Touch Electrode Layout Over Display Dams to Prevent Etching Defects
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Solution Overview
Problem
In display devices, particularly organic light emitting display devices, the formation of touch electrodes and lines on encapsulation films in non-display areas can lead to pattern defects due to uneven application of photoresist, causing unintentional etching during mask processes.
Innovation Solution
A touch display device with a blocking structure in the non-display area surrounding the display area, featuring first and second touch electrodes on the encapsulation film, connected by a first and second touch line with an insulating film contact hole, allowing for secure connection without pattern defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photoresist is applied to the encapsulation film on the dam in the non-display area, then touch electrodes and lines can be formed, but the photoresist is applied more thinly due to the height of the dam, causing pattern defects and unintentional etching
Solution Approach 1:
A planarization layer is introduced as an intermediary between the encapsulation film and the photoresist. This planarization layer fills the step difference created by the dam structure, providing a flat surface for uniform photoresist application. The planarization layer acts as a mediator that eliminates the height variation problem, allowing the photoresist to be applied at consistent thickness across the entire surface including areas over the dam structure, thereby preventing pattern defects and unintentional etching of touch lines
Data Source
AI summary
A display device can include a display area on a substrate and a non-display area located outside the display area on the substrate, a transistor in the display area; a planarization film on the transistor, a light emitting element on the planarization film in the display area and connected to the transistor, the light emitting element including a first electrode, a second electrode, and an emission layer between the first electrode and the second electrode, an encapsulation film on the light emitting element, at least two dams disposed along a periphery of the display area, a touch buffer film on the encapsulation film, a touch insulating film on the touch buffer film, a touch electrode on the touch insulating film, and a touch electrode connection line disposed under the touch electrode and configured to connect to the touch electrode in the non-display area via at least two contact holes.