Capacitive Touch Interface Electrode Inversion for Low Force Measurement
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Solution Overview
Problem
Capacitive touch interfaces for motor vehicle components face challenges in precision measurement of low force values and require a large number of components and complex assembly processes, making them incompatible with industrial production and increasing costs.
Innovation Solution
A capacitive touch interface with a mobile part and a fixed part separated by a damping element, featuring a capacitive pressure sensor with a mobile electrode and a fixed electrode arranged on an electronic card, allowing for precise measurement of pressing force without the need for a minimum clearance between electrodes, reducing component count, and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensors are arranged at the rear of the screen to measure displacement by bringing electrodes closer together, then pressure detection is enabled, but measurement precision for low force values deteriorates and a minimum clearance space is required
Solution Approach 1:
The patent inverts the traditional electrode arrangement by placing the fixed electrode on the mobile part (carried by the fixing member) and the mobile electrode on the fixed part (carried by the electronic card). This inversion allows the electrodes to be in contact in the rest position, eliminating the need for minimum clearance space while enabling precise measurement of low force values through the movement of the fixing member relative to the electronic card.
2Adaptability or versatility
If multiple separate components are used for the capacitive touch interface and pressure sensors, then functional requirements are met, but the number of components increases and assembly complexity increases
Solution Approach 1:
The patent merges the capacitive touch interface and pressure sensing functions into a single integrated structure. The electronic card serves both as the control interface for the capacitive touch surface and as the carrier for the fixed electrode of the pressure sensor. The fixing member that secures the mobile part also carries the mobile electrode, eliminating the need for separate sensor mounting components and reducing overall device complexity.
Solution Approach 2:
The electronic card is designed to perform multiple functions: it serves as the control interface for the capacitive touch surface, provides structural support, and carries the fixed electrode for pressure sensing. The fixing member similarly performs dual functions of mechanical attachment and electrical connection for the mobile electrode. This multi-functionality reduces the total number of components required.
3Reliability
If complex assembly procedures with blind assembly are used, then proper component alignment is achieved, but assembly time and cost increase
Solution Approach 1:
The patent enables self-aligning assembly through the design where the fixing member with the mobile electrode automatically aligns with the electronic card carrying the fixed electrode during assembly. The components guide themselves into the correct position through their geometric and electrical connections, eliminating the need for complex blind assembly procedures and reducing assembly time while maintaining proper alignment.
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 configuration enhances measurement precision for low force values, reduces the number of components, and simplifies assembly, making the interface more compatible with industrial production and cost-effective.
Implementation Method 1
at least one capacitive pressure sensor comprising a mobile electrode carried by the mobile part and a fixed electrode carried by the fixed part, the fixed electrode being arranged facing the mobile electrode to measure a distance between the mobile part and the fixed part representative of a pressing force exerted on the tactile surface capacitance
Data Source
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AI summary
The invention concerns an interface (1) for controlling at least one function of a motor vehicle component, comprising: - a moving portion (2) including a capacitive touch-sensitive surface (3), - a stationary portion (4) intended to be attached to the motor vehicle, - at least one damper element (5a, 5b, 5c, 5d) interposed between the moving portion (2) and the fixed portion (4), - at least one capacitive pressure sensor (6a, 6b, 6c, 6d) comprising a moving electrode (16; Tx) carried by the moving portion (2) and a stationary electrode (22; Rx) carried by the stationary portion (4), the stationary electrode (22; Rx) being arranged facing the moving electrode (16; Tx) in order to measure a distance (d) between the moving portion (2) and the stationary portion (4) representative of a pressure force exerted on the capacitive touch-sensitive surface (3), characterised in that: - the stationary electrode (22; Rx) is carried by an electronic card (13) of the stationary portion (4), - the moving electrode (16; Tx) is carried by an attachment member (17) of the moving portion (2) passing through the damper element (5a, 5b, 5c, 5d) and the electronic card (13) such that a pressure exerted on the capacitive touch-sensitive surface (3) moves the moving electrode (16; Tx) away from the stationary electrode (22; Rx). The invention also concerns a mounting method (100) for mounting such an interface (1).