Capacitive Pressure Sensor with Auxiliary Electrodes for Deformation Compensation
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Solution Overview
Problem
Conventional pressure touch control panels face high costs and complex assembly due to the integration of microelectromechanical sensors, and they struggle to accurately differentiate between touch and pressure sensing, leading to inefficiencies in 3D touch operation.
Innovation Solution
A capacitive pressure sensor design featuring an upper substrate with first and second electrode layers, a dielectric layer that deforms under pressure, and a capacitance sensing circuit that sends signals to second sensing electrodes to obtain pressure sensing signals, while using auxiliary and shielding signals to minimize measurement influence from dielectric deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microelectromechanical sensors are integrated at edge or corner of the display panel, then pressure sensing capability is achieved, but cost increases and assembly difficulty increases
Solution Approach 1:
The patent merges the pressure sensing function with the existing capacitive touch panel structure by integrating sensing electrodes directly into the display panel layers. The first sensing electrodes are formed on the second substrate and the second sensing electrodes are formed on the first substrate, combining touch and pressure sensing into a single integrated structure rather than adding separate microelectromechanical sensors.
Solution Approach 2:
The capacitive touch panel structure is designed to perform multiple functions: both touch detection and pressure sensing. The same electrode structures and dielectric layers that enable capacitive touch also facilitate pressure measurement through capacitance changes, eliminating the need for dedicated pressure sensing components.
2Reliability
If conventional pressure touch control panel uses microelectromechanical sensor, then pressure sensing is enabled, but manufacturing cost increases
Solution Approach 1:
The patent combines pressure sensing functionality with the standard capacitive touch panel manufacturing process. The sensing electrodes are formed using the same thin-film deposition and patterning techniques as the display panel, allowing pressure sensing to be manufactured alongside the display without requiring separate microelectromechanical sensor production lines.
Solution Approach 2:
The capacitive touch panel structure itself serves as the pressure sensing mechanism. The dielectric layer and electrode structures that are already present for touch operation also detect pressure through capacitance changes, eliminating the need for additional specialized sensing components and reducing manufacturing complexity.
3Reliability
If dielectric layer is used between electrode layers, then electrical insulation is provided, but dielectric deformation influences measurement accuracy
Solution Approach 1:
The patent extracts and compensates for the harmful effect of dielectric deformation by introducing auxiliary sensing electrodes that specifically detect the deformation signal. The fourth sensing electrodes (auxiliary electrodes) are positioned to detect capacitance changes caused by dielectric layer deformation, allowing this interference to be measured and subtracted from the pressure measurement.
Solution Approach 2:
The auxiliary sensing electrodes provide feedback about dielectric layer deformation, which is used to compensate for measurement errors in the pressure sensing. By monitoring the capacitance changes in the auxiliary electrodes that are caused by dielectric deformation, the system can distinguish between deformation-induced capacitance changes and pressure-induced capacitance changes.
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 design enhances the accuracy of pressure and touch sensing by reducing the impact of dielectric deformation, allowing for precise location and pressure detection, thereby improving the functionality and cost-effectiveness of pressure touch control panels.
Implementation Method 1
a dielectric layer arranged between the first electrode layer and the second electrode layer, the dielectric layer being compressively deformed under pressure and restoring to original shape and volume if pressure is not present
Implementation Method 2
a capacitance sensing circuit configured to send a capacitance-exciting signal to the at least one second sensing electrode and obtain a pressure sensing signal from the second sensing electrode
Data Source
AI summary
A capacitive pressure sensor includes an upper substrate having a first face and a second face opposite to the first face, a first electrode layer with a plurality of first sensing electrodes, a second electrode layer having at least one second sensing electrode, a dielectric layer arranged between the first and the second electrode layers, and a capacitance sensing circuit. In pressure sensing operation, the capacitance sensing circuit sends a capacitance-exciting signal to the at least one second sensing electrode and obtains a pressure sensing signal from the second sensing electrode.