Multi-Gap Speaker Coil Control for Extended Stroke Width
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Solution Overview
Problem
Existing speakers face challenges in enlarging stroke width while effectively controlling drive, as increasing winding width of the voice coil leads to reduced driving force, increased power consumption, and weight, which affects output sound pressure.
Innovation Solution
A speaker system with multiple magnetic gaps and voice coils positioned in alternating magnetic fields, using a displacement detector to control drive polarity based on coil position within these gaps, ensuring efficient drive control without excessive winding width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the winding width of the voice coil is increased to enlarge the stroke width, then the stroke width is improved, but the driving force becomes smaller
Solution Approach 1:
The voice coil is divided into multiple independent voice coils (first voice coil, second voice coil, third voice coil) arranged in the axial direction. Each voice coil has a winding width smaller than the magnetic gap width, allowing them to be independently controlled. This segmentation enables the stroke width to be enlarged through the combined displacement of multiple coils while maintaining adequate driving force from each individual coil within the magnetic gap.
Solution Approach 2:
The patent transitions from a single-voice-coil design to a multi-voice-coil design arranged in the axial dimension. By utilizing the axial direction to position multiple voice coils at different locations, the system achieves extended stroke width without requiring each individual coil to have excessive winding width, thus maintaining driving force effectiveness.
2Force
If the input gain of the voice coil is increased to increase the driving force, then the driving force is improved, but the power consumption increases
Solution Approach 1:
The patent implements dynamic control of voice coil activation based on the real-time position of the vibration system. The drive unit selectively drives only the voice coils that are currently positioned within the magnetic gap, as detected by the displacement detector. This dynamic approach ensures adequate driving force is applied only when needed, reducing unnecessary power consumption compared to continuously driving all voice coils at high gain.
Solution Approach 2:
The displacement detector provides feedback on the position of the vibration system to the drive unit. Based on this feedback, the drive unit intelligently determines which voice coils should be activated and adjusts the drive signal accordingly. This closed-loop control ensures driving force is applied efficiently without excessive power consumption.
3Length of moving object
If the winding width is increased to enlarge the stroke width, then the stroke width is improved, but the weight of the vibration system increases
Solution Approach 1:
The voice coil assembly is segmented into multiple lighter individual voice coils rather than one large heavy coil. The total stroke width is achieved through the combined effect of multiple smaller coils positioned at different axial locations, reducing the overall weight of the vibration system compared to a single large winding width coil.
Solution Approach 2:
The patent utilizes the axial dimension to arrange multiple voice coils vertically, achieving extended stroke width through spatial distribution rather than increasing the radial winding width. This dimensional approach allows stroke enlargement without proportionally increasing the weight of the vibration system.
4Length of moving object
If a single voice coil with large winding width is used to achieve large stroke width, then the stroke width is improved, but the control precision deteriorates
Solution Approach 1:
The vibration system is divided into multiple independently controllable voice coils instead of a single large coil. The displacement detector can precisely determine which specific voice coil is within the magnetic gap at any given time, enabling precise control of each segment. This segmentation improves control precision while maintaining the ability to achieve large overall stroke width through coordinated operation of multiple coils.
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 system achieves expanded stroke width with controlled drive, minimizing winding width and maintaining driving force, while avoiding asymmetric distortion and power inefficiencies.
Implementation Method 1
the first magnetic gap is configured to propagate magnetic flux in one of radial directions of the speaker, the second magnetic gap is configured to propagate magnetic flux in another of the radial directions of the speaker
Data Source
AI summary
An acoustic system provided with a speaker includes a displacement detector, and a drive unit, wherein the speaker includes a first magnetic gap, a second magnetic gap, and voice coils, wherein the first magnetic gap propagates magnetic flux in one of radial directions of the speaker, the second magnetic gap propagates magnetic flux in another of the radial directions of the speaker, a space between the first magnetic gap and the second magnetic gap in the axial direction is larger than a winding width of each of the voice coils, the vibration system vibrates between a position where at least a portion of the voice coils is positioned within the first magnetic gap and a position where at least a portion of the voice coils is positioned within the second magnetic gap, and the drive unit drives each of the voice coils using the audio signal as a drive signal.