Transparent Touch Display Cathode Division for Parasitic Capacitance Reduction
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Solution Overview
Problem
Conventional touch display devices with built-in touch sensors face challenges in achieving high transmittance and self-emissive performance, particularly when integrating touch sensors with self-emissive light emitting elements like OLEDs, as it complicates the design and manufacturing process and can affect light transmittance and touch sensing accuracy.
Innovation Solution
A transparent touch display device design that incorporates a touch sensor on a cathode electrode layer by cathode division, with touch lines positioned farthest from the anode electrode to minimize interference with light emitting elements and reduce parasitic capacitance, allowing for precise touch sensing and high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a touch sensor is integrated into a self-emissive display panel with OLED light emitting elements, then the device can provide touch sensing functionality, but the design and manufacturing complexity increases significantly and light transmittance is compromised
Solution Approach 1:
The patent merges the touch sensor electrodes with the cathode electrode layer of the OLED display, creating a unified structure where the touch cathode electrode and display cathode electrode are integrated into the same layer. This combination eliminates separate touch sensor manufacturing steps and simplifies the overall device structure while maintaining both touch sensing and light emission functions.
Solution Approach 2:
The cathode electrode layer serves dual functions: it acts as both the cathode for the OLED light emitting elements and as the touch sensor electrode. This multi-functional design allows the same structural element to perform both display and touch sensing roles, reducing device complexity.
2Adaptability or versatility
If touch sensor electrodes are placed in the display panel, then touch sensing is enabled, but light transmittance is reduced due to the presence of electrode materials
Solution Approach 1:
The patent employs transparent conductive materials for the touch cathode electrode in regions where light transmittance is critical, while using conventional conductive materials in areas where structural support or electrical connection is prioritized. This local differentiation optimizes both touch sensing performance and optical properties.
Solution Approach 2:
The cathode electrode layer is constructed using composite material structures, including transparent conductive oxides (TCO) combined with other conductive materials, to achieve both electrical conductivity for touch sensing and optical transparency for light transmission.
3Device complexity
If touch lines are positioned closer to the anode electrode, then the touch sensor structure is simplified, but parasitic capacitance increases and interferes with touch sensing accuracy
Solution Approach 1:
The patent extracts the touch sensing function from the pixel area and positions it in the non-display area, separating the touch cathode electrode from the light emitting elements. This spatial separation reduces parasitic capacitance interference while maintaining structural simplicity.
4Length of stationary object
If the display panel includes integrated touch sensors, then the overall device thickness can be reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The manufacturing process merges the formation of the cathode electrode layer with the formation of the touch sensor electrode layer into a single deposition step. This integrated manufacturing approach maintains process simplicity while achieving the thin profile benefits of integrated touch sensors.
Data Source
AI summary
A transparent touch display device according to embodiments of the disclosure may comprise a substrate including a pixel area, a first transmissive area positioned on a first side of the pixel area, and a second transmissive area positioned on a second side of the pixel area, a driving transistor disposed in the pixel area, an anode electrode disposed in the pixel area, positioned on the driving transistor, and electrically connected with a source electrode or drain electrode of the driving transistor, a light emitting layer positioned on the anode electrode, a display cathode electrode positioned on the light emitting layer, a first touch cathode electrode disposed in the first transmissive area and positioned on a first side of the display cathode electrode, a second touch cathode electrode disposed in the second transmissive area and positioned on a second side of the display cathode electrode, an encapsulation layer disposed on the display cathode electrode, the first touch cathode electrode, and the second touch cathode electrode, and a first touch line overlapping the first touch cathode electrode.