OLED Pixel Voltage-Stabilizing Capacitor for High-Refresh Compensation
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Solution Overview
Problem
The 4T2C internal compensation circuit in OLED display panels experiences poor compensation effects and low yield rates due to insufficient compensation time as refresh rates increase, particularly when transitioning from mobile phone to medium-sized products and higher refresh rates like 120 Hz.
Innovation Solution
The display panel incorporates a voltage stabilizing capacitor with a first and second capacitor configuration, where the pixel anode and auxiliary cathode form electrode plates, and the pixel cathode extends to the pixel defining layer to enhance capacitance, combined with a driving method that includes reset, compensation, data writing, and light-emitting stages to stabilize voltage input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the refresh rate is increased from 60 Hz to 120 Hz or higher, then the display performance is improved, but the compensation time becomes insufficient resulting in poor compensation effect
Solution Approach 1:
The pixel anode is divided into two functional parts: a first part that forms the first capacitor with the pixel cathode, and a second part that extends into the pixel defining layer to form the second capacitor with the auxiliary cathode. This segmentation allows the voltage stabilizing capacitor to be formed using existing pixel electrodes without requiring additional space, thereby maintaining compensation effectiveness at higher refresh rates.
Solution Approach 2:
The pixel anode and pixel cathode serve dual functions: they act as the发光 electrodes for the OLED and simultaneously serve as electrode plates for the voltage stabilizing capacitor. The pixel cathode extends to the pixel defining layer to establish electrical connection with the auxiliary cathode, enabling the capacitor function without adding separate electrode structures. This multi-functionality resolves the space constraint while maintaining compensation capability at high refresh rates.
2Area of moving object
If the pixel size is reduced to improve display density, then the display resolution is improved, but the compensation circuit stability deteriorates
Solution Approach 1:
The voltage stabilizing capacitor is formed by utilizing the vertical stacking dimension rather than expanding horizontally. The pixel anode extends into the pixel defining layer (vertical direction) to form the second capacitor with the auxiliary cathode. This three-dimensional capacitor configuration increases capacitance without increasing the planar pixel area, thereby maintaining compensation circuit stability in miniaturized pixels.
Solution Approach 2:
The voltage stabilizing capacitor is nested within the existing pixel structure. The pixel anode and pixel cathode that define the发光 area also serve as capacitor electrodes. The pixel cathode extends under the pixel defining layer to connect with the auxiliary cathode, nesting the capacitor function within the pixel structure without requiring additional space, thus maintaining stability in reduced-size pixels.
3Reliability
If a traditional voltage stabilizing capacitor is added to the 4T2C circuit, then the voltage stability is improved, but the circuit complexity and pixel area increase
Solution Approach 1:
The voltage stabilizing capacitor is merged with the existing pixel electrodes. The pixel anode serves as one electrode plate for both the first and second capacitors. The pixel cathode serves as the other electrode plate for the first capacitor and extends to form the connection for the second capacitor. This merging eliminates the need for separate capacitor electrode structures, reducing circuit complexity while maintaining voltage stability.
Solution Approach 2:
The pixel electrodes serve themselves dual purposes: they define the发光 area and simultaneously form the voltage stabilizing capacitor. The pixel cathode extends to the pixel defining layer to establish its own electrical connection for capacitor formation without requiring additional conductive structures. This self-service approach reduces the need for extra circuit elements, simplifying the overall circuit architecture while improving voltage stability.
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 improves voltage stability and compensation efficiency, enhancing the display panel's performance and yield by increasing capacitance and aperture ratio, thus addressing the limitations of the 4T2C circuit at higher refresh rates.
Implementation Method 1
the driving circuit includes a voltage stabilizing capacitor configured to stabilize a voltage input to the pixel anode
Data Source
AI summary
A display panel, a driving method, and a display apparatus are provided. The display panel includes multiple light-emitting elements and a driving circuit electrically connected to a pixel anode of each of the multiple light-emitting elements. The driving circuit includes a voltage stabilizing capacitor, which is configured to stabilize a voltage input to the pixel anode and includes a first capacitor and a second capacitor. A first part of the pixel anode and the pixel cathode are oppositely disposed to form two electrode plates of the first capacitor. A second part of the pixel anode extends into the pixel defining layer, and the second part of the pixel anode and the auxiliary cathode are oppositely disposed to form two electrode plates of the second capacitor. The pixel cathode extends to the surface of the pixel defining layer and is connected to the auxiliary cathode.