Resonant Demodulation Circuit for Low-Power Air Pulse Audio
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Solution Overview
Problem
Conventional speakers face challenges in covering the entire audio frequency band from 20 Hz to 20 KHz with high fidelity and sound pressure level, and ultrasonic air pulse generators consume high power, making them unsuitable for portable devices.
Innovation Solution
A demodulation signal generator coupled to an air-pulse generator, utilizing a resonance circuit and a flap pair to perform differential movement, generating demodulation signals with opposite polarity to drive the ultrasonic air pulse generator, reducing power consumption through energy recycling and resonance operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional speakers are used to cover the entire audio frequency band with high fidelity, then the radiating surface and back enclosure volume must be sufficiently large, but this increases device size and weight
Solution Approach 1:
The patent replaces the conventional mechanical speaker system (requiring large back enclosure and radiating surface) with an ultrasonic air pulse generator that uses electrostatic actuation to generate sound waves directly in air, eliminating the need for large mechanical structures
Solution Approach 2:
The invention changes the operating frequency parameter to ultrasonic range (above 20kHz) and uses pulse-width modulation to generate audible sound through parametric acoustic effect, allowing compact device size while maintaining sound quality
2Productivity
If ultrasonic air pulse generator operates at ultrasonic rate, then air pulses can be generated, but power consumption becomes high which is not suitable for portable devices
Solution Approach 1:
The patent uses periodic pulsed voltage signals with specific duty cycles to drive the ultrasonic air pulse generator, allowing the system to operate at ultrasonic frequencies while consuming low power during the off-periods of the pulse cycle
Solution Approach 2:
The invention optimizes the voltage amplitude and pulse width parameters to achieve efficient ultrasonic operation, and uses resonant frequency matching to maximize acoustic output while minimizing power consumption
3Power
If high power is supplied to ultrasonic air pulse generator, then sufficient sound pressure level is achieved, but this is not suitable for portable or consumer electronic devices
Solution Approach 1:
The patent exploits mechanical resonance of the diaphragm and air column at specific frequencies to amplify sound pressure level without requiring high input power, achieving efficient acoustic output through resonant vibration
Solution Approach 2:
The invention incorporates feedback control to optimize the driving signal parameters in real-time, ensuring maximum acoustic efficiency and minimum power consumption for the required sound pressure level
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 enables low-power operation of ultrasonic air pulse generators, effectively addressing the power consumption issue while maintaining high fidelity sound reproduction, suitable for portable devices.
Implementation Method 1
The resonance circuit and the flap pair co-perform a resonance operation, such that the first demodulation signal and the second demodulation signal are generated via the co-performed resonance operation
Implementation Method 2
a modulated air pressure variation generated by the film structure
Implementation Method 3
The resonance circuit and the flap pair co-perform a resonance operation
Data Source
AI summary
A demodulation signal generator, coupled to an air-pulse generator comprising a flap pair, includes a resonance circuit. The resonance circuit produces a first demodulation signal and a second demodulation signal. The resonance circuit and the flap pair co-perform a resonance operation, such that the first demodulation signal and the second demodulation signal are generated via the co-performed resonance operation and have opposite polarity. The flap pair performs a differential movement to form an opening to perform a demodulation operation on a modulated air pressure variation.