Capacitive Force Input Surface With Adaptive Touch Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive input devices face reliability issues due to varying measured values when the operating force acts over a larger surface compared to the input means, leading to inconsistent switching and control behavior, particularly at the edges of the operating surface, resulting in malfunctions such as missed function triggers.
Innovation Solution
The input device incorporates a capacitive force sensor and a touch sensor with an evaluation unit that detects characteristic values like touch location and surface area, allowing for adaptive threshold adjustment based on measured quantities, ensuring reliable function triggering by correlating switching or control functions with both touch and force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the operating surface is extended compared to the size of the input means, then the operating area is increased and ease of operation is improved, but the measured value varies greatly leading to unreliable function triggering
Solution Approach 1:
The system performs a preliminary touch detection step before the operation detection step. The evaluation unit detects characteristic values (touch location, contact surface area) in advance, then uses these values to adapt the threshold for force measurement. This preliminary adaptation ensures that the force threshold is optimized for the specific touch conditions before the actual force measurement occurs, preventing missed triggers at edge locations.
Solution Approach 2:
The evaluation unit dynamically changes the threshold parameter for force measurement based on the detected characteristic values from touch detection. When a touch is detected at different locations or with different contact areas, the system adjusts the force threshold accordingly. This parameter adaptation compensates for the varying capacitance measurements that occur when force is applied at different positions on the extended operating surface.
2Area of stationary object
If the operating surface is extended compared to the size of the input means, then the operating area is increased, but the location of action varies greatly causing inconsistent measured values
Solution Approach 1:
The system applies different measurement thresholds locally based on where the touch occurs on the operating surface. By detecting the touch location as a characteristic value and using it to adapt the force measurement threshold, the system creates a localized measurement strategy. Each region of the operating surface has an optimized threshold tailored to its specific capacitance characteristics, ensuring consistent measurement precision across the entire extended surface.
3Ease of operation
If capacitive measurement is used for operating force, then the measurement is contactless and ease of operation is improved, but the measured value varies with touch conditions and ambient changes
Solution Approach 1:
The system uses feedback from the touch detection step to adjust the force measurement threshold. The evaluation unit continuously monitors touch characteristics (location, contact area) and uses this feedback information to adapt the threshold for subsequent force measurements. This closed-loop approach compensates for variations in touch conditions and ambient changes, maintaining reliable operation detection despite the contactless nature of capacitive sensing.
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 approach enhances the reliability of capacitive force measurement by compensating for variations in touch conditions and ambient changes, providing consistent user experience across the operating surface.
Implementation Method 1
detect, in an operation-detection step shifted in time in relation to the touch-detection step, a measured quantity changing, e.g., continuously changing, with the operating force, by generating a first measuring capacitance between the first and second electrodes
Implementation Method 2
detect, in a touch-detection step, by means of the capacitive touch sensor, an associated characteristic value of a touch on the operating surface during the operation
Implementation Method 3
a first electrode made of a conductive material, which yields elastically under the action of an operating force acting during an operation
Data Source
AI summary
An input device is disclosed, including a capacitive force sensor, a capacitive touch sensor, and an evaluation unit, where the capacitive force sensor includes an operating surface and a first conductive electrode, and a second conductive electrode; wherein the evaluation unit is configured to detect an associated characteristic value of a touch on the operating surface during the operation, such as a location surface of action of the touch, by means of the capacitive touch sensor, and wherein the evaluation unit is further configured to detect a measured quantity changing with the operating force by generating a first measuring capacitance between the first and second electrodes and to assign a switching or controlling function to the operation in accordance with the characteristic value detected by the capacitive touch sensor and with the measured quantity detected in the operation-detection step.