OLED Aperture Ratio via Substrate Conductive Layer
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Solution Overview
Problem
Organic light emitting displays face challenges in increasing the aperture ratio and electrostatic capacity due to reduced pixel size, leading to decreased brightness and picture quality, as well as difficulties in minimizing manufacturing costs and securing necessary capacitance.
Innovation Solution
The solution involves forming a conductive layer on the substrate as a wiring line and using it as an electrode for the capacitor, allowing for control of the aperture ratio and electrostatic capacity, particularly in a front surface light emitting structure with a metal/insulating layer/metal (MIM) capacitor configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution is increased and pixel size is reduced, then the display resolution is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent moves the capacitor from a planar configuration to a three-dimensional structure by forming it between the substrate and the first insulating layer. This vertical stacking approach allows the capacitor to occupy the space beneath the pixel circuit, effectively utilizing the third dimension (depth) to increase capacitance without consuming additional horizontal area, thereby maintaining a high aperture ratio even at reduced pixel sizes.
Solution Approach 2:
The capacitor is nested within the pixel structure by positioning it between the substrate and the first insulating layer, which are already part of the pixel stack. This nested configuration allows the capacitor to be integrated into the existing pixel architecture without requiring separate dedicated space, enabling high-resolution displays to maintain sufficient aperture ratios.
2Area of stationary object
If the capacitor size is reduced to accommodate smaller pixels, then the pixel size is reduced, but the electrostatic capacity is insufficient
Solution Approach 1:
The patent transitions from a two-dimensional planar capacitor to a three-dimensional structure by utilizing the vertical space between the substrate and the first insulating layer. This dimensional change allows the capacitor to achieve sufficient electrostatic capacity even when the horizontal footprint is reduced to accommodate smaller pixel sizes.
Solution Approach 2:
The patent changes the geometric parameters of the capacitor by increasing its vertical height (the distance between the substrate and the first insulating layer) rather than increasing its horizontal area. This parameter change allows the capacitor to maintain or increase electrostatic capacity while fitting within the reduced pixel dimensions required for high-resolution displays.
3Ease of manufacture
If the TFTs and capacitors do not overlap to minimize masks, then the manufacturing complexity is reduced, but the pixel size is limited
Solution Approach 1:
The patent resolves the conflict between manufacturing simplicity and pixel size by moving the capacitor to a different vertical level (between the substrate and first insulating layer) rather than requiring horizontal overlap with TFTs. This spatial reorganization eliminates the need for additional masking steps to create overlapping structures, while still achieving compact pixel designs suitable for high-resolution displays.
Data Source
AI summary
In an organic light emitting display, a conductive layer is formed on the bottom surface of a substrate, and the conductive layer is used as a wiring line for supplying a power source, and as the electrode of a capacitor. Therefore, it is possible to easily secure the aperture ratio of a pixel, to easily solve the problem of IR drops by controlling the area or thickness of the conductive layer, and to easily secure the electrostatic capacity of the capacitor. In particular, in the case of a front surface light emitting structure, since a capacitor of a metal/insulating layer/metal (MIM) structure may be formed in a light emitting region, enough aperture ratio and electrostatic capacity may be secured. Therefore, a high resolution organic light emitting display may be easily realized, and enough aperture ratio and electrostatic capacity are secured so as to realize high picture quality.