OLED Pixel Circuit Leakage Current Suppression
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Solution Overview
Problem
Existing organic light-emitting display devices face issues with leakage current, which can lead to flicker phenomena, especially when driven with low-frequency signals.
Innovation Solution
The proposed solution involves a pixel circuit configuration that minimizes leakage current by eliminating paths to the initialization power source, thereby preventing voltage variations at the common node that could cause flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel circuit includes a path to the initialization power source, then the circuit can be initialized properly, but leakage current occurs causing flicker phenomenon
Solution Approach 1:
The patent removes the fourth transistor that provided the leakage path to the initialization power source while preserving the initialization function through alternative transistor configurations. This extraction eliminates the harmful leakage current that caused flicker while maintaining the necessary initialization capability.
Solution Approach 2:
The patent inverts the conventional approach by connecting the initialization power source to different nodes and using alternative transistor switching sequences. Instead of the traditional path through the fourth transistor, the initialization is achieved through reconfigured paths that prevent simultaneous conduction and leakage.
2Use of energy by moving object
If the pixel is driven with low-frequency signals, then power consumption is reduced, but flicker phenomenon becomes more prominent
Solution Approach 1:
The patent converts the harmful effect of low-frequency driving (which exacerbates flicker) into a benefit by redesigning the circuit to eliminate the root cause of flicker (leakage current). The reconfigured transistor network ensures that even at low frequencies, no leakage paths exist, thereby allowing energy-efficient low-frequency operation without the detrimental flicker effect.
3Ease of manufacture
If the pixel circuit uses conventional transistor configuration, then manufacturing is simplified, but voltage variations at common node cause flicker
Solution Approach 1:
The patent segments the pixel circuit into distinct functional blocks with clearly defined transistor roles. By dividing the circuit functions among multiple transistors and removing the problematic fourth transistor, the design maintains manufacturing simplicity while eliminating voltage variations at the common node that caused flicker.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces flicker and ensures stable image display by minimizing leakage current, even under low-frequency driving conditions.
Implementation Method 1
An organic light-emitting display device displays an image using organic light-emitting diodes that generate light by recombination of electrons and holes
Data Source
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AI summary
A pixel includes an organic light-emitting diode (OLED), a storage capacitor, and first to fourth transistors. The first transistor includes a gate electrode (GE), a first electrode (FE), and a second electrode (SE), and is configured to control, in response to a voltage of a first node (FN) coupled to the GE, current supplied from a first power source (PS) coupled to the FE to a second PS via the OLED. The storage capacitor is coupled between the FN and the first PS. The second transistor is coupled between a data line and the first transistor. The third transistor includes a FE coupled to the FN and a SE coupled to the SE of the first transistor. The fourth transistor includes a FE coupled to the FN and a SE coupled to the SE of the first transistor, and is configured to transmit an initialization voltage to the FN.