Voice Coil Motor Yoke Weight Reduction via Porous Segmentation
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Solution Overview
Problem
Voice coil motors used in imaging apparatuses face challenges in reducing weight while maintaining necessary thrust, as the use of magnetic materials for yokes increases weight due to their high specific gravity, and forming cutout portions to reduce weight can hinder coil movement.
Innovation Solution
A voice coil motor design featuring a yoke with a magnet holding portion and a coil insertion portion, where openings are strategically formed as rectangular slits or through-holes to reduce weight while maintaining thrust, and a trapezoidal coil shape is used to optimize thrust distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the volume of the yoke is increased to obtain necessary thrust, then the thrust is improved, but the weight is increased due to the high specific gravity of magnetic materials
Solution Approach 1:
The patent applies the porous materials principle by forming through-holes in the yoke, transforming the solid magnetic material into a porous structure. This reduces the amount of magnetic material used while maintaining the necessary magnetic flux paths, thereby reducing weight without significantly compromising thrust generation capability
Solution Approach 2:
The patent segments the yoke structure by creating through-holes that divide the solid yoke into multiple sections. This segmentation allows reduction of magnetic material volume while maintaining structural integrity and magnetic circuit functionality, resolving the contradiction between thrust and weight
2Weight of moving object
If a cutout portion is formed in the magnet holding yoke to reduce weight, then the weight is reduced, but it becomes difficult to form the magnet holding yoke and coil movement is hindered
Solution Approach 1:
Instead of forming cutout portions in the magnet holding yoke as in conventional designs, the patent inverts the approach by forming through-holes in the coil insertion portion. This reversal allows weight reduction while maintaining the magnet holding yoke's structural integrity and ease of manufacture
Solution Approach 2:
The patent extracts the weight reduction function from the magnet holding yoke and relocates it to the coil insertion portion. The through-holes are formed in the coil insertion portion rather than the magnet holding yoke, separating the weight reduction function from the magnet mounting function
3Weight of moving object
If the cross-sectional area of the magnet holding yoke is reduced to form cutout portion, then weight is reduced, but the formation of magnet holding yoke becomes difficult
Solution Approach 1:
The patent inverts the conventional approach by forming through-holes in the coil insertion portion rather than reducing the cross-sectional area of the magnet holding yoke. This maintains the magnet holding yoke's cross-sectional integrity and ease of manufacture while achieving weight reduction elsewhere
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 design achieves a necessary thrust while significantly reducing the weight of the voice coil motor, allowing for efficient movement of lenses in imaging apparatuses, improving portability and focusing speed.
Implementation Method 1
the coil is moved along the coil insertion portion by the application of current
Implementation Method 2
the coil is moved along the coil insertion portion by the application of current
Implementation Method 3
The yoke includes a magnet holding portion and a coil insertion portion that is formed in parallel with the magnet holding portion with a gap therebetween. The magnet is fixed to a surface of the magnet holding portion facing the coil insertion portion.
Data Source
AI summary
A yoke of a voice coil motor includes an outer yoke as a magnet holding portion and an inner yoke as a coil insertion portion. A magnet is fixed to the surface of the outer yoke facing the inner yoke. The inner yoke is inserted into a coil. Openings are provided toward both end positions of the outer yoke from a middle position of movement positions of the coil. The openings are formed to pass through the outer yoke. The outer yoke can be made lighter while a necessary thrust is ensured.