Linear Vibration Motor Magnetic Damping for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Linear vibration motors in mobile and wearable devices experience excessive noise due to external forces causing the movable portion to shake and potentially collide with the fixed portion, leading to unwanted noise.
Innovation Solution
A linear vibration motor design featuring a conductive sheet assembly and secondary magnet set that generates an induced current and repulsive force when the movable portion moves, slowing down vibrations by interacting with the magnetic field, while elastic members provide a restoring force to manage displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable portion is supported by elastic members to provide restoring force, then the vibration function is achieved, but the movable portion may hit the fixed portion under external force causing noise
Solution Approach 1:
A magnetic damping assembly is introduced as an intermediary between the movable portion and the fixed portion. This assembly includes a conductive plate and a magnet arranged facing each other with a gap, where the conductive plate is coupled to the movable portion and the magnet is fixed to the fixed portion. When the movable portion moves, eddy currents are generated in the conductive plate due to the magnetic field, creating a damping force that prevents direct impact between the movable and fixed portions, thereby reducing noise while maintaining vibration function.
2Object-affected harmful factors
If magnetic fluid is used to reduce noise on impact, then noise is reduced, but the structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The patent replaces the magnetic fluid approach with a magnetic damping assembly consisting of a conductive plate and a magnet. This mechanical/electromagnetic system generates eddy currents when the movable portion moves relative to the magnet, creating a non-contact damping force. This substitution eliminates the need for magnetic fluid application and containment structures, simplifying manufacturing while achieving the same noise reduction effect through electromagnetic induction rather than magnetic fluid resistance.
3Object-affected harmful factors
If the conductive sheet assembly and secondary magnet set are positioned close to each other, then the damping effect is enhanced, but the risk of contact and short circuit increases
Solution Approach 1:
The magnetic damping assembly is positioned very close to the movable portion to maximize the magnetic field interaction and eddy current effect, achieving strong damping with minimal gap. The design accepts the proximity for optimal performance while relying on the non-contact nature of the electromagnetic field to prevent electrical short circuits, as the damping force is generated through magnetic field interaction rather than direct electrical contact between the conductive plate and magnet.
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 effectively reduces noise by generating a repulsive force through induced currents, thereby minimizing the impact of external forces and maintaining vibration quality.
Implementation Method 1
by arranging an electric conductor, generates an induced current when the electric conductor moves with respect to a magnetic field
Implementation Method 2
the elastic members including a first connecting part, an elastic part and a second connecting part... providing a restoring force when the movable portion being displaced
Implementation Method 3
the coil set and the main magnet set provide driving to move the movable portion to generate vibration
Data Source
AI summary
A linear vibration motor includes a fixed portion, a movable portion, and a suspension portion; the fixed portion further includes an outer frame, a coil set, a conductive sheet set, a connecting circuit and a terminal; the movable portion includes a bracket, a primary magnet set, at least a secondary magnet set; the suspension portion includes a pair of elastic members connected to the fixed portion and the movable portion, and provides a restoring force when the movable portion is displaced; the coil set and the primary magnet set provide a driving force to drive the movable portion to generate vibration; the conductive sheet set and the secondary magnet set provide damping when the movable portion moves.