Backlight Shielding Electrode for Display Waterfall Effect
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Solution Overview
Problem
The 'waterfall phenomenon' occurs in display devices due to the protrusion of semiconductor patterns reacting to backlight light, affecting capacitance and causing bright and dark band-shaped portions to appear, which degrades display quality.
Innovation Solution
Incorporating a transverse stem electrode, longitudinal stem electrode, branch electrodes, a connector, and a pixel electrode contact portion, along with a backlight shielding electrode, to prevent light from affecting the semiconductor pattern and maintain consistent capacitance, and optionally including a color filter between the data wiring and pixel electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the semiconductor pattern protrudes beyond the data wiring pattern (due to single mask process), then manufacturing precision is improved, but the protrusion receives backlight light causing capacitance variation and waterfall phenomenon
Solution Approach 1:
A light shielding electrode is introduced as an intermediary element between the backlight and the protruding semiconductor pattern. This electrode blocks incident light from reaching the semiconductor pattern, preventing capacitance variation and the waterfall phenomenon while allowing the single mask process to continue
Solution Approach 2:
The light shielding electrode is positioned specifically at the location where the semiconductor pattern protrudes beyond the data wiring pattern. This localized shielding approach addresses the light sensitivity problem only in the critical area without affecting other regions of the display device
2Measurement precision
If the data wiring pattern width is reduced (for higher resolution), then display quality is improved, but the semiconductor pattern protrusion becomes more significant relative to wiring width
Solution Approach 1:
The light shielding electrode serves as a mediator that decouples the relationship between wiring width and protrusion management. By blocking light at the protrusion location, the system can use narrower data wiring patterns for higher resolution without the protrusion causing display defects
3Reliability
If a light shielding electrode is added to prevent waterfall phenomenon, then display quality is improved, but device complexity increases
Solution Approach 1:
The light shielding electrode is merged with the existing electrode structure of the display device. It is formed using the same manufacturing processes and materials as other electrodes, integrating it into the overall device architecture rather than adding a completely separate component
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
Prevents the 'waterfall phenomenon' by shielding the semiconductor pattern from backlight light, ensuring consistent display quality and reducing image degradation.
Implementation Method 1
a backlight shielding electrode disposed below a contact hole, the backlight shielding electrode being electrically insulated from the data wiring pattern and the pixel electrode contact portion... preventing light from affecting the semiconductor pattern
Implementation Method 2
amorphous silicon varies in conductivity based on an amount of incident light
Data Source
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AI summary
A display device (10) includes a substrate (1), gate wiring (121, 122) on the substrate, the gate wiring including a gate line (121) and a gate electrode (122), data wiring (162, 165, 166) which is disposed on the substrate and is insulated from the gate wiring, the data wiring including a data line (162), a source electrode (165), and a drain electrode (166), a semiconductor layer (140) formed on a gate insulating layer (130), and a pixel electrode (180) which is disposed above the data wiring and insulated from it by intervening layers (169, 170), wherein the pixel electrode (180) is connected to the drain electrode (166) through a contact hole (175), the display device (10) being characterised by a backlight shielding electrode (128) formed below the contact hole (175) in the same layer as the gate wiring (121, 122), in order to avoid variations of conductivity of the semiconductor layer (140) when it is illuminated with light by a backlight unit. The provision of the backlight shielding electrode (128) reduces the occurence of bright and dark stripes on the display (waterfall effect).