Fan Noise Cancellation via Virtual Error Signal
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Solution Overview
Problem
Computer systems face challenges in simultaneously achieving efficient heat dissipation and noise reduction, as faster fan speeds for better heat dissipation generate more noise, and the increasing heat from powerful CPUs complicates this issue.
Innovation Solution
An electronic system incorporating a fan module, embedded controller, reference microphone, micro speaker module, and ANC controller that uses a virtual error signal based on transfer functions to generate noise-cancellation signals, allowing for efficient heat dissipation while minimizing noise through active noise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fan speed is increased for better heat dissipation, then heat dissipation efficiency is improved, but noise level increases
Solution Approach 1:
The patent captures the harmful noise generated by the fan using a reference microphone, processes it through transfer functions to predict the noise at the error microphone location, and then generates an anti-noise signal through the micro speaker. This converts the harmful fan noise into a controllable signal that can be canceled, allowing the fan to operate at high speeds for effective heat dissipation without the penalty of high noise levels.
Solution Approach 2:
The patent introduces several intermediary elements: transfer functions (P(Z), C(Z), D(Z)) that mediate between the fan noise and the error microphone, a virtual error microphone that mediates the noise prediction, and a micro speaker that mediates the delivery of anti-noise signals. These intermediaries enable precise control of noise cancellation without requiring direct physical measurement at the error location.
2Measurement precision
If a physical error microphone is used for noise control, then noise cancellation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent creates a virtual copy of the error microphone's function through mathematical modeling. Instead of placing a physical microphone at the error location, the system uses transfer functions to copy and predict what the error microphone would measure based on measurements from the reference microphone. This virtual copying achieves the same measurement precision without the physical complexity of additional microphones.
Solution Approach 2:
The patent replaces the mechanical/physical approach of placing a microphone at the error location with a mathematical/digital approach using transfer functions and signal processing. The physical measurement system is substituted with a computational model that calculates the expected noise at the error microphone location based on fan noise characteristics and pre-determined transfer functions.
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 system effectively cancels noise generated by the fan module during operation, improving both heat dissipation and noise reduction without the need for a physical error microphone, enhancing the overall performance and efficiency of noise control.
Implementation Method 1
The reference microphone is configured to detect a wide-band noise generated during an operation of the fan module and provide a corresponding wide-band noise signal
Implementation Method 2
The micro speaker module is configured to generate a noise-cancellation signal according to the speaker control signal
Implementation Method 3
An electronic system normally adopts a fan capable of accelerating the exchange of air for heat dissipation purpose
Data Source
AI summary
An electronic system includes a fan module, a reference microphone, a micro speaker module, and an active noise cancellation controller. The micro speaker module provides a noise-cancellation signal according to a micro speaker control signal for canceling the noises generated during the operation of the electronic system. The reference microphone outputs a wide-band noise signal associated with the operation of the fan module. The active noise cancellation controller outputs a virtual error signal according to a first transfer function between the reference microphone and a physical microphone when the fan module operates with a predetermined fan speed, a second transfer function between the micro speaker module and the physical microphone when the fan module is not in operation, and the wide-band noise signal. The active noise cancellation controller provides the micro speaker control signal according to a synchronization signal, the wide-band noise signal and the virtual error signal.