Back-Gate Transistor Circuit for OLED Threshold Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display apparatuses using organic EL elements face challenges in achieving high display quality, high color reproducibility, and reduced power consumption due to variations in threshold voltage of driving transistors, which affect the current flowing through the organic EL elements.
Innovation Solution
A semiconductor device comprising first and second transistors, switches, capacitors, and a display element, where the transistors include a back gate and the switches control electrical continuity between the transistors and the display element, allowing for precise control of the voltage applied to the organic EL element and correction of threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driving transistor is provided in each pixel to control current through the organic EL element, then the display quality can be improved by correcting threshold voltage variations, but the device complexity increases due to the need for additional correction circuits and operations
Solution Approach 1:
The patent combines the threshold voltage correction function with the existing driving transistor structure by introducing a back gate electrode. This allows the same transistor to serve both as the driving transistor for current control and as the correction mechanism, eliminating the need for separate correction circuits and reducing overall device complexity while maintaining display quality
Solution Approach 2:
The driving transistor is designed to perform multiple functions: it serves as the primary transistor for controlling current through the organic EL element and simultaneously as the correction mechanism for threshold voltage variations through its back gate. This multi-functionality reduces the number of separate components needed and simplifies the overall circuit structure
2Reliability
If a correction period is provided to correct threshold voltage variation of the transistor, then the display quality is improved, but the power consumption increases due to additional active periods
Solution Approach 1:
The threshold voltage correction is performed continuously during the display operation period rather than as a separate discrete correction period. The back gate voltage is adjusted continuously to compensate for threshold voltage variations, allowing correction to occur during normal display operation without requiring additional dedicated correction time, thus reducing power consumption while maintaining display quality
3Area of moving object
If the pixel circuit area is reduced to achieve downsizing, then the display apparatus size is reduced, but the manufacturing precision requirements increase due to tighter spacing and smaller dimensions
Solution Approach 1:
The patent utilizes the back gate electrode positioned in a different spatial dimension (above or below the channel region) to achieve threshold voltage correction without increasing the planar area of the transistor. This three-dimensional approach allows correction functionality to be added without expanding the pixel circuit footprint, thereby maintaining compact size while reducing the need for high-precision lateral spacing
Data Source
AI summary
The invention of the application is the invention regarding a semiconductor device and a method for driving the semiconductor device. The semiconductor device includes first and second transistors, first to fifth switches, first to third capacitors, and a display element. The first transistor (M2) comprises a back gate, a gate of the first transistor is electrically connected to the first switch (M1), the second switch (M3) and the first capacitor (C1) are positioned between the gate of the first transistor and a source of the first transistor, the back gate of the first transistor is electrically connected to the third switch (M4), the second capacitor (C2) is positioned between the back gate of the first transistor and the source of the first transistor, the source of the first transistor is electrically connected to the fourth switch (M6) and a drain of the second transistor (M5), a gate of the second transistor is electrically connected to the fifth switch (M7), the third capacitor (C3) is positioned between the gate of the second transistor and a source of the second transistor, and the source of the second transistor is electrically connected to the display element (61).