Air Pulse Speaker Driver for Compact High-Fidelity Audio
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Solution Overview
Problem
Conventional speakers face challenges in producing high-fidelity sound due to the need for multiple drivers to cover the full range of human audible frequencies, leading to large size and high production costs, and internal volume issues causing nonlinearity and distortion in sound production, especially in compact devices like smartphones and smartglasses.
Innovation Solution
A sound producing device utilizing an air pulse generating element with a membrane and a first air chamber, where the membrane is actuated to change chamber pressure and generate air pulses with a non-zero offset in sound pressure level, propagating these pulses through openings at an ultrasonic pulse rate higher than the maximum human audible frequency, effectively producing high-fidelity sound without the need for multiple drivers or large enclosures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple drivers (tweeters, mid-range drivers, woofers) are used to cover the full range of human audible frequencies, then the sound quality is improved, but the device size and production cost increase
Solution Approach 1:
The patent combines multiple driver functions into a single speaker driver by using pulse amplitude modulation to generate ultrasonic carrier waves that are modulated by the audio signal. This single driver produces both high-frequency and low-frequency sounds through the same membrane, eliminating the need for separate tweeters, mid-range drivers, and woofers while maintaining full frequency range coverage
Solution Approach 2:
The patent changes the operating parameters of the speaker driver by using ultrasonic frequency carrier waves (above 20 kHz) that are amplitude modulated by the audio signal. This parameter change allows a single driver to produce a wide frequency range, as the ultrasonic carrier enables the membrane to achieve high acceleration for high-frequency sounds while the modulation technique preserves low-frequency information
2Reliability
If multiple drivers are used to cover the full range of human audible frequencies, then the sound quality is improved, but the production cost increases
Solution Approach 1:
The patent combines multiple driver functions into a single speaker driver by using pulse amplitude modulation to generate ultrasonic carrier waves that are modulated by the audio signal. This single driver produces both high-frequency and low-frequency sounds through the same membrane, eliminating the need for separate tweeters, mid-range drivers, and woofers while maintaining full frequency range coverage
Solution Approach 2:
The speaker driver is designed to perform multiple functions simultaneously - it acts as both a high-frequency tweeter and a low-frequency woofer through the pulse amplitude modulation technique. The same driver unit covers the entire audible frequency spectrum, making it a universal component that replaces multiple specialized drivers
3Volume of moving object
If the speaker enclosure volume is reduced for compact devices, then the device size is reduced, but nonlinearity and distortion in sound production increase
Solution Approach 1:
The patent changes the operating parameters of the speaker driver by using ultrasonic frequency carrier waves (above 20 kHz) that are amplitude modulated by the audio signal. This parameter change allows a single driver to produce a wide frequency range, as the ultrasonic carrier enables the membrane to achieve high acceleration for high-frequency sounds while the modulation technique preserves low-frequency information
Solution Approach 2:
The patent employs periodic ultrasonic carrier waves that are amplitude modulated by the audio signal. This periodic action at ultrasonic frequencies allows the membrane to vibrate in a controlled manner that produces high-frequency sounds without requiring large excursions, thereby reducing distortion and nonlinearity even in small 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 device achieves high-fidelity sound production with reduced size and cost, maintaining sound pressure levels while minimizing the need for multiple drivers and large enclosures, enhancing sound quality in compact devices.
Implementation Method 1
The membrane is actuated to change a chamber pressure of the first air chamber to generate a plurality of air pulses
Implementation Method 2
the air pulses are propagated through the at least one opening, the air pulses produce a non-zero offset in terms of sound pressure level
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A sound producing device (SD) includes at least one air pulse generating element (100). Each of the at least one air pulse generating element (100) includes a membrane (120), a first air chamber (CHI) and at least one opening, wherein a chamber pressure exists in the first air chamber (CHI). The membrane (120) is actuated to change the chamber pressure of the first air chamber (CHI) to generate a plurality of air pulses, the air pulses are propagated through the at least one opening, the air pulses produce a non-zero offset in terms of sound pressure level, and the non-zero offset is a deviation from a pressure value of an ambient pressure outside the sound producing device (SD).