Sound Chamber Design for Acoustic Testing

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Solution Overview

Problem

Conventional methods for testing and calibrating semiconductor components that convert sound into electrical signals lack precision due to the presence of standing waves, which distort test results.

Innovation Solution

A method and device where the sound chamber's greatest clear length is less than half the wavelength of the highest frequency sound wave, preventing standing waves, and a device design with a piezo module decoupled from the housing using an inertial mass member and flexible mounting to minimize vibrations and distortions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sound chambers are used for testing semiconductor components, then the testing can be performed, but standing waves distort the test results and reduce measurement precision

Engineering Contradiction:

Improvetest result accuracyVSAvoidstanding waves

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by carefully controlling the dimensional parameters of the sound chamber. Specifically, the greatest clear length of the sound chamber is limited to less than half the wavelength of the highest frequency sound wave being tested. This parameter constraint prevents standing waves from forming within the chamber, thereby eliminating their distorting effect on measurement results and improving measurement precision.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the sound chamber size is reduced to prevent standing waves, then measurement precision improves, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvetest result accuracyVSAvoidsound chamber design

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent resolves the contradiction between precision and complexity by establishing clear parameter guidelines. The sound chamber's greatest clear length is constrained to be less than half the wavelength of the highest test frequency. This parameter rule provides a straightforward design criterion that prevents standing waves while maintaining manufacturing feasibility, avoiding overly complex designs.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary approach by using a flexible mounting system with an inertial mass member. This intermediary mechanism decouples the piezo element from the housing, allowing the sound chamber to maintain its size constraints while accommodating the testing requirements without increasing overall device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If piezo elements are directly mounted in the sound chamber, then sound production is simple, but vibrations and structure-borne sound distort the measurements

Engineering Contradiction:

Improvesound wave accuracyVSAvoidvibrations and structure-borne sound

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent employs an intermediary mounting system consisting of a flexible mounting and an inertial mass member. This intermediary mechanism isolates the piezo element from direct contact with the housing and sound chamber walls. The flexible mounting allows the piezo element to vibrate freely while the inertial mass member filters out unwanted vibrations and structure-borne sound, thereby improving measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies the extraction principle by separating the piezo element from the housing structure through flexible mounting. This extraction removes the harmful connection between the piezo element and the housing that would otherwise transmit vibrations and structure-borne sound to the sound chamber, eliminating these distorting factors from the measurement system.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Enables precise and reliable testing and calibration of semiconductor components by eliminating standing waves and reducing sound distortions, ensuring accurate measurement across a wide frequency range.

Implementation Method 1

For sound production, it is known to use piezo elements, which make it possible to produce the desired frequencies in the sound chamber

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

semiconductor components which convert sound into electrical signals

Methodology Applied

Scientific EffectElectroacoustic conversion:

Implementation Method 3

an inertial mass member having a greater mass than the piezo module is arranged adjacent to the central housing part, the piezo module being supported against said member

Methodology Applied

Scientific EffectInertial damping: Inertia

Implementation Method 4

the piezo module is flexibly mounted at a distance from the side walls of said hollow chamber

Methodology Applied

Scientific EffectVibration isolation: Damping

Data Source

PatentUS8848931B2Method and device for testing and calibrating electronic semiconductor components which convert sound into electrical signals

Publication Date: 2014.09.30 COHU GMBH

AI summary

A method for testing and calibrating electronic semiconductor components which convert sound into electrical signals acoustically irradiates the components in a sound chamber whose largest free length is less than half the wavelength of the highest frequency of the sound waves produced during the test.