Single-Driver PAM Speaker for Wide-Range Sound Output
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional speakers face challenges in producing high-fidelity sound across a full range of human audible frequencies due to the need for multiple drivers and enclosures, which increases size and cost, and struggle to efficiently produce low-frequency sounds without large bass speakers.
Innovation Solution
A sound producing apparatus utilizing a pulse amplitude modulation (PAM) module to generate driving signals at a pulse rate higher than the maximum audible frequency, allowing a single sound producing device to produce sound across a wide frequency range without the need for multiple drivers or large enclosures, using a PAM-UPA scheme that creates air pulses at ultrasonic frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple drivers (tweeters, mid-range drivers, woofers) are used to cover full audible frequency range, then frequency coverage is improved, but device size and complexity increase
Solution Approach 1:
A single speaker driver is designed to perform multiple functions by responding to different signal types: sinusoidal signals for traditional audio reproduction and square wave pulses for ultrasonic air pulse generation. This allows one driver to replace what would traditionally require multiple specialized drivers, achieving full frequency coverage without increasing device complexity
Solution Approach 2:
The system dynamically changes the temporal characteristics of the driving signal (switching between sinusoidal and square wave forms) to alter the physical behavior of the same speaker driver. This parameter change enables the driver to operate in different modes (acoustic radiation vs. air pulse generation) without physical modification, resolving the contradiction between versatility and complexity
2Adaptability or versatility
If conventional speaker drivers are used to produce low frequency sounds, then bass output is improved, but device size increases due to large bass speakers
Solution Approach 1:
The system replaces the traditional mechanical approach of using large bass speakers with a different physical mechanism: ultrasonic air pulses. By generating high-frequency square wave pulses that create acoustic radiation pressure, the system produces perceptible low-frequency sound effects without requiring large mechanical displacement, thus reducing speaker size while maintaining bass capability
Solution Approach 2:
The system uses periodic square wave pulses at ultrasonic frequencies to generate air pulses that create perceptible acoustic effects. The periodic nature of these high-frequency pulses creates a pumping effect on air molecules that can be perceived as low-frequency sound, allowing small speakers to achieve bass output traditionally requiring large drivers
3Adaptability or versatility
If speaker enclosure is used to contain back-radiating wave, then sound quality is improved, but device size increases
Solution Approach 1:
The invention extracts and eliminates the need for traditional speaker enclosures by using a different sound generation mechanism. The ultrasonic air pulse generation method produces sound that radiates efficiently without requiring enclosure-based acoustic management, allowing high sound quality in compact form factors without the volume constraints of traditional enclosures
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 a compact, cost-effective sound producing device capable of producing high sound pressure levels across a wide frequency range, including low frequencies, with reduced size and harmonic distortion, while eliminating the need for separate tweeters and woofers.
Implementation Method 1
A sound producing apparatus utilizing a pulse amplitude modulation (PAM) module to generate driving signals at a pulse rate higher than the maximum audible frequency
Implementation Method 2
a sound producing device coupled to the driving circuit, configured to produce sound according to the driving signal
Data Source
AI summary
A sound producing apparatus is provided. The sound producing apparatus comprises a driving circuit, comprising a pulse amplitude modulation (PAM) module, configured to generate an driving signal according to an audio input signal, wherein the driving signal comprises a pulse amplitude modulated signal generated according to the audio input signal, the pulse amplitude modulated signal comprises a plurality of pulses at a pulse rate, two consecutive pulses among the plurality of pulses are temporally spaced by a pulse cycle, the pulse rate is a reciprocal of the pulse cycle, and the pulse rate is larger than a maximum audible frequency; and a sound producing device, coupled to the driving circuit, configured to produce sound according to the driving signal.