Capacitive Pressure Sensor Electrode Contact Strategy
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Solution Overview
Problem
Capacitive touchscreens in motor vehicles cannot accurately detect low force values and require a predefined minimum clearance between electrodes, leading to imprecision in pressure measurement.
Innovation Solution
An interface with a capacitive tactile surface featuring a mobile part with a capacitive pressure sensor, where the mobile and fixed electrodes are in indirect contact in the rest position, and the mobile electrode is carried by a damping element, allowing for increased accuracy in pressure measurement without the need for a minimum clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive sensors are arranged at the rear of the screen to measure displacement, then pressure detection capability is improved, but measurement precision deteriorates for low force values
Solution Approach 1:
The patent inverts the conventional electrode arrangement by placing electrodes in indirect contact in the rest position rather than requiring a predefined clearance. This inversion allows the electrodes to be closer together initially, and the gap increases with applied force, thereby improving measurement precision for low force values while maintaining pressure detection capability
Solution Approach 2:
The patent changes the physical state and arrangement parameters of the electrodes - specifically transitioning from a predefined clearance state to an indirect contact state in rest position. This parameter change enables the electrode gap to dynamically reflect applied force more accurately, resolving the contradiction between detection capability and measurement precision
2Reliability
If a predefined space between electrodes is maintained in rest position, then measurement range is ensured, but device complexity increases
Solution Approach 1:
The patent inverts the conventional approach by eliminating the predefined clearance requirement. Instead of maintaining a fixed minimum space, the electrodes are arranged in indirect contact in the rest position, with the gap naturally forming based on applied force. This simplifies the device structure while ensuring reliable measurement through the dynamic gap formation
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
Enhances the precision of capacitive pressure sensor measurements, particularly for low force values, and eliminates the requirement for a predefined clearance between electrodes, improving user input interpretation.
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
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
The invention relates to an interface (1) for controlling at least one function of a motor vehicle component, comprising: - a moving part (2) including a capacitive touch surface (3), - a fixed part (4) intended to be fixed to the motor vehicle, - at least one damping element (5a, 5b, 5c, 5d) interposed between the moving part (2) and the fixed part (4), - at least one capacitive pressure sensor (6a, 6b, 6c, 6d) comprising a moving electrode (16; Tx; 27) carried by the moving part (2) and a fixed electrode (22; Rx) carried by the fixed part (4), the fixed electrode (22; Rx) being arranged opposite the moving electrode (16; Tx;27) to measure a distance (d) between the moving part (2) and the fixed part (4) representative of a pressure force exerted on the capacitive touch surface (3), characterized in that the moving electrode (27) and the fixed electrode (22) are in contact in the rest position, pressure exerted on the capacitive touch surface (3) moving the moving electrode (16; Tx; 27) away from the fixed electrode (22; Rx). The invention also relates to a method of mounting (100) such an interface (1).