Direct Digital Speaker Array Using Electrostatic Actuation
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Solution Overview
Problem
Current speaker technologies face limitations in generating loud sound levels without the need for high switching voltages and struggle with short stroke transducers producing insufficient sound pressure, while also requiring complex and expensive switching electronics.
Innovation Solution
A direct digital speaker apparatus comprising an array of pressure-producing elements that can produce both positive and negative pressure pulses, controlled by a timing pattern to achieve desired directivity patterns, using a combination of magnetic and electrostatic forces to enable long stroke movements without the need for high driving voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional speaker technologies use high switching voltages to generate loud sound levels, then sound pressure level is improved, but device complexity and cost increase due to high voltage switching electronics
Solution Approach 1:
The speaker system is divided into multiple independent pressure-producing elements (micro-speakers) arranged in an array. Each element can be independently controlled by simple switching electronics, eliminating the need for complex high-voltage switching circuits while achieving high sound pressure levels through constructive interference of sound waves from multiple elements.
Solution Approach 2:
The patent replaces conventional electromagnetic voice coil actuators with electrostatic micro-actuators that use electrostatic force to drive diaphragms. This substitution enables direct digital control of each micro-speaker element without requiring complex high-voltage switching electronics, as the electrostatic actuators can be driven by simple voltage switching at lower power levels.
2Length of moving object
If short stroke transducers are used to reduce device size, then compactness is improved, but sound pressure output deteriorates due to insufficient diaphragm displacement
Solution Approach 1:
Multiple short-stroke transducers are segmented and arranged in an array configuration. By simultaneously actuating multiple elements with appropriate timing and phase control, the system achieves cumulative sound pressure output that compensates for the short stroke of individual elements, maintaining compact size while delivering sufficient sound pressure.
Solution Approach 2:
The patent combines the output of multiple short-stroke transducers through coherent addition of their acoustic waves. By controlling the phase and timing of each element in the array, the sound waves merge constructively to produce high sound pressure levels, effectively combining the weak output of individual short-stroke elements into a strong collective output.
3Length of moving object
If electromagnetic actuators are used to achieve long stroke movements, then stroke length is improved, but driving voltage requirements increase
Solution Approach 1:
The patent substitutes electromagnetic actuation with electrostatic actuation for the micro-speaker elements. The electrostatic actuators use a fixed stator electrode and a movable diaphragm electrode, creating electrostatic force that directly drives the diaphragm over long strokes without requiring high driving voltages. The electrostatic force is generated by voltage switching between adjacent electrodes, enabling large displacements at low power consumption.
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 generates louder sound levels with improved sound pressure while eliminating the need for high switching voltages and complex electronics, achieving efficient sound production with a scalable and cost-effective design.
Implementation Method 1
The transducer operation based on an electromagnetic force
Implementation Method 2
an electro-acoustic transducing unit including electrostatic driving
Implementation Method 3
each moving element constrained to travel alternately back and forth along a respective axis... each moving element defining a cross section which is perpendicular to the moving element's axis
Data Source
AI summary
Direct digital speaker apparatus receiving a digital input signal and generating sound accordingly, the apparatus comprising an array of pressure-producing elements and a controller operative to compute a timing pattern determining if and when each pressure-producing element is actuated so as to achieve a desired directivity pattern.