Ventilative Diaphragm for Electrostatic Speaker Air Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Electrostatic speakers face challenges with air resistance and ground effect between the diaphragm and fixed electrode, leading to reduced sound pressure, especially in low frequencies, and have complex manufacturing processes with non-ventilative diaphragms that are prone to discharge and high manufacturing costs.

Innovation Solution

A ventilative diaphragm with Korean paper, featuring a hemispherical shape and fine holes, and a concave-convex surface on the fixed electrode to reduce ground effect, combined with a thermoplastic adhesive for easier manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-ventilative diaphragm is used to maintain high surface resistance and prevent discharge, then electrical stability is improved, but air resistance and ground effect increase leading to reduced sound pressure especially in low frequencies

Engineering Contradiction:

Improveelectrical stabilityVSAvoidair resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The diaphragm is designed with a porous structure that allows air to pass through, reducing air resistance and ground effect between the diaphragm and fixed electrode. This porous design maintains electrical stability while enabling better airflow, directly resolving the contradiction between electrical reliability and air resistance.

Inventive Principle:

Principle #31Porous materials

2Reliability

If the diaphragm is made non-ventilative to prevent discharge, then electrical stability is improved, but manufacturing complexity increases due to coating processes

Engineering Contradiction:

Improveelectrical stabilityVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The diaphragm uses a composite structure combining a porous base material with conductive coatings. This composite approach achieves both electrical stability through the conductive layer and airflow capability through the porous structure, while simplifying manufacturing compared to traditional multi-step coating processes on non-ventilative diaphragms.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If holes are formed in the fixed electrode to reduce ground effect, then sound pressure is improved, but the area for electrostatic force generation is reduced

Engineering Contradiction:

Improveground effectVSAvoidelectrostatic force area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

Instead of forming holes in the fixed electrode, the invention uses a porous diaphragm structure that allows airflow while maintaining a continuous electrostatic surface. This approach reduces ground effect through the diaphragm's porosity rather than electrode perforation, preserving the full electrostatic force generation area on the fixed electrode.

Inventive Principle:

Principle #31Porous materials

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 ventilative diaphragm reduces air resistance and ground effect, enhancing sound pressure and frequency reproduction across the entire frequency range, simplifying manufacturing, and allowing for uniform radial sound spread without increasing the speaker's size or complexity.

Implementation Method 1

A plurality of holes are formed in the diaphragm to ventilate air between the diaphragm and the fixed electrode, thereby reducing air resistance

Methodology Applied

Scientific EffectAir resistance reduction through ventilation: Porosity

Implementation Method 2

a concave-convex surface on the fixed electrode to reduce ground effect

Methodology Applied

Scientific EffectGround effect reduction: Ground Effect

Implementation Method 3

an electrostatic field is generated in response to the audio signal. The variable electrostatic field generated around the fixed electrode interacts with a fixed electrostatic field of the diaphragm which causes the diaphragm to be both pulled and pushed, resulting in the generation of sound

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Data Source

PatentUS8284967B2Electrostatic speaker having ventilative diaphragm

Publication Date: 2012.10.09 YANG KILSEOB

AI summary

The present invention relates to an electrostatic speaker including a fixed electrode and a diaphragm that is arranged with a predetermined gap from the fixed electrode and has a plurality of ventilation holes. The ventilative diaphragm reduces air resistance caused by the ground effect between the fixed electrode and the diaphragm, and increases the sound pressure output from the speaker. As a result, the ventilative diaphragm makes it possible to obtain a uniform frequency reproduction characteristic over the entire frequency range. In particular, when the diaphragm is made from Korean paper, it is possible to effectively reduce the ground effect occurring between the fixed electrode and the diaphragm due to the air permeable characteristic of the Korean paper and the air resistance due to a surge input signal, while satisfying physical characteristics of the existing diaphragm. In addition, since the Korean paper has high formability, it is possible to easily form the diaphragm in a hemispherical shape. As a result, it is possible to radially and uniformly spread the sound by a simple structure.