Air-Pulse Volume Control for SQNR-Safe Audio Fidelity
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Solution Overview
Problem
Conventional audio systems face challenges in achieving superior audio fidelity and power efficiency due to Signal-to-Quantization Noise Ratio (SQNR) degradation and inefficient volume control mechanisms, leading to compromised sound quality and increased power consumption.
Innovation Solution
A smart volume controller utilizing an air-pulse generating device with adjustable demodulation and modulation amplitudes, along with operating frequency, to precisely control sound volume, thereby enhancing audio fidelity and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If digital volume reduction is used to control volume, then power consumption is reduced, but audio fidelity deteriorates due to SQNR degradation
Solution Approach 1:
The patent replaces the conventional electrical digital volume control mechanism with a mechanical/acoustic field-based air-pulse generating device. This device uses ultrasonic vibration to generate air pulses that directly modulate sound pressure, bypassing the need for digital signal attenuation that causes quantization noise. The substitution of electrical signal processing with acoustic field manipulation resolves the contradiction by achieving volume control without SQNR degradation.
Solution Approach 2:
The patent changes the control parameter from electrical signal amplitude (which causes quantization noise when reduced) to ultrasonic vibration frequency and air pulse density. By controlling the frequency and density of air pulses generated by ultrasonic vibration, the system achieves volume control while maintaining full digital signal resolution, thus improving audio fidelity while allowing for power optimization.
2Manufacturing precision
If DAC operates at maximum resolution for fidelity, then audio quality is improved, but power consumption increases
Solution Approach 1:
The patent extracts the volume control function from the electrical signal processing domain and relocates it to the acoustic field domain. By separating the full-resolution DAC operation from volume attenuation, the system maintains maximum signal fidelity throughout the electrical chain while using air-pulse generation as a post-DAC volume control mechanism that does not compromise signal resolution.
Solution Approach 2:
The patent introduces air pulses as an intermediary between the electrical signal and the audible sound. The air-pulse generating device converts ultrasonic vibrations into audible sound pressure waves that carry the full-resolution electrical signal information, acting as a mediator that preserves signal fidelity while enabling independent volume control through pulse density modulation.
3Device complexity
If traditional transducers are used for volume control, then device complexity is reduced, but audio quality deteriorates due to noise and linearity issues
Solution Approach 1:
The patent employs ultrasonic mechanical vibration to generate air pulses for volume control. The ultrasonic transducer vibrates at high frequency to create periodic air pressure changes that form audible sound waves. This mechanical vibration approach provides precise, linear, and noise-free volume control compared to traditional electrical attenuation methods, while maintaining relatively simple device architecture.
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 provides flexible volume control, achieving bit-perfect audio quality and reduced power consumption by addressing SQNR degradation and optimizing power usage without compromise.
Implementation Method 1
The air-pulse generating device produces sound via generating a plurality of air pulses at an ultrasonic pulse rate
Data Source
AI summary
A controller configured to control a sound producing module includes a volume controlling unit configured to determine a demodulation amplitude and a modulation amplitude corresponding to a target volume. The sound producing module comprises a driving circuit and an air-pulse generating device. The driving circuit generates a demodulation driving signal according to the demodulation amplitude and generates a modulation driving signal according to the modulation amplitude, so as to drive the air-pulse generating device. The air-pulse generating device produces sound via generating a plurality of air pulses at an ultrasonic pulse rate.