Auto-focus Apparatus Using Shape Memory Alloy Wire
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Solution Overview
Problem
Existing auto-focus systems in cameras require complex mechanical structures and higher costs due to the use of coils and magnets to adjust the lens position for focusing.
Innovation Solution
An auto-focus apparatus utilizing a shape memory alloy wire and a transparent elastic spacer between two lenses, where the wire changes length in response to electrical signals to adjust the distance between the lenses, thereby changing the focal length and focusing position without the need for additional mechanical components like coils and magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coils and magnets are used to adjust the lens system position, then the lens can be moved along the optical direction for focusing, but the mechanical structure becomes complicated and the cost increases
Solution Approach 1:
The patent replaces the traditional electromagnetic actuation system (coils and magnets) with a shape memory alloy wire system. The shape memory alloy wire directly converts electrical energy to mechanical deformation, eliminating the need for complex electromagnetic components and mechanical transmission structures. This substitution simplifies the overall mechanical structure while maintaining the focusing capability.
Solution Approach 2:
The patent utilizes the temperature-dependent shape memory effect of the alloy wire to change its length. By applying electrical current to heat the shape memory alloy wire, it transforms from a deformed state to its original shape, thereby changing the lens system position. This parameter change (temperature-induced length change) provides a simple and effective actuation mechanism.
2Reliability
If coils and magnets are used to adjust the focal point, then the lens system can be moved, but the device size increases due to additional mechanical components
Solution Approach 1:
The patent eliminates bulky electromagnetic actuators and their associated mechanical transmission components by using shape memory alloy wires. These wires can be made very thin and flexible, significantly reducing the volume required for the focusing mechanism. The direct actuation capability of the shape memory alloy wire eliminates the need for intermediate mechanical components, thereby compacting the device size.
Solution Approach 2:
The shape memory alloy wire acts as a flexible, thin actuator that can be integrated into the compact lens assembly. Unlike rigid electromagnetic components, the wire can be routed through tight spaces and integrated within the existing lens structure, minimizing the additional volume required for focusing functionality.
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 configuration simplifies the auto-focus system, reduces size, and lowers costs by using a SMA wire and elastic spacer to deform and adjust the lens spacing for precise focusing, enabling effective auto-focus and zoom functions without complex mechanical structures.
Implementation Method 1
a shape memory alloy wire having a first fixing part connecting with the first lens, a second fixing part connecting with the second lens, and a connecting part connecting the first fixing part to the second fixing part
Implementation Method 2
a transparent elastic spacer sandwiched between the first lens and the second lens
Data Source
AI summary
The invention provides an auto-focus apparatus for a camera. The auto-focus apparatus includes a first lens; a second lens spaced from the first lens; a transparent elastic spacer sandwiched between the first lens and the second lens; and a shape memory alloy wire having a first fixing part connecting with the first lens, a second fixing part connecting with the second lens, and a connecting part connecting the first fixing part to the second fixing part. The shape memory alloy wire can change the distance and deform the transparent elastic spacer between the first and second lenses for performing auto-focus function.