Touch Display Planarization for Non-Display Area Patterning
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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
1Reliability
If photoresist is applied to the encapsulation film in the non-display area to form touch electrodes and lines, then touch sensing functionality is achieved, but pattern defects occur due to uneven photoresist application on the dam structure
Solution Approach 1:
A planarization film is formed on the encapsulation film in the non-display area before forming the touch electrodes and lines. This preliminary action creates a flat surface that enables uniform photoresist application during subsequent patterning processes, preventing pattern defects while maintaining touch sensing functionality.
Solution Approach 2:
The planarization film acts as an intermediary layer between the encapsulation film and the touch electrode structure. It mediates the surface irregularity caused by the dam structure, providing a uniform base for photoresist application and subsequent pattern formation.
2Reliability
If the encapsulation film extends to the non-display area to prevent overflow, then protection of display elements is improved, but touch line formation becomes difficult due to the dam structure
Solution Approach 1:
The planarization film is formed in advance on the encapsulation film in the non-display area, creating a flat surface that facilitates subsequent touch line formation processes. This preliminary planarization enables standard photolithography and etching procedures to be used without modification.
Solution Approach 2:
The planarization film is selectively formed only in the non-display area where the dam structure exists, providing local surface correction without affecting the overall device structure or display area.
Data Source
AI summary
A touch display device in one example includes a blocking structure disposed on a substrate and surrounding at least a part of a display area of the substrate, and first touch electrode lines extending in a first direction in the display area. Each of the first touch electrode lines includes first touch electrodes. The touch display device further includes first touch lines disposed on the substrate where a same signal is applied to the first touch electrodes of one of the first touch electrode lines by one of the first touch lines, second touch electrode lines disposed between the first touch electrodes in the display area, and second touch lines disposed on the substrate. Each of the second touch electrode lines is electrically connected to one of the second touch lines.