OLED Brightness Uniformity via Localized Wiring Resistance
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Solution Overview
Problem
Organic light emitting displays experience non-uniform brightness due to IR drop in power source wiring lines, leading to inconsistent picture quality as the display size increases, with existing solutions like rearranging wiring lines or increasing line width having limitations such as increased resistance and shorting risks.
Innovation Solution
The design includes a display panel with sub pixels having varying resistance values, with those closer to the power source supply pad having higher resistance values that gradually increase, using larger active layers and fewer contact holes for power source supply switching elements to manage voltage and prevent IR drop, ensuring uniform voltage delivery across all sub pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the line width of power source wiring lines is increased to reduce IR drop, then voltage uniformity improves, but the risk of shorting between wiring lines increases
Solution Approach 1:
The patent applies local quality by differentiating the line width of power source wiring lines based on their position relative to the power source supply pad unit. Specifically, wiring lines in a first region (closer to the power source) have a first line width, while wiring lines in a second region (farther from the power source) have a second line width that is greater than the first line width. This localized adjustment compensates for IR drop in distant regions without uniformly increasing line width across the entire display panel, thereby reducing shorting risk while maintaining voltage uniformity.
2Illumination intensity
If power source wiring lines are arranged in row lines to compensate for IR drop, then brightness uniformity improves, but resistance of wiring lines increases proportionally to length
Solution Approach 1:
The patent implements local quality by varying the line width of power source wiring lines according to their spatial position. Wiring lines in the first region (adjacent to the power source supply pad unit) have a smaller line width, while wiring lines in the second region (separated from the power source supply pad unit) have a larger line width. This localized differentiation compensates for the increased resistance in longer wiring lines without requiring all wiring lines to have uniformly increased width, thus maintaining brightness uniformity while managing overall resistance.
3Productivity
If the display panel is enlarged to meet market demands, then productivity and versatility improve, but non-uniformity of brightness due to IR drop increases
Solution Approach 1:
The patent applies local quality by dividing the display panel into multiple regions (first region and second region) based on distance from the power source supply pad unit, and assigning different line widths to power source wiring lines in each region. This allows the display panel to be enlarged while maintaining brightness uniformity, as the larger wiring lines in the second region compensate for the increased IR drop in longer wiring paths.
Solution Approach 2:
The patent implements parameter changes by varying the line width parameter of power source wiring lines based on their position in the display panel. By changing this geometric parameter locally, the patent compensates for IR drop effects in enlarged displays without requiring changes to the overall display size or power source voltage.
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 effectively compensates for IR drop-induced brightness non-uniformity, stabilizing picture quality and improving the reliability of organic light emitting displays by maintaining consistent voltage across sub pixels despite increased power source wiring line lengths.
Implementation Method 1
non-uniformity of brightness due to the IR drop of the power source wiring lines increases as the length of the power source wiring lines increases
Implementation Method 2
the generation of light by recombination of electrons supplied by a cathode and holes supplied by an anode takes place
Data Source
AI summary
An organic light emitting display is capable of preventing brightness from being non-uniform due to IR drop so as to improve reliability of the organic light emitting display. The organic light emitting display comprises: a display panel having a display region and a non-display region; a plurality of sub pixels defined by perpendicularly intersecting a plurality of gate lines and a plurality of data lines formed in the display region of the display panel; and a power source supply pad unit provided in the non-display region of the display panel for supplying a power source voltage to the plurality of sub pixels. A resistance value of sub pixels arranged in a first region adjacent to the power source supply pad unit is higher than a resistance value of sub pixels of a second region which is separated from the power source supply pad unit, with the first region interposed therebetween.