OLED Pixel Driving Circuit Leakage Current Reduction
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Solution Overview
Problem
OLED display panels face challenges in reducing power consumption and preventing flicker when using low-frequency driving due to high leakage current in P-type transistors, which affects display brightness uniformity and resolution.
Innovation Solution
A pixel driving circuit incorporating both N-type and P-type transistors, with a smaller-sized N-type transistor in the storage sub-circuit to minimize leakage current, and a compensation capacitor to enhance resolution, along with a driving method that includes reset, data writing, and light-emitting phases to control the transistors and OLED emission effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-frequency driving is used to reduce power consumption, then energy efficiency is improved, but flicker occurs due to high leakage current in P-type transistors
Solution Approach 1:
The patent changes the transistor type parameter from P-type to N-type in the storage sub-circuit. N-type transistors have significantly lower leakage current characteristics, which eliminates the flicker problem while maintaining low-frequency driving benefits for power consumption reduction
Solution Approach 2:
The patent introduces a compensation capacitor that copies and stores the threshold voltage of the driving transistor. This compensation mechanism corrects for voltage drift and maintains stable OLED driving current, preventing flicker during low-frequency operation
2Device complexity
If P-type transistors are used in the storage sub-circuit, then device complexity is reduced, but leakage current increases affecting display brightness uniformity
Solution Approach 1:
The patent changes the transistor type parameter from P-type to N-type in the storage sub-circuit. N-type transistors have significantly lower leakage current characteristics, which eliminates the flicker problem while maintaining low-frequency driving benefits for power consumption reduction
3Device complexity
If threshold voltage drift of driving transistor is not compensated, then device complexity is reduced, but resolution and brightness uniformity deteriorate
Solution Approach 1:
The patent introduces a compensation capacitor that copies and stores the threshold voltage of the driving transistor. This compensation mechanism corrects for voltage drift and maintains stable OLED driving current, preventing flicker during low-frequency operation
Data Source
AI summary
Provided are a pixel driving circuit, a driving method and a display panel. The pixel driving circuit includes a driving transistor, a storage sub-circuit, a data writing sub-circuit, an initialization sub-circuit, a first light-emission control sub-circuit, a second light-emission control sub-circuit and a light-emitting element. The data writing sub-circuit is configured to write a data signal to a first electrode of the driving transistor in response to a second scan signal. The storage sub-circuit is configured to store the data signal written by the data writing sub-circuit. The initialization sub-circuit is configured to apply a reset voltage of an initial voltage terminal to the light-emitting element in response to a first scan signal. The first light-emission control sub-circuit is configured to apply a voltage of a first power terminal to the first electrode of the driving transistor in response to a first light-emission signal.