Non-magnetic Stainless Steel Leaf Spring for High Thrust
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Solution Overview
Problem
Existing autofocus lens driving devices in portable compact cameras face challenges in achieving both high impact resistance and lens inclination performance, with beryllium copper leaf springs being toxic and detrimental to magnetic performance when used in VCM methods.
Innovation Solution
The use of high hardness non-magnetic stainless steel leaf springs with relative magnetic permeability greater than 1.1, designed with specific structural features such as slits and arm configurations, to support the lens holder radially and enhance thrust while maintaining impact resistance and lens alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If beryllium copper leaf spring is used, then impact resistance is improved, but magnetic performance deteriorates and environmental safety worsens
Solution Approach 1:
The patent changes the material parameter from beryllium copper to stainless steel with specific magnetic permeability (μr≥1.1), transforming the leaf spring's magnetic characteristics while maintaining mechanical strength. This material substitution eliminates toxicity and reduces magnetic interference with the VCM system.
Solution Approach 2:
The patent employs stainless steel as a composite material solution that combines mechanical strength for impact resistance with controlled magnetic permeability properties, creating a material that simultaneously addresses both structural and magnetic performance requirements.
2Strength
If leaf spring stiffness in plane direction is increased to improve impact resistance, then lens inclination performance deteriorates
Solution Approach 1:
The patent applies local quality by giving different arm portions (first and second arm portions) different cross-sectional areas, allowing each portion to have optimized stiffness characteristics. This local differentiation enables the leaf spring to provide adequate impact resistance while maintaining lens inclination precision.
Solution Approach 2:
The patent changes the structural parameter of the arm portions by varying their cross-sectional areas, transforming the uniform structure into a non-uniform one with optimized local stiffness distribution, thereby resolving the contradiction between impact resistance and lens alignment precision.
3Force
If high magnetic permeability material is used to increase thrust, then magnetic interference with VCM increases
Solution Approach 1:
The patent optimizes the magnetic permeability parameter to a specific range (μr≥1.1), transforming the material's magnetic characteristics to generate sufficient thrust through magnetic attraction while controlling the level of magnetic interference with the VCM system.
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 solution provides a lens driving device with improved impact resistance and lens inclination performance, achieving high thrust and compatibility with both impact and tilt requirements, while being environmentally friendly and non-magnetic, thus avoiding the drawbacks of beryllium copper.
Implementation Method 1
a leaf spring made of stainless steel having relative magnetic permeability which is not less than 1.1
Data Source
AI summary
A leaf spring supports a pillar shaped movable portion disposed in a center portion with respect to a cylindrical fixed portion disposed around the movable portion in the direction of a center axis shiftably so as to position the movable portion in a radial direction. The leaf spring is made of stainless steel having relative magnetic permeability which is not less than 1.1.