Electrostatic Loudspeaker With Integrated Driving Circuit
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Solution Overview
Problem
Moving-coil loudspeakers have a heavy vibration system that limits their application in portable products and exhibit poor high-frequency response and non-flat frequency characteristics, while existing electrostatic loudspeakers face challenges in achieving efficient sound radiation and miniaturization.
Innovation Solution
The electrostatic loudspeaker design incorporates a backplate with metal films, a diaphragm, and a substrate with insulative spacers, along with a driving circuit element and connection paths to form capacitors, allowing for efficient sound radiation and miniaturization, and optionally includes a shielding case to prevent electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If moving-coil loudspeaker is used, then mature manufacturing process and variety are achieved, but heavy quality and poor high-frequency response occur
Solution Approach 1:
The patent replaces the mechanical vibration system of moving-coil loudspeakers with an electrostatic field-driven system. The electrostatic loudspeaker uses a diaphragm and backplate forming a capacitor, driven by voltage signals to create electrostatic forces that move the diaphragm without mechanical coils or magnets, thereby eliminating the heavy vibration system while maintaining manufacturability through standardized electrostatic component fabrication.
2Productivity
If moving-coil loudspeaker is used, then market share is achieved, but non-flat frequency response and poor high-range performance occur
Solution Approach 1:
The patent changes the fundamental operating parameters from electromagnetic interaction to electrostatic field interaction. By using voltage-driven electrostatic forces instead of current-driven electromagnetic forces, the system achieves a flatter frequency response and better high-range performance, as the electrostatic force is directly proportional to voltage and inversely proportional to the square of the distance between diaphragm and backplate, providing more linear control over the frequency spectrum.
3Volume of moving object
If electrostatic loudspeaker is miniaturized, then portability is improved, but sound radiation efficiency may be reduced
Solution Approach 1:
The patent integrates the driving circuit element directly within the back chamber of the loudspeaker structure, nesting the electronic control components inside the acoustic housing. This eliminates the need for external amplifier boxes or separate control units, allowing the electrostatic loudspeaker to be miniaturized while maintaining sufficient power output through efficient internal signal processing and direct drive of the diaphragm-backplate capacitor.
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
This design enhances high-frequency response, reduces distortion, and achieves a compact, lightweight structure suitable for portable consumer products with improved acoustic characteristics and resistance to electromagnetic interference.
Implementation Method 1
the capacitor electrically connects with a pair of power sources to polarize the two electrodes, the diaphragm and stationary electrode, to produce an electrostatic field therebetween
Implementation Method 2
a backplate having a metal film acting as one electrode of a capacitor and defining a plurality of sound apertures therein; a diaphragm spaced a distance from the backplate insulatively to form the capacitor; the diaphragm comprising a metal film acting as the other electrode of the capacitor
Data Source
AI summary
An electrostatic loudspeaker includes a backplate having a metal film acting as one electrode of a capacitor and defining a number of sound apertures therein; a diaphragm insulatively spaced a distance from the backplate to form the capacitor; the diaphragm comprising a metal film acting as the other electrode of the capacitor; a back chamber having a substrate and an insulative spacer for joining edge portions of the diaphragm and the substrate; a driving circuit element for converting electrical signals from exterior input pads into driving signals to drive the diaphragm to vibrate and sound; the driving circuit element being mounted on an inner surface of the substrate and being accommodated in the back chamber; and a first, second and third connection paths for respectively electrically connecting the driving circuit element with the two electrodes of the capacitor, and the exterior input pads. An electrostatic loudspeaker with two backplates is also disclosed.