High Aspect Ratio Microspeaker Dual Plane Suspension

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Solution Overview

Problem

High aspect ratio microspeakers face stability issues due to their elongated shape, which can lead to rocking modes that decrease sound pressure output and affect audio performance in compact consumer electronics devices.

Innovation Solution

A dual suspension system is implemented, with a primary suspension member attached around the diaphragm and a secondary suspension member attached to the width sides of the voice coil, providing stability by suppressing rocking modes without interfering with the diaphragm's vibrational movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a single plane suspension system is used in high aspect ratio microspeakers, then the device can be miniaturized to fit compact consumer electronics, but the diaphragm stability deteriorates due to increased rocking modes

Engineering Contradiction:
Improvemicrospeaker sizeVSAvoiddiaphragm stability
Core Design Contradiction:
Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent introduces a second suspension plane perpendicular to the first suspension plane, transforming the single-plane suspension system into a two-plane suspension system. This dimensional addition provides stability in the rocking mode direction without increasing the footprint area, allowing the microspeaker to maintain compact size while improving diaphragm stability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If the diaphragm aspect ratio is increased to improve sound pressure output, then the audio performance is improved, but the rocking mode severity increases reducing stability

Engineering Contradiction:
Improvesound pressure outputVSAvoidrocking mode stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

By adding suspension elements in a second plane perpendicular to the first suspension plane, the patent stabilizes the diaphragm against rocking modes. This allows the use of higher aspect ratio diaphragms for improved sound pressure output without suffering from excessive rocking instability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent modifies the suspension system configuration by changing the arrangement and orientation of suspension elements, specifically adding a second plane of suspension. This parameter change in the suspension architecture enables the diaphragm to maintain stability at higher aspect ratios, thereby achieving improved sound pressure output.

Inventive Principle:
Principle #35Parameter changes

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 dual suspension system enhances the stability of high aspect ratio microspeakers, increasing the frequency at which rocking modes occur above the working range, thereby improving sound pressure output and overall audio performance in compact devices.

Implementation Method 1

A voice coil, having an upper end and a lower end, may be attached to a bottom face of the diaphragm at its upper end. The transducer may further include a magnet assembly. The magnet assembly may include a magnet and a yoke.

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Implementation Method 2

An upper suspension member and a lower suspension member. The upper suspension member may connect the sound radiating surface to the frame and be above the voice coil. The lower suspension member may connect the voice coil to the frame.

Methodology Applied
Scientific EffectMechanical suspension:

Data Source

PatentEP3170318B1High aspect ratio microspeaker having a two-plane suspension
Publication Date: 2019.05.29 APPLE INC
  • EP3170318B1 patent drawingFigure 1A~1B
  • EP3170318B1 patent drawingFigure 2~3
  • EP3170318B1 patent drawingFigure 4~6

AI summary

A microspeaker includes a frame and a diaphragm having length sides that are longer than its width sides. A magnet is positioned below the diaphragm. A yoke includes a base portion positioned below the magnet and sidewalls which extend from the base portion, the yoke sidewalls positioned only along a length dimension of the magnet. A voice coil includes an upper end attached to a bottom face of the diaphragm and a lower end positioned within a gap formed between the length dimension of the magnet and the yoke sidewalls. A first suspension member is attached to the length sides and the width sides of the diaphragm and the frame. The first suspension member is within a first plane. A second suspension member is attached to the lower end of the voice coil and the frame. The second suspension member is in a second plane different from the first plane.