PCB Loudspeaker Coil With Variable Width Conductors
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Solution Overview
Problem
Existing electrodynamic loudspeakers suffer from distortion due to the non-linearity of the force factor for different voice coil deflections, which is exacerbated by the need for high coil designs to maintain linearity, making it challenging to achieve a compact design for planar loudspeakers.
Innovation Solution
A coil design featuring a printed circuit board with at least two windings of different widths, applied directly to the board, allowing for an extremely compact and arbitrarily shaped coil. The varying widths of the conductors compensate for non-linear areas, enabling the coil to operate linearly over its entire width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coil is designed to be high in order to achieve a linear range of the force factor, then the linearity of the force factor is improved, but the construction height increases which is disadvantageous for planar loudspeakers
Solution Approach 1:
The patent applies local quality by varying the conductor width across different radial positions in the coil. Conductors at different radii have different widths, creating non-uniform current density distribution that compensates for the non-linear magnetic field in the gap. This local variation in conductor geometry allows a low construction height while maintaining force factor linearity throughout the coil's operational range.
Solution Approach 2:
The patent changes the physical parameter of conductor width as a function of radial position. By making the conductor width variable rather than constant, the current density can be optimized at each radial position to compensate for the exponential decay of magnetic flux density with radius. This parameter change enables achieving linear force factor with reduced construction height.
2Device complexity
If conventional mechanically wound coils are used, then the coil structure is simple, but the shape and arrangement are limited and manufacturing is more expensive
Solution Approach 1:
The patent replaces the traditional mechanical winding process with a printed circuit board fabrication process. Conductors are created through printing, stamping, or laser cutting techniques directly onto the PCB substrate, eliminating the need for mechanical coiling equipment. This substitution enables arbitrary conductor shapes and arrangements while significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The printed circuit board serves multiple functions simultaneously: it provides the structural support for the coil, acts as the insulation medium, carries the conductive traces, and enables precise geometric control of conductor dimensions. This multi-functionality simplifies the overall coil structure while improving manufacturability and design flexibility.
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 coil achieves linear deflection in a magnetic field with minimal non-linear distortions, allowing for a compact design while maintaining efficient operation, which is particularly beneficial for planar loudspeakers.
Implementation Method 1
For example, a current-carrying conductor can then be held in a magnetic field. This exerts a force on the sound panel connected to the drive unit.
Implementation Method 2
the drive unit is designed as an electrodynamic drive
Data Source
AI summary
Coil, preferably for driving a loudspeaker, comprising a printed circuit board and at least two windings formed as conductors, wherein the conductors have different widths.