Pixel Driving Circuit Bias Adjustment for OLED Flicker Control
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Solution Overview
Problem
Organic light-emitting display devices face issues such as non-uniform brightness and flickering due to threshold voltage drift and hysteresis effects in the drive transistors, leading to display non-uniformity and perceptible flickers.
Innovation Solution
A pixel driving circuit with a threshold compensation module and bias adjustment module to detect and compensate for threshold voltage deviations, and a bias adjustment mechanism to balance the gate and drain potentials of the drive transistor, thereby stabilizing the drive current and reducing flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If threshold compensation is implemented to correct transistor threshold voltage drift, then display uniformity is improved, but device complexity increases due to additional circuit modules
Solution Approach 1:
The patent combines the threshold compensation function and bias adjustment function into a single integrated circuit module. The bias adjustment module shares circuit elements with the threshold compensation module, merging multiple compensation functions into one unified structure rather than using separate independent modules for each function.
Solution Approach 2:
The bias adjustment module is designed to perform multiple functions: it adjusts the bias state of the drive transistor to compensate for threshold voltage drift, and also works in conjunction with the threshold compensation module to maintain display uniformity. This multi-functional design reduces the need for separate dedicated circuits for each compensation task.
2Object-affected harmful factors
If bias adjustment is applied to compensate for hysteresis effect during grayscale switching, then flicker perception is reduced, but energy consumption increases due to additional bias signal processing
Solution Approach 1:
The bias adjustment module proactively adjusts the bias state of the drive transistor before and during grayscale transitions to prevent hysteresis effects from causing flicker. By performing the bias adjustment in advance and continuously during operation, the system prevents flicker perception rather than correcting it after it occurs, reducing the need for additional corrective energy consumption.
Solution Approach 2:
The circuit incorporates feedback mechanisms where the bias adjustment module continuously monitors and adjusts the bias state based on the operating conditions and threshold voltage drift. This feedback control ensures that energy is consumed only when necessary to maintain display uniformity and reduce flicker, rather than using continuous high-energy compensation.
Data Source
AI summary
Provided is a display panel. The display panel includes a pixel driving circuit including a drive transistor, a data write module, a light emission control module, a threshold compensation module and a bias adjustment module. The control terminal of the drive transistor is connected to the first node. The first terminal of the drive transistor is connected to a third node. The second terminal of the drive transistor is connected to a second node. The light emission control module is connected in series with the drive transistor and connected in series with a light-emitting element. The threshold compensation module is connected in series between the control terminal of the drive transistor and the second terminal of the drive transistor. The first terminal of the bias adjustment module is connected to a bias signal terminal. The second terminal is connected to the second terminal of the drive transistor.