Pixel Electrode Narrow Width Region Current Control
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Solution Overview
Problem
In active matrix display devices using light emitting elements, defects such as bright pixel defects occur due to uncontrollable current flow caused by damaged TFTs or short circuits, leading to increased power consumption and temperature issues affecting surrounding pixels.
Innovation Solution
A display device with a pixel electrode having a layered structure of metal and transparent films, featuring a narrow width region where the wiring and pixel electrode connect, ensuring the metal film and wiring do not contact, thereby increasing the pixel electrode's resistance when high current flows, cutting off or reducing the current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pixel electrode with a simple structure is used, then the manufacturing process is simple, but the device reliability deteriorates due to uncontrollable current flow when TFT damage occurs
Solution Approach 1:
The pixel electrode is segmented into multiple conductive layers (first conductive layer and second conductive layer) with different materials and properties. The first conductive layer has higher resistance and the second has lower resistance, creating a segmented structure that provides both ease of manufacture and reliable current control through the layered architecture.
Solution Approach 2:
The pixel electrode uses a composite structure combining different conductive materials in layers. The first conductive layer uses a material with higher resistance (such as ITO or IZO) while the second conductive layer uses a material with lower resistance (such as Al or Mo), creating a composite electrode that balances manufacturing simplicity with current control reliability.
2Ease of manufacture
If a uniform width pixel electrode is used, then the manufacturing process is simple, but the current distribution becomes uncontrolled when defects occur
Solution Approach 1:
The pixel electrode implements local quality by having different widths in different regions. The first conductive layer has a first width and the second conductive layer has a second width that is different from the first width. This local variation in dimensions allows the electrode to maintain simple manufacturing while achieving controlled current distribution through the width difference that creates resistance variation.
3Power
If the pixel electrode width is increased, then the current carrying capacity is improved, but the resistance decreases leading to less effective current limiting
Solution Approach 1:
The invention applies parameter changes by varying the resistance parameter through material selection and dimensional changes. The first conductive layer has higher resistance and smaller width, while the second conductive layer has lower resistance and different width. This parameter variation allows the electrode to provide both sufficient current carrying capacity and effective current limiting when defects occur.
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 bright pixel defects by selectively cutting off or reducing current to the pixel, minimizing effects on surrounding pixels due to power consumption or temperature increases, ensuring better product quality.
Implementation Method 1
the pixel electrode has a layered structure of a metal film and a transparent electrode film except a part of the area where the wiring is connected to the pixel electrode; the pixel electrode has a narrow width region in the area where the wiring is connected to the pixel electrode; at least a part of the pixel electrode in the narrow width region is formed only of a transparent conductive film
Data Source
AI summary
It is an object of the present invention to prevent a bright pixel defect caused by continuous current flow into a pixel, or to provide a display device in which effects on the surrounding pixels due to concentration of current on a part of the pixel can be suppressed. A display device according to the invention has a wiring for supplying current provided over an insulating surface, and a pixel electrode connected to the wiring. The pixel electrode has a layered structure of a plurality of different conductive films. Further, the pixel electrode has a narrow width region at least in a region where the wiring and the pixel electrode are electrically connected to each other. For example, a layered structure of a metal film and a transparent electrode can be used as a plurality of different conductive films.