Display Pixel Bank Structures with Undercuts for High-Resolution Separation
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Solution Overview
Problem
Display devices with high pixel integration face challenges in separating light emitting elements for each emission area due to reduced space, leading to difficulties in implementing high-resolution displays without short-circuit defects caused by contact between pixel electrodes and bank structures.
Innovation Solution
A display device design featuring a bank structure with undercut formations under pixel electrodes, utilizing different metal layers and insulating layers to space apart pixel electrodes without etching, thereby reducing gaps and preventing short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel integration degree is increased to achieve high resolution, then display resolution is improved, but emission area is reduced making it difficult to separate light emitting elements
Solution Approach 1:
The patent introduces a vertical dimension by forming the bank structure with multiple layers having different heights. The first bank layer has a first height and the second bank layer has a second height greater than the first height, creating a stepped configuration that provides additional separation space in the vertical direction to accommodate closely spaced pixel electrodes.
Solution Approach 2:
The bank structure is divided into multiple segments (first bank layer and second bank layer) with different heights and positions. This segmentation creates multiple separation zones between adjacent pixel electrodes, enabling effective separation even when emission areas are reduced due to high pixel integration.
2Measurement precision
If pixel electrodes are spaced closer to increase pixel integration, then display resolution is improved, but short-circuit defects increase due to contact between pixel electrodes and bank structure
Solution Approach 1:
The patent introduces insulating layers as intermediary structures between the pixel electrodes and the bank structure. These insulating layers act as mediators that prevent direct contact and potential short-circuits between the pixel electrodes and the bank structure, enabling closer spacing of pixel electrodes without compromising reliability.
Solution Approach 2:
The stepped bank structure creates vertical separation between the pixel electrode and the bank structure through the height difference between the first and second bank layers. This vertical dimension provides additional insulation and prevents contact, reducing short-circuit defects while allowing higher pixel integration.
3Ease of manufacture
If traditional mask process is used to separate light emitting elements, then manufacturing is simplified, but it cannot achieve adequate separation in high pixel integration designs
Solution Approach 1:
The bank structure is formed with predetermined height differences between its layers before the pixel electrode deposition process. This preliminary action creates built-in separation features that automatically define the spacing between pixel electrodes, eliminating the need for complex post-deposition etching or masking steps to achieve precise separation.
Data Source
AI summary
A display device includes a substrate including an emission area and a non-emission area; a first bank layer positioned on the emission area of the substrate; a first bank insulating layer positioned on a side surface of the first bank layer; a second bank layer positioned on the first bank layer and including a tip protruding more than the side surface of the first bank layer toward the non-emission area; a pixel electrode positioned on the second bank layer; a light emitting layer positioned on the pixel electrode; a residual pattern positioned on the non-emission area of the substrate and spaced apart from the pixel electrode wherein the residual pattern and the pixel electrode include a same material; and a pixel defining layer positioned on the residual pattern and covering the first bank layer, the second bank layer, and the pixel electrode.