Display Device Frame Narrowing via Slit-Exposed Conductive Layer
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Solution Overview
Problem
In organic EL display devices, the separation of lead-out wiring lines and thin film transistors in the frame region makes it difficult to achieve frame narrowing, as they are not provided in the same region, hindering the integration of a drive circuit within the frame.
Innovation Solution
A display device design where a slit is formed in the second flattening film to surround the display region, allowing a first conductive layer from the fourth metal film to be exposed and a thin film transistor (TFT) from the drive circuit to be positioned on the base substrate side of this conductive layer within the frame region, enabling the integration of the drive circuit in a monolithic manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-out wiring line and TFT are disposed separately in the frame region, then electrical connectivity is maintained, but frame width increases making frame narrowing difficult
Solution Approach 1:
The patent merges the lead-out wiring line and TFT into the same region (frame region) by forming the lead-out wiring line on the same substrate as the TFT. The lead-out wiring line is formed by a transparent conductive layer that extends from the display region through the frame region, while the TFT is formed in the frame region using the same layered structure, allowing both components to coexist in close proximity without compromising electrical connectivity or increasing frame width excessively.
Solution Approach 2:
The patent utilizes vertical layering to resolve the spatial conflict between lead-out wiring line and TFT. By forming multiple conductive layers at different heights (first conductive layer, second conductive layer, third conductive layer) and using insulating layers to separate them, the patent allows both the lead-out wiring line and TFT to occupy the same planar region while maintaining distinct electrical pathways through the vertical dimension.
2Length of stationary object
If drive circuit is integrated in the frame region, then frame narrowing is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent employs a universal layered structure that serves multiple functions. The same sequence of layers (substrate, insulating layers, conductive layers, semiconductor layers, electrode layers) is used to form both the light-emitting elements in the display region and the TFTs in the frame region. This multi-functional approach allows the manufacturing process to produce both display pixels and drive circuit transistors using identical materials and deposition techniques, reducing overall manufacturing complexity despite the integrated design.
Solution Approach 2:
The patent segments the device into distinct functional regions (display region and frame region) while using a unified manufacturing process. The display region contains light-emitting elements with their specific layer structure, while the frame region contains TFTs with their specific layer structure. By segmenting the functional requirements but maintaining process unity, the patent achieves frame narrowing without proportionally increasing manufacturing complexity.
Data Source
AI summary
In a TFT layer provided on a base substrate, a first metal film, a first inorganic insulating film, a second metal film, a second inorganic insulating film, a third metal film, a first flattening film, a fourth metal film, and a second flattening film are sequentially layered. In a frame region, a slit is formed in the second flattening film to surround a display region, a first conductive layer formed by the fourth metal film is provided on the first flattening film exposed from the slit, and a TFT of a drive circuit is provided on the base substrate side of the first conductive layer to overlap with the first conductive layer.