Power Source Line Electrode Resistance Ratio for OLED Luminance Uniformity
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Solution Overview
Problem
Conventional display devices face issues with luminance variations and color hues due to voltage drops in power source lines, leading to decreased light emission efficiency and shortened element lifetime, especially when trying to maximize numerical aperture.
Innovation Solution
A display element configuration with a resistance ratio of at least 10^5 between the power source line electrode and the current path through the control element and electro-optical element, allowing for balanced current distribution and reduced luminance variations without additional correction circuits or complex conductor designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the numerical aperture is made large by reducing electrode width, then light emission efficiency increases, but voltage drop increases causing luminance variations
Solution Approach 1:
The invention changes the electrical parameter (resistance ratio) by configuring the power source line electrode to have a resistance Re that satisfies Rx/Re≥10^5, where Rx is the resistance of the current path through the electro-optical element. This parameter change ensures that the voltage drop across the power source line is negligible compared to the voltage across the electro-optical element, thereby maintaining uniform luminance while allowing small electrode widths for high light emission efficiency.
2Use of energy by moving object
If the power source line electrode width is reduced to maximize numerical aperture, then light emission efficiency improves, but resistance increases causing voltage drop
Solution Approach 1:
The invention establishes a quantitative parameter relationship Rx/Re≥10^5 to control the resistance Re of the power source line electrode. This ensures that even when the electrode width is reduced to maximize numerical aperture and improve power consumption, the resistance remains sufficiently low to prevent significant voltage drop, thus resolving the contradiction between low power consumption and low resistance.
3Reliability
If conventional correction circuits are added to correct luminance variations, then luminance uniformity improves, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for complex correction circuits by directly addressing the root cause of luminance variations through proper resistance design. Instead of adding correction circuits to compensate for voltage drops, the invention prevents voltage drops from occurring in the first place by ensuring the power source line electrode has sufficiently low resistance (Rx/Re≥10^5), thereby simplifying the overall device structure.
Solution Approach 2:
The power source line electrode is designed to inherently provide the necessary electrical characteristics (low resistance) to ensure uniform voltage distribution across all electro-optical elements. This self-service approach eliminates the need for external correction mechanisms, as the electrode itself performs the function of maintaining luminance uniformity through its optimized resistance properties.
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 maintains high numerical aperture, excellent light emission efficiency, and long element lifetime while minimizing luminance variations and color hues, even when displaying white light.
Implementation Method 1
a resistance ratio Rx/Re between a resistance Re of the power source line electrode per display element and a resistance Rx of a path of the current flowing through the control element and the electro-optical element
Implementation Method 2
light emission is controlled by the amount of current flowing through an electro-optical element, such as an organic EL element or an inorganic EL element
Data Source
AI summary
A display element included in a display device is provided with a TFT circuit portion and a pixel aperture portion to which an organic EL element material is applied and which emits light in accordance with a current from the TFT circuit portion, as well as a scanning signal line electrode, a data signal line electrode and a power source line electrode. The resistance Re of the power source line electrode can be reduced, because the electrode width at a portion where the power source line electrode is in contact with the pixel aperture portion is larger than the electrode width at other portions. The resistance ratio Rx/Re between the electrode resistance Re and a combined resistance Rx of a current path from the power source line electrode through the pixel aperture portion is at least 105. Thus, a display element and a display device are realized, which have little luminance variation within the display screen, which have a high numerical aperture, a high light emission efficiency and a long lifetime.