OLED Display Panel Threshold Voltage Drift Compensation
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Solution Overview
Problem
Current OLED display panels face non-uniformity issues due to threshold voltage drift in driving thin film transistors (TFTs) caused by external stress and manufacturing processes, leading to inconsistent electric currents and display unevenness.
Innovation Solution
An OLED display panel with an external compensation unit that obtains initial threshold voltages of driving TFTs, generates a sum data signal by combining these voltages with input signals, and transmits it to pixel circuits for internal compensation to adjust and stabilize the threshold voltages, thereby compensating for both initial and permanent drifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external compensation is implemented by utilizing external driving chips, then compensating ability is improved, but compensating process complexity and operation time increase
Solution Approach 1:
The compensation function is segmented into two parts: external compensation for initial threshold voltage non-uniformity using external driving chips, and internal compensation for permanent drift using additional TFTs within the pixel circuit. This segmentation allows each part to specialize in specific compensation tasks, improving overall compensating ability while managing complexity through functional division.
Solution Approach 2:
External compensation is performed as a preliminary action before display operation to establish initial threshold voltage compensation. This preliminary compensation reduces the burden on internal compensation mechanisms during operation, improving overall system reliability while separating the compensation phases in time.
2Productivity
If internal compensation is implemented by adding extra TFTs and signal lines, then compensating process simplicity and operation speed are improved, but circuit complexity and compensating ability are limited
Solution Approach 1:
The compensation function is segmented into two parts: external compensation for initial threshold voltage non-uniformity using external driving chips, and internal compensation for permanent drift using additional TFTs within the pixel circuit. This segmentation allows each part to specialize in specific compensation tasks, improving overall compensating ability while managing complexity through functional division.
Solution Approach 2:
The additional TFTs (TFT10, TFT11, TFT12) and storage capacitor (CST1) act as intermediary elements that enable internal compensation functionality. These intermediary components mediate between the data signal input and the OLED, allowing the pixel circuit to perform real-time threshold voltage compensation without directly modifying the external driving chip architecture.
3Device complexity
If 2T1C pixel circuits are used, then device simplicity is maintained, but threshold voltage drift compensation capability is insufficient
Solution Approach 1:
The compensation function is segmented into two parts: external compensation for initial threshold voltage non-uniformity using external driving chips, and internal compensation for permanent drift using additional TFTs within the pixel circuit. This segmentation allows each part to specialize in specific compensation tasks, improving overall compensating ability while managing complexity through functional division.
Solution Approach 2:
The invention changes the circuit parameters by adding specific TFTs and a storage capacitor to the 2T1C configuration. This transforms the basic 2T1C circuit into a compensation-capable circuit while maintaining its fundamental simplicity. The parameter change enables the circuit to adapt to threshold voltage drift without completely redesigning the pixel structure.
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 solution ensures more uniform current flow through OLEDs, significantly improving display uniformity and quality by independently compensating for threshold voltage drifts caused by manufacturing non-uniformities and external stress, reducing inaccuracy in current flow from 25% to 5% and maintaining uniformity even during emission.
Implementation Method 1
obtain initial threshold voltages of driving thin film transistors (TFTs) of each of the plurality of pixel circuits
Implementation Method 2
obtain a sum data signal by summing up each of the initial threshold voltages and an input signal corresponding to each of the plurality of pixel circuits
Implementation Method 3
perform internal compensations according to the sum data signal to compensate drift of threshold voltages of the driving TFTs
Implementation Method 4
The electrons and holes meet the luminance material layer to form excitons and to active luminance molecules. The luminance molecules emit visible lights caused from radiation relaxations.
Data Source
AI summary
The present disclosure provides an organic light-emitting diode (OLED) display panel and a driving method thereof. The OLED display panel includes a plurality of pixel circuits and an external compensation unit connected to the plurality of pixel circuits. The external compensation unit externally compensates the pixel circuits, obtains initial threshold voltages of driving thin-film transistors (TFTs) of each pixel circuits, obtains a sum data signal by summing up each of the initial threshold voltages and an input signal corresponding to each pixel circuits, and transmits the sum data signal to each pixel circuits. The external compensation compensates non-uniformity initial threshold voltages of each driving TFTs caused from manufacture of OLED display panel and compensates the permanent drift of the actual threshold voltage caused from external stress. The internal compensation instantly compensates relatively slight drift of actual threshold voltage occurring during the emitting of the OLED display panel.