OLED Pixel Circuit Leakage Reduction via Transistor Type Differentiation
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Solution Overview
Problem
Existing OLED pixel circuits face issues with screen flickering due to voltage leakage at the control terminal of the driving sub-circuit, which affects the uniformity and quality of the display.
Innovation Solution
The proposed pixel circuit includes a driving sub-circuit, a data writing sub-circuit, a first and second light-emitting control sub-circuit, a compensation sub-circuit, and a first reset sub-circuit, with specific transistor types and connections to minimize leakage paths and optimize light-emitting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OLED pixel circuits are used, then the display can operate with standard circuit design, but voltage leakage at the control terminal causes screen flickering and reduced display uniformity
Solution Approach 1:
The patent extracts and eliminates the harmful voltage leakage paths from the control terminal by reconfiguring the circuit topology. Specifically, the driving sub-circuit is designed with optimized transistor connections that prevent leakage current from reaching the control terminal, thereby removing the harmful factor while maintaining normal display operation.
Solution Approach 2:
The patent applies different transistor types (first transistor type vs. second transistor type) to different locations within the pixel circuit. The driving sub-circuit uses transistors with specific characteristics optimized for minimizing leakage, while other sub-circuits use transistors optimized for their respective functions. This local differentiation of transistor properties reduces overall voltage leakage and improves display uniformity.
2Reliability
If the pixel circuit uses multiple sub-circuits with different transistor types, then voltage leakage is reduced and display uniformity improves, but circuit complexity increases
Solution Approach 1:
The patent designs the pixel circuit where the same driving sub-circuit structure serves multiple functions: it drives the light-emitting element, stores compensation voltage, and prevents voltage leakage simultaneously. The compensation sub-circuit also participates in both threshold compensation and leakage reduction. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in circuit complexity.
Solution Approach 2:
The patent merges the compensation function and the driving function into a closely integrated structure where the compensation sub-circuit and driving sub-circuit share common elements and signal paths. This merging reduces the total component count and interconnection complexity compared to having completely separate circuits for each function, while still achieving the benefits of reduced voltage leakage.
Data Source
AI summary
A pixel circuit and a driving method thereof, and a display device are provided. The pixel circuit includes a driving sub-circuit, a data writing sub-circuit, a first light-emitting control sub-circuit, a second light-emitting control sub-circuit, a compensation sub-circuit, and a first reset sub-circuit, and is configured to generate a driving current to control a light-emitting element to emit light, the first reset sub-circuit comprises a first transistor, the compensation sub-circuit comprises a second transistor, the first transistor and the second transistor are both polysilicon oxide thin film transistors, and an active layer type of the first transistor and an active layer type of the second transistor are different from an active layer type of a transistor comprised in at least one selected from a group consisting of the driving sub-circuit, the data writing sub-circuit, the first light-emitting control sub-circuit, and the second light-emitting control sub-circuit.