Sensing Electrode Open Region Parasitic Capacitance
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Solution Overview
Problem
In display devices, the decreasing thickness of mobile devices leads to interference with touch sensing functions due to spatial variations in the pixel defining layer, causing parasitic capacitance and reducing touch sensitivity, especially with noise signals affecting the touch panel's performance.
Innovation Solution
The integration of an input sensor with a reduced noise property, where a portion of the sensing electrode is removed and an open region is formed to correspond to the pixel definition layer, and a bridge pattern is used to improve sensitivity without increasing noise, including a mesh-shaped structure and insulating layers to manage parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of display devices is decreased, then the device becomes more compact and portable, but parasitic capacitance increases due to spatial variations in the pixel defining layer, reducing touch sensing sensitivity
Solution Approach 1:
The sensing electrode is extracted or removed from the region overlapping with the second portion of the pixel defining layer. This extraction eliminates the source of parasitic capacitance in the problematic area while preserving the sensing function in regions where the pixel defining layer does not cause interference.
Solution Approach 2:
The sensing electrode is designed with non-uniform distribution - it is present in some regions and absent in others. Specifically, the sensing electrode is removed from areas overlapping with the thicker second portion of the pixel defining layer, creating local variations in electrode configuration to mitigate parasitic capacitance in critical regions.
2Area of stationary object
If a complete sensing electrode is used, then touch sensing coverage is maximized, but noise signals from the electrode interfere with touch panel performance
Solution Approach 1:
The sensing electrode is extracted from specific regions where it generates harmful noise signals. By removing the electrode material from areas overlapping with the pixel defining layer, the source of noise is eliminated while the remaining electrode portions continue to provide touch sensing functionality.
Solution Approach 2:
The sensing electrode is segmented into multiple regions with different configurations. Some regions contain the sensing electrode for touch detection, while other regions (overlapping with the pixel defining layer) have the electrode removed or reduced to minimize noise generation.
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 enhances the sensitivity of the input sensor while reducing noise interference, thereby improving the overall touch sensing performance in display devices.
Implementation Method 1
interference with the touch sensing function, such as parasitic capacitance, may be caused due to spatial variations in the pixel defining layer, which reduces the distance between an electrode in the display panel and a sensing electrode
Data Source
AI summary
A display device may include a display panel and an input sensor. The input sensor including a sensing electrode and an insulating layer. The display panel may include a light emitting element and a pixel definition layer. The light emitting element may include a first electrode in contact with a base surface, a second electrode, and a light emitting layer between the first electrode and the second electrode. The pixel definition layer may include a first portion defining an opening exposing the first electrode, and a second portion provided on and at least partially overlapping with the first portion. The sensing electrode is provided on the plurality of thin films overlapped with the first portion of the pixel definition layer and defining an open region at least partially overlapping the second portion of the pixel definition layer.