Organic EL Display Wiring Layout for Thermal Management
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Solution Overview
Problem
Organic electroluminescence (EL) devices in display apparatuses are prone to thermal deterioration due to Joule heat generated at the edges, leading to irregularities in luminance and color, and are vulnerable to moisture ingress, causing defective pixels and dark spots, which compromises the reliability and performance of the display.
Innovation Solution
A display apparatus design where the common voltage line is extended to the perimeter and overlaps with the power lines through an insulating layer, with the power lines and pixel circuit supply lines strategically positioned outside the common voltage line to minimize heat transfer, and a protective film is used to prevent moisture ingress, while maintaining a minimal frame area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the external connection terminal is disposed at the peripheral portion of the display area, then the frame area can be minimized, but Joule heat is concentrated at the edge causing thermal deterioration of the organic EL device
Solution Approach 1:
The patent extracts the harmful heat-generating components (power lines and contact holes) from the peripheral region where the external terminal is located. By positioning power lines inside the display area and contact holes outside the display area, the design separates the terminal function from the heat generation function, minimizing thermal impact on the organic EL device while maintaining compact frame dimensions.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the power lines and the extended second electrode (common voltage line). This insulating layer acts as a thermal barrier that prevents heat generated by the power lines from transferring to the organic EL device, thereby protecting the device from thermal deterioration while allowing the power lines to be positioned close to the display area.
2Device complexity
If the contact hole or interconnecting line is located in the neighborhood of the display area, then the wiring can be simplified, but the periphery is locally heated causing early deterioration of the organic EL device
Solution Approach 1:
The patent segments the wiring structure into distinct functional zones: power lines are positioned inside the display area boundary, contact holes are positioned outside the display area boundary, and the extended second electrode serves as a transition zone. This spatial segmentation ensures that heat-generating elements are isolated from the sensitive organic EL device while maintaining wiring simplicity.
Solution Approach 2:
The extended second electrode (common voltage line) serves as an intermediary structure that connects the power lines to the external terminal while maintaining thermal isolation. By overlapping the power lines with this extended electrode through an insulating layer, the patent creates a thermal barrier that prevents local heating of the organic EL device while preserving the wiring connection.
3Area of stationary object
If the first interconnecting line is disposed inside the second interconnecting line, then the wiring space is optimized, but heat from the power line directly impacts the common voltage line and display area
Solution Approach 1:
The patent introduces an insulating layer as a thermal intermediary between the first interconnecting line (power line) and the second interconnecting line (common voltage line). This insulating layer allows the power line to be positioned inside the common voltage line for space optimization while simultaneously blocking heat transfer to the common voltage line and the display 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
This design effectively reduces thermal deterioration of organic EL devices, enhances reliability by minimizing heat impact on the display area, and prevents moisture-induced defects, ensuring consistent luminance and color across the display.
Implementation Method 1
through an insulating layer disposed therebetween
Implementation Method 2
disposed along a side of the display area to have an overlapping area overlapping with the extended second electrode through an insulating layer disposed therebetween
Implementation Method 3
an external connection terminal disposed at a peripheral portion along any one of sides of the display area and electrically connected to the first interconnecting line and the second interconnecting line
Implementation Method 4
the second interconnecting line being electrically connected to the extended second electrode in a contact hole provided in the insulating layer in the overlapping area
Data Source
AI summary
A display apparatus capable of preventing thermal deterioration of an organic EL layer to improve a reliability without increasing a frame area thereof includes a display area, a circuit and wiring area, a pixel circuit common supply line, a contact hole, an external connection terminal, and an adhesion area. In the display area, EL devices and pixel circuits are arranged in a matrix. In the contact hole, a common voltage line and a transparent electrode electrically connected to an output of the EL device are electrically connected to each other. To the external connection terminal, an image signal, a control signal, and electric power are externally supplied. The contact hole and the common voltage line are disposed to surround a peripheral of the display area. To the pixel circuit common supply line, the electric power is supplied from the external connection terminal. In a peripheral portion of the display area where the external connection terminal is disposed, the pixel circuit common supply line is disposed outside the contact hole and the common voltage line with respect to the display area.