Capacitive Sensor With Segmented Electrodes For Force And Position Detection
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Solution Overview
Problem
Existing capacitance-based input devices fail to detect pressing force and position accurately due to insufficient capacitance change when low pressing force is applied, leading to unreliable input detection.
Innovation Solution
A detecting sensor configuration with a flexible board and opposing surfaces, featuring position detection electrodes and pressing force detection electrodes, allows independent detection of input position and force by utilizing capacitance changes between electrodes and a user's finger, even with low pressing force, through an insulating film and control IC integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electrode configuration is used for both position and pressing force detection, then device complexity is reduced, but measurement precision deteriorates because the same electrode cannot independently detect both position and force
Solution Approach 1:
The electrode system is segmented into two independent sets: position detection electrodes (first electrode) and pressing force detection electrodes (second electrode). This segmentation allows each electrode type to be optimized for its specific detection function, with position electrodes arranged to detect touch location and force electrodes arranged to detect capacitance changes due to pressing force, thereby resolving the contradiction between device simplicity and detection precision.
Solution Approach 2:
The sensor achieves multi-functionality by integrating both position detection and pressing force detection capabilities into a single sensor device. The first electrode detects position through capacitance coupling with the touch object, while the second electrode detects pressing force through capacitance changes, allowing the sensor to perform multiple detection functions simultaneously without requiring separate sensing systems.
2Ease of operation
If low pressing force is applied, then ease of operation is improved, but measurement precision deteriorates because insufficient capacitance change occurs between electrodes
Solution Approach 1:
The invention changes the detection parameter from relying on displacement-induced capacitance change to relying on direct capacitance coupling. By using the first electrode to detect capacitance changes caused by the touch object's proximity and the second electrode to detect capacitance changes caused by pressing force, the system can detect both position and force even with minimal pressing force, as the capacitance coupling mechanism is highly sensitive to small changes.
Solution Approach 2:
The invention replaces the mechanical displacement-based detection mechanism with an electrical capacitance-based detection mechanism. Instead of relying on physical displacement of electrodes to generate detectable signals, the system uses capacitance coupling between electrodes and the touch object, which is much more sensitive to small changes and allows detection with minimal pressing force.
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
Enables precise detection of input position and pressing force, ensuring reliable user input operations even with minimal pressing force, enhancing the accuracy and reliability of input device functionality.
Implementation Method 1
When a user's finger touches the insulating film, a capacitance is produced between the finger and the position detection electrode. Consequently, it is possible to detect the pressing position based on a change in this capacitance.
Implementation Method 2
When the user presses the first board, a distance between the pressing force detection first electrode and the plurality of pressing force detection second electrodes decreases, and the capacitance produced between the electrodes changes (increases).
Data Source
AI summary
A detecting sensor is disclosed that includes position detection electrodes provided on a surface of a board which has flexibility, and are provided at a distance in a planar direction. Furthermore, the detecting sensor includes an insulator film provided on the surface of the board that covers the electrodes; pressing force detection electrodes provided on a back surface of the board; and a pressing force detection electrode provided to oppose to the electrodes with a gap therebetween. Consequently, it is possible to provide the detecting sensor that can reliably receive a user's input operation and precisely detect a pressing position and a pressing force.