Pixel Circuit Driving Method for Display Device Brightness Uniformity
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Solution Overview
Problem
In electroluminescent display devices, the non-uniform threshold voltage of driving transistors leads to inconsistent driving current for light-emitting diodes, resulting in uneven display brightness and affected image quality due to fabrication process variations and device aging.
Innovation Solution
A pixel circuit comprising a data write circuit, a driving control circuit, and a light-emitting control circuit, where the driving control circuit generates a driving current based on a data signal, and the light-emitting control circuit connects the driving control circuit with the cathode of a light-emitting device, ensuring stable light emission by decoupling the driving current from threshold voltage fluctuations through a storage capacitor and controlled transistor connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pixel circuits are used with driving transistors, then the display device can be manufactured with standard processes, but the threshold voltage variations cause inconsistent driving current and uneven display brightness
Solution Approach 1:
The patent introduces a storage capacitor as an intermediary element between the driving transistor and the light-emitting diode. This capacitor stores the driving current at a specific voltage level and releases it during the light-emitting phase, effectively decoupling the driving current from threshold voltage fluctuations. The storage capacitor acts as a buffer that maintains current consistency despite transistor parameter variations, thereby resolving the contradiction between manufacturing feasibility and display uniformity
Solution Approach 2:
The pixel circuit is divided into distinct functional stages: a data write stage for charging the storage capacitor, and a light-emitting stage for discharging through the LED. By segmenting the operation into separate phases with controlled transistor switching, the circuit isolates the driving current generation from threshold voltage variations, ensuring consistent brightness while maintaining standard manufacturing processes
2Device complexity
If the driving current is directly controlled by the driving transistor, then the circuit structure is simple, but the threshold voltage drift leads to current instability and affected display quality
Solution Approach 1:
The storage capacitor is charged to the required voltage level in advance during the data write stage, before the light-emitting stage begins. This preliminary charging action stores the exact driving current value needed, which is then maintained throughout the light-emitting phase. By performing the current setting action in advance and isolating it from subsequent threshold voltage drift, the circuit achieves current stability without significantly increasing complexity
Solution Approach 2:
The storage capacitor serves as an intermediary that decouples the driving current from the driving transistor's threshold voltage. During the light-emitting stage, the capacitor maintains a stable voltage that translates to consistent current through the LED, regardless of transistor parameter variations. This intermediary element adds minimal complexity while dramatically improving current stability and display quality
Data Source
AI summary
The present disclosure can provide a pixel circuit, a driving method thereof and a display device. By arranging a data write circuit, a driving control circuit, a light-emitting control circuit and a light-emitting device, the data write circuit provides a data signal of the data signal end for the driving control circuit in response to a signal of a first scanning signal end; the driving control circuit generates a driving current according to the data signal; and the light-emitting control circuit connects the driving control circuit with a cathode of the light-emitting device in response to a signal of a second scanning signal end, so that the driving current is input into the light-emitting device to control the light-emitting device to emit light. Besides, a voltage of the first power end is larger than that of the second power end.