Boosting Capacitor Asymmetric Connecting Portion for OLED Luminance Uniformity
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Solution Overview
Problem
In organic light emitting display devices, differences in capacitance between boosting and storage capacitors can lead to luminance variations across pixels due to process variations, affecting uniformity in display gradation.
Innovation Solution
The design of the boosting capacitor includes a semiconductor layer with a hammer shape, a main body portion, a contact portion, and a connecting portion, where the connecting portion has a width smaller than the main body and contact portions, and is electrically coupled with the storage capacitor, minimizing capacitance differences caused by area and position variations during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the boosting capacitor is designed to be smaller in capacity than the storage capacitor, then the pixel can achieve proper voltage boosting function, but the capacitance varies more significantly due to process variations
Solution Approach 1:
The patent changes the geometric parameters of the boosting capacitor, specifically making the connecting portion width equal to or smaller than half the main body portion width, and adjusting the overlapping area ratio between conductive layers and semiconductor layer to 30-70%. These parameter changes optimize the capacitance value while reducing sensitivity to process variations.
Solution Approach 2:
The patent introduces asymmetric design in the boosting capacitor structure, where the connecting portion has a different width compared to the main body portion. This asymmetric configuration helps in achieving stable capacitance characteristics by reducing the impact of alignment variations during manufacturing processes.
2Quantity of substance
If the boosting capacitor has larger overlapping area, then the capacitance value increases, but the luminance difference between pixels increases due to capacitance variations
Solution Approach 1:
The patent optimizes the overlapping area parameters to achieve a balance between capacitance value and uniformity. Specifically, the overlapping area ratio between the first conductive layer and semiconductor layer is set to 30-70%, which provides sufficient capacitance while minimizing the impact of process variations on luminance uniformity.
3Reliability
If the connecting portion width is increased, then the electrical connection is improved, but the capacitance difference due to area variation increases
Solution Approach 1:
The patent employs asymmetric design where the connecting portion width is specifically controlled to be equal to or smaller than half the main body portion width. This creates an optimized balance between electrical connection reliability and capacitance control, reducing sensitivity to area variations while maintaining proper electrical connectivity.
Data Source
AI summary
A pixel including a boosting capacitor, wherein the boosting capacitor includes: a semiconductor layer, a first conductive layer overlapping the semiconductor layer at an overlapping portion, and a first insulating film therebetween, and wherein the semiconductor layer includes: a main body portion, a contact portion outside the overlapping portion and coupling the boosting capacitor with another component, and a connecting portion integrally provided with the main body portion and the contact portion to couple the main body portion with the contact portion at an interface of the first conductive layer and having a width smaller than that of the main body portion and the contact portion.