Capacitive Touch Switch Assembly for Precise Automated Mounting

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Solution Overview

Problem

Existing capacitive touch switch sensor element devices face challenges in precise and cost-effective assembly, particularly due to difficulties in attaching elastic, electrically conductive plastic to printed circuit boards, leading to inaccuracies and increased production costs.

Innovation Solution

A sensor element device with a housing featuring fastening means and an electrically conductive plastic collar that forms a structural unit with a capacitive touch switch, allowing for tool-free attachment to a component carrier and enabling automated assembly, using elastic conductive materials like silicone rubber for secure and precise contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If elastic electrically conductive plastic is attached to a circuit board to form a sensor element device, then the capacitive touch switch functionality is achieved, but precise positioning and assembly accuracy deteriorate due to the difficulty of attaching elastic material with pinpoint accuracy

Engineering Contradiction:
Improvecapacitive touch switch functionalityVSAvoidpositioning accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent combines the sensor element device with a housing that integrates multiple functions: mechanical support, positioning features (protrusions fitting into recesses), electrical connections (contact elements), and indicator light housing. This merging of functions into a single integrated component eliminates the need for separate attachment of elastic conductive plastic to the circuit board, thereby achieving both reliable functionality and precise positioning through the housing's structural features.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of manufacture

If traditional attachment methods are used for sensor element devices, then assembly can be performed, but production time and manufacturing complexity increase due to the need for precise manual attachment

Engineering Contradiction:
Improveassembly capabilityVSAvoidproduction speed
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The sensor element device is segmented into distinct functional components within an integrated housing structure: the elastic conductive plastic is contained within a defined space, electrical contacts are separately positioned, and the indicator light is housed in a dedicated compartment. This segmentation allows each component to be manufactured and positioned independently with standard tolerances, enabling automated assembly while maintaining overall device functionality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The housing acts as an intermediary structure that mediates between the circuit board and the sensor elements. It provides a standardized interface with protrusions and recesses for precise positioning, integrated electrical contacts for connection, and a contained space for the elastic conductive plastic. This intermediary housing enables automated assembly processes while ensuring reliable electrical and mechanical connections.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple separate components are used for sensor element device assembly, then flexibility in design is maintained, but assembly complexity and cost increase particularly for large series production

Engineering Contradiction:
Improvedesign flexibilityVSAvoidassembly complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the housing, electrical contacts, indicator light structure, and sensor element containment into a single integrated component assembly. This reduces the number of separate parts that need to be handled during assembly, simplifying the manufacturing process for large series production while maintaining design flexibility through the modular nature of the integrated unit that can be positioned at different locations on the control panel.

Inventive Principle:
Principle #5Merging (Combining)

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 rapid, automated, and precise assembly of capacitive touch switches with improved accuracy and reduced costs, facilitating mass production while maintaining effective capacitive sensing and illumination functionality.

Implementation Method 1

This electrically conductive plastic forms the functional capacitive sensor element for the capacitive touch switch on the control panel, by which the approach or placement of a finger on the top of the control panel above the sensor element assembly can be detected

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

the sensor element includes an indicator light with a light source, the light direction of which points towards the underside of the control panel, ideally illuminating through it

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Implementation Method 3

It can have a hardness of 30 to 80 Shore A, preferably 40 to 70, and particularly 50 to 60. This allows it to be compressed by a relatively small contact force and to fit snugly against the underside of the control panel while simultaneously providing a spring effect

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2853027B1Arrangement with sensor element device on a component carrier for a capacitive touch switch of an operating device, operating device, and cooking hob with such an arrangement
Publication Date: 2020.02.19 E G O ELEKTRO GERAETEBAU GMBH
  • EP2853027B1 patent drawingFigure 1~3
  • EP2853027B1 patent drawingFigure 4~5

AI summary

The invention relates to a sensor element device (11) for a capacitive touch switch of an operating device which sensor element device points by means of a top face (20) toward the bottom face of a control panel of the operating device and has an illuminated display having a lighting means. A housing (22) is provided around the lighting means, said housing having fastening means (24a, 24b) for fastening the sensor element device to a component carrier. Electrically conductive plastic (30) that extends along an outer edge of the housing is provided on the outside of the housing or the assembly in the region toward the top face. A contacting means (33a, 33b) extends from the electrically conductive plastic in the direction of the bottom face to the component carrier for electrical connection thereto.