Repairing Organic Light Emitting Display Sub-Pixels via Capacitor Merging
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Solution Overview
Problem
Organic light emitting displays face brightness deviation and change over time due to defective transistors in sub-pixels, which occur when source and drain electrodes are poorly patterned or contaminated, leading to reduced current distribution between adjacent sub-pixels.
Innovation Solution
The implementation of repair patterns and capacitors between sub-pixel regions, where the first and second repair patterns are formed of the same material as the anode and on the same layer, connecting defective sub-pixels to adjacent operable sub-pixels through welding or laser cutting, allowing for parallel connection of storage capacitors to increase current supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current is distributed from normal sub-pixel to defective sub-pixel through repairing process, then defective sub-pixel can be activated, but current amount in both sub-pixels is reduced to about 1/2 causing brightness deviation
Solution Approach 1:
The patent merges storage capacitors from multiple sub-pixels (defective and normal) into a shared capacitor structure. By combining the capacitance of multiple capacitors in parallel, the system maintains sufficient current supply to the defective sub-pixel while preventing excessive current reduction in adjacent normal sub-pixels, thus resolving the brightness deviation issue.
Solution Approach 2:
The repaired sub-pixel structure serves multiple functions: it activates the defective sub-pixel, maintains current distribution balance across all sub-pixels, and provides a universal solution that can be applied to any defective sub-pixel in the display panel. The shared capacitor structure serves both the defective and normal sub-pixels simultaneously.
2Reliability
If repairing process connects defective sub-pixel to normal sub-pixel, then current can be supplied to defective area, but current reduction causes brightness change over time
Solution Approach 1:
By merging storage capacitors from multiple sub-pixels into a shared structure, the patent ensures stable current supply over time. The combined capacitance provides sufficient charge storage to maintain consistent brightness in the previously defective sub-pixel, preventing brightness degradation during extended operation.
3Manufacturing precision
If source and drain electrodes are poorly patterned or contaminated, then transistor becomes defective, but this leads to brightness deviation and change over time
Solution Approach 1:
The patent implements preliminary repair structures (repair patterns and shared capacitors) that are prepared in advance during manufacturing. These structures remain dormant during normal operation but can be activated to compensate for defective transistors, allowing the display to maintain functionality even when electrode patterning or contamination causes transistor failures.
Data Source
AI summary
A repair path is established between a sub-pixel with a defective drive transistor and another sub-pixel with an operable drive transistor to connect storage capacitors in the two sub-pixels in parallel. Another repair path is established to operate a light emitting device by the operable drive transistor of the second sub-pixel. Terminals of the storage capacitors in the two pixels are connected to a gate of the operable drive transistor. The voltage at the terminals of the storage capacitors are maintained above the threshold voltage of the operable drive transistor is switched on for a longer time due to the combined capacitance of the two storage capacitance. Hence, the sub-pixel with the defective drive transistor and the other sub-pixel of the operable drive transistor remain turned on for a longer time. Hence, despite providing a lower level of current to each of the light emitting devices in the two sub-pixels, the intensity of light produced remains relatively high due to increased turn on time of the operable drive transistor.