Capacitive Touch Assembly Using Elastic Conductor

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Solution Overview

Problem

Capacitive touch assemblies in control panels are costly and complex to manufacture due to the need for high-cost conductive materials and specialized attachment processes, which increase production costs and complexity.

Innovation Solution

A capacitive touch assembly using an elastic conductor pre-compressed between a cover plate and a printed circuit board assembly, eliminating the need for foils and specialized attachment processes, with a helical section and fishhook-like structure for reliable electrical connection and tactile feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If wires are integrated on a foil and attached to a panel film by gluing, then capacitive sensing touch function is realized, but manufacturing cost increases and process complexity rises

Engineering Contradiction:
Improvecapacitive sensing touch functionVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the foil component from the traditional capacitive touch assembly. Instead of using a foil with integrated wires that requires gluing to a panel film, the invention uses a printed circuit board assembly with conductive patterns directly formed on the board. This extraction of the foil component simplifies the manufacturing process by eliminating the need for special attachment machinery and gluing processes, while maintaining the capacitive sensing touch function through the printed circuit board structure.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If silver paste line, indium tin oxide (ITO), and/or PEDOT are printed on the foil, then conductive pathways are formed, but material cost increases

Engineering Contradiction:
Improveconductive pathwayVSAvoidconductive material cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent replaces expensive conductive materials like silver paste, ITO, and PEDOT that are used on foils with standard printed circuit board trace materials. The conductive pathways are formed using conventional PCB fabrication processes with copper traces and standard solder masks, which are significantly cheaper than the specialized conductive materials required for foil-based capacitive touches. This substitution maintains the conductive pathway functionality while dramatically reducing material costs.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If a connector is required to connect the foil to a printed circuit board, then electrical connection is established, but cost rises

Engineering Contradiction:
Improveelectrical connectionVSAvoidconnector cost
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges the foil, connector, and printed circuit board into a single integrated printed circuit board assembly. The capacitive touch elements are directly printed or formed as conductive patterns on the PCB itself, eliminating the need for separate foil components and external connectors. The electrical connections are established through the PCB's internal copper traces and vias, which are inherently part of the board structure. This merging of components eliminates connector costs and simplifies the overall assembly.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If panel film is attached to foil by using a special film applicator, then attachment is achieved, but process complexity and requirements increase

Engineering Contradiction:
ImproveattachmentVSAvoidmanufacturing ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the panel film attachment step from the manufacturing process. By using a printed circuit board assembly where the capacitive touch elements are directly formed on the PCB, the invention removes the need for a separate panel film and the specialized film applicator required to attach it. The PCB itself serves as both the structural support and the capacitive sensing element, eliminating the multi-step attachment process and its associated complexity and quality requirements.

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

This design reduces material and process costs, simplifies manufacturing, and provides a better tactile experience by ensuring consistent contact and tactile feedback similar to physical press keys.

Implementation Method 1

capacitive sensing touch function... the elastic conductor can convert a mechanical touch signal into an electrical signal

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

elastic conductor... provides a better tactile experience by ensuring consistent contact and tactile feedback similar to physical press keys

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3419174B1Capacitive touch assembly and control panel
Publication Date: 2021.03.03 VALEO COMFORT & DRIVING ASSISTANCE
  • EP3419174B1 patent drawingFigure 1~2
  • EP3419174B1 patent drawingFigure 3~4
  • EP3419174B1 patent drawingFigure 5~6

AI summary

The present invention provides a capacitive touch assembly including a cover plate (22) and a printed circuit board assembly (25). The capacitive touch assembly further includes a conductor located between the cover plate (22) and the printed circuit board assembly (25) and electrically connected to the printed circuit board assembly (25). The present invention further provides a control panel including the capacitive touch assembly. The capacitive touch assembly provided by the present invention is cost effective and has a simple manufacturing process.