In-Cell Touch Electrode Separation for Organic Light Emitting Display
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Solution Overview
Problem
In-cell type touch integrated display devices face a trade-off between touch sensitivity and viewing angle due to parasitic capacitance caused by the proximity of touch electrodes to light emitting units, limiting the display's ability to maintain high sensitivity while widening the viewing angle.
Innovation Solution
The integration of a multi-buffer layer on the RGB color filters of the upper substrate, along with a planarization layer between the color filters and the multi-buffer layer, helps to maximize the separation distance between touch electrodes and light emitting units, reducing parasitic capacitance and enhancing viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the separation distance between the upper substrate and lower substrate is decreased to improve viewing angle, then the viewing angle is improved, but the parasitic capacitance between the electrode and touch electrode increases, reducing touch sensitivity
Solution Approach 1:
The patent introduces a new spatial dimension by forming the touch electrode layer on the upper substrate rather than on the lower substrate. This dimensional repositioning increases the separation distance between the light emitting electrode and touch electrode in the vertical direction, thereby reducing parasitic capacitance while maintaining improved viewing angle characteristics.
Solution Approach 2:
The upper substrate acts as an intermediary element that separates the light emitting electrode on the lower substrate from the touch electrode layer. By placing the touch electrode layer on the upper substrate, the upper substrate mediates the interaction between these two electrodes, reducing their electrical coupling and parasitic capacitance while still allowing optical functionality.
2Object-generated harmful factors
If the separation distance between the electrode and touch electrode is increased to reduce parasitic capacitance, then touch sensitivity is improved, but the viewing angle decreases
Solution Approach 1:
The patent resolves this contradiction by changing the spatial arrangement from a horizontal separation to a vertical separation through dimensional repositioning. The touch electrode layer is formed on the upper substrate, creating vertical separation from the light emitting electrode on the lower substrate. This maintains large separation distance for low parasitic capacitance while the optical path remains unobstructed for wide viewing angle.
3Device complexity
If the touch electrode layer is formed on the lower substrate, then the structure is simplified, but the parasitic capacitance increases and touch sensitivity decreases
Solution Approach 1:
Instead of simplifying the structure by keeping the touch electrode layer on the lower substrate, the patent deliberately moves it to the upper substrate, accepting increased structural complexity. This dimensional repositioning creates sufficient separation distance to reduce parasitic capacitance and improve touch sensitivity, demonstrating that performance improvement justifies the additional structural 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 configuration maintains touch sensitivity while increasing the viewing angle by minimizing parasitic capacitance and allowing light to be emitted at various angles without obstruction, thus improving the overall performance of the organic light emitting display device.
Implementation Method 1
a light emitting unit for emitting light to an upper surface
Implementation Method 2
a color filter layer 40 including a color filter for three primary colors (RGB: red, green, blue) to display color
Implementation Method 3
touch electrodes configured with transmitting electrode (Tx) and receiving electrode (Rx) used in performing a touch operation on the second substrate, and to generate mutual capacitance within the touch electrodes, thereby measuring a change amount of the mutual capacitance
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
An organic light emitting display device (100) and a fabrication method comprising a touch electrode layer (150) including touch electrodes (152) and touch lines (155) on an upper substrate (130) which are directly formed on the upper substrate (130) to secure a large distance between the touch electrodes (152) and cathode as well as minimize a distance between the upper and lower substrates (110, 130), thereby widening the viewing angle of an image while reducing a parasitic capacitance.