Negative-Stiffness Audio Transducer Stabilization by Air Pressure Control

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Solution Overview

Problem

Conventional audio transducers with positive stiffness suspension components face efficiency losses due to the need to overcome stiffness, and negative stiffness components suffer from stability issues and instability under operational disturbances, leading to short operational lifetimes.

Innovation Solution

Implement suspension components with negative stiffness values and a stabilizer system that includes sensors, a controller, and an air pump to maintain stable operation by adjusting air pressure and using multiple control loops to accurately determine and correct the diaphragm's position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If negative stiffness suspension components are used, then power consumption is reduced and efficiency is improved, but stability deteriorates and stress concentration occurs leading to failure

Engineering Contradiction:

Improvepower consumptionVSAvoidstability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies parameter changes by transitioning from positive stiffness to negative stiffness in the suspension component design. This fundamental parameter change reduces the energy required to move the diaphragm while maintaining controlled stability through carefully engineered geometric features that distribute stress and prevent catastrophic failure under normal operating conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements beforehand cushioning through stress-distributing geometric features built into the negative stiffness suspension components. These features, designed in advance, prevent stress concentration and potential failure modes before they occur during normal operation, thereby maintaining reliability while utilizing negative stiffness for energy efficiency

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If positive stiffness suspension components are used, then stability is maintained, but power consumption increases due to stiffness resistance

Engineering Contradiction:

ImprovestabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies inversion by reversing the conventional approach to suspension stiffness. Instead of using positive stiffness to maintain stability, the patent employs negative stiffness suspension components that reduce energy consumption while incorporating geometric features to maintain adequate stability and prevent failure, thereby inverting the traditional design paradigm

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If negative stiffness suspension components are used, then efficiency is improved, but stress concentration leads to component failure

Engineering Contradiction:

ImproveefficiencyVSAvoidstress resistance

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies local quality by incorporating specific geometric features at critical locations within the negative stiffness suspension components. These localized features, such as narrowed sections and corrugated portions, are strategically placed to distribute stress and prevent concentration at weak points, thereby maintaining strength and preventing failure while preserving the efficiency benefits of negative stiffness

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12634634B2Systems and methods for stabilizing a playback device

Publication Date: 2026.05.19 SONOS INC

AI summary

A negative-stiffness audio transducer can include a frame, a voice coil, and a suspension assembly resiliently attaching the voice coil to the frame. The suspension assembly provides a negative stiffness to axial movement of the voice coil. The transducer further includes a diaphragm coupled to the voice coil such that the voice coil moves the diaphragm in an axially inward direction or an axially outward direction in response to an electrical signal. A stabilizer can be used to selectively move the diaphragm axially inward or outward to maintain the audio transducer in an operational state.