Force Sensor Electrode Layout for Small-Force Detection
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Solution Overview
Problem
Existing detection devices fail to accurately detect small forces due to warping caused by differences in linear expansion coefficients between the protective film and sensor layer, leading to inconsistent contact areas with detection electrodes.
Innovation Solution
The detection device includes an array substrate with recessed surfaces and a sensor layer separated from detection electrodes, allowing the contact area to vary proportionally with applied force, using conductive resin material printed on the substrate and separated from detection electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor layer is printed on the protective film and stacked on the array substrate, then the manufacturing process is simplified, but the protective film warps due to different linear expansion coefficients causing the sensor layer to be too far from the detection electrode to detect small forces
Solution Approach 1:
A resin layer is introduced as an intermediary between the sensor layer and the array substrate. This resin layer has a linear expansion coefficient that matches the sensor layer, preventing warping when the sensor layer is printed on the protective film. The resin layer acts as a mediator that maintains the proper distance between the sensor layer and detection electrode while enabling the simplified manufacturing process of printing on the protective film first.
2Measurement precision
If the sensor layer is printed on the array substrate, then the sensor layer is in contact with the detection electrode, but the device fails to detect small forces because the contact area cannot vary with applied force
Solution Approach 1:
The resin layer serves as a mediator between the sensor layer and the array substrate, replacing direct contact. This allows the sensor layer to be positioned close to the detection electrode without actual contact, enabling the contact area to vary dynamically with applied force while maintaining detection sensitivity. The resin layer facilitates this controlled interaction without the sensor layer being permanently fixed to the substrate.
3Ease of manufacture
If the protective film and sensor layer are stacked with different linear expansion coefficients, then the manufacturing is easier, but the protective film warps causing inconsistent detection performance
Solution Approach 1:
The resin layer is introduced as a mediator between the protective film and the array substrate. It has a linear expansion coefficient that matches the sensor layer, creating a stable interface that prevents warping of the protective film during temperature changes. This intermediary layer maintains the flatness and structural stability of the entire stack while allowing the easier manufacturing process of printing the sensor layer on the protective film.
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 enables precise detection of varying forces by maintaining consistent separation between the sensor layer and detection electrodes, enhancing the device's sensitivity and accuracy.
Implementation Method 1
When force is applied to the detection surface, the facing surface moves toward the detection electrode and the common electrode and comes into contact with the detection electrode and the common electrode. As a result, a current flows from the common electrode to the detection electrode via the sensor layer. When the force applied to the detection surface is large, the contact area of the facing surface in contact with the common electrode and the detection electrode increases. As a result, the current flowing from the common electrode to the detection electrode increases.
Data Source
AI summary
According to an aspect, a detection device includes an array substrate and a sensor layer stacked in the order as stated. A direction in which the sensor layer is disposed when viewed from the array substrate is a first stacking direction. A direction opposite to the first stacking direction is a second stacking direction. The array substrate includes: a first surface facing in the first stacking direction; a plurality of recessed surfaces recessed from the first surface in the second stacking direction; and a plurality of detection electrodes provided on the respective recessed surfaces. The sensor layer is formed by curing conductive resin material printed on the first surface. The sensor layer and the detection electrodes are separated from each other.