Biaxially Stretched Diaphragm with Dual Ridge Patterns

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Solution Overview

Problem

The production process of diaphragms for condenser microphones introduces mechanical anisotropy due to temperature-dependent tensile strength, leading to individual differences in natural resonance frequencies based on the stretched direction and orientation of the film.

Innovation Solution

A biaxially stretched film with a first pattern of large-pitched ridges and grooves and a second pattern of smaller-pitched ridges and grooves, where the second pattern is aligned along specific directions, reducing mechanical anisotropy by stabilizing tension across different orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the tension of the diaphragm is increased to improve the counteract force against adsorption to the fixed electrode, then the frequency response in the low frequency band deteriorates (limit shifts to high frequency region)

Engineering Contradiction:

Improvecounteract force against adsorptionVSAvoidfrequency response

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The diaphragm surface is divided into multiple small compartments by forming ridges and grooves. This segmentation creates multiple small diaphragm regions that vibrate independently, improving the frequency response in the low frequency band while maintaining adequate counteract force against adsorption.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If the diaphragm is made through corrugating to achieve multiple compartments, then the mechanical anisotropy becomes small, but individual differences in natural resonance frequencies occur due to temperature-dependent tensile strength during production

Engineering Contradiction:

Improvemechanical anisotropyVSAvoidnatural resonance frequency consistency

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The diaphragm employs two distinct patterns of ridges and grooves with different pitches. The first pattern has a larger pitch and the second pattern has a smaller pitch, creating local variations in stiffness distribution. This dual-pattern design compensates for temperature-dependent tensile strength variations during production, reducing individual differences in natural resonance frequencies while maintaining low mechanical anisotropy.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The diaphragm combines two different corrugation patterns (first pattern with larger pitch, second pattern with smaller pitch) into a single structure. This composite corrugation design creates a more uniform mechanical response across different orientations and temperature conditions, reducing both mechanical anisotropy and individual differences in resonance frequencies.

Inventive Principle:

Principle #40Composite materials

3Reliability

If a single pattern of ridges and grooves is used to reduce mechanical anisotropy, then the frequency response improves, but individual differences in natural resonance frequencies increase due to stretched direction dependence

Engineering Contradiction:

Improvefrequency responseVSAvoidnatural resonance frequency consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #40Composite 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

This approach results in diaphragms with reduced mechanical anisotropy, minimizing individual differences in natural resonance frequencies and improving frequency response across various orientations, even when heat is applied during the production process.

Implementation Method 1

the entire surface of the biaxially stretched film has a first pattern and a second pattern, the first pattern has ridges and grooves with a first pitch, the second pattern has ridges and grooves with a second pitch

Methodology Applied

Scientific EffectMechanical anisotropy reduction through patterned structure:

Data Source

PatentUS10123130B2Diaphragm, electroacoustic transducer, and electroacoustic transducer apparatus

Publication Date: 2018.11.06 AUDIO TECHNICA CORP

AI summary

A diaphragm is provided that has small mechanical anisotropy even when heat is applied to the diaphragm in the production process. The diaphragm includes a biaxially stretched film stretched in a first direction (the machine direction) and a second direction (the transverse direction), wherein the entire surface of the biaxially stretched film has a first pattern and a second pattern, the first pattern has ridges and grooves with a first pitch, the second pattern has ridges and grooves with a second pitch, the second pitch is smaller than the first pitch, the second pattern is formed along the first direction or the second direction, and the length of regions defined by the first pattern in the first direction differs from the length of the regions in the second direction.