Printed Steering Wheel Sensor Mat With Integrated Shielding Loops
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Solution Overview
Problem
Current steering wheel sensor mats face challenges due to interference from the metal steering wheel frame, complex manufacturing processes, and limited flexibility in design and materials, leading to inefficiencies in manufacturing and installation times.
Innovation Solution
The development of sensor mats with printed sensing and shielding loops using conductive ink on a versatile base substrate and insulating material, allowing for customizable designs and reduced noise interference, which can be stretched to fit the steering wheel rim without breaking and includes features like polymeric foam layers for read-through prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire loops are sewn to fabric or foam substrate to form sensor mats, then the sensor mat can detect driver's hand presence, but the manufacturing process becomes time consuming and complex
Solution Approach 1:
The patent replaces the mechanical sewing process with a printing process. Conductive ink is printed directly onto the substrate to form sensing loops and shielding loops, eliminating the need for wire stitching and sewing operations. This substitution of mechanical assembly with a printing process significantly reduces manufacturing complexity and time while maintaining the electrical functionality of the sensor mat.
Solution Approach 2:
The patent combines multiple functions into a single integrated mat structure. The sensing loops, shielding loops, and insulating layers are all printed and assembled onto one substrate, creating a unified sensor mat that provides both sensing and electromagnetic shielding functions simultaneously, rather than requiring separate components.
2Object-affected harmful factors
If separate sensor mat and shield mat are designed and manufactured, then shielding can be provided, but the design and manufacturing process becomes time consuming
Solution Approach 1:
The patent merges the sensor mat and shield mat into a single integrated structure. Both the sensing loops and shielding loops are printed onto the same substrate with insulating material between them, eliminating the need to manufacture and assemble separate sensor and shield mats. This integration maintains the shielding function while significantly reducing design and manufacturing time.
Solution Approach 2:
The printed circuit board substrate serves multiple functions simultaneously: it provides the structural base for the sensor mat, acts as an insulating layer between sensing and shielding loops, and enables the formation of both sensing and shielding circuits through the printing process. This multi-functionality reduces the number of separate components needed.
3Reliability
If conventional sensor mat design is used, then basic sensing function is achieved, but flexibility in design and material selection is limited
Solution Approach 1:
The patent enables extensive parameter changes in the design process. The printing process allows for easy modification of loop patterns, sizes, shapes, and positions on the substrate. Different conductive ink formulations can be used to achieve varying resistance values, and the layout can be customized for different steering wheel configurations without requiring new tooling or fixtures.
Solution Approach 2:
The patent employs composite material structures combining conductive ink, insulating materials, and substrate materials. The conductive ink can be formulated with different materials (silver, carbon, copper) to achieve desired electrical properties. The insulating layers can be made from various dielectric materials, and the substrate can be selected from different fabric or foam types, creating a composite structure that optimizes both electrical performance and mechanical properties.
4Area of stationary object
If sensor mat is placed close to metal steering wheel frame, then space is utilized efficiently, but electrical interference increases
Solution Approach 1:
The patent introduces insulating material as an intermediary layer between the sensing loops and the metal steering wheel frame. This insulating layer, printed or applied between the sensor mat and the frame, acts as a barrier that blocks electrical interference and capacitive coupling from the conductive frame while allowing the sensor mat to maintain close proximity to the frame for effective space utilization.
Solution Approach 2:
The patent converts the potentially harmful electrical interference from the metal frame into a beneficial shielding effect. By printing shielding loops around the sensing loops and connecting them to ground, the electromagnetic field generated by the shielding loops counteracts the interference from the frame, transforming the interference problem into an active noise cancellation solution.
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 solution enhances the manufacturing efficiency and reduces installation time by allowing for customizable and flexible sensor mat designs that minimize electrical interference and material usage, improving the accuracy and reliability of hand detection systems in steering wheels.
Implementation Method 1
sensor mats around a rim of the steering wheel frame that are configured for detecting the presence of a driver's hand using capacitive-type sensing
Implementation Method 2
separated from the sensing loops by a layer of insulating material
Data Source
AI summary
Systems and methods of printing sensor loops on a sensor mat for use in a steering wheel are disclosed herein. For example, the sensor mat may include a base substrate, one or more printed sensing loops, and an insulating material. The printed sensing loops are made with conductive ink that is disposed upon the base substrate or the insulating layer from a print head and adheres thereto. These sensor mats are versatile with respect to the type of base substrate and insulating materials that may be used, the shape of the sensing loops, and the area each loop may occupy. Shielding loop(s) may also be printed adjacent the sensing loop(s). This configuration allows shielding for the sensing loops as part of the sensing mat, which may reduce the thickness of the steering wheel rim and manufacturing and installation times.