Alternating Power Pads for OLED Voltage Drop Control
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Solution Overview
Problem
In OLED display devices, luminance inequality and white spots occur due to voltage drops and rises in power lines, especially in larger panels, leading to uneven pixel luminance and image quality issues.
Innovation Solution
The implementation of a display device with a substrate having a pixel unit powered by two different voltages, where first and second power pads are alternately disposed in the peripheral area, spaced apart to prevent voltage drop and rise overlap, using first and second power lines to supply high and low voltage levels respectively, ensuring uniform voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display panel size is increased, then the display area is enlarged, but the luminance inequality between pixels increases due to longer power lines
Solution Approach 1:
The power supply system is segmented into multiple independent power pads (first power pads for high voltage, second power pads for low voltage) distributed across the peripheral area. This segmentation allows the power to be supplied from multiple locations simultaneously, reducing the effective current path length and minimizing IR drops across the enlarged display panel area.
Solution Approach 2:
Different regions of the display panel are provided with locally optimized power supply characteristics through the alternating arrangement of first and second power pads. Each local region receives power from the nearest power pads, ensuring that pixels throughout the large display area experience similar voltage levels and maintain uniform luminance.
2Reliability
If power pads are placed close together, then the power distribution is improved, but voltage drops and rises overlap causing white spots
Solution Approach 1:
The patent employs an asymmetric power pad configuration where first power pads (high voltage) and second power pads (low voltage) are alternately arranged but maintained at specific spacing. This asymmetric yet structured arrangement ensures that the high voltage drop region and low voltage rise region do not overlap, preventing white spots while maintaining effective power distribution.
Solution Approach 2:
The alternating arrangement of first and second power pads creates intermediate zones between high voltage and low voltage supply regions. These intermediate zones act as buffers that prevent the overlap of voltage drops and rises, eliminating the harmful effect of white spots while maintaining reliable power distribution across the display panel.
3Length of stationary object
If power lines are made longer to cover larger panels, then the display size is increased, but voltage drops increase causing luminance inequality
Solution Approach 1:
The power distribution network is segmented into multiple short segments radiating from various power pads located in the peripheral area. This segmentation replaces a single long power line with multiple shorter power lines, significantly reducing the total resistance and voltage drops while still covering the entire large display panel 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 configuration minimizes luminance inequality and prevents white spots, enhancing image quality by maintaining consistent voltage levels across the display panel, thereby improving overall display performance.
Implementation Method 1
While passing through a power line, a voltage drop (IR drop) occurs in the power voltage
Implementation Method 2
a voltage rise (IR rise) occurs in the ground voltage
Implementation Method 3
Organic light emitting display devices display images using organic light emitting diodes (OLEDs) that emit light through recombination of electrons and holes
Data Source
AI summary
A display device which includes a substrate having a pixel unit that receiving first and second voltages is disclosed. In one aspect, the first and second power lines are coupled to the first and second voltages, and are supplied to the pixel unit via first and second power pads. In some aspects, the first and second power pads are alternately disposed while being spaced apart from each other in at least a portion of the peripheral area, and the second power pads are disposed in the space between the respective first power pads.