Free-Form Touch Surface Mapping With Capacitive Switching Elements

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Solution Overview

Problem

Existing touch-sensitive technologies struggle to effectively integrate with free-form surfaces, particularly in complex environments like motor vehicles, where curved and irregular surfaces require spatially resolved user input detection.

Innovation Solution

A device with a free-form surface and a position detection device, where switching elements with opposite ends on the surface and sensor surface allow for capacitive coupling, enabling the use of mass-produced, inexpensive sensors to detect touches on any shaped surface, including those with small radii of curvature and edges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If touch-sensitive sensors are integrated into free-form surfaces with small radii of curvature and edges, then spatially resolved user input detection is enabled on complex shapes, but the manufacturing complexity and sensor integration difficulty increase significantly

Engineering Contradiction:
Improveadaptability to free-form surfacesVSAvoidsensor integration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces mediating elements (switching elements) as intermediaries between the free-form surface and the sensor surface. These elements have first ends assigned to detection positions on the free-form surface and second ends assigned to sensor positions on the sensor surface, enabling touch detection on complex geometries without requiring the sensor itself to conform to the free-form shape.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent separates the detection function into two dimensions: the free-form surface dimension (where user interaction occurs) and the sensor surface dimension (where detection actually happens). By projecting detection positions from the three-dimensional free-form surface onto a two-dimensional sensor surface through mediating elements, the system enables touch detection on complex shapes using planar sensors.

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

2Ease of manufacture

If mass-produced, inexpensive sensors are used for touch detection, then manufacturing cost is reduced, but the ability to detect touches on curved and irregular surfaces is limited

Engineering Contradiction:
Improvemanufacturing costVSAvoidcompatibility with curved surfaces
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent divides the detection system into separate functional components: the free-form surface structure, the mediating switching elements, and the planar sensor. This segmentation allows each component to be optimized independently - the sensor can be a simple, mass-produced planar device while the mediating elements handle the adaptation to curved surfaces.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a universal detection system where a single planar sensor design can be used with various free-form surfaces by changing only the mediating elements. The same sensor can detect touches on different curved surfaces by reconfiguring the switching elements, providing multi-functionality without requiring custom sensors for each application.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If a flat sensor surface is used with free-form surfaces, then manufacturing simplicity is maintained, but accurate spatial mapping between touch positions and sensor positions becomes difficult

Engineering Contradiction:
Improvesensor manufacturing simplicityVSAvoidspatial position mapping accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent incorporates assignment information that maps detection positions on the free-form surface to sensor positions on the sensor surface. This feedback mechanism allows the system to correctly interpret which sensor position corresponds to which location on the free-form surface, enabling accurate spatial mapping despite the geometric transformation.

Inventive Principle:
Principle #23Feedback

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 spatially resolved touch detection on free-form surfaces, allowing for flexible and intuitive user input on complex shapes, such as vehicle steering wheels, with improved durability and resistance to electrostatic discharge.

Implementation Method 1

switching elements with opposite ends on the surface and sensor surface allow for capacitive coupling, enabling the use of mass-produced, inexpensive sensors to detect touches on any shaped surface

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3542254B1Device having a touch-sensitive free-form surface and method for the production thereof
Publication Date: 2021.09.29 VOLKSWAGEN AG
  • EP3542254B1 patent drawingFigure 1
  • EP3542254B1 patent drawingFigure 2
  • EP3542254B1 patent drawingFigure 3a~3d

AI summary

The invention relates to a device (1) having a touch-sensitive free-form surface (100), comprising the free-form surface (100) as outer surface, a position detection unit (200) having a sensor surface (210). The sensor surface (210) and the free-form surface (100) have different geometric shapes, and between the sensor surface (210) and the free-form surface (100), a plurality of switching elements (300) are arranged, each having a first end (310) and an opposing second end (320). The first ends (310) are assigned to different detection positions (110) on the free-form surface (100), and the second ends (320) are assigned to different sensor positions (220) on the sensor surface (210) of the position detection unit (200) such that touches of the free-form surface (100) can be transmitted to the sensor surface (210) via the switching elements (300) and can be detected by the position detection unit (200) in a spatially resolved manner. The invention further relates to a method for producing such a device.