3Tr2C Inverter Circuit for Uniform Organic EL Pixel Luminance
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Solution Overview
Problem
In active matrix organic electroluminescence (EL) displays, variations in threshold voltage and mobility across pixels lead to non-uniform light emission luminance due to manufacturing process variations, causing issues with power consumption and luminance consistency.
Innovation Solution
The introduction of a 3Tr2C inverter circuit configuration with specific transistor and capacity element arrangements, including a first transistor, a second transistor, and a third transistor, along with first and second capacity elements, which control electrical connections and voltages to stabilize output voltage and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a 2Tr1C pixel circuit configuration is used to control current through organic EL elements, then the circuit can function with fewer transistors, but variations in threshold voltage and mobility cause non-uniform light emission luminance
Solution Approach 1:
The invention divides the correction function into two separate circuits: a threshold voltage correction circuit and a mobility correction circuit. This segmentation allows each circuit to independently address specific parameter variations, improving luminance uniformity without requiring a complete redesign of the pixel circuit architecture.
Solution Approach 2:
The invention introduces intermediate correction circuits between the signal line and the organic EL element. These intermediary circuits measure and compensate for threshold voltage and mobility variations, acting as mediators that correct the effects of manufacturing variations before they affect the final luminance output.
2Manufacturing precision
If threshold voltage and mobility corrections are implemented, then luminance uniformity improves, but power consumption increases due to additional correction operations
Solution Approach 1:
The invention implements periodic correction operations where threshold voltage and mobility are measured and corrected at specific intervals during the display operation. This periodic action allows the system to maintain luminance uniformity while minimizing continuous power consumption associated with constant correction operations.
Solution Approach 2:
The correction circuits are designed to automatically measure and compensate for threshold voltage and mobility variations without requiring external intervention. The circuits self-regulate by continuously monitoring their own operation parameters and applying corrections, reducing the need for additional control overhead and associated power consumption.
3Adaptability or versatility
If WS pulses are used for both signal writing and threshold/mobility correction, then the writing line can be multiplexed, but voltage transients cause variations in correction accuracy
Solution Approach 1:
The invention performs threshold voltage and mobility measurements during dedicated measurement periods before the actual signal writing operation. By conducting corrections in advance, the system avoids the interference of voltage transients that occur during signal writing, ensuring higher correction accuracy while still utilizing the same writing line infrastructure.
Solution Approach 2:
The invention dynamically switches the writing line between different functions: during measurement periods, the line is used for threshold and mobility correction; during display periods, the line is used for signal writing. This dynamic time-division multiplexing allows the system to maintain both line multiplexing capability and correction accuracy by separating measurement and writing operations in time.
Data Source
AI summary
An inverter circuit includes: first to third transistors; and first and second capacity elements. The first transistor makes/breaks connection between an output terminal and a first voltage line in response to potential difference between an input terminal and the first voltage line or its correspondent. The second transistor makes/breaks connection between a second voltage line and the output terminal in response to potential difference between a gate of the second transistor and the output terminal or its correspondent. The third transistor makes/breaks connection between a gate of the second transistor and a third voltage line in response to potential difference between the input terminal and the third voltage line or its correspondent. The first and second capacity elements are inserted in series between the input terminal and the gate of the second transistor. A junction between the first and second capacity elements is connected to the output terminal.