Drop-Resistant MEMS Actuator-Imager Assembly for Six-Axis Shock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MEMS electrostatic actuators used for autofocus and optical image stabilization in cameras are vulnerable to damage from drops and severe shocks, particularly when moving parts carrying heavy loads like image sensors collide with fixed parts, leading to chipping and image quality degradation.
Innovation Solution
A drop-resistant mechanism incorporating flexible and hard stoppers within the MEMS actuator structure to decelerate and stop the moving mass along all six directions, combined with a BGA substrate package for additional support along the z-axis, using materials like Parylene and ductile components to absorb shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If MEMS actuators are used to move heavy loads like image sensors, then the actuator can achieve autofocus and optical image stabilization functions, but the actuator becomes vulnerable to damage from drops and severe shocks due to the brittle silicon material
Solution Approach 1:
The patent applies beforehand cushioning by introducing a cushioning layer between the moving mass and the package substrate. This cushioning layer is designed to deform under impact, absorbing shock energy before it reaches the brittle silicon actuator components. The cushioning layer is positioned to intercept drops and severe shocks, preventing direct contact with the actuator's moving parts and thereby preventing chipping and structural damage.
Solution Approach 2:
The patent uses an intermediary approach by introducing a cushioning layer as a mediator between the moving mass and the package substrate. This intermediary layer absorbs and dissipates impact energy through controlled deformation, protecting the brittle silicon actuator components from direct impact forces. The cushioning layer acts as a shock-absorbing intermediary that prevents harmful forces from reaching the fragile actuator structure.
2Ease of operation
If mechanical stoppers are used to stop the moving mass along in-plane axes, then the actuator can prevent excessive motion, but the stoppers cannot effectively stop the mass along the out-of-plane z-axis without causing damage to the sensor surface
Solution Approach 1:
The patent applies beforehand cushioning by positioning the cushioning layer to intercept impacts along the out-of-plane z-axis before they reach the sensor surface. The cushioning layer deforms under impact, absorbing shock energy and preventing direct contact between moving parts and the sensor surface, thereby avoiding damage while maintaining motion control capability.
Solution Approach 2:
The patent uses the cushioning layer as an intermediary between the moving mass and the sensor surface along the out-of-plane direction. This intermediary layer absorbs impact energy through controlled deformation, preventing direct transmission of forces that would damage the sensor surface while still allowing the actuator to control motion within operational parameters.
3Strength
If the moving parts are made of silicon material, then the actuator achieves the required mechanical properties, but the brittle silicon material is susceptible to chipping when moving parts collide with fixed parts during drops
Solution Approach 1:
The patent applies beforehand cushioning by introducing a cushioning layer that deforms under impact to absorb shock energy before it reaches the silicon actuator components. This prevents direct impact forces from causing chipping in the brittle silicon material, while the silicon retains its required mechanical strength for actuator operation.
Solution Approach 2:
The patent uses a cushioning layer as an intermediary between impacting objects and the silicon actuator components. This intermediary layer absorbs and dissipates impact energy through controlled deformation, preventing direct transmission of forces that would cause chipping in the brittle silicon material while allowing the silicon to maintain its structural integrity and mechanical strength.
4Force
If flexible stoppers are used to decelerate the moving mass, then the actuator can reduce impact forces, but the stoppers require precise positioning and spacing to effectively stop the mass without interfering with normal operation
Solution Approach 1:
The patent applies segmentation by dividing the stopper mechanism into multiple flexible stoppers spaced at different distances from the moving mass. Each stopper is positioned to engage at different stages of impact, providing progressive deceleration. The first stopper engages closest to the moving mass, followed by subsequent stoppers at increasing distances, creating a staged deceleration profile that reduces peak impact forces while managing complexity through modular positioning.
Solution Approach 2:
The patent uses dynamics by making the stoppers flexible rather than rigid, allowing them to deform under impact and provide progressive deceleration. The flexible nature of the stoppers enables them to adapt to impact forces dynamically, providing softer initial contact followed by increasing resistance as the impact progresses, thereby reducing peak forces while maintaining a relatively simple overall structure.
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
Prevents structural damage and maintains image quality by effectively stopping the moving parts without chipping, ensuring reliable operation under mechanical stress.
Implementation Method 1
a first set of flexible stoppers attached to the moving mass and spaced a first distance from a stationary outer periphery are used to decelerate the moving mass
Implementation Method 2
the moving mass is stopped at a second (hard stop)
Implementation Method 3
using materials like Parylene and ductile components to absorb shocks
Data Source
AI summary
A MEMS actuator assembly package features a number of drop test resistant mechanisms is disclosed. These mechanisms are used to decelerate and finally stops the heavy load of the image sensor attached to the MEMS actuators along all six directions of the in-plane and out-of-plane axes (±x, ±y, ±z). The MEMS actuator assembly package comprises first and second sets of flexible stoppers attached to the MEMS actuator along with a set of hard stoppers that engage in a sequential manner with the moving mass of the loaded actuator to decelerate it, bringing it to a complete stop when exposed to mechanical shock along the four directions of the in-plane axes (x and y). When the assembly package is exposed along the positive and negative direction of the z-axis, the moving mass is stopped by features built in the package.