Display Substrate With External Compensation for High-PPI OLED
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Solution Overview
Problem
N-Metal-Oxide-Semiconductor (N-MOS) internal compensation circuits in medium-sized and large-sized OLED displays face challenges in achieving high pixels per inch (PPI) due to their complexity, making it difficult to optimize pixel density.
Innovation Solution
A display substrate design with specific electrode and capacitor configurations, including non-overlapping projections and optimized conductive pattern layers, along with a driving method involving reset, compensation, data writing, and light-emitting phases, to enhance pixel circuit efficiency and reduce overlap areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If internal compensation pixel circuits are used, then driving system cost is reduced and integration is improved, but pixel circuit complexity increases making it difficult to achieve high PPI
Solution Approach 1:
The patent extracts the compensation function from the pixel circuit by using a separate compensation transistor located outside the pixel circuit boundary. This compensation transistor is controlled by a scan signal line and compensation signal line, allowing it to perform compensation operations without increasing the complexity of the pixel circuit itself. The compensation node is also positioned outside the pixel circuit, further separating the compensation function from the main pixel circuit structure.
Solution Approach 2:
The patent introduces a compensation signal line as an intermediary between the scan signal line and the compensation transistor. This intermediary allows the compensation operation to be controlled without directly increasing pixel circuit complexity. The compensation signal line acts as a mediator that transmits control signals to the compensation transistor, enabling external compensation while maintaining pixel circuit simplicity.
2Adaptability or versatility
If internal compensation pixel circuits are used, then integration is improved, but pixel circuit complexity increases making it difficult to achieve high PPI
Solution Approach 1:
The patent extracts the compensation function from the pixel circuit by using a separate compensation transistor located outside the pixel circuit boundary. This compensation transistor is controlled by a scan signal line and compensation signal line, allowing it to perform compensation operations without increasing the complexity of the pixel circuit itself. The compensation node is also positioned outside the pixel circuit, further separating the compensation function from the main pixel circuit structure.
Solution Approach 2:
The compensation transistor can operate in multiple modes depending on the control signals received. It can perform compensation operations during the compensation phase and can be controlled through different signal lines (scan signal line or compensation signal line). This multi-functionality allows the same structure to serve integration purposes while maintaining pixel circuit simplicity.
3Reliability
If electrode and capacitor configurations with overlapping projections are used, then electrical connection is achieved, but pixel density is reduced
Solution Approach 1:
The patent resolves the overlap issue by transitioning to a stacked configuration in the vertical dimension. The first electrode of the light-emitting element is positioned in a first planar region, while the pixel circuit is positioned in a second planar region at a different vertical level. This dimensional separation eliminates planar overlap while maintaining electrical connection through vertical vias that pass through the substrate, thereby increasing pixel density without compromising electrical reliability.
Solution Approach 2:
The patent implements a nested structure where the first electrode is positioned above the pixel circuit in the vertical dimension. The pixel circuit components (transistors, capacitors) are arranged in the substrate plane, while the light-emitting element's first electrode is positioned above them, connected through vertical conductive paths. This nesting arrangement allows electrical connection while minimizing planar overlap area.
Data Source
AI summary
Provided are a display substrate and a driving method thereof. The display substrate includes a first storage circuit and a second storage circuit, a first terminal of the first storage circuit being electrically connected to the control terminal of the driving circuit, a second terminal of the first storage circuit being electrically connected to the first terminal of the driving circuit, and the first storage circuit being configured to store the data signal; a first terminal of the second storage circuit being electrically connected to the first electrode of the light-emitting element and a second terminal of the second storage circuit being electrically connected to a second electrode of the light-emitting element.