Armature Acoustic Receiver Pre-Distortion for Linearity
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Solution Overview
Problem
Armature-based receivers exhibit non-linear transfer characteristics due to changing permeability, magnetic saturation, and mechanical hysteresis, leading to distortion and reduced sound pressure level (SPL) output, especially when over-magnetized, which limits their acoustic output accuracy and efficiency.
Innovation Solution
A pre-distorted electrical excitation signal is generated using a computable non-linear function to compensate for the non-linearity in armature-based receivers, improving their performance by reducing distortion and increasing SPL for a specified distortion level or enhancing linearity for a specified SPL, through a feed-forward system that adapts to changes in receiver characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard electrical excitation signal is applied to the armature-based receiver, then the receiver operates with simple drive circuitry, but the output exhibits distortion and reduced SPL due to non-linear transfer characteristics
Solution Approach 1:
The patent applies pre-distortion to the electrical excitation signal before it is applied to the armature-based receiver. The pre-distorted signal is generated by applying a non-linear function to the input signal, which compensates for the receiver's non-linear transfer characteristic. This preliminary action corrects the distortion before it occurs in the receiver, improving acoustic output accuracy without requiring complex feedback systems.
Solution Approach 2:
The patent modifies the electrical excitation signal parameters by applying a pre-distortion function that alters the signal's amplitude and phase characteristics. This parameter change compensates for the receiver's non-linear behavior, transforming the signal to achieve linear output characteristics despite the receiver's inherent non-linearity.
2Power
If the receiver operates at higher SPL levels, then the acoustic output is stronger, but distortion increases due to magnetic saturation and mechanical hysteresis
Solution Approach 1:
The pre-distortion function is designed to compensate for the receiver's non-linear behavior at higher SPL levels. By pre-correcting the excitation signal with an inverse non-linear function, the system maintains low distortion even when operating at high sound pressure levels, allowing strong acoustic output without sacrificing accuracy.
3Power
If the receiver uses over-magnetization to increase sensitivity, then the output SPL is improved, but distortion increases due to magnetic saturation
Solution Approach 1:
The patent applies a pre-distortion function that compensates for the effects of over-magnetization and magnetic saturation. By modifying the excitation signal parameters to account for the non-linear magnetic characteristics, the system maintains high sensitivity while reducing distortion caused by magnetic saturation in the over-magnetized state.
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 pre-distorted signal effectively reduces total harmonic distortion (THD) and increases SPL by up to 4 dB for a specified distortion level, even in over-magnetized receivers, resulting in a more accurate and efficient acoustic output.
Implementation Method 1
Application of the excitation or input signal to the receiver coil modulates the magnetic field, causing deflection of the reed between the magnets
Implementation Method 2
The coil is disposed about a portion of an armature (also known as a reed), a movable portion of which is disposed in equipoise between magnets
Implementation Method 3
Armature-based receivers exhibit non-linear transfer characteristics due to changing permeability, magnetic saturation, and mechanical hysteresis
Implementation Method 4
Armature-based receivers exhibit non-linear transfer characteristics due to changing permeability, magnetic saturation, and mechanical hysteresis
Data Source
AI summary
A pre-distorted electrical excitation signal is generated for an acoustic transducer having an armature and a non-linear transfer characteristic by applying an electrical input signal (x) representative of a desired acoustic output to a computable non-linear function that is a function of the electrical input signal (x). When applied to an input of the transducer, the pre-distorted electrical excitation signal results in an improved acoustic output signal.