MEMS Autofocus Camera Lens Actuation
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Solution Overview
Problem
Contemporary camera phones with fixed focus mechanisms struggle in low light conditions due to their sensitivity to ambient lighting and limited aperture, resulting in lower resolution images and increased battery consumption from frequent flash use.
Innovation Solution
A miniature autofocus camera system utilizing a MEMS stage with a magnet and coil actuator to precisely control lens movement, allowing for variable focus and reduced reliance on flash, thereby enhancing image quality and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed focus mechanism is used in camera phones, then the device size is reduced and manufacturing is simplified, but image quality deteriorates in low light conditions and resolution is limited
Solution Approach 1:
The patent implements a dynamic focus mechanism where the lens can move along the optical axis to adjust focus distance. This allows the camera to transition from a static fixed-focus design to a dynamic variable-focus system, enabling sharp imaging at different distances while maintaining compact form factor through controlled lens displacement.
Solution Approach 2:
The patent replaces traditional mechanical autofocus mechanisms with a piezoelectric actuator system. The piezoelectric element converts electrical signals directly into precise mechanical displacement of the lens, eliminating complex gears, motors, or springs while achieving accurate focus adjustment in a miniaturized package suitable for mobile phones.
2Stability of the object's composition
If a pinhole lens is used to approximate fixed focus, then depth of field is increased, but light admission is reduced and sensitivity to ambient lighting increases
Solution Approach 1:
The patent dynamically adjusts the lens aperture and position based on focusing distance requirements. By moving the lens along the optical axis and adjusting aperture size, the system optimizes the balance between depth of field and light admission for each shooting scenario, rather than using a fixed pinhole aperture that limits light in all conditions.
Solution Approach 2:
The patent changes key optical parameters including lens position along the optical axis and aperture diameter based on object distance and lighting conditions. This allows the system to maintain adequate depth of field when needed while maximizing light admission in low-light scenarios, resolving the contradiction between these two optical requirements.
3Stability of the object's composition
If a pinhole lens is used for fixed focus, then sufficient depth of field is achieved, but resolution is limited due to diffraction
Solution Approach 1:
The patent uses dynamic lens positioning to optimize the balance between depth of field and resolution. By precisely controlling lens displacement along the optical axis, the system can achieve sharp focus at specific distances while maintaining adequate depth of field, avoiding the diffraction-limited resolution of a fixed pinhole aperture.
Solution Approach 2:
The patent employs a piezoelectric actuator to precisely control lens position, enabling fine-tuned focus adjustment that maximizes resolution. This mechanical precision substitution allows the lens to be positioned exactly where needed to achieve optimal sharpness without the resolution degradation inherent in fixed pinhole designs.
4Illumination intensity
If flash mechanisms are used to provide adequate light in low light conditions, then image brightness is improved, but battery power consumption increases
Solution Approach 1:
The patent optimizes optical parameters including aperture diameter and lens position to maximize light gathering capability in low-light conditions. By adjusting these parameters to admit more ambient light, the system reduces or eliminates the need for flash illumination, thereby preserving battery power while maintaining adequate image brightness.
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 miniature autofocus camera provides improved image quality in low light conditions while minimizing the need for flash, leading to extended battery life in personal electronic devices.
Implementation Method 1
a piezoelectric element configured to move the lens along an optical axis of the camera in response to an applied voltage
Implementation Method 2
a metal cover configured to mitigate electromagnetic interference with the camera
Data Source
AI summary
A method and system for facilitating focusing of a miniature camera are disclosed. One or more lenses can be attached to a MEMS stage. The MEMS stage can be moved by a Lorentz actuator. The MEMS stage can be configured to limit movement of the lens(es) to a single degree of freedom to inhibit misalignment thereof with respect to an imaging sensor. The stage can be biased to a predefined position thereof, e.g., for focus at infinity. A metal cover can inhibit electromagnetic interference and can limit movement of the lens(es).