofocus a camera... VCMs use a combination of springs and electromagnetic force to adjust a position of a lens relative to an image sensor
Implementation Method 3
VCMs use a combination of springs and electromagnetic force to adjust a position of a lens relative to an image sensor
Data Source
AI summary
Techniques and apparatuses are described that enable non-canting VCM-actuated autofocus. These techniques and apparatuses enable multiple focal distances that are substantially free of imaging errors caused by canting of a lens housing. These multiple focal distances are provided by multiple positions of a lens housing relative to an image sensor. These positions can be free of cant through use of mechanical stops and corresponding mechanical stop-mates. By so doing, lower cost, faster focusing, higher image quality, lower power, or lower settling time can be achieved.