Spring Metal Foil Thickness Control for Camera Leaf Springs
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Solution Overview
Problem
The challenge lies in achieving uniform thickness in high-hardness metal foils for leaf springs used in camera module drive mechanisms, as variations in thickness lead to inconsistent spring load and deflection, necessitating precise control of thickness differences in both rolling and width directions to minimize variations in spring width.
Innovation Solution
A metal foil with a first region having a square shape, where the difference in thickness values between maximum and minimum points in the rolling and width directions is controlled to ensure an absolute difference of less than or equal to 0.8 μm, allowing for consistent spring member formation through careful rolling and annealing processes, and subsequent wet-etching to maintain desired shape and isotropic etching balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-hardness metal is used for the leaf spring to satisfy spring load and deflection requirements, then the spring performance is improved, but the difficulty of achieving uniform thickness through rolling increases
Solution Approach 1:
The patent applies parameter changes by controlling the difference value between maximum and minimum thickness in the rolling direction versus the width direction to be within a specific range (absolute value less than or equal to 0.8 μm). This quantitative parameter control enables uniform thickness achievement in high-hardness metal foils that are difficult to process through conventional rolling alone.
2Ease of manufacture
If the metal foil thickness varies, then the amount of etching varies during wet-etching, but this causes variations in the width of the leaf spring in the thickness direction
Solution Approach 1:
The patent applies preliminary action by controlling the thickness uniformity of the metal foil before the wet-etching process. By ensuring the difference value between maximum and minimum thickness values meets the specified condition prior to etching, the patent prevents etching-induced width variations, thereby maintaining spring width consistency without requiring complex etching process adjustments.
3Ease of manufacture
If conventional rolling is used on high-hardness metal foil, then production is simpler, but the thickness uniformity deteriorates
Solution Approach 1:
The patent applies feedback by establishing a quantitative criterion (the difference value condition between thickness variations in rolling and width directions) that provides measurable feedback on rolling quality. This feedback mechanism enables continuous monitoring and adjustment of the rolling process to maintain thickness uniformity within the required tolerance, balancing manufacturing simplicity with precision requirements.
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 approach limits variations in spring width and thickness, ensuring consistent spring performance and durability by maintaining precise thickness control, which enhances the reliability of camera module drive mechanisms.
Implementation Method 1
A metal foil, which is the raw material for the leaf spring, is thinned to a predetermined thickness through rolling
Implementation Method 2
The leaf spring is formed by wet-etching a metal foil
Data Source
AI summary
A metal foil includes a first region on which the spring member is formed. The first region has a square shape with one side being 300 mm. A difference value between a maximum value and a minimum value of a first thickness at each of points on a straight line in a rolling direction in the first region is a first difference value. A difference value between a maximum value and a minimum value of a second thickness at each of points on a straight line in a width direction orthogonal to the rolling direction is a second difference value. An absolute value of the difference value obtained by subtracting the second difference value from the first difference value is less than or equal to 0.8 μm.