Automotive Touch Input Device Inductive Position Sensor
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Solution Overview
Problem
Existing automotive input devices with touch sensitive surfaces face reliability issues due to mechanical stress on printed circuit boards and electrical components, particularly when exposed to bumpy roads and wear from haptic feedback, leading to reduced performance and lifespan.
Innovation Solution
An automotive input apparatus utilizing an inductive position sensor with a sensing coil and metal portion, supported by coil springs, which detects displacement without mechanical contact, generating haptic feedback through a contact-less sensing technology, thereby avoiding stress on printed circuit boards and allowing flexible placement of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a touch force sensing feature is implemented using piezo elements or strain gauges, then haptic feedback can be generated, but mechanical stress and wear on the printed circuit board and electrical components increase
Solution Approach 1:
The patent replaces mechanical contact-based sensing (piezo elements, strain gauges) with capacitive sensing technology. The touch surface and backplate form a capacitor where touch force changes the capacitance, eliminating the need for mechanical force sensors that stress the printed circuit board. This substitution resolves the contradiction by maintaining haptic feedback functionality while removing the mechanical stress source.
Solution Approach 2:
The patent introduces a resilient support structure as an intermediary between the touch surface and the printed circuit board. This resilient support absorbs and isolates mechanical forces, preventing them from reaching and damaging the printed circuit board and electrical components. The intermediary element allows the system to maintain structural integrity while protecting sensitive components from mechanical stress.
2Reliability
If mechanical force sensing is used for haptic feedback, then tactile feedback can be provided, but wear and tear on components increases over time
Solution Approach 1:
The patent replaces mechanical wear-prone components (piezo elements, strain gauges, moving parts) with a capacitive sensing system that has no mechanical wear. The capacitive sensors detect touch force through electrical field changes rather than mechanical contact, eliminating friction and wear. This extends the service life of the input apparatus while maintaining haptic feedback functionality.
3Ease of operation
If piezo elements are used for force detection, then haptic feedback can be triggered, but the system becomes more complex
Solution Approach 1:
The patent makes the touch surface serve multiple functions: it acts as both the user interface for touch input and one electrode of the capacitive sensor. The backplate serves as both structural support and the other electrode. This multi-functionality eliminates the need for separate mechanical force sensing components, reducing device complexity while maintaining ease of haptic feedback generation through the same capacitive sensing mechanism.
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 provides high reliability and performance with low manufacturing costs, reducing wear and tear on components, and enabling easy recalibration, while maintaining the functionality of haptic feedback without mechanical strain.
Implementation Method 1
an inductive position sensor which is configured to generate a sensor signal that varies with varying distance of the sensing coil to the metal portion
Implementation Method 2
The touch sensitive input device is supported by at least one resilient supporting device, in the present example by a spring mechanism comprising two coil springs
Data Source
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AI summary
An automotive input apparatus (1) comprises at least one touch sensitive input device (2) which is operable by a user and has at least one touch surface (21) for sensing a touch of a user's finger (9) for performing at least one input function, wherein the at least one touch sensitive input device (2) is arranged such as to allow displacement of the at least one touch surface (21) from a first position to at least one second position upon a force (F) applied by the user's finger on the at least one touch surface (21), and to provide at least one of a tactile feeling for the user's finger (9), an acoustic feedback signal and an optical feedback signal upon the displacement, and at least one inductive position sensor (10) which comprises a sensing coil (5) configured to interact with a metal portion (6, 23, 31, 35) of the input apparatus (1), wherein an inductance of the sensing coil (5) is variable in accordance with a distance between the sensing coil (5) and the metal portion (6, 23, 31, 35). The sensing coil (5) is arranged at a side (22) of the touch sensitive input device (2) which is opposite to the touch surface (21), and one of the sensing coil (5) and the metal portion (6, 23, 31, 35) is arranged to be displaced relative to the other of the sensing coil (5) and the metal portion (6, 23, 31, 35) with the displacement of the touch surface (21), wherein the inductive position sensor (10) is configured to generate at least one output signal (OS) for triggering the respective tactile feeling, acoustic feedback signal or optical feedback signal upon sensing a relative displacement of the sensing coil (5) and the metal portion (6, 23, 31, 35).