PAM-Driven Speaker Architecture for Full-Range Sound Output
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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 with pulse rates higher than the maximum audible frequency, allowing a single device to produce sound with a wider frequency range without the need for multiple drivers or large enclosures, using a force-based or position-based sound producing device with membrane electrodes and a driving circuit that includes a sampling, summing, and converting module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple drivers (tweeters, mid-range drivers, woofers) are used to cover the full audible frequency range, then the frequency coverage is improved, but the device size and complexity increase
Solution Approach 1:
The patent applies a single driver that can operate across the entire audible frequency range (20Hz-20kHz) by using pulse amplitude modulation technology. The driver is driven at ultrasonic frequencies (above 20kHz) with PAM modulation, allowing it to produce audible sound through nonlinear interaction with air or mechanical resonance, thus one driver performs the function of multiple traditional drivers
Solution Approach 2:
The patent changes the operating parameters of the driver by using pulse amplitude modulation at ultrasonic frequencies. Instead of driving the driver directly at audible frequencies, the system modulates ultrasonic pulses according to the audio signal, fundamentally changing how the driver operates to achieve full frequency range coverage
2Power
If conventional speaker enclosures are used to improve low-frequency response, then the bass output is improved, but the device size increases
Solution Approach 1:
The patent replaces the traditional mechanical acoustic enclosure system with an electronic signal processing system. Instead of using large enclosures, ports, and passive radiators to achieve bass response, the system uses pulse amplitude modulation of ultrasonic frequencies to generate audible bass through nonlinear air interaction or driver mechanics, eliminating the need for large acoustic enclosures
3Power
If the pulse rate is increased above the maximum audible frequency, then the sound pressure level across frequency range is improved, but the driving signal complexity increases
Solution Approach 1:
The patent uses periodic ultrasonic pulses modulated according to the audio signal to drive the speaker. By transmitting a series of periodic pulses at ultrasonic frequencies with amplitude modulation, the system achieves high sound pressure levels while the periodic nature simplifies the driving signal generation compared to direct high-frequency sinusoidal modulation
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 apparatus achieves high sound pressure levels across a broader frequency range, including low frequencies, with reduced size and cost, by using a PAM module to drive a treble speaker or MEMS device, enabling efficient production of sound beyond the capabilities of conventional speakers.
Implementation Method 1
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
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.