OLED Light Panel Brightness Variation via Current Density
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Solution Overview
Problem
Current OLED lighting technologies face challenges in achieving uniform brightness and tonal variation across large area panels, leading to a lack of aesthetic appeal and increased complexity and cost due to the need for individual addressability of each pixel.
Innovation Solution
The implementation of a lighting device with a plurality of OLEDs, where groups of OLEDs are driven at different current densities to achieve controlled brightness variation, utilizing a common organic layer stack and varying emissive areas or resistances to create tonal variation across the panel, allowing for both cost-effective and aesthetically pleasing lighting solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If groups of OLEDs are driven at different current densities to achieve brightness variation, then tonal variation and aesthetic appeal are improved, but device complexity increases due to need for different current control circuits
Solution Approach 1:
The patent applies local quality by creating different groups of OLEDs with distinct current-density characteristics through varying organic layer stack compositions. Each group is designed with specific material properties that cause them to operate at different current densities under the same voltage, enabling localized brightness variation without complex control circuits.
Solution Approach 2:
The patent changes physical and chemical parameters of the organic layer stacks, including doping concentrations, material compositions, and layer thicknesses, to create OLEDs with different current-density characteristics. This allows brightness variation to be achieved through material property changes rather than complex electrical control.
2Manufacturing precision
If uniform brightness is achieved across large area panels, then manufacturing precision is improved, but aesthetic appeal deteriorates due to lack of tonal variation
Solution Approach 1:
The patent deliberately introduces local quality variations by creating different OLED groups with different organic layer stacks. These groups are designed to produce different brightness levels, transforming the uniformity constraint into an aesthetic feature through controlled material composition variations.
Solution Approach 2:
The patent creates dynamic brightness characteristics by designing OLEDs that respond differently to current density changes. This allows the panel to exhibit tonal variation under different operating conditions while maintaining manufacturing precision through standardized fabrication processes.
3Measurement precision
If individual addressability is implemented for each pixel, then brightness control precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple OLEDs into groups that share common control characteristics. By designing groups of OLEDs with matched organic layer stacks, multiple pixels can be controlled together with a single current density setting, reducing the need for individual addressability while maintaining adequate brightness control precision.
Solution Approach 2:
The patent creates universal control mechanisms where a single voltage or current setting can control multiple OLED groups simultaneously. The different organic layer stack designs enable these groups to respond differently to the same control signal, providing both simplified control and brightness variation.
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 approach enables controlled brightness variation and tonal variation across OLED panels without the need for individual addressability of each pixel, reducing manufacturing complexity and cost while maintaining high light output and aesthetic appeal.
Implementation Method 1
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Implementation Method 2
each OLED in the first group is driven at a first current density, and where each OLED in the second group is driven at a second current density that is different from the first current density
Data Source
AI summary
Embodiments may provide a light source with a controlled brightness variation. A first device is provided that includes a substrate and a plurality of OLEDs disposed on the substrate. Each of the OLEDs includes a first electrode, a second electrode, and an organic electroluminescent (EL) material disposed between the first and the second electrodes. The plurality of OLEDs comprise a first group and a second group where a first current density is supplied to the first group of the plurality of OLEDs and a second current density that is different from the first current density is supplied to the second group of the plurality of OLEDs. Each of the plurality of OLEDs is commonly addressable and at least one of the OLEDs in the first group of OLEDs has substantially the same device structure as at least one of the OLEDs in the second group of OLEDs.