AMOLED Pixel Circuit Wiring Layout for Leakage Current Reduction
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Solution Overview
Problem
The AMOLED display devices face issues with increased black luminance due to leakage currents in the driving transistor, leading to poor contrast ratio quality.
Innovation Solution
The organic light emitting display device incorporates a specific pixel layout with additional transistors and power sources, including a high potential pixel power source, low potential pixel power source, and initialization power source, along with a unique wiring connection between adjacent pixels to minimize leakage current and prevent increased black luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional pixel circuit layout is used, then the device structure is simple, but leakage current increases black luminance and deteriorates contrast ratio
Solution Approach 1:
The pixel circuit is divided into multiple functional blocks with dedicated transistors for different operations. The initialization transistor and emission control transistor are separated from the driving transistor, allowing independent control of initialization and emission phases. This segmentation prevents leakage current from the driving transistor from affecting the emission control, thereby reducing black luminance increase.
Solution Approach 2:
The initialization transistor is activated before the emission control transistor to pre-establish the voltage state at the first node. This preliminary initialization ensures that when the emission control transistor activates, the node is already in the correct state, preventing leakage current from causing unwanted luminance changes during the emission phase.
2Object-affected harmful factors
If additional transistors and power sources are added, then leakage current is reduced and contrast ratio improves, but device complexity increases
Solution Approach 1:
The first node serves multiple functions: it is the control node for the driving transistor, the initialization node for the initialization transistor, and the emission control node for the emission control transistor. By making this node universal, the patent reduces the need for separate nodes and wiring, thereby limiting the increase in device complexity while achieving multi-functional control.
Solution Approach 2:
The initialization transistor and emission control transistor share common wiring connections with the driving transistor, particularly through the first node. This merging of connections reduces the overall wiring complexity and the number of separate power source connections needed, achieving leakage current reduction without proportional increase in device complexity.
Data Source
AI summary
An organic light emitting display device includes: a scan driver configured to sequentially supply a scan signal to scan lines, and supply an emission control signal to emission control lines; a data driver configured to supply a data signal to data lines; a pixel unit (pixel region) including pixels connected with the scan lines, the emission control lines, and the data lines and receiving a first power source which is a high potential pixel power source, a second power source which is a low potential pixel power source, and a third power source which is an initialization power source; and a wiring connecting an anode electrode of an organic light emitting diode of a first pixel in a first horizontal line and a first electrode of a transistor connected with the third power source of a second pixel in a second horizontal line while being adjacent to the first pixel.