Camera Module Using Shape Memory Alloy Wire for OIS and AF
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Solution Overview
Problem
The increasing complexity and size of camera modules in portable electronic devices pose challenges in mounting and miniaturizing functions like autofocusing (AF) and optical image stabilization (OIS), necessitating alternative OIS driving methods.
Innovation Solution
A camera module design incorporating a support structure with movable bodies and a driving unit featuring shape memory alloy wires and springs, allowing for efficient OIS and AF operations within a limited space, utilizing multiple OIS driving units and an AF driving unit to achieve perpendicular and optical axis directional movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OIS driving methods are used, then OIS function is achieved, but camera module size increases and mounting becomes difficult
Solution Approach 1:
The patent implements nesting by placing the second movable body inside the first movable body, creating a nested configuration where the AF driving unit is housed within the OIS movable body structure. This allows multiple functional units to occupy overlapping spatial volumes, reducing the overall camera module size while maintaining both OIS and AF functions.
Solution Approach 2:
The patent utilizes the vertical dimension by arranging the first and second movable bodies in the thickness direction of the camera module. The driving units are positioned at different heights, with the OIS driving unit above the AF driving unit, enabling compact integration along the Z-axis while maintaining functional independence.
2Adaptability or versatility
If multiple driving units are integrated, then functional versatility improves, but structural complexity increases
Solution Approach 1:
The first movable body serves multiple functions: it acts as the moving platform for OIS correction and simultaneously houses the second movable body for AF adjustment. The support structure provides both mechanical support and guidance for both driving units. This multi-functionality reduces the number of separate components needed, simplifying the overall structure despite the versatility of functions achieved.
Solution Approach 2:
The patent merges the OIS and AF driving units into a single integrated assembly where both units share common structural elements. The first and second movable bodies are combined in a nested arrangement, and both driving units utilize the same support structure and guidance mechanisms, reducing structural complexity while maintaining functional independence.
3Ease of manufacture
If shape memory alloy wires are used, then manufacturing cost decreases, but driving force control becomes more challenging
Solution Approach 1:
The patent introduces coil springs as intermediary elements between the shape memory alloy wires and the movable bodies. The springs serve as mechanical mediators that convert the nonlinear force characteristics of the SMA wires into controlled linear motion, facilitating easier control of the driving force while maintaining the cost advantages of SMA materials.
Solution Approach 2:
The coil springs act as cushioning elements that pre-compress and store elastic energy, providing a controlled release of force to the movable bodies. This beforehand cushioning effect smooths out the force delivery from the SMA wires, making the driving force more controllable and predictable during operation.
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
This design enables a stroke capable of driving the OIS system within a compact camera module, reducing material costs and simplifying manufacturing while maintaining functional integrity.
Implementation Method 1
a driving wire formed of a shape memory alloy
Implementation Method 2
the driving wire is formed of a shape memory alloy and has a martensite start temperature of -20° C. or lower and an austenite finish temperature of 40° C. or lower
Implementation Method 3
a spring disposed to overlap the driving wire. The first and second movable bodies are moved by driving force applied in one direction by the driving wire, and driving force applied in another direction by the spring
Data Source
AI summary
A camera module includes a support structure having an internal space, a first movable body movably disposed inside the support structure, a second movable body elevatably disposed in an internal space of the first movable body, and a driving unit disposed in at least one of a space between the support structure and the first movable body and a space between the first movable body and the second movable body. The driving unit includes a driving wire, formed of a shape memory alloy, and a spring disposed to overlap the driving wire. The first and second movable bodies are moved by driving force applied in one direction by the driving wire, and driving force applied in another direction by the spring.