Dual Gate Transistor for OLED Luminance Variation
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Solution Overview
Problem
Active matrix display devices with light-emitting elements face challenges in achieving high resolution due to variations in threshold voltage among driving transistors, which affect luminance consistency across pixels.
Innovation Solution
A display device structure incorporating a transistor with a first and second gate, switches, capacitors, and a light-emitting element, where the transistor includes an oxide semiconductor in its channel formation region, allowing for correction of threshold voltage variations through specific wiring connections and switch operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circuit structure with multiple transistors is used to correct threshold voltage variations, then luminance consistency is improved, but device complexity increases
Solution Approach 1:
The transistor is divided into two gates (first gate and second gate) that can be independently controlled. The first gate controls the main current flow while the second gate adjusts the threshold voltage. This segmentation allows threshold voltage correction without adding multiple complete transistor structures, thus improving luminance consistency while limiting complexity increase.
Solution Approach 2:
The dual-gate transistor structure serves multiple functions: the first gate controls current magnitude while the second gate corrects threshold voltage variations. This multi-functionality eliminates the need for separate correction circuits, reducing overall device complexity while maintaining luminance consistency across pixels.
2Ease of manufacture
If all transistors in pixels have the same polarity to omit manufacturing steps, then manufacturing ease is improved, but threshold voltage variation control deteriorates
Solution Approach 1:
By segmenting the gate control into two independent gates with different functionalities, the invention maintains uniform transistor polarity for easy manufacturing while providing separate control mechanisms. The first gate handles main operation and the second gate handles threshold voltage adjustment, resolving the conflict between manufacturing simplicity and voltage control precision.
Data Source
AI summary
To provide a display device in which variation in luminance among pixels is suppressed. The display device includes a transistor including first and second gates, first to third switches, first and second capacitors, a light-emitting element, and first and second wirings. The first gate is electrically connected to the first wiring through the first switch, a terminal of the transistor is electrically connected to the first gate through the third switch, and the second gate is electrically connected to the second wiring through the second switch. An anode of the light-emitting element is electrically connected to the terminal of the transistor. The first capacitor holds the capacitance between the first gate and the terminal of the transistor. The second capacitor holds the capacitance between the second gate and the terminal of the transistor.