Voice-Coil Vibration Generator With Reverse-Field Separation
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Solution Overview
Problem
Existing vibration generating devices suffer from the issue of reverse magnetic fields affecting the voice coil, leading to uneven magnetic field strengths and forces, which degrade performance.
Innovation Solution
The device incorporates a reverse magnetic field separating portion, such as an annular recess, at the outer peripheral edge of the pole piece to redirect the reverse magnetic field away from the voice coil, ensuring balanced magnetic field strengths and forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a second magnetic circuit with a second magnet is provided to generate a reverse magnetic field, then the magnetic field strength in the magnetic gap is improved, but the reverse magnetic field acts on the voice coil causing uneven forces and performance degradation
Solution Approach 1:
The pole piece is divided into a large-diameter lower portion and a small-diameter upper portion, creating distinct magnetic circuit paths. This segmentation allows the magnetic field to be controlled in different radial zones, directing flux through desired paths while preventing reverse field formation in the voice coil region.
Solution Approach 2:
Different portions of the pole piece are given different diameters to create locally optimized magnetic properties. The lower portion has larger diameter to provide sufficient magnetic flux, while the upper portion has smaller diameter to prevent reverse field generation, allowing each region to serve its specific function.
2Ease of manufacture
If the pole piece has a uniform diameter, then the manufacturing is simplified, but the magnetic field distribution becomes uneven causing large differences in force generation
Solution Approach 1:
The pole piece intentionally uses asymmetric diameter distribution rather than uniform diameter. The lower portion has larger diameter for sufficient flux generation, while the upper portion has smaller diameter for proper field confinement, creating an asymmetric structure that optimizes magnetic field distribution.
Solution Approach 2:
The solution moves from considering only the vertical dimension to incorporating radial dimension variations. By changing the diameter (radial dimension) at different heights, the magnetic field distribution is controlled three-dimensionally, preventing reverse field formation while maintaining manufacturing feasibility.
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 design suppresses the effect of reverse magnetic fields, maintaining consistent movement forces on the voice coil and preventing performance degradation.
Implementation Method 1
a magnetic field is formed between the pole piece and the cylindrical portion
Implementation Method 2
When current flows through the voice coil, the voice coil reciprocatingly moves along the axis line
Implementation Method 3
a reverse magnetic field separating portion that is provided at an outer peripheral edge of the other end side of the pole piece, and that moves a reverse magnetic field away from the magnetic field
Data Source
AI summary
A vibration generating device includes: a first magnetic circuit including a pole piece, a first magnet, and a yoke that forms a magnetic gap between the pole piece; a second magnetic circuit including the pole piece, a second magnet and that repels the first magnet, and the yoke; a voice coil that is disposed in the magnetic gap and that vibrates while being affected by a magnetic field generated by the first magnetic circuit; and a reverse magnetic field separating portion that is provided at an outer peripheral edge of the pole piece, and that moves a reverse magnetic field, which is formed by the second magnetic circuit and which is opposite in direction to the magnetic field, away from the magnetic field.