Rectangular Diaphragm Corner Radius Inversion for Stiffness

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Solution Overview

Problem

Conventional diaphragms for electroacoustic transducers have suboptimal acoustic properties due to larger mean inner radius values at inner corner regions compared to outer corner regions, leading to reduced stiffness, increased wobbling, smaller fixing surfaces, and higher mechanical stresses, which can result in tears and acoustic distortions.

Innovation Solution

The diaphragm design features smaller mean inner radius values at inner corner regions compared to larger mean outer radius values at outer corner regions, with both corner regions having the same direction of curvature, enhancing stiffness and providing a larger moving surface for sound pressure production, while maintaining mechanical stability and facilitating voice coil winding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the mean inner radius value of inner corner regions is made larger than the mean outer radius value of outer corner regions (conventional design), then the diaphragm is easier to manufacture, but the stiffness in the inner corner regions is reduced leading to increased wobbling and degraded acoustic properties

Engineering Contradiction:
Improveease of manufactureVSAvoidstiffness
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent inverts the conventional radius relationship by making the inner corner radius smaller than the outer corner radius. This reversal of the traditional design approach increases stiffness in the inner corner regions where it is most needed for acoustic performance, while still maintaining manufacturability through the consistent curvature direction design

Inventive Principle:
Principle #13The other way round (Inversion)

2Strength

If the mean inner radius value of inner corner regions is made smaller than the mean outer radius value of outer corner regions (invention), then the stiffness is increased reducing wobbling, but the manufacturing complexity increases

Engineering Contradiction:
ImprovestiffnessVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating different radius values at specific locations (inner corner vs outer corner) while maintaining the same curvature direction. This localized differentiation optimizes stiffness where needed without requiring complex manufacturing processes throughout the entire diaphragm structure

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If the inner corner regions have opposite direction of curvature compared to outer corner regions (prior art), then the manufacturing is simplified, but the fixing surface area is reduced and mechanical stresses increase leading to tears and acoustic distortions

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmechanical stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent uses asymmetry in the radius values (inner corner radius different from outer corner radius) while maintaining symmetry in the curvature direction. This asymmetric radius design with symmetric curvature direction optimizes both mechanical stability and manufacturing feasibility

Inventive Principle:
Principle #4Asymmetry

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 improves the diaphragm's stiffness, reduces wobbling, increases the sound pressure production surface, and enhances mechanical stability, leading to better playback quality and easier voice coil manufacturing with reduced mechanical stresses.

Implementation Method 1

the diaphragm inner region (20) is provided for converting between sound waves and electrical signals

Methodology Applied
Scientific EffectVibration: Vibration

Data Source

PatentEP1900248B1Diaphragm for an electroacoustic transducer, and electroacoustic transducer
Publication Date: 2013.01.02 KNOWLES ELECTRONICS ASIA
  • EP1900248B1 patent drawingFigure 1~2
  • EP1900248B1 patent drawingFigure 3~5
  • EP1900248B1 patent drawing

AI summary

A diaphragm (6) for an electroacoustic transducer is preferably designed to be essentially rectangular and has a diaphragm inner region (20) for sound conversion and a diaphragm outer region (21) for attaching the diaphragm (6) and a diaphragm intermediate region (22) which lies between the diaphragm inner region (20) and the diaphragm outer region (21), wherein the diaphragm inner region (20) is delimited toward the outside by preferably rectilinear sides (23, 24, 25, 26) and the diaphragm outer region (21) is delimited toward the inside again by preferably rectilinear sides (31, 32, 33, 34), and wherein the aforementioned sides (23, 24, 25, 26) of the diaphragm inner region (20) are joined to rounded outer corner regions (27, 28, 29, 30) with a mean outer radius value R and the aforementioned sides (31, 32, 33, 34) of the diaphragm outer region (21) are joined to rounded inner corner regions (35, 36, 37, 38) with a mean inner radius value r, wherein the mean inner radius value r of each inner corner region (35, 36, 37, 38) is smaller than the mean outer radius value R of the opposite outer corner region (27, 28, 29, 30).