Asymmetric Prism Shaft for Compact Image Stabilization
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Solution Overview
Problem
Existing camera devices in electronic apparatuses, such as smartphones, face challenges in miniaturization due to the requirement of a large space for rocking the prism to correct image blur, as the rocking shaft does not coincide with the reflecting surface of the prism.
Innovation Solution
An optical element driving device with a supporting shaft having cylindrical end portions and a center portion with specific outer peripheral surfaces, allowing the prism to be rocked in a manner that minimizes space requirements, and a plate spring to facilitate easy return to the initial position, utilizing supporting bearings and a resin with viscoelasticity to dampen shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rocking shaft is positioned away from the reflecting surface of the prism, then the prism can be supported in a rockable manner, but a large space is required for rocking which prevents device miniaturization
Solution Approach 1:
The supporting shaft employs an asymmetric cross-sectional shape (e.g., L-shaped, T-shaped, or cross-shaped) rather than a symmetric circular shape. This asymmetric geometry allows the shaft to rock within a smaller angular range while maintaining stable support, thereby reducing the space required for rocking motion and enabling device miniaturization without compromising the rockable support function
2Reliability
If the prism is rocked at a larger angle for effective blur correction, then image blur correction performance is improved, but the device size increases
Solution Approach 1:
The asymmetric cross-sectional shape of the supporting shaft creates unequal moment arms on either side of the shaft axis. This asymmetry allows the prism to achieve effective blur correction through a smaller rocking angle, as the asymmetric geometry optimizes the optical path adjustment efficiency, thereby maintaining correction performance while reducing the required rocking amplitude and device size
3Strength
If the supporting shaft has a larger diameter for structural strength, then shock resistance is improved, but the device becomes harder to miniaturize
Solution Approach 1:
The asymmetric cross-sectional shape of the supporting shaft optimizes the distribution of structural strength. The asymmetric geometry allows strategic placement of material in high-stress regions while minimizing material in low-stress regions, achieving adequate shock resistance with a smaller overall shaft cross-sectional area compared to a symmetric design, thus enabling device miniaturization without sacrificing structural integrity
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
Enables a compact prism driving device that effectively corrects image blur while being easy to miniaturize and resistant to impacts, allowing the prism to return to its initial position efficiently.
Implementation Method 1
a resin with viscoelasticity to dampen shocks
Implementation Method 2
a plate spring to facilitate easy return to the initial position
Data Source
AI summary
An optical element driving device is described that includes a fixed portion having supporting holes, a holding member having a supporting surface formed by a supporting portion supporting an optical element, and a supporting shaft supporting the holding member with respect to the fixed portion in a rockable manner. The supporting shaft has two end portions of cylindrical shape for the supporting holes, and a center portion with first and second outer peripheral surface. The first outer peripheral surface is flush with an outer peripheral surface of the cylindrical shape along an axis line of the cylindrical shape. The second outer peripheral surface is located further inside than the first outer peripheral surface. A center of the first outer peripheral surface is on the supporting surface, and the entire second outer peripheral surface is closer to the first outer peripheral surface than the supporting surface.