Active Vibration Cancellation in Compact Speakerphones

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Solution Overview

Problem

Designing small, high-quality speakerphones that minimize mechanical coupling between microphones and speakers is challenging due to space constraints and the non-linear nature of this coupling, which complicates echo cancellation and increases signal processing demands.

Innovation Solution

Incorporating a second speaker or actuator that generates opposing vibration forces to counteract those from the primary speaker, using an accelerometer for feedback to adjust these forces, and employing configurations like back-to-back or offset speaker placements to reduce mechanical coupling while maintaining a compact size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If rubber mounts are used to minimize mechanical coupling between speaker and microphone, then mechanical coupling is reduced, but device size increases and fragility increases

Engineering Contradiction:

Improvemechanical couplingVSAvoiddevice size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent extracts the harmful mechanical coupling effect by introducing an active counter-vibration system that generates opposing forces to cancel out the mechanical coupling between speaker and microphone, eliminating the need for passive rubber mounts that occupy space

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical isolation system (rubber mounts) with an active control system using accelerometers and signal processing to generate counter-vibration forces, substituting mechanical solution with a hybrid electro-mechanical approach

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If distance between microphone and speaker is increased to reduce acoustic and mechanical coupling, then coupling is reduced, but device size increases

Engineering Contradiction:

Improveacoustic and mechanical couplingVSAvoiddevice size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The patent converts the harmful mechanical vibrations and acoustic coupling into a beneficial effect by using the accelerometer to detect speaker vibrations and generating active counter-forces that cancel the coupling, turning the problem into a solution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the vibration parameters (amplitude, frequency, phase) of a counter-speaker or actuator to generate opposing forces that actively cancel the mechanical coupling between the primary speaker and microphone, allowing close proximity without coupling issues

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If small speakerphone size is maintained, then compactness is achieved, but mechanical coupling between microphone and speaker increases

Engineering Contradiction:

Improvedevice sizeVSAvoidmechanical coupling

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a dynamic active control system that continuously adapts to varying vibration conditions in real-time, using accelerometers to monitor speaker vibrations and dynamically adjusting counter-vibration forces to maintain effectiveness across different operating conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback loop where accelerometers mounted on the speaker and/or microphone detect vibration levels, and this information is used to adjust the counter-vibration forces from the second speaker or actuator, creating a closed-loop control system that actively maintains low mechanical coupling

Inventive Principle:

Principle #23Feedback

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

This approach effectively minimizes mechanical vibrations, simplifies design, reduces production costs, and maintains duplex functionality in small speakerphones, allowing clear communication without the need for additional vibration-reducing components.

Implementation Method 1

an accelerometer mounted in the speakerphone to determine an amount of vibration at the microphone

Methodology Applied

Scientific EffectAccelerometer detection: Accelerometer

Implementation Method 2

a second speaker or actuator, different from the first speaker or microphone, to generate opposing vibration forces

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Data Source

PatentEP3763132B1Method and system of varying mechanical vibrations at a microphone

Publication Date: 2024.05.15 MICROSOFT TECHNOLOGY LICENSING LLC

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AI summary

An improved method and system for varying an amount of mechanical coupling in a speakerphone is disclosed. Solutions and implementations provided vary the amount of mechanical coupling between one or more speakers and one or more microphones of the speakerphone to generate high-quality sounds. Implementations include receiving a signal for a first speaker, transforming the signal to send to a second speaker or actuator to generate either complementary or opposing vibration forces to those generated by the first speaker, and an accelerometer to measure the amount of vibration caused by the speaker and adjust the transformation applied to the signal to increase or decrease the amount of mechanical coupling, as needed.