Display Device Second Organic Layer Fills Inorganic Rifts
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Solution Overview
Problem
The integration of a touch panel into a display device is hindered by the uneven surface of the sealing film, which affects the formation of the touch electrode due to the rifts in the organic layer, leading to inadequate exposure and resist thickness issues during photolithography.
Innovation Solution
A display device configuration where a second organic layer fills the concave parts in the inorganic layer, providing a contiguous and planar surface for the touch electrode, moderating the unevenness and enabling effective touch sensing functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing film is formed over the organic layer to seal moisture-sensitive display elements, then moisture protection is improved, but surface unevenness is caused due to rifts in the organic layer
Solution Approach 1:
An intermediate layer is introduced between the sealing film and the organic layer to fill the rifts and concave portions. This intermediary layer acts as a mediator that compensates for the surface unevenness caused by the rifts, providing a flat upper surface for the sealing film while maintaining the moisture sealing function.
Solution Approach 2:
The solution addresses the surface unevenness problem by adding a layer in the vertical dimension (thickness direction) rather than trying to modify the existing organic layer structure. This dimensional approach allows the sealing film to be placed on a flattened surface without altering the underlying rift structure.
2Adaptability or versatility
If photolithography is applied to form touch electrodes on the sealing film, then touch sensing function is achieved, but exposure quality deteriorates due to surface unevenness causing resist thickness variation
Solution Approach 1:
The intermediate layer serves as a mediator that provides a flat surface for photolithography processing. By filling the concave portions and rifts, it ensures uniform resist thickness during exposure, thereby maintaining high manufacturing precision while enabling the touch sensing function.
Solution Approach 2:
The intermediate layer is formed in advance before the photolithography process. This preliminary action of filling the surface unevenness ensures that subsequent exposure and resist coating processes can be performed with high precision, avoiding the quality deterioration that would otherwise occur.
3Device complexity
If the sealing film directly covers the rifted organic layer, then device structure is simplified, but touch electrode formation becomes impossible due to inadequate exposure and resist accumulation
Solution Approach 1:
The intermediate layer acts as a necessary mediator that enables touch electrode formation. By providing a flat surface, it allows proper resist coating and exposure, making the manufacturing process feasible while maintaining relatively simple device structure.
Solution Approach 2:
The introduction of the intermediate layer changes the surface topology parameter from uneven to flat. This parameter change enables the photolithography process to proceed correctly, allowing touch electrode formation without compromising device structure simplicity.
Data Source
AI summary
A display device includes: a first organic layer; display elements over the first organic layer in correspondence with the pixels; an inorganic layer sealing the display elements and the first organic layer; a second organic layer on a part of the inorganic layer; and a touch electrode on a surface of the inorganic layer and a surface of the second organic layer. The first organic layer has a rift in the peripheral area to surround the display area. The inorganic layer includes a concave part over the rift, and extends from the display area to the peripheral area continuously. The second organic layer is on the concave part of the inorganic layer. The surface of the second organic layer on which a touch electrode is put is contiguous to and is surrounded by the surface of the inorganic layer on the concave part.