MEMS Autofocus Actuator with Snap-Out-of-Plane Deflection
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Solution Overview
Problem
Current MEMS autofocus actuators for miniature cameras face challenges in surviving impact and drop testing, and integrating a single lens element increases complexity and manufacturing issues, limiting their commercial success.
Innovation Solution
A MEMS autofocus actuator design featuring a silicon structure with electrostatic comb drive members, where deflection beams snap out of plane to displace the lens holder, allowing movement parallel to the optical axis, and resilient members prevent lateral movement, enhancing stability and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single lens element is mounted in the MEMS actuator to minimize size, then the actuator size is reduced, but the lens assembly complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The lens assembly is segmented into a lens holder component that is separately manufactured and then integrated with the MEMS actuator. This segmentation allows the lens holder to be pre-formed with precise optical positioning features, reducing assembly complexity while maintaining compact overall size.
Solution Approach 2:
A lens holder acts as an intermediary component between the MEMS actuator and the lens element. This intermediary structure simplifies the integration process by providing a dedicated mounting interface that decouples the optical positioning requirements from the actuator's moving mechanism.
2Device complexity
If the MEMS actuator is designed for compact size with deflection beams, then the structure is more integrated, but impact and drop resistance is reduced
Solution Approach 1:
The lens holder is designed with integrated cushioning features that absorb impact forces before they reach the delicate MEMS deflection beams. This beforehand cushioning protects the integrated structure from damage during drops and impacts while maintaining the compact design.
Solution Approach 2:
The lens holder utilizes composite material construction combining rigid support structures with more compliant impact-absorbing materials. This composite approach maintains structural integration for compactness while providing enhanced impact and drop resistance.
3Speed
If deflection beams are made flexible to enable lens movement, then focusing capability is improved, but lateral stability is reduced
Solution Approach 1:
The lens holder features locally differentiated structural properties: regions with high flexibility where lens movement is needed, and regions with high rigidity where lateral stability is required. This local quality variation allows the structure to simultaneously achieve fast focusing capability and lateral stability.
Solution Approach 2:
The lens holder design separates the degrees of freedom by allowing flexible deflection in the vertical dimension (enabling focusing movement) while maintaining rigid constraints in the lateral dimensions (providing stability). This dimensional differentiation resolves the contradiction between flexibility and stability.
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 design improves impact resistance and manufacturing ease while maintaining low power consumption and fast focusing speed, addressing the limitations of existing MEMS actuators.
Implementation Method 1
one or more electrostatic drive members, such as a comb drive, attached to a silicon MEMS structure
Data Source
AI summary
A micro-electro-mechanical systems (MEMS) autofocus actuator having a support member for supporting a lens element, the support member including a stationary portion and a movable portion, the movable portion attached to the stationary portion by a movable support beam. An electrostatic drive member is attached to the stationary portion and the movable portion to drive movement of the movable portion with respect to the stationary portion. A lens holder is suspended within the support member by a resilient arm member attached to the movable portion and a deflection beam attached to the stationary portion so that in a non-actuated state, the lens element is in a first focal position that is substantially out-of-plane with respect to the stationary portion, and in an actuated state, the lens element is in a second focal position, the second focal position being different from the first focal position.