Oxide-Polysilicon Pixel Circuit Layout for OLED Flicker Reduction
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Solution Overview
Problem
Existing display technologies face challenges in achieving uniform display brightness and reducing flickering due to variations in transistor threshold voltages, particularly in flexible display apparatus using OLEDs or QLEDs, which affect the overall display quality.
Innovation Solution
The display substrate incorporates a pixel drive circuit with a compensation transistor of oxide and a drive transistor of polysilicon, where the gate electrode of the compensation transistor is connected to a compensation scan signal line, and the electrodes are connected via connection electrodes, ensuring non-overlapping projections and specific extension lengths to optimize signal control and minimize transistor threshold voltage effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a compensation transistor of oxide and a drive transistor of polysilicon are used in the pixel drive circuit, then display uniformity is improved by eliminating the influence of transistor threshold voltages on drive current, but device complexity increases due to the need for additional connection electrodes and signal lines
Solution Approach 1:
The pixel drive circuit is divided into functionally distinct transistors: a compensation transistor (Tcomp) for threshold voltage compensation and a drive transistor (Tdrive) for current generation. The compensation transistor includes separate first and second electrodes (Tcomp1, Tcomp2) connected through first and second connection electrodes (Con1, Con2), allowing independent control and compensation of threshold voltage effects while maintaining precise drive current control.
Solution Approach 2:
The first connection electrode (Con1) serves as an intermediary element that electrically connects the first electrode of the compensation transistor to the gate electrode of the drive transistor without direct overlap with the compensation scan signal line. This intermediary structure enables precise electrical coupling while avoiding parasitic capacitance and interference, achieving display uniformity through controlled signal transmission.
2Measurement precision
If the first connection electrode and compensation scan signal line are positioned to avoid overlapping projections, then signal control precision is improved by minimizing interference, but the required extension length of connection electrodes increases
Solution Approach 1:
The first connection electrode (Con1) extends in a direction perpendicular to the compensation scan signal line (S4), utilizing the vertical dimension to achieve non-overlapping projections on the substrate plane. This dimensional arrangement allows the connection electrode to reach the gate electrode of the drive transistor while avoiding parasitic capacitance and interference from the scan signal line, achieving both signal control precision and compact layout.
3Manufacturing precision
If the extension length of the first connection electrode is made less than the extension length of the compensation active layer, then manufacturing precision is improved by simplifying fabrication, but the electrical connection reliability may be compromised
Solution Approach 1:
The first connection electrode (Con1) is designed with a localized extension that is shorter than the compensation active layer but sufficiently long to reliably connect the first electrode of the compensation transistor to the gate electrode of the drive transistor. The electrode width and material properties are optimized in this localized region to ensure low resistance and high reliability electrical connection, while the overall structure remains simple for manufacturing.
Data Source
AI summary
Disclosed are a display substrate and a preparation method therefor, and a display apparatus. The display substrate includes a plurality of circuit units, at least one circuit unit includes a pixel drive circuit including at least a compensation transistor of oxide (T2) and a drive transistor of polysilicon (T3), a gate electrode of the compensation transistor (T2) is connected to a compensation scan signal line (24), the compensation scan signal line (24) is configured to control the turn-on and turn-off of the compensation transistor (T2); a first electrode of the compensation transistor (T2) is provided on a side of the compensation scan signal line (24) close to the drive transistor (T3) and is connected to a gate electrode of the drive transistor (T3) through a first connection electrode (51).