Peripheral Electrode Ion Trapping via Alignment Film Thickness Variation
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Solution Overview
Problem
Existing display devices with electrodes in peripheral regions face issues of deteriorating display quality due to ion accumulation, which can cause black unevenness and decreased brightness, despite efforts to prevent ion diffusion using trap electrodes.
Innovation Solution
A display device configuration with a specific alignment film thickness variation, where the portion overlapping with the trap electrode in the peripheral region has a smaller thickness than the portion overlapping with the display electrode, and the electrode is formed in the same layer as the pixel electrode, with a longer distance from the substrate, to enhance ion trapping efficiency while preventing burn-in phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrode is disposed in the peripheral region to trap ions, then ion trapping efficiency is improved, but display quality deteriorates due to burn-in phenomena
Solution Approach 1:
The alignment film is designed with different thicknesses in different regions: a first thickness in the display region and a second thickness (smaller than the first) in the peripheral region where the trap electrode is located. This local variation in film thickness allows the trap electrode to effectively trap ions while preventing burn-in phenomena in the display region, thus resolving the contradiction between ion trapping efficiency and display quality.
2Object-affected harmful factors
If the alignment film thickness is reduced in the peripheral region, then burn-in phenomena are prevented, but ion trapping efficiency may be reduced
Solution Approach 1:
The alignment film thickness is locally optimized: thinner (second thickness) in the peripheral region to prevent burn-in, and thicker (first thickness) in the display region to maintain ion trapping efficiency. This spatially differentiated design resolves the contradiction between burn-in prevention and ion trapping efficiency.
3Device complexity
If the first electrode is positioned closer to the substrate, then device complexity is reduced, but ion trapping efficiency decreases
Solution Approach 1:
Instead of changing the horizontal position of the electrode, the invention utilizes the vertical dimension by varying the alignment film thickness. The trap electrode is positioned in the peripheral region with a thinner alignment film (second thickness) over it, creating an electric field that effectively traps ions while maintaining simple device structure.
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 effectively traps ions in the peripheral region, reducing their presence in the display area and preventing burn-in, thereby improving display quality and maintaining electrode efficiency.
Implementation Method 1
a first electrode between the insulating film and the alignment film in the peripheral region and having a front surface in contact with the alignment film. The first electrode is supplied with an electric potential in the peripheral region
Implementation Method 2
A distance from the insulating substrate to the front surface of the first electrode is longer than a distance from the insulating substrate to the front surface of the first display electrode
Data Source
AI summary
A display device includes a substrate having a display region and a peripheral region outside the display region; a liquid crystal layer; an insulating film between the liquid crystal layer and the substrate; an alignment film between the insulating film and the liquid crystal layer and having a front surface in contact with the liquid crystal layer; a pixel electrode having a front surface in contact with the alignment film in the display region; and an electrode having a front surface in contact with the alignment film in the peripheral region. Also, the electrode is supplied with an electric potential in the peripheral region. Each of the alignment film, the pixel electrode, and the electrode is formed on the insulating film. A distance from the substrate to the front surface of the electrode is longer than a distance from the substrate to the front surface of the pixel electrode.