Fan Generating Pink Noise via Shutter and Blade Geometry
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Solution Overview
Problem
Existing noise generation technologies, such as acoustic white noise machines, do not effectively produce pink noise, which has equal energy per octave and is desirable for sleep, as they fail to replicate the natural distribution of sound frequencies.
Innovation Solution
A fan design that includes a movable shutter and centrifugal fan blades, allowing it to generate a pink noise sound profile both when air is exiting and not exiting through the outlet vent, by configuring the housing and fan blades to produce a specific sound pressure level across various frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fan is designed to generate pink noise, then the sound frequency distribution matches the desired pink noise profile (equal energy per octave), but the device complexity increases due to specific housing and fan blade configurations
Solution Approach 1:
The fan blades are designed with specific geometries and the housing includes particular structural features that locally modify the airflow characteristics to generate pink noise frequency distribution, rather than requiring uniform modifications throughout the entire device
Solution Approach 2:
The movable shutter mechanism allows dynamic adjustment of the outlet air vent opening, enabling the fan to maintain pink noise generation across different operating conditions while simplifying the overall design by using a single adjustable component rather than multiple fixed structures
2Productivity
If the outlet air vent is opened to allow air exit, then the fan operates with airflow, but the pink noise profile may be disrupted; if closed, then airflow is blocked but pink noise generation is maintained
Solution Approach 1:
The movable shutter enables dynamic control of the outlet air vent, allowing the system to adapt between different operating modes (airflow vs. pink noise generation) by adjusting the shutter position, thus resolving the contradiction between productivity and noise profile consistency
Solution Approach 2:
By changing the physical state of the outlet air vent from open to closed via the movable shutter, the system modifies the operating parameters to achieve different functional outcomes while maintaining pink noise generation capability across both states
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 fan generates a pink noise sound profile that closely matches the desired energy distribution per octave, with deviations within 20% of the ideal pink noise curve, making it perceptually equivalent to a digital pink noise generator, and maintains this profile regardless of the shutter position.
Implementation Method 1
the fan generates a pink noise sound profile both when air is exiting the fan housing through an air outlet vent and when air is not exiting the housing through the outlet air vent
Data Source
AI summary
A fan is provided that includes a fan blade movable relative to a housing. The housing and the fan blade are configured such that the fan generates a pink noise sound profile both when air is exiting the fan housing through an air outlet vent and when air is not exiting the housing through the outlet air vent.