Headphone Cable Assembly Shielding for EMI and Sensor Reliability

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Solution Overview

Problem

Conventional wireless headphone devices face challenges with electromagnetic interference due to the distribution of electronic components between earpieces, which affects the performance of analog sensors and features like active noise cancellation, and the increased complexity of the headbow cable assembly makes manufacturability difficult.

Innovation Solution

The implementation of a cable assembly with conductors shielded from each other, such as using a spiral shield around active and power conductors, to reduce electromagnetic interference and a termination assembly to properly align and connect individual conductors to earpiece terminals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electronic components are distributed between earpieces to reduce electromagnetic interference, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improveanalog sensor performanceVSAvoidcable assembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cable assembly is segmented into multiple functional sections with different shielding configurations. Power conductors have shielding oriented in one direction while analog sensor conductors have shielding oriented in the perpendicular direction, allowing each segment to address specific interference sources independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the cable assembly have different shielding characteristics tailored to their specific functions. The power conductors receive shielding optimized for power frequency interference, while analog sensor conductors receive shielding optimized for high-frequency electromagnetic interference, ensuring each conductor type gets the appropriate level and type of protection.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If multiple conductors are placed close together in the cable assembly, then ease of manufacture is improved, but electromagnetic interference increases

Engineering Contradiction:

Improvecable assembly manufacturingVSAvoidelectromagnetic interference

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The shielding structure is rotated 90 degrees between adjacent conductor groups. This dimensional change in shielding orientation creates perpendicular magnetic shielding paths that block interference in multiple directions simultaneously, allowing conductors to be placed closer together without increasing electromagnetic interference.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

A magnetic shielding layer acts as an intermediary between adjacent conductors. This intermediate shielding structure prevents direct electromagnetic coupling between conductors while maintaining their physical proximity, thus enabling easier manufacturing without compromising electromagnetic compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If conductors are shielded with spiral shields, then electromagnetic interference is reduced, but device complexity increases

Engineering Contradiction:

Improvesignal distortionVSAvoidcable assembly structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Multiple shielding functions are merged into a single integrated cable assembly structure. The spiral shields for different conductor groups are combined in a way that they work together synergistically, reducing overall electromagnetic interference while avoiding the complexity of separate shielding systems for each conductor.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cable assembly structure is designed to provide universal electromagnetic protection across different conductor types. The same basic spiral shield configuration serves multiple functions: protecting power conductors from high-frequency interference and protecting analog sensor conductors from power frequency interference, simplifying the overall design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution reduces electromagnetic interference, improves the performance of analog sensors, and simplifies the manufacturability of the headphone device by minimizing signal distortion and aligning conductors effectively.

Implementation Method 1

a shield at least partially disposed between the one or more power conductors and the one or more microphone conductors

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS11778359B2Cable assemblies for headphone devices

Publication Date: 2023.10.03 SONOS INC

AI summary

Headphone playback devices can include a cable assembly including a plurality of conductors extending between a first earpiece and a second earpiece. The cable assembly includes a jacket, a power conductor disposed within the jacket and coupled between a power source in the first earpiece and a wireless transceiver in the second earpiece. The cable assembly further includes a microphone conductor at least partially disposed within the jacket and coupled to a microphone in one of the earpieces. A shield is at least partially disposed between the power conductor and the microphone conductor to reduce electromagnetic interference between the two.