Pixel Driving Circuit Threshold Compensation for Display Uniformity
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Solution Overview
Problem
Silicon-based display panels using OLED elements face issues with display non-uniformity due to threshold voltage drift in drive transistors, leading to brightness inconsistencies and afterimages, which affect the display quality and color richness.
Innovation Solution
A pixel driving circuit incorporating a drive transistor, a light emission control transistor, capacitors, a reset circuit, and a threshold compensation circuit, where the threshold voltage is compensated and the data signal voltage is divided across capacitors to maintain consistent brightness levels, independent of the drive transistor's threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a drive transistor is used to generate drive current for the OLED element, then the OLED element can emit light with self-luminescence and high luminescence efficiency, but threshold voltage drift occurs in the drive transistor resulting in display non-uniformity
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the light emission stage. The threshold compensation circuit calculates and stores the threshold voltage of the drive transistor in advance (during initialization or previous frames), so that when threshold drift occurs, the pre-stored compensation data can be immediately applied to correct the drive current, maintaining display uniformity without affecting the real-time performance of the OLED element
Solution Approach 2:
The patent implements feedback by using the threshold compensation circuit to continuously monitor and adjust for threshold voltage drift in the drive transistor. The circuit measures the actual threshold voltage, compares it with the expected value, and applies corrective feedback to the drive current calculation, ensuring that display uniformity is maintained despite threshold drift occurring over time or due to process variations
2Reliability
If threshold voltage compensation is implemented to eliminate display non-uniformity, then display uniformity improves, but the circuit complexity increases with additional compensation circuits
Solution Approach 1:
The patent merges the threshold compensation circuit with the existing pixel driving circuit structure. The compensation circuit shares nodes and transistors with the drive circuit, and the compensation data is stored in the same capacitor that also stores drive voltage information. This integration approach adds threshold compensation functionality while minimizing the increase in overall circuit complexity
Solution Approach 2:
The patent applies universality by designing the threshold compensation circuit to perform multiple functions: it compensates for threshold voltage drift, stores compensation data, and integrates with the existing drive transistor and capacitor structure. The same capacitor serves both as a storage element for drive voltage and as part of the threshold compensation mechanism, reducing the need for separate dedicated components
Data Source
AI summary
Provided are a pixel driving circuit, a method for driving the pixel driving circuit, a silicon-based display panel and a display device. The pixel driving circuit is used for driving a light-emitting element to emit light. At an initial stage, a reset circuit provides a reset signal to a third node; a light emission control transistor is in a first on state to transmit the reset signal to a second node; a threshold compensation circuit transmits the reset signal to a first node; and a data write circuit transmits a non-enable level Vofs of a data signal to a second terminal of a first capacitor. At a threshold compensation stage, the threshold compensation circuit provides a threshold voltage of a drive transistor to the first node for compensation.