MEMS Bimorph Actuator for Compact Camera Autofocus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing camera modules in mobile devices face challenges with high power consumption and size constraints due to the use of Voice Coil Motor (VCM) for automatic focus, which limits their integration in lightweight and compact mobile electronics.
Innovation Solution
A micro electro mechanical systems (MEMS) device with a bimorph driving unit and elastic units that utilize thermal expansion differences between materials to achieve vertical displacement, reducing power consumption and size by eliminating the need for a coil and magnet, and simplifying the automatic focus mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If VCM (Voice Coil Motor) is used for automatic focus, then the lens barrel can be driven vertically, but power consumption increases and device size increases
Solution Approach 1:
The patent replaces the electromagnetic VCM system with a MEMS-based mechanical system. The driving unit uses a bimorph structure with first and second material layers having different thermal expansion coefficients that bend when heated by a heating element, directly pushing the lens barrel vertically without requiring coils, magnets, or complex electromagnetic components.
Solution Approach 2:
The patent utilizes thermal expansion differences between the first material layer and second material layer in the bimorph structure. When the heating element heats the driving unit, the layers expand at different rates causing the structure to bend, which generates the vertical force needed to move the lens barrel.
2Volume of moving object
If VCM is used for automatic focus, then the lens barrel can be driven, but the device size increases due to coil and magnet
Solution Approach 1:
The patent replaces the electromagnetic VCM system with a MEMS-based mechanical system. The driving unit uses a bimorph structure with first and second material layers having different thermal expansion coefficients that bend when heated by a heating element, directly pushing the lens barrel vertically without requiring coils, magnets, or complex electromagnetic components.
Solution Approach 2:
The patent extracts and removes the coil and magnet components from the automatic focus system. By eliminating these bulky electromagnetic components and replacing them with a compact MEMS driving unit, the overall device size is reduced while maintaining the vertical driving function.
3Ease of operation
If springs are disposed at upper and lower parts of the barrel to guide linear motion, then the lens barrel returns to initial position, but device complexity increases
Solution Approach 1:
The patent merges the return mechanism into the driving unit structure itself. The elastic layer in the bimorph structure and the frame structure provide the return force, eliminating the need for separate upper and lower springs. The driving unit automatically returns to its initial position through the elastic recovery of its own 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
The MEMS device enables low power consumption and size reduction in camera modules, allowing for more efficient and cost-effective automatic focus functionality, suitable for integration in mobile devices.
Implementation Method 1
The thermal emission layer emits heat according to the control current
Implementation Method 2
the first material layer and the second material layer have mutually different thermal expansion coefficients
Implementation Method 3
the elastic unit includes a bimorph driving unit coupled to the fixed substrate and bent according to the control current
Data Source
AI summary
The disclosure provides a MEMS device including: a fixed substrate having a cavity; a driving unit disposed in the cavity and floating above the fixed substrate; and an elastic unit for physically connecting the fixed substrate with the driving unit and varying the height of the driving unit according to a control current, wherein the elastic unit includes a bimorph driving unit connected to the fixed substrate and bent according to the control current, a spring connected to the driving unit, and a frame connecting the bimorph driving unit to the spring. Therefore, in order to overcome the limitations according to the power consumption and the size-reduction due to a coil and a magnet, the MEMS device drives one lens and thus can reduce the power consumption and the size thereof.