Signal processing device, signal processing method, program, and rangehood apparatus

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Solution Overview

Problem

Active noise control devices face degradation in noise cancellation performance due to changes in environmental conditions such as temperature, humidity, and atmospheric pressure, as well as disturbance components like extraneous sounds, which existing technologies fail to effectively address.

Innovation Solution

A signal processing device comprising a sound cancelling filter, a coefficient calculator, and an oscillation suppressor, which calculates a second filter coefficient by applying a window function to the first filter coefficient, is used in conjunction with a sound input/output device to suppress oscillations and maintain noise cancellation performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a window function is applied to suppress degradation due to sound reflection, then noise cancellation performance degradation from reflection is reduced, but oscillation caused by environmental changes and disturbance components cannot be suppressed

Engineering Contradiction:

Improvenoise cancellation performance stabilityVSAvoidability to handle environmental changes and disturbance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies different window functions (first and second window functions with different characteristics) dynamically selected based on the operational state of the active noise control device. When oscillation is detected, the system switches to the second window function which is more effective at suppressing oscillation, while using the first window function for normal reflection suppression, thus adapting to different operational conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameters of the window function applied to the filter coefficient based on the operational state. By switching between different window function types and adjusting their application based on detected oscillation or environmental conditions, the system optimizes the balance between suppressing reflection degradation and preventing oscillation

Inventive Principle:

Principle #35Parameter changes

2Productivity

If filter coefficient is updated based on noise and synthetic sound, then noise cancellation adapts to current conditions, but oscillation and divergence occur due to environmental changes and disturbance components

Engineering Contradiction:

Improvenoise cancellation adaptabilityVSAvoidsystem stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the system continuously monitors for oscillation and disturbance components in the active noise control process. Based on this feedback, the system adjusts the application of window functions to filter coefficients, thereby stabilizing the system while maintaining adaptability to changing conditions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies window functions as a preventive measure to cushion against potential oscillation and divergence before they fully develop. By proactively applying appropriate window functions based on detected trends or initial disturbance signs, the system prevents instability while maintaining noise cancellation effectiveness

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10591169B2Signal processing device, signal processing method, program, and rangehood apparatus

Publication Date: 2020.03.17 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

In a signal processing device, a signal processing method, a recording medium, and a rangehood apparatus, a filter coefficient is set in a sound cancelling filter, and the sound cancelling filter outputs a cancellation signal. A coefficient calculator calculates a first filter coefficient. An oscillation suppressor calculates a second filter coefficient by applying a window function to the first filter coefficient to set the second filter coefficient as the filter coefficient.