Pixel Circuit Coupling Layout for Uniform High-Frequency Driving
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Solution Overview
Problem
Existing pixel circuits for light-emitting devices face issues with uneven display brightness due to variations in threshold voltage of drive transistors, leading to prolonged active levels for data voltage writing and compensation, which hinders high-frequency driving.
Innovation Solution
A pixel circuit design with separate paths for threshold voltage compensation and data voltage writing, utilizing coupling control circuits and a threshold compensation circuit to stabilize node voltages, allowing for longer compensation times and improved drive rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If threshold voltage compensation and data voltage writing are performed using the same path and timing, then the circuit structure is simple, but display brightness becomes uneven and drive frequency is limited
Solution Approach 1:
The patent divides the pixel circuit into separate functional paths: a first path for threshold voltage compensation (involving nodes N1 and N2, and transistor M2) and a second path for data voltage writing (involving node N1 and transistor M9). This segmentation allows independent optimization of each function, enabling precise brightness control while maintaining uniform display quality across all pixels.
2Manufacturing precision
If threshold voltage compensation time is extended to improve accuracy, then display quality improves, but the active level duration increases which hinders high-frequency driving
Solution Approach 1:
The patent performs threshold voltage compensation in advance during a dedicated compensation phase before the data writing phase. The compensation result is stored in node N2, which then remains stable during subsequent operations. This preliminary action allows extended compensation time for high accuracy without extending the active level duration of the data writing operation, thereby enabling high-frequency driving.
3Productivity
If separate paths are used for threshold voltage compensation and data voltage writing, then drive frequency and display quality improve, but circuit complexity increases
Solution Approach 1:
The patent merges the threshold voltage compensation path and data voltage writing path at node N1, where both signals converge. The compensation result stored at N2 is coupled to N1 through capacitor C2, while data voltage is also written to N1 through transistor M9. This merging approach allows separate processing paths to operate independently during their respective phases while sharing common nodes, thus improving drive frequency and display quality without excessive increase in circuit complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-frequency driving, enhances display quality, improves luminous stability, and improves the display effect, particularly in applications like gaming, by separating threshold voltage compensation and data voltage writing processes.
Implementation Method 1
The first coupling control circuit includes: a first capacitor; and a first electrode plate of the first capacitor is coupled to the gate of the drive transistor, and a second electrode plate of the first capacitor is coupled to the first node
Implementation Method 2
the second coupling control circuit includes: a second capacitor; and a first electrode plate of the second capacitor is coupled to the first node, and a second electrode plate of the second capacitor is coupled to the second node
Data Source
AI summary
A pixel circuit, a display panel, a display device, and a driving method are provided. The pixel circuit includes: a light-emitting device; a drive transistor configured to generate driving current for driving light-emitting device to emit light according to data voltage; a data writing circuit configured to provide, in response to scan signal terminal signal, data voltage of a data signal terminal to a first node; a threshold compensation circuit configured to write threshold voltage of drive transistor to a second node; a first coupling control circuit between the first node and the gate of the drive transistor and configured to stabilize voltages of first node and the gate of the drive transistor; a second coupling control circuit between the first and second nodes, and configured to stabilize voltages of first and second nodes and couple an amount of voltage variation of the first node to the second node.