Orthogonal Noise-Cancelling Signal Segmentation for Low-Frequency Interference

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Solution Overview

Problem

Existing noise-cancelling earphones using passive and active mechanisms struggle to effectively cancel low-frequency noise due to directional mismatches in noise cancellation signals, limiting their efficiency.

Innovation Solution

An audio playback device with a noise-cancelling mechanism that includes an external sound-receiving circuit, a fixed-coefficient filtering circuit, an operation circuit, an audio playback circuit, and an adjusting circuit, which generates an inverted signal with orthogonal components and adjusts parameters using an optimization algorithm to improve noise cancellation by combining main and auxiliary inverted components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If passive noise cancellation using earplugs and earpads is used, then high-frequency noise can be reduced by 15-25 dB, but low-frequency noise cannot be cancelled

Engineering Contradiction:

Improvenoise cancellation effectivenessVSAvoidfrequency range coverage

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The noise cancellation signal is segmented into two orthogonal components (main inverted component and auxiliary inverted component) that are substantially 90 degrees out of phase. This segmentation allows the system to address different frequency ranges independently, with the main component handling primary noise cancellation and the auxiliary component providing additional coverage particularly for low-frequency noise.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a phase dimension by creating two orthogonal signal components that are substantially 90 degrees out of phase. This dimensional transformation from a single signal to multi-phase signals enables broader frequency range coverage while maintaining effective noise cancellation across different frequencies.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If active noise cancellation is used to cancel low-frequency noise, then frequency range coverage is improved, but the direction of the generated signal cannot match the noise resulting in reduced cancellation efficiency

Engineering Contradiction:

Improvefrequency range coverageVSAvoidnoise cancellation efficiency

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts the amplitude and phase of the two orthogonal signal components based on real-time noise characteristics. By making the signal components adaptive rather than fixed, the system can optimize the cancellation efficiency for different frequency ranges while maintaining broad frequency coverage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameters of the noise cancellation signal by creating two components with different phase relationships (substantially orthogonal phases) and independently adjustable amplitudes. This parameter transformation allows the system to match the direction and characteristics of noise across different frequencies, improving overall cancellation efficiency.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If a single inverted signal is generated for noise cancellation, then the system structure is simple, but the noise cancellation efficiency is limited

Engineering Contradiction:

Improvesignal processing structureVSAvoidnoise cancellation efficiency

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The single inverted signal is segmented into two orthogonal components that can be independently adjusted. This segmentation increases noise cancellation efficiency by allowing separate optimization for different frequency ranges while maintaining a relatively simple overall system structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges two orthogonal signal components (main inverted component and auxiliary inverted component) into a unified noise cancellation system. This combination allows the system to achieve improved noise cancellation efficiency across broad frequency ranges while keeping the structural complexity manageable through coordinated signal processing.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10783870B1Audio playback device and method having noise-cancelling mechanism

Publication Date: 2020.09.22 REALTEK SEMICON CORP

AI summary

An audio playback device having a noise-cancelling mechanism is provided that includes an external sound-receiving circuit that receives external noise, a fixed-coefficient filtering circuit, an operation circuit, an audio playback circuit, an internal sound-receiving circuit and an adjusting circuit. The fixed-coefficient filtering circuit generates an inverted signal including a main and an auxiliary inverted components having the same amplitude and phases orthogonal to each other according to the external noise. The operation circuit multiplies the inverted signal by adjusting parameters to generate an adjusted inverted signal. The audio playback circuit receives and playbacks an audio signal and the adjusted inverted signal to generate a playback result. The internal sound-receiving circuit receives the playback result to generate a received sound signal. The adjusting circuit generates the adjusting parameters according to an error signal between the received sound signal and the audio signal and the inverted signal.