Pixel Circuit Node-Voltage Adjustment for Flicker-Stable Emission
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Solution Overview
Problem
Display devices experience screen flicker due to unstable gate voltage in pixel driving circuits, leading to unstable display performance.
Innovation Solution
A pixel circuit design incorporating a driving sub-circuit, compensation sub-circuit, adjustment sub-circuit, and writing sub-circuit, along with additional components like transistors and capacitors, to stabilize node voltages and reduce voltage differences, thereby mitigating flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel driving circuit is used, then the circuit structure is simple, but the gate voltage of the driving transistor becomes unstable causing screen flicker
Solution Approach 1:
The pixel circuit is divided into multiple functional sub-circuits: driving sub-circuit, compensation sub-circuit, adjustment sub-circuit, and writing sub-circuit. Each sub-circuit performs a specific function to stabilize gate voltage independently, resolving the contradiction by organizing complexity into manageable segments that collectively improve reliability.
Solution Approach 2:
The compensation sub-circuit performs preliminary compensation of threshold voltage variations before the driving transistor operates. By pre-adjusting the gate voltage to account for expected variations, the circuit maintains stability without requiring complex real-time control mechanisms.
2Stability of the object's composition
If additional sub-circuits are added to stabilize voltage, then luminance retention improves, but the number of components increases
Solution Approach 1:
Multiple sub-circuits are merged into a single integrated pixel circuit structure sharing common nodes and transistors. The driving, compensation, adjustment, and writing functions are combined in a unified circuit architecture, reducing the overall component count while maintaining luminance retention stability.
Solution Approach 2:
The first transistor group serves multiple functions: it acts as a switching element in the compensation sub-circuit, a control element in the adjustment sub-circuit, and participates in both initialization and light-emitting phases. This multi-functionality reduces the total number of components needed while achieving stable luminance retention.
3Productivity
If the first transistor group is used in multiple phases, then circuit efficiency improves, but the control complexity increases
Solution Approach 1:
The first transistor group operates in periodic cycles corresponding to different display phases (initialization phase and light-emitting phases). Control signals are applied periodically to switch the transistor group between different functional states, improving circuit efficiency while managing complexity through rhythmic, predictable control patterns.
Solution Approach 2:
The first transistor group dynamically transitions between different operational modes: serving as a compensation switch during initialization, as an adjustment control during light-emitting phases, and being controlled by different gate voltages (VGL1, VGL2, VGL3) depending on the phase. This dynamic adaptability improves efficiency while the control complexity is managed through phase-synchronized signal generation.
Data Source
AI summary
A pixel circuit includes a driving sub-circuit coupled to a first node, a second node and a third node, a compensation sub-circuit coupled to the first node, the third node and a first scan signal terminal, an adjustment sub-circuit, and a writing sub-circuit. The compensation sub-circuit includes a first transistor group, and the first transistor group includes at least two first transistors connected in series. A fourth node is formed between a second electrode of a first first transistor and a first electrode of a second first transistor. The adjustment sub-circuit is coupled to the fourth node and at least one control terminal. The adjustment sub-circuit is configured to, in light-emitting phases, adjust a voltage of the fourth node under a control of a signal from the at least one control terminal, so as to reduce a voltage difference between the fourth node and the first node.