OLED Pixel Circuit Area Reduction and Contrast Improvement
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Solution Overview
Problem
The existing OLED display panels face challenges in reducing the occupied area of pixel circuits, which affects the resolution and fails to ensure accurate low gray scale and full black display under a full dark frame, leading to suboptimal contrast.
Innovation Solution
A pixel circuit design that includes multiple light-emitting circuits, drive circuits, compensating circuits, and initializing circuits, along with specific control signals and timing diagrams, to reduce the area occupied by the pixel circuit while ensuring accurate initialization and emission control, thereby improving resolution and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the pixel circuit area is reduced to improve resolution, then the display resolution is improved, but the initialization and emission control accuracy deteriorates
Solution Approach 1:
The pixel circuit is segmented into multiple specialized sub-circuits: initialization circuit (with initialization transistor and capacitor), emission control circuit (with emission control transistor), drive circuit (with drive transistor), and compensating circuit (with compensating transistor and capacitor). Each sub-circuit performs a specific function, allowing the overall circuit to be optimized for both area and precision. The segmentation enables independent optimization of each function block.
Solution Approach 2:
The patent utilizes temporal dimension by implementing sequential operation phases (initialization phase, compensation phase, emission phase) controlled by different timing signals. This allows multiple functions to be performed in sequence within a compact spatial footprint, effectively reducing the pixel circuit area while maintaining functional completeness and precision.
2Manufacturing precision
If multiple light-emitting circuits are integrated to improve emission control, then the emission control accuracy is improved, but the device complexity increases
Solution Approach 1:
The emission control signal serves multiple functions: it controls the emission control transistor to enable/disable light emission, it coordinates with the drive transistor for current regulation, and it works with the compensating circuit for threshold voltage compensation. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby controlling overall complexity while improving emission control accuracy.
Solution Approach 2:
The patent merges the emission control function with the drive circuit by using the emission control signal to simultaneously control both the emission control transistor and the drive transistor. This integration reduces the number of independent control paths and simplifies the overall circuit architecture while maintaining precise emission control.
3Area of stationary object
If the pixel circuit area is reduced to improve resolution, then the display resolution is improved, but the contrast ratio deteriorates
Solution Approach 1:
The initialization circuit performs preliminary action by pre-charging the initialization capacitor to a reference voltage before the emission phase. This preliminary initialization ensures that the OLED starts from a known state, enabling precise control of the emission current and thereby maintaining high contrast ratio even in the reduced pixel circuit area. The compensating circuit also performs preliminary compensation for threshold voltage variations.
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
A pixel circuit (100), a display panel (1) and a driving method. The pixel circuit (100) includes a first light-emitting circuit (102), a first drive circuit (104), a first compensating circuit (106), a first data write circuit (108), a first reset circuit (110), a first storage circuit (112), a first initializing circuit (114), a first light-emitting control circuit (116), a second light-emitting circuit (118), a second drive circuit (120), a second compensating circuit (122), a second data write circuit (124), a second reset circuit (126), a second storage circuit (128), a second initializing circuit (130), a second light-emitting control circuit (132), a third light-emitting circuit (134), a third light-emitting control circuit (136), a third drive circuit (138), and a third initializing circuit (140). The pixel circuit not only can reduce the area occupied by the pixel circuit and improve the resolution of the display panel but also can perform initialization discharge on organic light-emitting diodes, ensure the accuracy under a low gray scale and full black under a full dark frame, and effectively improve the contrast of the entire display panel.