MEMS Electrostatic Actuator Pillar Design for Camera Lens Focusing
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Solution Overview
Problem
Contemporary MEMS linear comb drives lack sufficient force and movement to be suitable for applications such as lens focusing and zooming in cellular telephone cameras, as they are limited to short distances and cannot handle heavier loads like camera lenses.
Innovation Solution
A MEMS electrostatic actuator design featuring a base and stage with interleaved pillars, where the application of voltage to selected pillars generates electrostatic forces, allowing for greater movement and force, with optional chamfering to increase surface area and enhance force generation, enabling the actuator to move camera lenses for focusing and zooming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a contemporary linear comb drive is used, then the device can move small structures over small distances, but it lacks sufficient force and movement for moving camera lenses
Solution Approach 1:
The patent transitions from a planar comb drive structure to a three-dimensional pillar-based structure. The interlaced pillars extend in the vertical dimension, creating overlapping electrostatic fields that generate significantly higher forces while maintaining a compact footprint suitable for mobile devices.
Solution Approach 2:
The actuator is segmented into multiple discrete pillars arranged in interlaced rows on the base and stage. This segmentation allows independent electrostatic actuation of each pillar, enabling precise force control and cumulative force generation across multiple pillars to achieve the required lifting force for camera lenses.
2Length of moving object
If a contemporary linear comb drive is used, then the structure is compact, but the movement distance is limited to less than the length of the electrodes
Solution Approach 1:
By extending pillars vertically and creating interlaced three-dimensional arrangements, the electrostatic interaction occurs over a larger effective area and distance. This dimensional transformation enables both increased movement range and sustained force generation throughout the travel distance, overcoming the limitation of planar comb drives.
3Area of stationary object
If contemporary motors are used to provide focusing and zooming, then sufficient force and movement are achieved, but the motors are too large for use in cellular telephones
Solution Approach 1:
The patent replaces traditional mechanical motors with an electrostatic actuation system. The interlaced pillar structure generates electrostatic forces that directly move the stage, eliminating the need for bulky mechanical motor components while achieving the required force and movement for camera lens actuation in compact mobile devices.
4Force
If the pillars are chamfered to increase surface area, then the electrostatic force is enhanced, but the manufacturing complexity increases
Solution Approach 1:
The patent modifies the pillar geometry by adding chamfers, which increases the surface area and enhances electrostatic force generation. This geometric parameter change is achieved through standard semiconductor fabrication processes, balancing performance improvement with manufacturability.
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 MEMS electrostatic actuator achieves sufficient force and distance to effectively move camera lenses, providing adjustable focus and zoom capabilities in cellular telephone cameras, with increased stability and force generation due to the three-dimensional pillar arrangement and chamfered surfaces.
Implementation Method 1
a voltage applied to selected pillars of the base and/or the stage effects the generation of electrostatic forces that cause the stage to move with respect to the base
Implementation Method 2
the base pillars and/or the stage pillars are chamfered so as to increase an amount of parallel surface area of the base pillars and the stage pillars, so as to enhance the electrostatic force between the base pillars and the stage pillars
Data Source
AI summary
In accordance with an embodiment of the present invention, an electrostatic actuator has a base having a plurality of base pillars formed thereon and has a stage having a plurality of stage pillars formed thereon. The controlled application of voltage signals to the base pillars and/or the stage pillars results in electrostatic force that effects movement of the stage with respect to the base.