Mixed-Transistor Display Circuits for Low-Leakage OLED Driving
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Solution Overview
Problem
Head-mounted displays (HMDs) require high-resolution images, but existing display devices struggle to maintain image quality due to leakage currents and voltage fluctuations, especially when using organic light-emitting diodes (OLEDs) for virtual or augmented reality applications.
Innovation Solution
The display device incorporates transistors, including field effect and oxide semiconductor transistors, with specific signal control periods to minimize leakage currents, utilizing a capacitor and multiple transistors to stabilize voltage levels, thereby improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transistors are used in display devices for HMDs, then the device complexity is reduced, but leakage currents increase and image quality deteriorates
Solution Approach 1:
The transistor gate is divided into two separate gates (first gate electrode and second gate electrode) that can be independently controlled. This segmentation allows separate control of threshold voltage and drive current, enabling precise management of leakage currents while maintaining image quality without requiring entirely new transistor structures.
Solution Approach 2:
The patent changes the electrical parameters of the transistor by applying different voltages to the two gates. The first gate controls threshold voltage to minimize leakage, while the second gate controls drive current for image quality. This parameter control approach resolves the contradiction between simple structure and low leakage without increasing fundamental device complexity.
2Measurement precision
If OLEDs are used for high-resolution displays in HMDs, then image resolution is improved, but voltage fluctuations increase and image quality deteriorates
Solution Approach 1:
The dual-gate transistor structure provides inherent feedback control where the threshold voltage controlled by the first gate responds to and compensates for voltage fluctuations in the OLED. This feedback mechanism stabilizes the drive voltage to high-resolution OLEDs, maintaining image quality without sacrificing resolution.
3Reliability
If more transistors are added to control leakage currents, then leakage reduction is improved, but device complexity increases
Solution Approach 1:
The dual-gate transistor performs multiple functions within a single device structure. The first gate handles threshold voltage control for leakage reduction, while the second gate manages drive current for image quality. This multi-functionality achieves leakage control without adding separate transistors, avoiding increased device complexity.
Data Source
AI summary
The present disclosure relates to a display device capable of improving image quality. According to an embodiment of the disclosure, a display device comprises a light emitting element, a first transistor connected to the light emitting element, a second transistor connected between a data line and the first transistor, a third transistor connected between a gate electrode of the first transistor and a common voltage line, a fourth transistor connected between a driving voltage line and the first transistor, and a capacitor connected between the gate electrode of the first transistor and a drain electrode of the first transistor. At least one of the second transistor or the fourth transistor in the display device may be a field effect transistor, and at least one of the first transistor or the third transistor in the display device may be an oxide semiconductor transistor.