Projector Cooling Apparatus With Microphone-Free Fan Noise Reduction
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Solution Overview
Problem
Existing muffling apparatuses for fan noise reduction, such as those described in JP-A-2005-133588 and JP-A-10-20866, either incur high manufacturing costs due to the inclusion of microphones or have limited effectiveness in reducing a wide range of noise frequencies.
Innovation Solution
A projector and cooling apparatus configuration that utilizes a fan, loudspeaker, and control section to generate interference sound waves based on stored frequency characteristic data, eliminating the need for a microphone and effectively reducing discrete frequency, broadband, and environmental noise by interfering with noise leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microphone is used to monitor noise in the duct structure, then the noise reduction effectiveness is improved, but the manufacturing cost and apparatus size increase
Solution Approach 1:
The patent generates a copied version of the fan noise waveform through signal processing and plays it back through the loudspeaker to create destructive interference. Instead of using a microphone to detect actual noise, the system creates a synthetic anti-noise signal based on predicted noise characteristics, eliminating the need for expensive sensing hardware while maintaining noise reduction effectiveness
Solution Approach 2:
The patent replaces the mechanical/acoustic sensing system (microphone) with an electronic signal processing system. The control section processes electrical signals to generate anti-noise waveforms, substituting physical noise detection with computational waveform synthesis and playback through the loudspeaker
2Measurement precision
If a microphone is used to monitor noise, then the noise monitoring accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The system creates an accurate copy of the expected noise waveform through signal processing techniques, generating anti-noise signals that match the characteristics of actual fan noise without requiring physical microphone measurement. This approach achieves monitoring accuracy through computational methods rather than expensive hardware
Solution Approach 2:
The patent replaces expensive, delicate microphone components with more economical electronic signal processing elements. The system uses standard loudspeaker hardware and control section processing capabilities that are less costly than precision acoustic sensing equipment, making the noise reduction system more manufacturable
3Manufacturing precision
If discrete frequency noise is targeted for reduction, then the noise reduction precision is improved, but the range of noise frequencies that can be reduced is limited
Solution Approach 1:
The patent employs dynamic waveform generation that can adapt to different noise characteristics. The control section processes signals to generate anti-noise waveforms that can target specific discrete frequencies when needed, while also being capable of addressing broader frequency ranges by adjusting the signal processing parameters, making the system both precise and versatile
Solution Approach 2:
The system changes the parameters of the generated anti-noise waveform dynamically based on the noise conditions. By adjusting frequency, amplitude, and phase parameters of the synthesized anti-noise signal, the system can effectively reduce discrete frequency noise with high precision while also extending its capability to handle broader频谱 ranges
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 solution simplifies the apparatus configuration and expands the range of noise frequencies that can be reduced, achieving effective noise reduction without the need for a microphone and improving noise reduction capabilities.
Implementation Method 1
a loudspeaker that outputs a sound wave according to a drive signal inputted to the loudspeaker... generates a waveform of interference sound that interferes with the first noise... effectively reducing discrete frequency noise, broadband noise, and in-apparatus environmental noise
Data Source
AI summary
A projector includes an exterior enclosure having an intake port and a discharge port, a heat source, a fan that causes a cooling gas to flow to the heat source, a loudspeaker that is disposed between one of the two openings, and the fan in the channel of the cooling gas and outputs a sound wave according to a drive signal inputted to the loudspeaker, a characteristic data storage section that stores frequency characteristic data on the frequency characteristics of discrete frequency noise, broadband noise, and in-apparatus environmental noise, and a control section that generates the drive signal, and the control section includes a characteristic acquisition section that acquires the frequency characteristic data corresponding to the rotational speed of the fan per unit time, a waveform generation section that generates the waveform of an interference sound, and a signal output section that outputs the drive signal.