Dummy Pixel Circuit Topology for OLED Leakage Suppression
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Solution Overview
Problem
In display devices with organic EL, dummy pixels can experience impact ionization due to electric fields, leading to increased off-leakage currents and unintended light emission, which affects the overall performance and efficiency of the display.
Innovation Solution
The implementation of a display device design where dummy pixels are arranged around the pixel area with a specific circuit configuration, including driving transistors and light-emitting elements, where the light-emitting element is not connected to the driving transistor, and a potential difference is applied between the electrodes to prevent light emission, thereby reducing current flow and consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dummy pixels are provided around the pixel area to improve display performance, then image quality is improved, but off-leakage current increases due to impact ionization
Solution Approach 1:
The patent extracts the light-emitting element from the dummy pixel circuit configuration, specifically disconnecting the anode of the light-emitting element from the drain of the driving transistor. This extraction removes the source of impact ionization (the high electric field at the drain) from the dummy pixel, thereby eliminating the off-leakage current issue while preserving the dummy pixel's structural presence for image quality improvement.
Solution Approach 2:
The patent applies different connection configurations to different regions: real pixels maintain the conventional connection (anode connected to drain) for normal operation, while dummy pixels use a modified connection (anode not connected to drain) to prevent impact ionization. This local differentiation allows each region to have optimized properties for its specific function.
2Device complexity
If dummy pixels are configured with driving transistors and light-emitting elements, then structural completeness is improved, but unintended light emission occurs due to current flow
Solution Approach 1:
The patent extracts the harmful current flow path by disconnecting the anode of the light-emitting element in dummy pixels from the drain of the driving transistor. This removes the pathway through which off-leakage current would flow and cause unintended light emission, while keeping the light-emitting element physically present in the dummy pixel structure.
3Ease of manufacture
If conventional dummy pixel configuration is used to maintain pixel array uniformity, then manufacturing simplicity is improved, but afterimages appear due to leakage current
Solution Approach 1:
The patent applies a localized modification only to dummy pixels (disconnecting the anode from the drain) while leaving real pixels with conventional connections. This minimal local change prevents afterimages in dummy pixels without requiring redesign of the entire pixel array, thus maintaining manufacturing simplicity.
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 suppresses light emission in dummy pixels, reduces current consumption, and enhances the operational efficiency and image quality of the display device by minimizing afterimages and improving moving image quality.
Implementation Method 1
each of the pixel and the dummy pixel includes a light-emitting element including a first electrode and a second electrode... the light-emitting element does not emit light at a potential difference between the first potential and the second potential
Implementation Method 2
In the dummy pixel, impact ionization may occur due to the electric field at the drain end of the driving transistor, and this may cause a significant increase in an off-leakage current between the source and the drain
Data Source
AI summary
A display device comprises a pixel area in which a plurality of pixels are arranged, and a dummy pixel area which is provided around the pixel area and in which a plurality of dummy pixels are arranged. Each of the pixel and the dummy pixel includes a light-emitting element including a first electrode and a second electrode, and a driving transistor. The first electrode of the light-emitting element is connected to the driving transistor in the pixel, and in the dummy pixel, the light-emitting element is not connected to the driving transistor, a first potential is supplied to the first electrode, a second potential is supplied to the second electrode, and the light-emitting element does not emit light at a potential difference between the first potential and the second potential.