OLED Pixel Circuit with Shield Capacitor for Crosstalk Reduction
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Solution Overview
Problem
In organic light-emitting display apparatuses, the variability in data voltage stored in storage capacitors leads to luminance fluctuations, and the initialization voltage applied to the anode of the light-emitting diode causes emission delays due to capacitor characteristics.
Innovation Solution
The proposed solution involves a pixel design that includes a light-emitting device, a driving TFT, a storage capacitor, and compensation TFTs, with specific initialization voltages applied using scan signals to address emission delays and maintain constant luminance without degrading crosstalk characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same initialization voltage is applied to the anode of the organic light-emitting diode before light emission, then the capacitor characteristic of the OLED is addressed, but light emission is delayed
Solution Approach 1:
The patent applies a first initialization voltage to the gate of the driving TFT before data writing to pre-charge the storage capacitor, and applies a second initialization voltage to the anode of the OLED to prepare the capacitor characteristic. This preliminary action ensures that when the data voltage is written and light emission begins, the capacitor is already in the optimal state, eliminating emission delay while maintaining stable capacitor characteristics throughout operation
2Stability of the object's composition
If initialization voltages are applied to maintain constant data voltage in the storage capacitor, then luminance stability is improved, but emission delay occurs due to capacitor characteristics
Solution Approach 1:
The patent performs preliminary initialization of both the gate (first initialization voltage) and anode (second initialization voltage) before data writing occurs. This ensures the storage capacitor and OLED capacitor are pre-prepared to maintain constant data voltage during operation, achieving luminance stability without causing emission delay since the initialization happens in advance of the light emission phase
Solution Approach 2:
The patent uses two different initialization voltage levels: a first initialization voltage applied to the gate of the driving TFT and a second initialization voltage applied to the anode of the OLED. By changing the voltage parameters at different locations and times, the patent optimizes both the storage capacitor stability and the OLED capacitor response, achieving constant luminance without emission delay
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 design effectively addresses emission delays and maintains resolution and pixel size while preventing crosstalk degradation, improving display quality by ensuring consistent light emission and reduced voltage fluctuations.
Implementation Method 1
An organic light-emitting display apparatus includes a light-emitting device, e.g., an organic light-emitting diode, having a brightness varying depending on a current
Implementation Method 2
a storage capacitor for storing the data voltage
Implementation Method 3
a shielding layer extending in a first direction, between the second conductive layer and the third conductive layer
Data Source
AI summary
A pixel includes a light-emitting device, a driving TFT for controlling a magnitude of a current from a power line to the light-emitting device according to a gate-source voltage, a storage capacitor disposed between the power line and a gate of the driving TFT, a scan TFT to transfer a data voltage to a source of the driving TFT in response to a first signal, first and second compensation TFTs serially connected between a drain and the gate of the driving TFT, a gate initialization TFT to apply a first voltage to the gate of the driving TFT in response to a second signal, an anode initialization TFT to apply a second voltage to an anode of the light-emitting device in response to a third signal, and a shield capacitor disposed between a node between the first and second compensation TFTs and the power line or a second voltage line.