OLED Touch Display Panel Time Division Multiplexing
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Solution Overview
Problem
The development of flexible AMOLED touch display panels with folding screens faces challenges such as increased cost and peeling issues during the bending process due to the sensitivity of OLED luminescent materials to temperature and the inability to integrate touch sensors into the driving chip.
Innovation Solution
An OLED touch display panel with a patterned cathode using a low-temperature polysilicon array substrate and embedded sensor pads, where voltage signal traces are multiplexed as touch signal traces, and a time division multiplexing circuit unit is added outside the display area to enable in-cell touch functionality without additional layers or traces, reducing cost and preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a touch sensor is attached to the AMOLED as an add-on type, then the touch function is provided, but the cost increases and peeling occurs during bending process
Solution Approach 1:
The patent merges the touch sensor layer with the OLED structure by forming the touch sensor directly on the OLED luminescent layer, creating an integrated on-cell type touch display panel where the touch sensor and display layers are combined into a single structure, eliminating the need for separate add-on touch panels
Solution Approach 2:
The patent makes the OLED luminescent layer serve dual functions: as the light-emitting layer for display and as the substrate for the touch sensor, allowing the same layer to perform both display and touch sensing functions simultaneously
2Device complexity
If an on-cell type touch display panel is made by coating directly on the AMOLED, then the structure is simplified, but the OLED luminescent material is damaged due to temperature sensitivity
Solution Approach 1:
The patent changes the temperature parameter by introducing a low-temperature CVD process that operates below 80°C, allowing the coating process to proceed without damaging the temperature-sensitive OLED luminescent material while still forming the required touch sensor structure
Solution Approach 2:
The patent applies different coating processes to different regions: using low-temperature CVD specifically for the touch sensor areas where temperature control is critical, while maintaining the integrity of the OLED luminescent layer through targeted local processing
3Ease of manufacture
If a common mask evaporation process is used to form the cathode, then the process is simple, but the electric field is shielded and in-cell touch structure cannot be used
Solution Approach 1:
The patent segments the cathode into multiple patterned layers (first cathode layer and second cathode layer) with different functionalities: the first layer serves as the primary cathode for OLED operation, while the second layer is designed with openings to allow electric field penetration for in-cell touch sensing, thereby resolving the conflict between simple fabrication and touch functionality
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 solution allows for a cost-effective and reliable in-cell touch structure in flexible AMOLED panels by reducing the need for extra traces and layers, preventing peeling during bending, and integrating touch and display driver functions efficiently.
Implementation Method 1
a time division multiplexing circuit unit is added outside the display area to enable in-cell touch functionality
Implementation Method 2
OLEDs are diodes which use organic semiconductor material and luminescent material in an electric field to perform carrier injection and recombination to emit light
Implementation Method 3
voltage signal traces are multiplexed as touch signal traces
Data Source
AI summary
An organic light emitting diode touch display panel and a method for driving time division multiplexing are disclosed. The OLED touch display panel with a patterned cathode uses a pixel definition layer of a LTPS array substrate to form sensor pads. By adding a time division multiplexing circuit unit to each voltage signal traces outside the display area of the touch display panel, the power signal traces of the source and drain layer of the LTPS array substrate are multiplexed, and peeling during the flexible screen bending process can be prevented.