Flexible PCB Capacitive Interface for Compound-Curved Audio Housings

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Solution Overview

Problem

Conventional capacitive sensing interfaces in audio devices with compound curved surfaces face issues due to mechanical stresses and detachment when using planar, flexible printed circuit boards, leading to decreased sensitivity and potential interface failure.

Innovation Solution

Incorporating a flexible printed circuit board with slits that conform to the compound curve of the inner surface, allowing the PCB to effectively adhere without high-strength adhesives and reducing mechanical stress, while also considering faceted surfaces for enhanced coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a planar, flexible PCB is used in a capacitive sensing interface on a compound curved surface, then the interface can be manufactured with conventional methods, but mechanical stresses cause detachment and interface failure

Engineering Contradiction:

Improveconventional manufacturing methodsVSAvoidinterface reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The flexible PCB is divided into multiple sections by slits that allow each section to independently conform to the compound curved surface. This segmentation enables the PCB to adapt to the curved geometry without creating excessive mechanical stress, thereby preventing detachment and improving interface reliability while still using conventional manufacturing methods

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The flexible PCB is designed with a curved configuration that matches the compound curved surface of the audio device. By incorporating curvature into the PCB design rather than using a planar board, the interface conforms to the device geometry, reducing mechanical stress and preventing detachment while maintaining reliability

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If a planar, flexible PCB is fastened to a compound curved surface, then the interface can be assembled, but stresses impact performance and cause failure

Engineering Contradiction:

Improveinterface assemblyVSAvoidinterface performance

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The physical parameters of the flexible PCB are modified by adding slits and curving it to match the compound curved surface. This changes the PCB's mechanical properties, allowing it to flex and conform to the curved geometry without creating stress concentrations that would lead to failure, thus maintaining both ease of assembly and interface performance

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4176588B1Audio device with flexible circuit for capacitive interface

Publication Date: 2023.12.27 BOSE CORP

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AI summary

Various aspects include audio devices with a capacitive sensing interface along a compound curved wall. Some aspects of the disclosure relate to wearable audio devices with a capacitive sensing interface and a flexible printed circuit board (PCB) for detecting a touch command at the interface. In certain cases, the flexible PCB has at least one slit for conforming to the compound curve of the wall. In additional implementations, the inner surface of the wall is faceted and the flexible PCB conforms to the facets in the wall.