Pixel Driving Circuit Initialization Voltage Variation
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Solution Overview
Problem
Display devices face challenges in reducing threshold voltage deviation and flicker phenomenon at low grayscale levels due to gate-source voltage variations during on-bias stress operations, which affect picture quality and power consumption.
Innovation Solution
A pixel driving circuit with a specific configuration including transistors and a storage capacitor, where the initialization voltage is varied based on the data voltage applied, reducing threshold voltage deviation and mitigating flicker issues by optimizing the operation of transistors and initialization voltage settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the data voltage applied for the on-bias stress step is increased to improve the initial frame response characteristic, then the initial frame response characteristic is improved, but the black luminance increases
Solution Approach 1:
The patent applies an initialization voltage to the second node before the on-bias stress operation. This preliminary action sets the transistor in a known initial state, allowing the subsequent on-bias stress to be performed at a lower data voltage while still achieving effective threshold voltage compensation and maintaining low black luminance.
Solution Approach 2:
The patent changes the voltage parameter by applying a specific initialization voltage level before the on-bias stress operation. This parameter change enables the system to achieve the desired threshold voltage compensation effect at lower stress voltages, thereby reducing black luminance while maintaining initial frame response performance.
2Measurement precision
If the on-bias stress operation is performed immediately after the initialization step to reduce threshold voltage deviation, then the threshold voltage deviation is reduced, but the flicker phenomenon occurs at low grayscale levels
Solution Approach 1:
The patent applies an initialization voltage to the second node before the on-bias stress operation. This preliminary action prepares the transistor by setting its threshold voltage to a known state, which allows the subsequent on-bias stress to be performed more effectively at lower voltages. This reduces threshold voltage deviation while minimizing the conditions that cause flicker at low grayscale levels.
Data Source
AI summary
Disclosed is a display device comprising a light emitting element, and a pixel driving circuit connected to the light emitting element and configured to include first to fourth nodes, wherein the pixel driving circuit includes a driving transistor connected to the first to third nodes, a plurality of switching transistors, a storage capacitor, and a plurality of signals and voltage lines, wherein an initialization voltage applied through an initialization line among the plurality of signals and voltage lines is varied based on a data voltage.