Tactile Sensor Light Guide with Mixing Chambers

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Solution Overview

Problem

Touch sensors in prior art suffer from inconsistent light spectra due to manufacturing tolerances, leading to color differences between light sources, which is aesthetically undesirable and limits the variability of the emitted color spectrum, especially when using white light diodes, and often fails to produce satisfactory white light when using RGB diodes.

Innovation Solution

A touch sensor design featuring a light guide with separate light entry surfaces and reflective boundaries forming light mixing chambers, allowing light from multiple sources, such as a white LED and an RGB LED, to be coupled and mixed, resulting in a precise and adjustable color spectrum, with the mixed light exiting through a common surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If white light diodes are used as light sources, then the light spectrum can be generated, but manufacturing tolerances cause color differences between diodes which is aesthetically undesirable

Engineering Contradiction:
Improvelight spectrum generationVSAvoidcolor consistency
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent combines multiple light sources (white light diodes and RGB diodes) into a single illumination system. By merging different types of light sources that emit different spectra, the system achieves both broad spectrum coverage and color consistency through the mixing chamber that homogenizes the combined light output.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a light mixing chamber as an intermediary component between the light sources and the light guide. This mixing chamber contains diffusing elements that act as mediators to homogenize the light from multiple sources, eliminating color differences and achieving uniform spectral output.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If RGB diodes are used as light sources, then the light spectrum can be adjusted, but satisfactory white light often cannot be produced

Engineering Contradiction:
Improvelight spectrum adjustabilityVSAvoidwhite light quality
Core Design Contradiction:
Adaptability or versatilityVSIllumination intensity

Solution Approach 1:

The patent merges RGB diodes with white light diodes in the same illumination system. The RGB diodes provide adjustable color components while the white light diodes provide a consistent white light base, and their combined light is mixed in the mixing chamber to produce both satisfactory white light and adjustable color output.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a composite light source system combining different types of diodes (RGB and white light) rather than relying on a single type. This composite approach leverages the strengths of each diode type to achieve both white light quality and color adjustability.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If multiple light guides are used to indicate different switching states, then the functionality is improved, but the device complexity increases

Engineering Contradiction:
Improveswitching state indicationVSAvoidnumber of light guides
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the light guide multi-functional by enabling it to display multiple different switching states through a single structure. By controlling the intensity and color of the combined light from multiple sources, the single light guide can indicate various states (on/off, different modes, etc.) without requiring separate light guides for each state.

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

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 expands the light spectrum's variability and ensures precise light generation, allowing for homogenization of the light spectrum, enabling clear identification of the push-button sensor in the dark and effective display of status information through adjustable light colors and intensities.

Implementation Method 1

light generated by a first of the light sources is coupled into the light guide through the first light entry surface, and wherein light generated by a second of the light sources is coupled into the light guide through the second light entry surface

Methodology Applied
Scientific EffectLight coupling: Optical Fibre

Implementation Method 2

for the light coupling into the light guide, a first reflector is located in front of the first light entry surface of the light guide and a second reflector of the second light entry surface

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

each of the two reflectors is a reflective boundary wall of a separate light mixing chamber, wherein the light generated by a first of the light sources is coupled into a first of the two separate light mixing chambers and the light generated by a second of the light sources is coupled into a second of the two separate light mixing chambers

Methodology Applied
Scientific EffectLight mixing: Scattering

Data Source

PatentEP3697177B1Tactile sensor with integrated light guide
Publication Date: 2021.01.13 GIRA GIERSIEPEN GMBH & CO KG
  • EP3697177B1 patent drawingFigure 1
  • EP3697177B1 patent drawingFigure 2
  • EP3697177B1 patent drawingFigure 3

AI summary

The invention relates to a touch sensor with a circuit board carrier for surface mounting, a circuit board mounted on the circuit board carrier on which at least one switching element and at least two light sources are arranged, and with at least one rocker switch for actuating the switching element, which has at least one light guide via which light generated by the light sources is directed to an operating surface of the rocker switch, characterized in that the light guide has a first light entry surface with a first upstream reflector for light coupling and a second light entry surface with a second upstream reflector for light coupling, wherein light generated by a first of the light sources is coupled into the light guide via the first reflector and light generated by a second of the light sources is coupled into the light guide via the second reflector.