Top Emission OLED Aperture Ratio and Power Loss Reduction
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Solution Overview
Problem
Existing active matrix type organic LED display devices face limitations in aperture ratio due to the presence of driving circuits, high current consumption, and challenges in forming transparent pixel electrodes for multi-color displays, especially as panel size increases.
Innovation Solution
The solution involves a top emission type display device configuration with a transparent pixel electrode on the opposite side of the substrate, a metal pixel electrode connected through a conduction portion, and a second current line with low resistance to reduce voltage drop and enhance current supply, along with an insulative partition wall for color-specific light emission material deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a bottom emission type display configuration is used with driving circuits on the substrate, then the display structure is simple, but the aperture ratio is limited due to driving circuit area blocking light transmission
Solution Approach 1:
The patent transitions from a bottom emission type display to a top emission type display, changing the light extraction dimension from the substrate side to the opposite side. This dimensional change allows the driving circuits to remain on the substrate while light is extracted through the transparent pixel electrode on the upper surface, thereby resolving the conflict between maintaining simple manufacturing structure and improving aperture ratio.
2Area of stationary object
If the display panel size is increased, then the display area is improved, but current consumption increases due to higher dielectric constant of transparent pixel electrode layer
Solution Approach 1:
The patent introduces a second current line with different material properties (lower resistance) specifically for current supply to the transparent pixel electrode. This local quality change allows the display area to be scaled up while managing current consumption by providing a dedicated low-resistance current path, separating the functions of signal transmission and power supply.
3Manufacturing precision
If separate current supply lines are formed for each color in multi-color display, then color display control is improved, but it becomes difficult to form the transparent pixel electrode layer into the desired shape
Solution Approach 1:
The patent segments the current supply function by introducing a second current line that is common to all colors, while maintaining separate signal lines for color control. This segmentation allows the transparent pixel electrode layer to be formed as a unified structure rather than separate patterns for each color, simplifying the formation process while preserving precise color control through the signal lines.
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 configuration significantly increases the aperture ratio, reduces power loss, stabilizes voltage, and enables high-quality color displays by minimizing leakage current and voltage drop, while allowing for efficient light emission and improved image quality.
Implementation Method 1
an organic LED device, comprising a hole transportation layer, a charge injection layer and an organic light emission layer
Data Source
AI summary
An active matrix type display includes a light emission device having a transparent pixel electrode and a metal pixel electrode on both surfaces of a light emitting layer and a driving circuit controlling the driving current of the light emission device. The driving circuit is formed on a substrate, and the light emission device is formed as a layer above the driving circuit with an intermediate layer of insulation material interposed therebetween. The metal pixel electrode device is connected with the driving circuit through a conduction portion which extends through the intermediate layer. Thus, light emitted from the light emission device can be prevented from reaching transistors by locating the transistors below the metal pixel electrode, and leakage current produced by the light of a transistor in the off state can be suppressed to prevent degradation of the image quality.