Steering Wheel Heater Wiring Pattern for Capacitance Detection
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Solution Overview
Problem
Existing steering wheel monitoring systems have low accuracy in detecting whether an operator is holding the wheel due to variations in capacitance measurements based on the contact area, leading to inconsistent detection of the holding state.
Innovation Solution
A heater device with a unique wiring pattern on the steering wheel, comprising a base member with a heater wire forming first and second wiring patterns connected in series, where the wire blocks are arranged in a circumferential direction and reversed, ensuring equal sensitivity to capacitance across pairs of wire blocks, improving detection accuracy by maintaining consistent impedance regardless of the contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple cord-shaped heater is disposed on the base member, then the device structure is simple, but the detection accuracy of operator hand position is low due to capacitance variations
Solution Approach 1:
The heater wire is divided into multiple wire blocks (first wiring pattern and second wiring pattern) arranged in series along the circumferential direction. Each wire block acts as an independent capacitance sensing element, allowing the system to detect hand position more accurately by comparing capacitance values across multiple segmented sections rather than using a single continuous heater element.
Solution Approach 2:
The first and second wiring patterns are arranged asymmetrically with reversed sequences of wire blocks. The first wiring pattern has wire blocks arranged from leading end to trailing end in one sequence, while the second wiring pattern has them reversed. This asymmetric arrangement ensures that corresponding wire blocks face each other in opposite orientations, compensating for capacitance variations and improving measurement consistency.
2Reliability
If the heater wire is arranged in a single wiring pattern, then the device complexity is low, but the detection consistency varies with contact area
Solution Approach 1:
The first and second wiring patterns are configured to create equipotential conditions for capacitance measurement. By arranging wire blocks in reversed sequences that face each other, the system ensures that corresponding wire blocks experience similar electrical conditions regardless of hand contact area, thereby achieving consistent detection reliability across different operating conditions.
Solution Approach 2:
The invention changes the configuration parameter of the wiring pattern from a single pattern to multiple series-connected patterns with reversed wire block arrangements. This parameter change transforms the capacitance measurement characteristics, making the detection less sensitive to variations in contact area and improving overall reliability.
3Measurement precision
If wire blocks are arranged in reversed sequences facing each other, then the capacitance measurement consistency is improved, but the manufacturing complexity increases
Solution Approach 1:
The heater wire is pre-segmented into discrete wire blocks that can be independently positioned and connected. This segmentation allows for modular assembly where the first and second wiring patterns can be constructed separately with their respective wire block sequences, then assembled in series. The segmented approach simplifies the complex reversed-arrangement configuration by breaking it into manageable units.
Solution Approach 2:
The wire blocks serve multiple functions: they act as both heating elements and capacitance sensing elements. This multi-functionality reduces the need for separate sensing components, thereby simplifying the overall manufacturing process despite the complex wiring pattern arrangement. The same segmented structure achieves both heating and precise position detection.
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 enhances the accuracy of detecting the operator's hand position on the steering wheel, providing consistent capacitance measurements and reducing false alarms, thereby improving safety by accurately determining the holding state.
Implementation Method 1
a sensor which is connected to one of a leading end and a trailing end of the heater wire and measures capacitance of the heater wire
Implementation Method 2
a heater wire disposed on the base member; the heater wire forms a first wiring pattern and a second wiring pattern which are connected in series
Data Source
AI summary
A heater device includes: a base member; a heater wire; and a sensor which measures capacitance of the heater wire, wherein the heater wire forms a first wiring pattern and a second wiring pattern connected in series, the first wiring pattern and the second wiring pattern each include N wire blocks, the N wire blocks included in the first wiring pattern and the second wiring pattern are disposed in a manner that arrangement of the N wire blocks included in the first wiring pattern and arrangement of the N wire blocks included in the second wiring pattern are reversed in the circumferential direction of the rim and facing each other in a direction perpendicular to the circumferential direction, and a sum of sensitivity of the sensor to capacitance of a pair of wire blocks facing each other is substantially equal to that of another pair.