Speaker Gain Compensation for Back-EMF Distortion Control
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Solution Overview
Problem
Mobile devices with integrated transducers face audio distortion due to changes in back electric motive force caused by user interactions, which affect the air dynamics and lead to collisions between the speaker membrane and the device enclosure, resulting in unpleasant audio effects.
Innovation Solution
A compensation module that determines when the transducer has moved from its equilibrium position by analyzing characteristics such as diaphragm excursion or air pressure, and adjusts the gain applied to the input signal to mitigate these distortions by attenuating the audio signal accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the transducer uses the empty space inside the device as its back volume without a separate enclosure, then the device size is minimized, but the audio performance deteriorates due to changes in air dynamics and back electric motive force
Solution Approach 1:
The system dynamically adjusts the gain of the audio signal in real-time based on detected changes in back electric motive force. The compensation module continuously monitors transducer characteristics and modifies the audio output accordingly, transforming a static system into a dynamic one that adapts to changing air pressure conditions within the shared back volume.
Solution Approach 2:
The invention implements a feedback mechanism where the compensation module detects changes in transducer characteristics (such as diaphragm excursion or air pressure) and uses this information to adjust the audio signal gain. This closed-loop feedback system compensates for back electric motive force changes caused by user interactions, maintaining audio performance despite the shared back volume configuration.
2Power
If the gain is increased to compensate for back electric motive force changes, then the audio output level is maintained, but the transducer may collide with the device enclosure causing distortion
Solution Approach 1:
The compensation module takes preliminary action by detecting back electric motive force changes and adjusting the gain before the transducer can collide with the enclosure. This preventive approach counteracts the harmful effect of reduced back EMF by proactively modifying the audio signal, preventing rather than correcting the distortion issue.
Solution Approach 2:
The system changes the gain parameter of the audio signal dynamically based on detected back electric motive force conditions. By adjusting this electrical parameter in response to mechanical conditions (air pressure changes), the system maintains optimal transducer operation without causing collisions, effectively decoupling output level from harmful mechanical effects.
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 solution effectively reduces audio distortion by dynamically adjusting the gain, preventing collisions and maintaining audio quality during user interactions, making it a robust and fast-acting method for compensating for back electric motive force changes.
Implementation Method 1
the transducer is driven by an output signal output by an amplifier, wherein the amplifier applies a gain to an input signal to generate the output signal
Implementation Method 2
a transducer in a device, wherein the transducer is driven by an output signal
Implementation Method 3
a back volume of the transducer is formed by an enclosure within the device
Data Source
AI summary
A method for compensating for a change in back electric motive force in a transducer in a device, wherein the transducer is driven by an output signal output by an amplifier, and a back volume of the transducer is formed by an enclosure within the device. The method comprises: receiving an input signal; determining, based on a characteristic of the transducer that the transducer has moved from an equilibrium position within the device; and based on the determination, adjusting a gain applied to the input signal by the amplifier to generate the output signal.