OLED Panel Parasitic Capacitance Adjustment for Color Deviation
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Solution Overview
Problem
Organic light-emitting display panels face color deviation due to current deviations across the panel plane, particularly in the edge regions, where the efficiency of green light emission is higher than red and blue, leading to luminance changes for small current variations.
Innovation Solution
The design includes a first display region with sub-pixels having a smaller overlap area between the gate electrode of the driving transistor and the anode electrode of the light-emitter, compared to a second display region, to adjust parasitic capacitance and maintain consistent luminance ratios, thereby reducing color deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the overlap area between the gate electrode and anode electrode is kept uniform across the panel, then the manufacturing process is simple, but color deviation occurs due to current deviation in different regions
Solution Approach 1:
The patent applies local quality by making the overlap area between the gate electrode and anode electrode position-dependent. Specifically, the overlap area in the edge region (first display region) is designed to be different from that in the central region (second display region). This local differentiation compensates for current deviation caused by the extraction effect at panel edges, ensuring uniform luminance characteristics across the entire panel while maintaining a relatively simple manufacturing process.
2Reliability
If the overlap area is increased in the edge region, then the parasitic capacitance increases to compensate for current loss, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameter (overlap area) of the electrode structure based on position. The overlap area is increased in the edge region compared to the central region to compensate for current loss. This approach changes a physical parameter of the existing structure rather than introducing new components or complex control mechanisms, thereby achieving current compensation with minimal increase in device complexity.
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 reduces color deviation by adjusting the parasitic capacitance, ensuring consistent driving current and luminance across the panel, minimizing the impact of current deviations and maintaining desired image quality.
Implementation Method 1
a storage capacitor to store a voltage difference between the driving voltage and a voltage of a gate electrode of the driving transistor
Implementation Method 2
a light-emitter connected to the output node to emit light based on the driving current transferred through the output node
Implementation Method 3
an overlap area of the gate electrode of the driving transistor and an anode electrode of the light-emitter
Data Source
AI summary
An organic light-emitting display panel includes a first display region including a plurality of first sub-pixels and a second display region including a plurality of second sub-pixels. Each of the sub-pixels includes a pixel circuit having a driving transistor to output driving current to an output node based on a data signal, a storage capacitor to store a voltage difference between the driving voltage and the gate voltage of the driving transistor, a switching transistor to transfer the data signal to the driving transistor, and a light-emitter connected to emit light based on the driving current. An overlap area of the gate electrode of the driving transistor and an anode electrode of the light-emitter in the first sub-pixel is smaller than an overlap area of the gate electrode of the driving transistor and an anode electrode of the light-emitter in the second sub-pixel.