Touch-on-encapsulation OLED Panel with Sub-line Signal Routing
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Solution Overview
Problem
The integration of touch panels into OLED display devices is challenging due to the encapsulation layer's complexity and the risk of damaging organic materials during high-temperature processing, making it difficult to fabricate OLED display panels with built-in touch panels without compromising display performance.
Innovation Solution
A touch-on-encapsulation (TOE) structure is implemented, where touch sensors are directly disposed on the encapsulation layer, reducing the distance between the touch sensor and the OLED electrode, and using a multi-electrode structure with sub-electrodes connected via contact holes to minimize parasitic capacitance and RC delay, thereby enhancing touch sensitivity and reducing fabrication complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an encapsulation layer is provided on the front surface of the OLED display panel to protect from moisture, air, and physical impacts, then reliability is improved, but device complexity and difficulty of processing increase
Solution Approach 1:
The patent merges the touch sensor fabrication process with the encapsulation layer formation process. The touch sensor electrodes are formed on the lower surface of the encapsulation layer, combining what were previously separate processes (touch sensor fabrication and encapsulation) into a single integrated manufacturing flow, thereby reducing overall processing complexity while maintaining protection functionality
Solution Approach 2:
The patent performs preliminary actions by forming the touch sensor electrodes on the lower surface of the encapsulation layer before the encapsulation layer is fully completed. This allows the touch sensor structure to be established early in the process sequence, enabling subsequent steps to build upon this foundation without requiring additional complex processing steps later
2Manufacturing precision
If high temperature processing is used to implement touch sensors with metal materials, then manufacturing precision is improved, but organic materials in the OLED display panel are damaged
Solution Approach 1:
The patent changes the temperature parameter of the fabrication process to a low temperature range (below 150°C) that is suitable for organic materials. This parameter change allows the touch sensor electrodes to be formed with sufficient precision while preventing thermal damage to the OLED organic layers, resolving the contradiction between manufacturing precision and material protection
Solution Approach 2:
The patent uses transparent conductive oxide (TCO) materials such as indium tin oxide (ITO) or indium zinc oxide (IZO) for the touch sensor electrodes instead of traditional metal materials. These TCO materials can be deposited at low temperatures and provide the necessary electrical conductivity without requiring high-temperature processing that would damage organic materials
3Device complexity
If touch sensors are integrated within the OLED display panel, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces the encapsulation layer as an intermediary substrate for forming the touch sensor electrodes. By using the lower surface of the encapsulation layer as the formation surface, the patent establishes a stable reference plane that facilitates precise positioning of touch sensor electrodes while simplifying the overall device structure and reducing fabrication complexity
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 approach allows for the successful integration of touch sensors within OLED display panels, improving touch sensitivity and reducing the thickness and complexity of the display device, while maintaining light-emitting efficiency and facilitating the fabrication of larger panels.
Implementation Method 1
capacitance touch sensing is commonly used to sense a touch and determine touch coordinates, using a plurality of touch electrodes disposed on a touch panel as touch sensors, based on a change in capacitance between touch electrodes or between a touch electrode and a pointer, such as a finger
Data Source
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AI summary
A touch display device is disclosed, comprising: a substrate comprising data lines (DL), gate lines (GL), and subpixels (SP); an encapsulation layer (400) over the substrate; touch sensors (TS) sensing a touch and disposed on the encapsulation layer (400); an insulation layer (1120) on the encapsulation layer (400); and a plurality of signal lines (SL) electrically connected to at least one electrode (SE1, SE2) of the touch sensors and comprising a first sub-line (SL1) and a second sub-line (SL2) electrically connected to the first sub-line (SL1), wherein the first sub-line (SL1) is disposed on the encapsulation layer (400), the insulation layer (1120) is disposed on the first sub-line (SL1), and the second sub-line (SL2) is disposed on the insulation layer (1120).