Segmented Voice Coil Linear Motor for Force Linearity
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Solution Overview
Problem
Linear motors experience non-linear force issues due to non-uniform magnetic fields, leading to reduced efficiency and increased distortion at high displacements, particularly when voltage is high or frequency is low, which complicates maintaining linear force across the voice coil's range.
Innovation Solution
A linear motor design featuring a voice coil with multiple segments of varying electrical resistance, where each segment's resistance is adjusted by differing wire lengths or materials, allowing for uniform force application across displacement by strategically directing current through the coil to counteract non-uniform magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional linear motor designs (overhung or underhung) are used to maintain coupling between magnetic flux and coil, then force linearity is improved, but efficiency decreases
Solution Approach 1:
The voice coil is divided into multiple segments with different resistance values. Each segment is positioned to experience different magnetic field strengths, and by controlling current distribution through these segments, the system achieves linear force output while maintaining better efficiency than traditional overhung or underhung designs.
Solution Approach 2:
Different segments of the voice coil are assigned different electrical resistance values to create localized variations in current flow. This allows each segment to contribute differently to the overall force, compensating for non-uniform magnetic field distribution and achieving linearity without the efficiency penalties of traditional designs.
2Stability of the object's composition
If dual gap or variable coil designs are used to linearize force, then distortion is reduced, but efficiency and sensitivity decrease
Solution Approach 1:
The system dynamically adjusts current distribution across the voice coil segments based on operating conditions. By varying the effective resistance of different segments, the system can maintain optimal efficiency across different displacement positions while preserving force linearity, avoiding the fixed-geometry compromises of dual-gap designs.
Solution Approach 2:
The electrical resistance of voice coil segments is varied to optimize performance. By changing the resistance parameters of different segments, the system achieves both force linearity and high efficiency, unlike dual-gap or variable coil designs that sacrifice efficiency for linearity.
3Length of moving object
If high voltage is applied to the voice coil, then displacement capability is increased, but non-linear force and distortion increase
Solution Approach 1:
The voice coil is segmented with different resistance values, allowing independent control of current in different regions. This enables the system to handle high voltage and large displacements while maintaining force linearity, as each segment can be optimized for its local operating conditions.
Solution Approach 2:
The system uses the different resistance segments to create a feedback mechanism where current distribution automatically adjusts based on displacement position and magnetic field strength, maintaining force linearity even at high voltages and large displacements where traditional designs fail.
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 achieves linear force distribution across a wide range of displacements while maintaining high efficiency, reducing distortion and sensitivity issues associated with previous methods.
Implementation Method 1
A voltage input is applied to a voice coil which generates a magnetic field that combines with a magnetic field from permanent magnets to create a linear motor
Implementation Method 2
As current is driven through the voice coil, the coil experiences a force perpendicular to the current direction
Implementation Method 3
The voice coil includes more than one segment. Each segment of the voice coil may have differing electrical resistance
Data Source
AI summary
An improved linear motor is provided useful in conjunction with audio equipment for reduced distortion audio output at high voice coil displacements. The improved linear motor may include a yoke, a gap plate which forms an air gap with the yoke, magnets coupled to the yoke and the gap plate, a former, and a voice coil coupled to the former. The magnets generate a magnetic field across the air gap, which is relatively narrow. The former and coil fit in the air gap and may move in a vertical direction. The voice coil includes more than one segment, each having differing electrical resistance. The differing resistances cause the force on the voice coil to be uniform regardless of displacement of the voice coil vertically within the air gap. Resistance differences between the segments may be caused by differing the wire lengths making up each segment of the coil. Likewise, each segment may be made of differing material to vary resistance.