OLED Pixel Circuit Scanner Merging for Luminance Uniformity
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Solution Overview
Problem
Existing active-matrix organic light-emitting diode (OLED) displays face challenges in achieving uniform luminance due to variations in threshold voltage of drive transistors, which require additional transistors and scanners, increasing manufacturing costs and complexity.
Innovation Solution
Incorporating a reference potential setting transistor and an initialization transistor into each pixel circuit, allowing the scanner for line-sequential scanning of sampling transistors to also scan initialization transistors, and sharing the scanner for sampling and reference potential setting, reducing the number of dedicated scanners needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If additional transistors and scanners are added to cancel threshold voltage variations, then luminance uniformity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the scanning functions for sampling transistors and initialization transistors into a single scanner. The scanner sequentially scans both types of transistors through shared scan lines, eliminating the need for separate dedicated scanners and reducing overall device complexity while maintaining the ability to cancel threshold voltage variations
Solution Approach 2:
The scan lines are designed to serve multiple functions: they control both sampling transistors and initialization transistors through the same physical infrastructure. This multi-functionality allows the system to maintain precise control over both transistor types without requiring additional dedicated scan lines or scanners, thereby reducing device complexity while preserving luminance uniformity
2Measurement precision
If dedicated scanners are added for each transistor type, then control precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the scanning operations for different transistor types into a single scanner that sequentially handles both sampling and initialization transistors. This consolidation reduces the number of scanners from multiple dedicated units to a single multi-functional unit, directly lowering manufacturing costs while maintaining control precision through sequential scanning
Solution Approach 2:
The scanner is designed with universal functionality to control multiple transistor types through shared scan lines. This multi-functional design eliminates the need for expensive dedicated scanners for each transistor type, reducing manufacturing costs while preserving the precision required for threshold voltage compensation
3Measurement precision
If separate scan lines are used for sampling and initialization, then control accuracy is improved, but device complexity increases
Solution Approach 1:
The scan lines are designed to serve dual purposes: controlling both sampling transistors and initialization transistors. By making the scan lines universal rather than dedicated, the patent reduces the total number of scan lines required while maintaining the ability to independently control each transistor type through sequential scanning operations
Solution Approach 2:
The patent employs periodic scanning where the same scan lines are used alternately for different transistor types at different time periods. This time-division multiplexing approach allows accurate control of both sampling and initialization transistors using shared scan lines, reducing device complexity while preserving control accuracy through periodic sequential operation
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 enables the cancellation of threshold voltage variations while reducing manufacturing costs and complexity by eliminating the need for additional scanners, thus providing a more cost-effective and efficient image display with improved uniformity.
Implementation Method 1
The light-emitting element emits light with a luminance dependent upon the video signal due to the output current (drain current) supplied from the drive transistor Td
Data Source
AI summary
Herein disclosed an image display including: row scan lines configured to supply a control signal; column signal lines configured to supply a video signal; and pixel circuits configured to be disposed at intersections between the scan lines and the signal lines, wherein each of the pixel circuits has at least a drive transistor, a sampling transistor connected to a gate of the drive transistor, a capacitive part connected between the gate and a source of the drive transistor, and a light-emitting element connected to the source of the drive transistor.