Segmented Cathode Reduces Parasitic Capacitance in Touch Displays
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Solution Overview
Problem
In electroluminescent display devices, parasitic capacitance between touch electrodes and the cathode degrades the performance of the touch sensor, as the cathode is formed all over the substrate, causing interference and reducing sensor effectiveness.
Innovation Solution
The cathode is patterned and separated from the touch sensor by a bank layer, reducing its area and increasing the distance between the touch sensor and the cathode, thereby minimizing parasitic capacitance and enhancing sensor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode is formed all over the substrate, then the light emitting device layer is fully covered and protected, but parasitic capacitance is generated between the touch electrodes and the cathode, degrading touch sensor performance
Solution Approach 1:
The cathode is segmented into pixel-level cathodes rather than being formed as a continuous layer across the entire substrate. This segmentation reduces the overlapping area between the cathode and touch electrodes, thereby minimizing parasitic capacitance while still providing adequate coverage for light emission in each pixel region.
Solution Approach 2:
The cathode structure is optimized with different properties in different regions: in pixel areas, the cathode is present to enable light emission, while in touch sensor areas, the cathode is removed or reduced to minimize parasitic capacitance. This local differentiation allows the system to simultaneously achieve both light emission functionality and touch sensor performance.
2Object-affected harmful factors
If the cathode area is reduced to minimize parasitic capacitance, then touch sensor performance is improved, but the light emitting coverage may be insufficient
Solution Approach 1:
The cathode is divided into discrete pixel-level segments that are strategically positioned to provide sufficient light emitting coverage while minimizing overlap with touch electrodes. This segmentation allows the cathode area to be optimized for both light emission efficiency and touch sensor performance by eliminating unnecessary overlapping regions.
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 reduces parasitic capacitance, improving the touch sensor's performance by minimizing interference and maintaining the display device's overall efficiency.
Implementation Method 1
a parasitic capacitance C is generated between each of the plurality of touch electrodes included in the touch sensor 50 and the cathode 34 included in the light emitting device layer 30
Data Source
AI summary
A display device according to an embodiment includes a substrate including a plurality of pixels including a first pixel and a second pixel, a light emitting device layer provided on the substrate and including an anode included in each of the first pixel and the second pixel, a first bank layer in a boundary between the first pixel and the second pixel, a light emitting layer on the anode, and a cathode on the light emitting layer, an encapsulation layer provided on the light emitting device layer, and a touch sensor provided on the encapsulation layer. The cathode includes a first cathode included in the first pixel and a second cathode included in the second pixel, and the first cathode and the second cathode are separated from each other by the first bank layer.