OLED Anode Line Width Compensation for Brightness Uniformity
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Solution Overview
Problem
In OLED display panels, the voltage drop along anode lines causes brightness inconsistencies across the screen, leading to a 'bright-dark screen' phenomenon and poor long-range uniformity, especially in High Brightness Mode, due to varying anode voltages affecting different colors differently.
Innovation Solution
The display substrate is designed with different coupling capacitance values for anodes of light-emitting devices, where the supply resistance is adjusted by varying the capacitance to compensate for voltage drops, ensuring uniform brightness across the panel by optimizing the coupling capacitance values and partitioning the substrate into compensation regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the anode line length is increased to cover more pixels, then the display area is expanded, but the voltage drop increases causing brightness inconsistency across the screen
Solution Approach 1:
The patent applies local quality by making the anode line resistance non-uniform through different width designs in different regions. The anode line has a first width in a first region and a second width in a second region, where the width varies to compensate for voltage drops at different positions, ensuring uniform brightness across the entire display area.
Solution Approach 2:
The patent changes the geometric parameter (width) of the anode line to compensate for voltage drops. By designing the anode line with different widths in different regions, the resistance is adjusted to compensate for the increasing distance from the anode connector, thereby maintaining uniform brightness across the display.
2Illumination intensity
If the anode line resistance is reduced by shortening the line, then voltage drop is reduced improving brightness uniformity, but the display area coverage is limited
Solution Approach 1:
The patent divides the display area into different regions with different anode line width requirements. The first region has a first width and the second region has a second width, allowing each region to have optimized resistance characteristics for its specific position relative to the anode connector.
Solution Approach 2:
The anode line is segmented into multiple regions with different width characteristics. This segmentation allows the anode line to have different resistance properties in different areas, compensating for voltage drops while maintaining full display area coverage.
3Ease of manufacture
If uniform anode line resistance is used across all pixels, then manufacturing is simplified, but brightness inconsistency occurs due to varying propagation distances
Solution Approach 1:
The patent implements local quality by designing the anode line with different widths in different regions. This creates position-dependent resistance characteristics that compensate for propagation distance variations, achieving uniform brightness while remaining manufacturable through standard photolithography processes.
Solution Approach 2:
The patent changes the anode line width parameter across different regions to achieve resistance compensation. This parameter variation is implemented through standard manufacturing processes, balancing manufacturing simplicity with brightness uniformity.
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 solution eliminates the 'bright-dark screen' phenomenon, improves long-range uniformity, and enhances the display effect, particularly in High Brightness Mode, by compensating for resistance-induced brightness deviations through differential coupling capacitance values.
Implementation Method 1
coupling capacitance values of the anodes of at least some of the light-emitting devices of the first color are different; for any two light-emitting devices of the first color having the anodes with different coupling capacitance values, the supply resistance of the light-emitting device having the anode with a larger coupling capacitance value is smaller than the supply resistance of the light-emitting device having the anode with a smaller coupling capacitance value
Data Source
AI summary
An embodiment of the present disclosure provides a display substrate, including: pixels including light-emitting devices, at least some pixels each include a light-emitting device of a first color, which includes a cathode and an anode; and an anode connector for supplying power to the anode of each light-emitting device through an anode line, a total resistance of the anode line connected between any light-emitting device and the anode connector is the supply resistance of the light-emitting device, coupling capacitance values of the anodes of at least some of the light-emitting devices of the first color are different; for any two light-emitting devices of the first color having anodes with different coupling capacitance values, the supply resistance of the light-emitting device having the anode with a larger coupling capacitance value is smaller than the supply resistance of the light-emitting device having the anode with a smaller coupling capacitance value.