LCD Common Wiring Segmentation for Step Coverage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid crystal display devices of the fringe field switching mode, short-circuiting between signal lines and common electrodes occurs due to poor step coverage of the gate insulation film, leading to dielectric breakdown and line defects, especially during the manufacturing process where static electricity is generated.
Innovation Solution
A liquid crystal display device configuration where the lower electrode covers the common wiring with multiple small steps, ensuring improved step coverage of the first insulation film, and an upper electrode with slits is used to generate the electric field, reducing dielectric breakdown and short-circuiting risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If physical vapor deposition or organometallic chemical vapor deposition is employed as a deposition method, then the manufacturing process can be completed, but a step is formed on the intersection of signal line and common wiring causing poor step coverage and dielectric breakdown
Solution Approach 1:
The patent segments the common wiring structure by introducing multiple intermediate wirings between the signal line and the original common wiring. This segmentation creates multiple smaller steps instead of one large step, improving step coverage of the gate insulation film. Each intermediate wiring forms a smaller step with the signal line, ensuring adequate dielectric thickness throughout.
Solution Approach 2:
The patent introduces intermediate wirings that extend in the row direction (horizontal dimension) to connect the common wiring to the signal line. This dimensional approach distributes the vertical step height across multiple horizontal segments, improving step coverage while maintaining electrical connection.
2Area of stationary object
If the common wiring is positioned to improve aperture ratio, then the display quality is enhanced, but the step coverage of the gate insulation film deteriorates causing short-circuiting
Solution Approach 1:
The patent segments the connection path between common wiring and signal line by introducing multiple intermediate wirings. This segmentation allows the common wiring to be positioned optimally for aperture ratio while the intermediate wirings create gradual steps that maintain adequate gate insulation film thickness, preventing short-circuiting.
Solution Approach 2:
The intermediate wirings act as mediators between the common wiring and signal line. They provide gradual transitions that maintain dielectric integrity while allowing the common wiring to be positioned for optimal aperture ratio, thus mediating between the conflicting requirements of display quality and reliability.
3Ease of manufacture
If static electricity cleaning is performed before photolithography, then the surface is cleaned, but dielectric breakdown occurs in the first insulation film
Solution Approach 1:
The patent provides beforehand cushioning by introducing intermediate wirings that create adequate step coverage and maintain sufficient gate insulation film thickness before the static electricity cleaning process. This preventive structure cushions against the harmful effects of static electricity, preventing dielectric breakdown during the cleaning process.
4Area of stationary object
If the lower electrode covers the common wiring with large step, then the coverage area is increased, but the film thickness of lateral surface region decreases causing poor coverage
Solution Approach 1:
The patent segments the large step into multiple smaller steps by introducing intermediate wirings. This segmentation maintains adequate film thickness on lateral surfaces while achieving the required coverage area through the extended structure of multiple wirings working together.
Solution Approach 2:
The patent uses horizontal extension (another dimension) of multiple intermediate wirings to achieve the required coverage area while maintaining acceptable vertical step heights. This dimensional approach allows adequate film deposition on lateral surfaces while covering the necessary area.
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
The configuration effectively suppresses short-circuiting and line defects, enhancing the reliability and display quality of the liquid crystal display device by maintaining sufficient dielectric strength and aperture ratio.
Implementation Method 1
a gate insulation film covering the common wiring and the lower electrode is formed so that a plurality of small steps are formed on the lower electrode
Implementation Method 2
an upper electrode which is formed on a second insulation film and overlaps with the lower electrode when viewed from above
Implementation Method 3
physical vapor deposition such as vacuum vapor deposition and sputtering
Implementation Method 4
static electricity is generated between the pure water and the n+a-Si layer, and spark is generated between the n+a-Si layer and the common wiring
Implementation Method 5
spark is generated between the n+a-Si layer and the common wiring due to the static electricity
Data Source
AI summary
A liquid crystal display device includes a pair of substrates of which one substrate is provided with a plurality of scanning lines and a plurality of common wirings, a first insulation film covering the scanning lines, the common wirings, and the one substrate, a plurality of signal lines provided on the first insulation film, a thin film transistor provided near an intersection part of the scanning lines and the signal lines, a lower electrode formed below the first insulation film and connected to the common wirings, a second insulation film formed on surfaces of the thin film transistor, the signal lines, and the first insulation film, and an upper electrode formed on the second insulation film and having a slit, a display region in which the liquid crystal layer is driven by an electric field, and a non-display region that is formed outside the display region.