Pre-Compensated Pixel Circuit for Uniform Display Brightness
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Solution Overview
Problem
Existing pixel circuits in display apparatuses face issues with uneven display brightness due to uneven threshold voltage of drive transistors, leading to long compensation times that hinder high-frequency driving and affect display quality.
Innovation Solution
A pixel circuit design that separates the threshold voltage compensation and data voltage writing paths, utilizing a coupling control circuit, signal writing circuit, and threshold compensation circuit to stabilize voltages and improve drive transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If threshold voltage compensation is performed using conventional pixel circuits, then display brightness uniformity is improved, but compensation time increases which hinders high-frequency driving
Solution Approach 1:
The pixel circuit is divided into distinct functional modules: a threshold voltage compensation circuit that operates independently from the data writing circuit. The compensation circuit includes a compensation transistor, compensation capacitor, and control switches that are spatially and functionally separated from the main data path, allowing compensation operations to occur without blocking data writing operations.
Solution Approach 2:
The threshold voltage compensation is performed in advance during a dedicated compensation phase before the data writing phase. The compensation transistor is turned on to transfer the threshold voltage to the compensation capacitor during the compensation phase, so that the drive transistor is pre-compensated before receiving the data signal, enabling high-frequency driving without compromising compensation quality.
2Manufacturing precision
If compensation time is extended to achieve better threshold voltage compensation, then display quality is improved, but driving frequency is reduced
Solution Approach 1:
The pixel circuit design allows continuous operation by overlapping the compensation phase and data writing phase in time. The independent compensation circuit performs threshold voltage compensation continuously in the background while the data writing circuit operates independently, ensuring that useful actions (compensation and data writing) continue without interruption, thereby maintaining both high precision and high driving frequency.
Solution Approach 2:
The circuit employs dynamic control of transistor switching states to optimize performance at different phases. Control switches dynamically adjust the connectivity between different circuit nodes during compensation phase versus data writing phase, enabling the circuit to adapt its configuration for optimal compensation precision during the compensation phase and optimal speed during the data writing phase.
Data Source
AI summary
Disclosed are a pixel circuit, a display panel, a display apparatus, and a drive method. The pixel circuit includes: a light emitting device; a drive transistor configured to generate current driving the light emitting device according to data voltage; a coupling control circuit configured to stabilize voltages of first node and gate electrode of the drive transistor and turn on the first node and second electrode of the drive transistor in response to signal of light emitting control signal end; a signal writing circuit configured to provide signal of data signal end for the first node in response to signal of a scanning signal end and provide signal of first power end for first electrode of the drive transistor in response to signal of light emitting control signal end; a threshold compensation circuit configured to write threshold voltage of the drive transistor to the gate electrode of the drive transistor.