Steering-Wheel Optical Finger Navigation with Homogeneous Ring Lighting

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Solution Overview

Problem

Existing optical finger navigation modules for vehicle steering wheels face issues with non-homogeneous ring illumination, temperature and humidity unsuitability, color variant conflicts, and inadequate activation forces and travel, making them unsuitable for automotive use.

Innovation Solution

An operating device with a mounting frame and optical finger navigation module, utilizing a snap connection between a light-blocking element and fastening frame, along with separate light-guiding elements for optimized light distribution and color, and a rubber-elastic element for strain relief and tolerance compensation, allowing for homogeneous illumination and improved usability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the ring illumination is integrated into the OFN with small overall depth, then the minimal depth requirement is met, but the illumination becomes non-homogeneous with up to 50 percent brightness difference

Engineering Contradiction:
Improveoverall depthVSAvoidhomogeneity of ring illumination
Core Design Contradiction:
Volume of moving objectVSIllumination intensity

Solution Approach 1:

The illumination system is segmented into separate components: the LED light source is separated from the illumination ring, with the light guided through optical elements (light guides or light channels) that distribute light homogeneously around the OFN. This segmentation allows independent optimization of depth and illumination quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Light guides or light channels serve as intermediary elements between the LED source and the illumination ring. These intermediaries transport and distribute light uniformly around the OFN, achieving homogeneous illumination while maintaining compact depth through efficient optical path design.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If a translucent surface is used for the illuminated area, then the ring lighting can be implemented, but the surface cannot withstand automotive temperatures and humidity levels

Engineering Contradiction:
Improvering lighting implementationVSAvoidresistance to temperature and humidity
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

A translucent film or coating is applied to the front surface of the opaque operating surface. This thin translucent layer allows light to pass through for illumination while the underlying opaque material maintains structural integrity and resistance to automotive environmental conditions.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The operating surface is constructed as a composite structure combining opaque automotive-grade material with a translucent illumination layer. This composite approach allows the bulk material to provide environmental resistance while the translucent layer enables light transmission for the ring illumination.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If color variants in the lighting are implemented, then different vehicle classes and equipment lines can be differentiated, but the OFN itself must change which conflicts with component standardization

Engineering Contradiction:
Improvelighting color variantsVSAvoidOFN component variations
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The illumination ring uses color-changing LED technology or interchangeable colored illumination rings that can be configured in different colors without changing the underlying OFN structure. This allows color variants for different vehicle classes while keeping the technical components standardized.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The lighting color is made adjustable through parameter changes in the illumination system (LED wavelength selection, phosphor composition, or control settings) rather than changing the OFN hardware. This enables color differentiation while maintaining component standardization across vehicle classes.

Inventive Principle:
Principle #35Parameter changes

4Force

If the activation forces and travels are increased for vehicle application, then unintentional activation is avoided, but the OFN guidance becomes inadequate with small installation depths

Engineering Contradiction:
Improveactivation forceVSAvoidOFN guidance
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The snap-action disc is tilted at an angle relative to the operating surface, creating a mechanical advantage through angular geometry. This tilting allows sufficient activation force and travel for vehicle conditions while maintaining compact depth by utilizing the angular displacement rather than linear travel.

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

Solution Approach 2:

The snap-action disc uses a curved or domed surface geometry that provides mechanical guidance and force multiplication. The curved profile allows the disc to deflect and return smoothly, providing adequate activation characteristics while maintaining small installation depth through efficient use of displacement.

Inventive Principle:
Principle #14Spheroidality (Curvature)

5Volume of moving object

If the snap-action disc is glued to the OFN, then the minimal depth design is achieved, but the activation characteristics are insufficient for vehicle application

Engineering Contradiction:
Improveoverall depthVSAvoidactivation force and travel
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The snap-action disc is tilted at an angle relative to the operating surface, creating a mechanical advantage through angular geometry. This tilting allows sufficient activation force and travel for vehicle conditions while maintaining compact depth by utilizing the angular displacement rather than linear travel.

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

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

The solution provides a vehicle-compatible optical finger navigation module with homogeneous ring illumination, wear-free contacting, and adjustable color, meeting automotive quality standards and ensuring safe and reliable operation under varying conditions.

Implementation Method 1

An operating device (11) with a mounting frame (12) and an optical finger navigation module (14) is proposed. A first light-guiding element (21) and the optical finger navigation module (14) are held in the fastening frame (19) by a light-blocking element (19).

Methodology Applied
Scientific EffectLight guidance: Optical Fibre

Implementation Method 2

The light blocking element (19) is fastened to the fastening frame (12) by means of a snap connection

Methodology Applied
Scientific EffectSnap connection: Mechanical Fastener

Implementation Method 3

Furthermore, on the side of the mounting frame (12) facing away from the optical finger navigation module (14), a switching dome (27) of a switch (27) can be arranged, which can be actuated by a movement of the mounting frame (12).

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2951664B1Operating device having an optical finger navigation module for a steering wheel
Publication Date: 2018.10.10 MERCEDES BENZ GROUP AG
  • EP2951664B1 patent drawingFigure 1~3
  • EP2951664B1 patent drawingFigure 4~5
  • EP2951664B1 patent drawingFigure 6~7

AI summary

The intention is to provide an operating device having an optical finger navigation module (15) for installation in a steering wheel of a motor vehicle, which allows reliable operation and can be produced favourably. An operating device having a fastening frame (12) in which a first light-guiding element and the optical finger navigation module (15) are held by means of a light-sealing element (19) is therefore proposed. The light-sealing element (19) is fastened to the fastening frame (12) by means of a snap connection. The fastening frame (12) has at least one guide element (13) which can be used to guide a movement of the fastening frame.