Display Device Light Leakage Prevention via Dual Shielding Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In active matrix type display devices using electroluminescence elements, light leakage from the monitor element portion occurs due to the difficulty in forming adequate light shielding films, leading to luminance variations with temperature changes and over time, which is undesirable as it increases power consumption and affects image display.
Innovation Solution
The implementation of a display device structure where a monitor element is provided with a first light shielding film overlapping its electrode and a second light shielding film electrically connected through a contact hole in the interlayer insulating film, ensuring the monitor element and its transistor do not overlap, and both shielding films are formed simultaneously with other wiring to prevent light leakage without increasing manufacturing steps or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light shielding film is provided to prevent light leakage from the monitor element, then light leakage is reduced, but the aperture ratio is decreased and manufacturing complexity increases
Solution Approach 1:
The patent transitions from a single-layer light shielding approach to a multi-layer structure where the first light shielding film is positioned at the substrate side and the second light shielding film is positioned at the interlayer insulating film side. This spatial distribution in different dimensions effectively blocks light leakage paths while maintaining aperture ratio by optimizing the positioning and transparency of each layer.
Solution Approach 2:
The light shielding function is segmented into two separate films: a first light shielding film formed simultaneously with gate lines, and a second light shielding film formed simultaneously with source/drain lines. This segmentation allows each film to be optimized for its specific function and positioned strategically to block light leakage without unnecessarily reducing the aperture ratio.
2Object-affected harmful factors
If a light shielding film is added to prevent light leakage, then light leakage is reduced, but manufacturing steps and cost increase
Solution Approach 1:
The patent merges the formation of light shielding films with the existing wiring formation processes. The first light shielding film is formed simultaneously with gate lines, and the second light shielding film is formed simultaneously with source/drain lines. This integration eliminates the need for separate light shielding film formation steps, thereby reducing manufacturing complexity and cost while still achieving effective light leakage prevention.
3Object-affected harmful factors
If the monitor element and transistor are separated to prevent overlap, then light leakage is reduced, but device area increases
Solution Approach 1:
Instead of separating the monitor element and transistor in the planar direction which would increase device area, the patent uses vertical dimensionality by positioning light shielding films at different levels (substrate side and interlayer insulating film side). This allows the monitor element and transistor to remain in close proximity while still preventing light leakage through the multi-layer shielding 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 structure effectively prevents light leakage while maintaining a comparable aperture ratio to the pixel portion, ensuring consistent luminance and reduced power consumption by keeping the current through the light-emitting element constant, thus enhancing the reliability and yield of the display device at a lower cost.
Implementation Method 1
a first light shielding film provided so as to overlap a first electrode of the monitor element... a second light shielding film provided so as to overlap the first light shielding film
Data Source
AI summary
A display device in which light leakage in a monitor element portion is prevented without increasing the number of steps and cost is provided. The display device includes a monitor element for suppressing influence on a light-emitting element due to temperature change and change over time and a TFT for driving the monitor element, in which the TFT for driving the monitor element is provided so as not to overlap the monitor element. Furthermore, the display device includes a first light shielding film and a second light shielding film, in which the first light shielding film is provided so as to overlap a first electrode of the monitor element and the second light shielding film is electrically connect to the first light shielding film through a contact hole formed in an interlayer insulating film. The contact hole is formed so as to surround the outer edge of the first electrode of the monitor element.