Heatable Fiber-Optic Touch Sensor for Steering Wheels
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Solution Overview
Problem
Existing steering wheel touch sensors face issues with imprecise contact detection, high assembly and cost due to the capacitive sensing principle, and high heat losses, particularly when integrated with heating elements.
Innovation Solution
A heatable fiber-optic touch sensor combining an optical waveguide with an electrical heat conductor, which changes transmission behavior with position or bending, allowing for accurate detection and efficient heating, integrated with minimal assembly effort and reduced costs, using materials like glass or plastic fibers and a resistance heater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensing principle is used for touch detection, then the detection can be implemented, but the detection precision is poor and false triggering occurs
Solution Approach 1:
The patent replaces the capacitive sensing principle with an optical sensing principle using fiber-optic touch sensors. The fiber-optic sensor detects touch through changes in light transmission caused by mechanical deformation of the fiber, eliminating the need for capacitive fields and their associated electromagnetic shielding requirements. This substitution improves detection precision and eliminates false triggering from objects like keys or coins that can interfere with capacitive sensors.
Solution Approach 2:
The patent changes the detection parameter from electrical capacitance to optical transmission properties. By measuring changes in light intensity or transmission through the fiber-optic sensor when touched, the system achieves more reliable and precise touch detection without the false positives inherent in capacitive sensing.
2Adaptability or versatility
If capacitive sensing and heating elements are integrated, then both functions can be provided, but assembly effort and costs increase
Solution Approach 1:
The patent merges the touch sensing and heating functions into a single integrated component - the fiber-optic touch sensor with integrated heating element. This consolidation eliminates the need for separate capacitive sensor arrays and heating elements, significantly reducing assembly steps and costs while maintaining both functions. The fiber-optic sensor can be directly embedded in the steering wheel cover without requiring electromagnetic shielding layers.
Solution Approach 2:
The patent extracts the electromagnetic shielding requirement from the system by removing the capacitive sensing principle. Since fiber-optic sensing uses light instead of electrical fields, the complex electromagnetic shielding infrastructure is eliminated, simplifying the overall assembly process and reducing the number of components that must be installed.
3Adaptability or versatility
If capacitive sensing planar component is placed over heating element, then both functions are integrated, but heat losses increase
Solution Approach 1:
The patent inverts the traditional layering approach by embedding the fiber-optic touch sensor within or alongside the heating element rather than placing a planar sensing component over it. This configuration allows the sensor to benefit from the thermal environment without creating additional thermal resistance layers, and the heating element can efficiently transfer heat to the steering wheel surface without being insulated by a planar sensor layer.
Solution Approach 2:
The patent replaces the planar capacitive sensing component with a fiber-optic sensor that has minimal thermal impact. The fiber-optic sensor does not require a planar structure that would act as a thermal barrier, and its thin, flexible nature allows it to be integrated without significantly impeding heat transfer from the heating element to the steering wheel surface.
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 precise detection of steering wheel contact, prevents false triggering, functions with gloves, and reduces assembly complexity and heat losses, providing a cost-effective solution with improved accuracy and response time.
Implementation Method 1
an optical waveguide which changes its transmission behavior, to be measured, with a change in position or bending
Implementation Method 2
The heat conductor can be a resistance heater, which converts electrical energy into heat by applying an electrical voltage and by the associated current flow and gives it off to the surroundings
Data Source
AI summary
The invention relates to a heatable touch sensor and a steering wheel. It has an optical waveguide which is connected to an electrical heat conductor. The optical waveguide changes its transmission behavior, which is determined, with a change in position or bending. The heat conductor is a resistance heater which emits heat by applying an electrical voltage and by the associated current flow. The touch sensor operates by means of optical interferometry, which enables a very high sensing accuracy.